[go: up one dir, main page]

WO2021113999A1 - Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial - Google Patents

Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial Download PDF

Info

Publication number
WO2021113999A1
WO2021113999A1 PCT/CL2019/050140 CL2019050140W WO2021113999A1 WO 2021113999 A1 WO2021113999 A1 WO 2021113999A1 CL 2019050140 W CL2019050140 W CL 2019050140W WO 2021113999 A1 WO2021113999 A1 WO 2021113999A1
Authority
WO
WIPO (PCT)
Prior art keywords
titanium
alloy
porosity
alloys
based alloy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CL2019/050140
Other languages
Spanish (es)
French (fr)
Inventor
Claudio AGUILAR RAMÍREZ
Christopher Gonzalo SALVO MEDALLA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universidad Tecnica Federico Santa Maria USM
Original Assignee
Universidad Tecnica Federico Santa Maria USM
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universidad Tecnica Federico Santa Maria USM filed Critical Universidad Tecnica Federico Santa Maria USM
Priority to PCT/CL2019/050140 priority Critical patent/WO2021113999A1/en
Publication of WO2021113999A1 publication Critical patent/WO2021113999A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/02—Inorganic materials
    • A61L27/04—Metals or alloys
    • A61L27/06—Titanium or titanium alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/08—Alloys with open or closed pores
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C14/00—Alloys based on titanium

Definitions

  • the present invention relates to titanium-based alloy foams, their preparation method and their use as a biomaterial in biomedical applications.
  • the aging of the population constitutes one of the most relevant social and demographic events in recent decades, characterized by the increase in people who are 60 years of age or older. Its relevance is due to the fact that this process has multiple impacts on society, not only in the fields of education and health, but also in the economy and in the composition of the workforce.
  • Biomaterials may be suitable to solve these problems (serve as implants), it is expected that these biomaterials exhibit appropriate properties such as: excellent resistance to corrosion in the body fluid medium, mechanical and fatigue resistance, low modulus of elasticity, low density and good wear resistance, and stay in service longer without failure.
  • Stainless steel, Co-based alloys, Co-Cr and Ti-6AI-4V alloys are used as implants under load conditions (Xiong, J., et al., “Mechanical properties and bioactive surface modification via alkali-heat treatment of a porous Ti-18Nb-4Sn alloy for biomedical applications. "Acta Biomater., 2008. 4 (6): p. 1963-1968; Aguilar, C., et al.,” Synthesis and characterization of Ti-Ta- Nb- Mn foams. Materials Science and Engineering ” ⁇ . C, 2016. 58: p. 420-431).
  • Ti and its alloys have interesting properties that include high mechanical strength, lightness, excellent resistance to oxidation, and high biocompatibility. Compared with stainless steel, alloys based on cobalt (Co-Cr), Ti and alloys based on Ti have better biocompatibility, corrosion resistance and a lower elastic modulus (Long M. and HJ Rack, “Titanium alloys in total joint replacement — a materials Science perspective. ”Biomaterials, 1998. 19 (18): p. 1621-1639), so its use as a biomaterial has increased.
  • Ti-6AI-4V was the first a + by microstructure alloy that is widely used today as a biomaterial.
  • V and Al ions can be released into the human body, increasing the likelihood of disease.
  • V ions are released into human tissues, the kinetics of enzyme activity associated with inflammatory response cells are altered, and Al ions increase the likelihood of developing Alzheimer's.
  • materials scientists are investigating the alloy of non-toxic elements to produce new Ti-based alloys that meet the properties required for biomaterials.
  • the alloying elements tested are: Nb, Ta, Mo, Ta, Mn.
  • the alloying elements that have a different biological impact, so the best candidates to be considered biocompatible are: Ta, Nb, Zr, Au, Sn, Ru and Mn.
  • the most promising alloying elements for synthesizing Ti-based alloys are the 3d, 4d and 5d transition metals.
  • Ti-based alloys with a + b microstructure have been obtained using alloying elements such as Nb and Fe, but the elastic modulus values are higher (more than 100 GPa) compared to the elastic modulus of human bones, between 4 and 30 GPa for cortical bones and between 0.01 and 2 GPa for human cancellous bone. If the orthopedic implant has a higher elastic modulus value than human bone, the phenomenon called stress shielding occurs, which causes a high resorption rate.
  • metallic foams are defined as a mixture of metallic structure with embedded pores (open and / or closed), and present mixed properties between metals and foams.
  • Metallic foams possess a unique combination of properties, such as their low density, permeability to air and water, ability to absorb impact energy, low thermal conductivity, and good electrical insulation.
  • the main disadvantage of foams is that their elastic limit decreases as porosity increases.
  • biomaterial that shows properties such as high biocompatibility, low density, high mechanical strength and fatigue resistance, low elastic modulus and good wear resistance. More particularly, it is desirable that the biomaterial has a Young's modulus that matches the surrounding bone, and that in turn is strong and durable enough to withstand the physiological loads that have been applied to it over the years. Therefore, it is required to find a material that presents a suitable balance between strength and stiffness to better match the behavior of the bone.
  • the present invention discloses Ti-based alloy foams with elastic moduli less than 30 GPa and an elastic limit greater than 200 MPa.
  • Figure 1 General diagram of the Powder Metallurgy process.
  • Figure 2 Microstructures in titanium alloys.
  • FIG. 3 Titanium binary alloys.
  • Figure 4 Modulus of elasticity for various alloys.
  • Figure 5 Photograph of a glove box.
  • Figure 6 Schematic and photograph of a planetary mill.
  • Figure 8 Photograph of a Compaction system.
  • Figure 9 Photograph of the equipment used in sintering.
  • Figure 10 SEM images of mechanically alloyed powders.
  • FIG. 11 EDS of mechanically alloyed powders.
  • Figure 12 Diffractogram of the Ti-13Ta-12Sn alloy (% at.)
  • Figure 14 SMEB images at 200X magnification of samples with bimodal microstructure.
  • Figure 15 Graph of apparent porosity as a function of theoretical porosity.
  • Figure 16 Graph of Density measured as a function of porosity.
  • Figure 17 Graph of the Modulus of elasticity measured as a function of porosity.
  • Figure 18 Graph of yield stress measured as a function of porosity.
  • cellular metals and "metallic foams” are used to refer to metals and alloys whose structure is porous.
  • cellular metals is used when the metal exhibits porous foams and the term metallic foams is used when a synthesis process is applied to obtain foams.
  • Metal foams with open pores can be obtained through solid, liquid or gaseous phases and the selection of the method depends on the type, distribution and size of the pores.
  • a simple solid state process to obtain foams with a distribution of pores and type of porosity (open and closed pores) is the "spacers" method. This method allows to control the shape, size and distribution of porosity through sintering temperature, time and dissolution temperature (if the spacer is salt). Spacers commonly used to synthesize Ti foams are: carbamide, ammonium hydrogen carbonate (NFI4FICO3), tapioca starch, salt (NaCl), magnesium, ACRAWAX® (AW), PMMA, sucrose and urea.
  • spacers commonly used to synthesize Ti foams are: carbamide, ammonium hydrogen carbonate (NFI4FICO3), tapioca starch, salt (NaCl), magnesium, ACRAWAX® (AW), PMMA, sucrose and urea.
  • the spacer should be selected based on the following criteria: i) size and shape, ii) cost, iii) reactivity of the Ti with the support, iv) presence of left residues, v) easy processability and vi) non-toxic element.
  • the residues In the case of biomedical foams, the residues must be bio-inert or biocompatible, that is, in the case of ammonium hydrogen carbonate, urea and tapioca starch, the human body can absorb residues that could cause some problems.
  • the NaCI particles have the advantage that their residues do not cause problems to the human body (they are not toxic) and they are easily removable by the process of dissolution in water.
  • ammonium bicarbonate as a spacer material has the advantages of not reacting with titanium during the process and is eliminated by the contribution of heat during sintering, due to its decomposition when subjected to a temperature above 35oC, producing ammonia vapors according to the reaction:
  • the porosity resulting from the preparation method and the mechanical properties obtained for the foams are highly dependent on the particle mixture of the support of the metal powder space.
  • Powder metallurgy or powder metallurgy is a manufacturing process that takes metallic powders with certain characteristics such as size, shape and packaging to create a figure of high hardness and precision.
  • One of the advantages of Powder Metallurgy is the ability to manufacture parts with complex shapes and dimensions close to those of the final product, with excellent tolerances, high quality and at a relatively low cost, that is, parts are obtained with greater homogeneity and control of the size of the grains, achieving the formation of strong bonds between the particles and, therefore, increases in the hardness and toughness of the materials.
  • This process is suitable for the manufacture of large series of small parts with great precision, for pure materials or unusual mixtures and to control the degree of porosity or permeability, in addition there is a reduction in costs due to the possibility of eliminating the processes of finishing, compared to other manufacturing methods such as forging or casting.
  • Figure 1 shows a general diagram of the stages of the basic powder metallurgy process.
  • the manufacture of PM components begins with the mixing of powders, additives and lubricants. This mixture is compacted as a piece inside a mold that has the desired shape, by applying pressure. After compaction, the mixture takes on the properties of a solid, whose state is called "green". Subsequently, the compact is sintered to temperatures below the melting point, under a controlled atmosphere, achieving a metallurgical bond between the particles.
  • the basic operations of compacting and heating can be combined in various ways in processes for the manufacture of metal powders.
  • alloying elements to pure titanium produce a range of possible microstructures in titanium alloys. That is, the addition of other elements to titanium can be obtained: Alpha alloys (a), Alpha-beta alloys (a-b) and beta alloys (b). These alloys are characterized by the phases (crystalline structures) that exist in the alloy when they are close to room temperature and possess different properties as shown in Figure 2. The temperatures at which the alpha and beta phases can exist are they alter as alloying elements are added to the titanium. Depending on their influence on the proportions of the alpha and beta phases below the beta trans, the alloying elements are divided into three groups:
  • Beta stabilizers stabilizes the beta phase at lower temperatures
  • Alpha (a) Alloys are characterized by their strength, toughness, yield stress and weldability.
  • Alpha stabilizing solutes are those that, as a function of concentration, raise the temperature of the (a + b) / a transus.
  • Such solutes are generally not transition metals (ie "simple metals", SM).
  • Beta alloys In the case of Beta Alloys (b), the transition solutes (metal) are stabilizers of the bcc phase. Therefore, all b-alloys generally contain large amounts of one or more of the so-called “b-isomorphs” forming additions: vanadium, niobium, tantalum (group V transition metals) and molybdenum (group VI transition metals). Beta alloys are metastable; that is, they tend to transform into a balance or balance of structures. The Beta alloys generate strength from the intrinsic strength of the beta structure and the precipitation of the alpha and other phases of the alloy through heat treatment after processing.
  • beta structure The most significant benefit provided by a beta structure is the increased formability of such alloys relative to the hexagonal crystal structure types (alpha and alpha-beta).
  • Formability can be defined as a measure of the amount of deformation that a material can undergo in a forming process without failure, such as localized thinning or fracture.
  • Other characteristics of beta alloy are: being heat treatable at high strength levels, excellent tensile strength up to 370 ° C, low creep resistance above 370 ° C, good solderability as solution treated, good toughness, slow rate fatigue crack growth and contains sufficient beta stabilizer to retain a fully beta structure at room temperature, which increases ductility.
  • the alloys a + b are such that, in equilibrium, generally at room temperature, they admit a mixture of phases a and b. Although many stabilized binary alloys b in thermodynamic equilibrium are two-phase, in practice alloys a + b generally contain mixtures of stabilizers a and b. A + b alloys generally exhibit good workability, as well as high room temperature strength and moderate elevated temperature strength. They can contain between 10 and 50% phase b at room temperature; if they contain more than 20%, they are not weldable. The properties of alloys a + b can be controlled by heat treatment, which is used to adjust the microstructural states and precipitation of component b. The alloys are formulated so that both the alpha phase (hcp) and the beta phase (bcc) exist at room temperature. These alloys, to some extent, compromise some of the characteristics of alpha and beta alloys.
  • the titanium-based alloy foam is Ti-13Ta-3Sn.
  • the titanium-based alloy foam is Ti-13Ta-6Sn.
  • the titanium-based alloy foam is Ti-13Ta-12Sn.
  • the titanium-based alloy foam has a porosity of up to 50%.
  • the titanium-based alloy foam has an elastic modulus of up to 30 GPa.
  • the titanium-based alloy foam has an elastic limit greater than 200 MPa.
  • the alloy preparation step is carried out by mechanical alloying.
  • the step of preparing the green specimens is carried out by compacting the alloy.
  • the step of preparing the green specimens uses a spacer material.
  • the spacer material is ammonium bicarbonate.
  • the sintering step of the compacted green specimens is carried out in a tube furnace.
  • the sintering step is carried out at 1300 ° C.
  • the present invention is directed to the use of the titanium-based alloy foam as a biomaterial.
  • the biomaterial is a bone implant.
  • the Ti-13Ta-12Sn alloy was prepared by mechanical alloying (grinding), using titanium, tantalum and tin metal powders as raw material. What controlling agent of the mechanical alloying process (grinding), triple stearic acid (CH3 (CH2) i6COOH) was used at 2% by weight.
  • Ammonium bicarbonate (NH4HCO3) was used as spacer material ((NH4HCO3).
  • Zirconium oxide balls YSZ (YSZ stabilized ZrÜ2) were used as grinding medium. Balls of 5 and 10 mm in diameter were used, in a ratio in mass of balls with respect to the powder of 10: 1.
  • YSZ stabilized ZrÜ2 Two YSZ zirconium oxide vessels (YSZ stabilized ZrÜ2) were used for grinding the powders.
  • Zinc stearate was used as a solid lubricant in the compaction of the green specimen.
  • the alloyed powders were recovered.
  • the green test tubes were then prepared. At this stage the powders are compacted in the compaction machine.
  • Samples with a bimodal microstructure were obtained by mixing 25% of the weight of the ground powders with 75% of the weight of the raw powders.
  • the bimodal microstructure (+ BM) is defined as a mixture of 25% nanoparticles and 75% micrometric particles.
  • Samples without bimodal microstructure (-BM) were obtained with raw powders.
  • an amount of spacer material was added according to the percentage of porosity that was wanted to obtain in the test tubes (0%, 30%, 40% and 50%).
  • Table 2 shows the mass of each of the elements.
  • Sintering was carried out in a tube furnace (see Figure 9) using a controlled argon atmosphere.
  • the green specimens to be sintered were introduced.
  • the cycle has two isotherms, the first corresponds to the volatilization of the spacer material, which is carried out at 180 ° C for an hour and a half.
  • the second isotherm corresponds to the sintering of the metal alloy, which is carried out at 1,300 ° C for 3 h. After cooling, the specimens were removed from the oven.
  • the morphology of the powders and foams obtained were studied by scanning electron microscopy (SEM).
  • the porosity of the foams was measured using image analysis software obtained using an optical microscope coupled to a Leica MC170 HD camera.
  • the ultrasonic measurements of the elastic modulus were carried out using ultrasonic transducers.
  • the measurement and calculation protocol is based on the ASTM D2845-08 standard.
  • Density measurement was performed with a 20 ml pycnometer and a balance with a sensitivity of 0.001 g, based on the ASTM D792-08 standard. Compression tests were carried out with a Zwick-Roell machine at a loading speed of 0.02 mm / min according to BS ISO 14317: 2015.
  • Figure 10 shows SEM images of mechanically alloyed powders for 50 h at magnification of a) 1000X, b) 5000X, c) 7500X and d) 10000X of the titanium alloy (Ti-13% Ta-12% Sn (% at.)) .
  • An irregular morphology was observed, with some agglomerated particles, rounded edges and others scattered.
  • a not very homogeneous size distribution was observed, with the formation of a spherical morphology.
  • the cold welding and fracture processes coexist during the grinding process, however, there is the predominance of cold welding, since it was observed that the particles have a spherical morphology.
  • Figure 12 shows the X-ray diffraction patterns of the Ti-13Ta-12Sn (atomic%) alloy powders ground at different times. The formation of a new phase with fcc structure was observed as time passed and simultaneously the decrease of the beta phase with the passing of the hours. The highest amount of alpha titanium was reported at 5 h, then, over time, its amount decreased until 40 h, where this phase is no longer present.
  • the pore size distribution varies significantly, since it is possible to find pores with sizes from 40 prm to 770 miti, even small black dots are observed that correspond to formed micropores, this phenomenon is notably appreciated in the bulk of the sample with bimodal structure (0% porosity).
  • the shape of the pores is completely irregular, this can be explained by the geometric shape of the spacer material used (ammonium bicarbonate).
  • Figure 14 shows the representative images at 200X magnification of the samples with bimodal microstructure with a) 0% porosity, b) 30% porosity, c) 40% porosity and d) 50% porosity; and without bimodal microstructure with e) 0% porosity, f) 30% porosity, g) 40% porosity and h) 50% porosity.
  • the interconnection of the pores, the irregularity of their shape and their different size distribution are observed, as well as the existence of two different shades. Determination of Porosity
  • the apparent porosity is the ratio of the volume of the open pores of the sample with its external volume and does not consider the volume of the closed pores.
  • the increase in porosity can be explained not only by the porosity introduced by the spacer material, but also by that generated with the sintering itself between the particles, that is, micropores were formed that increase the percentage of porosity.
  • the porosity in foams with bimodal structure is slightly higher than those without bimodal microstructure, so it is possible to conclude that the addition of bimodal microstructure promotes the generation of interconnected porosity.
  • the modulus of elasticity was obtained through the ultrasound test, the results are shown in Table 4 and graphed in Figure 17.
  • An inverse linear relationship is obtained with respect to the theoretical porosity, that is, as the% porosity increases, decreases the modulus of elasticity. This relationship is to be expected, since the modulus of elasticity of a porous material decreases as the porosity increases.
  • the modules obtained in both structures are compared, it is possible to appreciate that in the case of the bimodal microstructure, lower values were obtained compared to without bimodal microstructure; however, as the% porosity increases, the difference between the two lines decreases, and where the modulus of elasticity is modified according to the% porosity.
  • the specimens with bimodal microstructure have a lower value of Young's modulus compared to the specimens without bimodal microstructure; however, as the% porosity increases, the difference between the two lines decreases.
  • the specimens that meet this value for implantation in the human body would correspond to foams with a porosity of 30%, 40% and 50% with and without bimodal microstructure.
  • Specimens with bimodal microstructure and porosity meet the mechanical requirements to serve as biomedical implants, elastic modulus less than 30 GPa and yield stress in compression over 120 MPa.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Medicinal Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Dermatology (AREA)
  • Manufacturing & Machinery (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Materials For Medical Uses (AREA)

Abstract

The present invention relates to a titanium-based alloy foam having formula Ti-13Ta-XSn, wherein X = 3, 6, 9 and 12 at.% . The titanium-based alloy foam has a porosity of up to 50%, an elastic modulus of up to 30 GPa and an elastic limit greater than 200 MPa. The invention also relates to a method for preparing the titanium-based alloy foam, and to the use of same as biomaterial, in particular for bone implants.

Description

ESPUMA DE ALEACIÓN EN BASE A TITANIO; MÉTODO DE PREPARACIÓN DE DICHA ALEACIÓN; Y SU USO COMO BIOMATERIAL TITANIUM BASED ALLOY FOAM; METHOD OF PREPARING SAID ALLOY; AND ITS USE AS BIOMATERIAL

CAMPO DE APLICACIÓN SCOPE

La presente invención se refiere a espumas de aleaciones en base a titanio, su método de preparación y a su uso como biomaterial en aplicaciones biomédicas. The present invention relates to titanium-based alloy foams, their preparation method and their use as a biomaterial in biomedical applications.

ANTECEDENTES BACKGROUND

El envejecimiento de la población constituye uno de los acontecimientos sociales y demográficos más relevantes de las últimas décadas, se caracteriza por el aumento de las personas que tienen 60 años o más. Su relevancia se debe a que este proceso tiene múltiples impactos en la sociedad, no sólo en los ámbitos de educación y salud, sino también en la economía y en la composición de la fuerza de trabajo. The aging of the population constitutes one of the most relevant social and demographic events in recent decades, characterized by the increase in people who are 60 years of age or older. Its relevance is due to the fact that this process has multiple impacts on society, not only in the fields of education and health, but also in the economy and in the composition of the workforce.

Se estima, de acuerdo a proyecciones realizadas por el Instituto Nacional de Estadística (INE), que las personas mayores de 40 años en Chile alcanzarían un 44,1% y 54% del total de la población para los años de 2020 y 2050, respectivamente. Para el período 2010-2050, la esperanza de vida de la población chilena aumentará de 75 a 79 años y 81 a 85 años para los hombres y mujeres, respectivamente. It is estimated, according to projections made by the National Institute of Statistics (INE), that people over 40 years of age in Chile would reach 44.1% and 54% of the total population for the years 2020 and 2050, respectively. . For the period 2010-2050, the life expectancy of the Chilean population will increase from 75 to 79 years and 81 to 85 years for men and women, respectively.

Por otro lado, se estima que el 90% de la población mayor de 40 años de edad sufre de alguna enfermedad degenerativa, que conduce a la degradación de las propiedades mecánicas del hueso. On the other hand, it is estimated that 90% of the population over 40 years of age suffers from some degenerative disease, which leads to the degradation of the mechanical properties of bone.

Teniendo en cuenta esta información es posible inferir que una gran cantidad de personas debería tener problemas musculoesqueléticos como artrosis, artritis y osteoporosis. Estas enfermedades ocupan el segundo lugar (32%) dentro de las enfermedades crónicas reportados por las personas mayores. Taking into account this information it is possible to infer that a large number of people should have musculoskeletal problems such as osteoarthritis, arthritis and osteoporosis. These diseases rank second (32%) within the chronic diseases reported by older people.

Durante las últimas décadas, un gran número de metales y materiales se han desarrollado para ser utilizados en una amplia gama de aplicaciones médicas. Sin embargo, los implantes óseos metálicos tradicionales tienen un alto módulo de elasticidad comparado con el hueso humano, por ello los pacientes sufren problemas de reacciones adversas tales como desgaste prematuro del implante que conlleva a cirugía de reemplazo. During the last decades, a large number of metals and materials have been developed for use in a wide range of medical applications. However, traditional metal bone implants have a high modulus of elasticity compared to human bone, therefore patients suffer from adverse reactions problems such as premature wear of the implant that leads to replacement surgery.

Los biomateriales pueden ser adecuados para resolver estos problemas (servir como implantes), se espera que estos biomateriales exhiban propiedades apropiadas como: excelente resistencia a la corrosión en el medio fluido corporal, resistencia mecánica y a la fatiga, bajo módulo de elasticidad, baja densidad y buena resistencia al desgaste, y permanezca más tiempo en servicio sin fallas. Biomaterials may be suitable to solve these problems (serve as implants), it is expected that these biomaterials exhibit appropriate properties such as: excellent resistance to corrosion in the body fluid medium, mechanical and fatigue resistance, low modulus of elasticity, low density and good wear resistance, and stay in service longer without failure.

El acero inoxidable, las aleaciones Co-basadas, las aleaciones Co-Cr y Ti- 6AI-4V se utilizan como implantes bajo condiciones de carga (Xiong, J., et al., “Mechanical properties and bioactive surface modification vía alkali-heat treatment of a porous Ti-18Nb-4Sn alloy for biomedical applications”. Acta Biomater., 2008. 4(6): p. 1963-1968; Aguilar, C., et al., “Synthesis and characterization of Ti-Ta-Nb- Mn foams. Materials Science and Engineering”·. C, 2016. 58: p. 420-431 ). Si bien estos materiales metálicos presentan una buena resistencia mecánica, tienen un alto módulo elástico en comparación con los valores óseos humanos, y en los últimos años se ha demostrado que liberan iones tóxicos en el cuerpo humano. El Ti y sus aleaciones tienen propiedades interesantes que incluyen una alta resistencia mecánica, ligereza, excelente resistencia a la oxidación y alta biocompatibilidad. En comparación con el acero inoxidable, las aleaciones basadas en cobalto (Co-Cr), el Ti y las aleaciones basadas en Ti presentan una mejor biocompatibilidad, resistencia a la corrosión y un menor módulo elástico (Long M. and H.J. Rack, “Titanium alloys in total joint replacement—a materials Science perspective” . Biomaterials, 1998. 19(18): p. 1621 -1639), por lo que su uso como biomaterial ha aumentado. Una de las aleaciones más importantes a base de Ti es la Ti-6AI-4V, que fue la primera aleación con microestructura a + b y que hoy en día se utiliza ampliamente como biomaterial. Sin embargo, algunos estudios han demostrado que los iones V y Al pueden ser liberados al cuerpo humano aumentando la probabilidad de enfermedades. Cuando los iones V se liberan a los tejidos humanos se altera la cinética de la actividad enzimática asociada con las células de respuesta inflamatoria, y los iones Al aumentan la probabilidad de desarrollar Alzheimer. En este sentido, los científicos de materiales están investigando la aleación de elementos no tóxicos para producir nuevas aleaciones a base de Ti que cumplan con las propiedades requeridas para los biomateriales. Los elementos de aleación ensayados son: Nb, Ta, Mo, Ta, Mn. Los elementos de aleación que tienen un impacto biológico diferente, por lo que los mejores candidatos para ser considerados biocompatibles son: Ta, Nb, Zr, Au, Sn, Ru y Mn. Los elementos de aleación más promisorios para sintetizar las aleaciones basadas en Ti son los metales de transición 3d, 4d y 5d. Las aleaciones a base de Ti con microestructura a + b se han obtenido utilizando elementos de aleación como Nb y Fe, pero los valores del módulo elástico son superiores (más de 100 GPa) en comparación con el módulo elástico de los huesos humanos, entre 4 y 30 GPa para los huesos corticales y entre 0,01 y 2 GPa para el hueso esponjoso humano. Si el implante ortopédico tiene un valor de módulo elástico superior al hueso humano, se produce el fenómeno llamado blindaje de tensión, que provoca una alta tasa de reabsorción. Stainless steel, Co-based alloys, Co-Cr and Ti-6AI-4V alloys are used as implants under load conditions (Xiong, J., et al., “Mechanical properties and bioactive surface modification via alkali-heat treatment of a porous Ti-18Nb-4Sn alloy for biomedical applications. "Acta Biomater., 2008. 4 (6): p. 1963-1968; Aguilar, C., et al.," Synthesis and characterization of Ti-Ta- Nb- Mn foams. Materials Science and Engineering ”·. C, 2016. 58: p. 420-431). While these metallic materials exhibit good mechanical strength, they have a high elastic modulus compared to human bone values, and in recent years they have been shown to release toxic ions in the human body. Ti and its alloys have interesting properties that include high mechanical strength, lightness, excellent resistance to oxidation, and high biocompatibility. Compared with stainless steel, alloys based on cobalt (Co-Cr), Ti and alloys based on Ti have better biocompatibility, corrosion resistance and a lower elastic modulus (Long M. and HJ Rack, “Titanium alloys in total joint replacement — a materials Science perspective. ”Biomaterials, 1998. 19 (18): p. 1621-1639), so its use as a biomaterial has increased. One of the most important Ti-based alloys is Ti-6AI-4V, which was the first a + by microstructure alloy that is widely used today as a biomaterial. However, some studies have shown that V and Al ions can be released into the human body, increasing the likelihood of disease. When V ions are released into human tissues, the kinetics of enzyme activity associated with inflammatory response cells are altered, and Al ions increase the likelihood of developing Alzheimer's. In this sense, materials scientists are investigating the alloy of non-toxic elements to produce new Ti-based alloys that meet the properties required for biomaterials. The alloying elements tested are: Nb, Ta, Mo, Ta, Mn. The alloying elements that have a different biological impact, so the best candidates to be considered biocompatible are: Ta, Nb, Zr, Au, Sn, Ru and Mn. The most promising alloying elements for synthesizing Ti-based alloys are the 3d, 4d and 5d transition metals. Ti-based alloys with a + b microstructure have been obtained using alloying elements such as Nb and Fe, but the elastic modulus values are higher (more than 100 GPa) compared to the elastic modulus of human bones, between 4 and 30 GPa for cortical bones and between 0.01 and 2 GPa for human cancellous bone. If the orthopedic implant has a higher elastic modulus value than human bone, the phenomenon called stress shielding occurs, which causes a high resorption rate.

Por otro lado, se ha investigado que al comparar las aleaciones de Ti convencionales con los huesos humanos, estos últimos poseen una estructura porosa, no así los implantes comúnmente utilizados, lo que conlleva a dos problemas principales: i) diferente valor del módulo de Young entre el implante y el hueso, que produce el fenómeno denominado apantallamiento de tensiones, el cual provoca el aflojamiento en la unión y reabsorción ósea alrededor del implante; y ii) la estructura densa del implante dificulta el crecimiento del nuevo tejido óseo, disminuyendo su longevidad. On the other hand, it has been investigated that when comparing conventional Ti alloys with human bones, the latter have a porous structure, unlike commonly used implants, which leads to two main problems: i) different value of Young's modulus between the implant and the bone, which produces the phenomenon called stress shielding, which causes loosening in the union and bone resorption around the implant; and ii) the dense structure of the implant hinders the growth of new bone tissue, reducing its longevity.

Por otra parte, las espumas metálicas se definen como una mezcla de estructura metálica con poros incrustados (abiertos y/o cerrados), y presentan propiedades mixtas entre metales y espumas. Las espumas metálicas poseen una combinación única de propiedades, tales como su baja densidad, permeabilidad al aire y agua, capacidad de absorber energía de impacto, baja conductividad térmica y buen aislamiento eléctrico. Sin embargo, la principal desventaja de las espumas es que su límite elástico disminuye a medida que aumenta la porosidad. On the other hand, metallic foams are defined as a mixture of metallic structure with embedded pores (open and / or closed), and present mixed properties between metals and foams. Metallic foams possess a unique combination of properties, such as their low density, permeability to air and water, ability to absorb impact energy, low thermal conductivity, and good electrical insulation. However, the main disadvantage of foams is that their elastic limit decreases as porosity increases.

DESCRIPCIÓN DEL ARTE PREVIO En la publicación realizada por Kato et al (“Novel multilayer Ti foam with cortical bone strength and cytocompatibHity”, Acta Biomater., 2013. 3(9): p. 5802- 5809) se divulga el desarrollo de una espuma de titanio que presenta propiedades mecánicas compatibles con las capacidades de fijación cortical ósea y biológica mediante el apilamiento capa por capa de diferentes láminas de espuma con porosidades volumétricas del 80% y 17%. Asimismo, se divulga una espuma de Ti multicapa que tiene un módulo de Young de 11 -12 GPa y una resistencia a la elasticidad de 150-240 MPa en pruebas de compresión. Estudios de cultivo celular in vitro de la muestra revelaron una buena penetración celular en la espuma de mayor porosidad. La calcificación también se observó en la espuma de alta porosidad, lo que sugiere que esta espuma de Ti no inhibe la formación ósea. Como conclusión se indica que las características únicas de la espuma de Ti multicapa desarrollada la hace atractiva para su aplicación en el campo de la ortopedia. DESCRIPTION OF PRIOR ART In the publication made by Kato et al ("Novel multilayer Ti foam with cortical bone strength and cytocompatibHity", Acta Biomater., 2013. 3 (9): p. 5802-5809) the development of a titanium foam that presents mechanical properties compatible with cortical bone and biological fixation capabilities by layer by layer stacking of different foam sheets with volumetric porosities of 80% and 17%. Also, a multilayer Ti foam is disclosed having a Young's modulus of 11-12 GPa and a resistance to elasticity of 150-240 MPa in compression tests. In vitro cell culture studies of the sample revealed good cell penetration in the higher porosity foam. Calcification was also observed in the high porosity foam, suggesting that this Ti foam does not inhibit bone formation. As a conclusion it is indicated that the unique characteristics of the developed multilayer Ti foam make it attractive for its application in the field of orthopedics.

La publicación de C. Guerra et al (“Production and characterisation of mechanical properties of Ti-Nb-Ta-Mn alloys foams for biomedical applications”, Powder Metall. 2015, 58, p. 12-15) divulga la preparación de tres espumas de aleaciones basadas en titanio Ti-30Nb-13Ta-xMn (2, 4, 6% Mn). Los valores del módulo elástico obtenidos fueron de 15, 18 y 20 GPa para las aleaciones de 2, 4 y 6% de Mn respectivamente, valores muy cercanos al módulo del hueso humano (hueso cortical 25-30 GPa). Se indica que el módulo elástico aumenta al aumentar el contenido de Mn en la aleación. The publication by C. Guerra et al (“Production and characterization of mechanical properties of Ti-Nb-Ta-Mn alloys foams for biomedical applications”, Powder Metall. 2015, 58, p. 12-15) discloses the preparation of three foams of alloys based on titanium Ti-30Nb-13Ta-xMn (2, 4, 6% Mn). The elastic modulus values obtained were 15, 18 and 20 GPa for the 2, 4 and 6% Mn alloys respectively, values very close to the modulus of human bone (cortical bone 25-30 GPa). It is indicated that the elastic modulus increases with increasing Mn content in the alloy.

A pesar del desarrollo de estos biomateriales, aún existe la necesidad de contar con un biomaterial que muestre propiedades tales como alta biocompatibilidad, baja densidad, alta resistencia mecánica y resistencia a la fatiga, bajo módulo elástico y buena resistencia al desgaste. Más particularmente, es deseable que el biomaterial tenga un módulo de Young que coincida con el hueso circundante, y que a su vez sea lo suficientemente fuerte y duradero para soportar las cargas fisiológicas que se le han aplicado a lo largo de los años. Por lo tanto, se requiere encontrar un material que presente un equilibrio adecuado entre la resistencia y la rigidez para que coincida mejor con el comportamiento del hueso. Despite the development of these biomaterials, there is still a need for a biomaterial that shows properties such as high biocompatibility, low density, high mechanical strength and fatigue resistance, low elastic modulus and good wear resistance. More particularly, it is desirable that the biomaterial has a Young's modulus that matches the surrounding bone, and that in turn is strong and durable enough to withstand the physiological loads that have been applied to it over the years. Therefore, it is required to find a material that presents a suitable balance between strength and stiffness to better match the behavior of the bone.

BREVE DESCRIPCIÓN DE LA INVENCIÓN La presente invención propone como solución a los problemas detallados anteriormente, una espuma metálica de aleaciones en base a titanio (Ti-13Ta-XSn, en donde X = 3, 6, 9 y 12 %atómico), con microestructura bimodal y diferentes porcentajes de porosidad, las que presentan valores de módulo elástico y esfuerzo de fluencia adecuados para ser usados como biomateriales en implantes óseos. BRIEF DESCRIPTION OF THE INVENTION The present invention proposes as a solution to the problems detailed above, a metallic foam of titanium-based alloys (Ti-13Ta-XSn, where X = 3, 6, 9 and 12 atomic%), with bimodal microstructure and different percentages of porosity, those that present values of elastic modulus and yield stress suitable for use as biomaterials in bone implants.

En particular, la presente invención divulga espumas de aleación a base de Ti con módulos elásticos inferiores a 30 GPa y un límite elástico superior a 200 MPa. BREVE DESCRIPCIÓN DE LAS FIGURAS In particular, the present invention discloses Ti-based alloy foams with elastic moduli less than 30 GPa and an elastic limit greater than 200 MPa. BRIEF DESCRIPTION OF THE FIGURES

Figura 1 : Esquema general del proceso de Pulvimetalurgia. Figure 1: General diagram of the Powder Metallurgy process.

Figura 2: Microestructuras en aleaciones de titanio. Figure 2: Microstructures in titanium alloys.

Figura 3: Aleaciones binarias de titanio. Figure 3: Titanium binary alloys.

Figura 4: Módulo de elasticidad para diversas aleaciones. Figura 5: Fotografía de una Cámara de guantes. Figure 4: Modulus of elasticity for various alloys. Figure 5: Photograph of a glove box.

Figura 6: Esquema y fotografía de un Molino planetario. Figure 6: Schematic and photograph of a planetary mill.

Figura 7: Aleado mecánico. Figure 7: Mechanical alloying.

Figura 8: Fotografía de un sistema de Compactación. Figure 8: Photograph of a Compaction system.

Figura 9: Fotografía del equipo usado en la sinterización. Figura 10: Imágenes SEM de polvos aleados mecánicamente. Figure 9: Photograph of the equipment used in sintering. Figure 10: SEM images of mechanically alloyed powders.

Figura 11 : EDS de polvos aleados mecánicamente. Figure 11: EDS of mechanically alloyed powders.

Figura 12: Difractograma de la aleación Ti-13Ta-12Sn (%at.) Figure 12: Diffractogram of the Ti-13Ta-12Sn alloy (% at.)

Figura 13: Probetas sinterizadas. Figure 13: Sintered specimens.

Figura 14: Imágenes SMEB a 200X de magnificación de muestras con microestructura bimodal. Figure 14: SMEB images at 200X magnification of samples with bimodal microstructure.

Figura 15: Gráfico de Porosidad aparente en función de la porosidad teórica. Figure 15: Graph of apparent porosity as a function of theoretical porosity.

Figura 16: Gráfico de Densidad medida en función de la porosidad. Figura 17 Gráfico del Módulo de elasticidad medido en función de la porosidad. Figura 18: Gráfico del Esfuerzo de Fluencia medido en función de la porosidad. Figure 16: Graph of Density measured as a function of porosity. Figure 17 Graph of the Modulus of elasticity measured as a function of porosity. Figure 18: Graph of yield stress measured as a function of porosity.

DESCRIPCIÓN DETALLADA DE LA INVENCIÓN DETAILED DESCRIPTION OF THE INVENTION

La materia objeto de la presente proporciona una preparación novedosa y útil de una espuma de aleaciones en base a titanio, Ti-13Ta-XSn (X = 3, 6, 9 y 12 %at.). The subject matter hereof provides a novel and useful preparation of a titanium-based alloy foam, Ti-13Ta-XSn (X = 3, 6, 9 and 12 at.%).

Las expresiones "metales celulares" y "espumas metálicas" se utilizan para referirse a los metales y aleaciones cuya estructura es porosa. El término de metales celulares se utiliza cuando el metal exhibe espumas porosas y el término de espumas metálicas se utiliza cuando se aplica un proceso de síntesis para obtener espumas. The terms "cellular metals" and "metallic foams" are used to refer to metals and alloys whose structure is porous. The term cellular metals is used when the metal exhibits porous foams and the term metallic foams is used when a synthesis process is applied to obtain foams.

Las espumas metálicas con poros abiertos se pueden obtener a través de fases sólidas, líquidas o gaseosas y la selección del método depende del tipo, distribución y tamaño de los poros. Metal foams with open pores can be obtained through solid, liquid or gaseous phases and the selection of the method depends on the type, distribution and size of the pores.

Un proceso simple de estado sólido para obtener espumas con una distribución de los poros y el tipo de porosidad (poros abiertos y cerrados) es el método de “espaciadores”. Este método permite controlar la forma, tamaño y distribución de porosidad a través de la temperatura de sinterización, tiempo y temperatura de disolución (si el espaciador es de sal). Los espaciadores comúnmente utilizados para sintetizar las espumas de Ti son: carbamida, carbonato de hidrógeno de amonio (NFI4FICO3), almidón de tapioca, sal (NaCI), magnesio, ACRAWAX® (AW), PMMA, sacarosa y urea. El espaciador debe ser seleccionado en base a los siguientes criterios: i) tamaño y forma, ii) costo, iii) reactividad del Ti con el soporte, iv) presencia de residuos izquierdos, v) fácil procesabilidad y vi) elemento no tóxico. En el caso de las espumas biomédicas, los residuos deben ser bioinertes o biocompatibles, es decir, en el caso del carbonato de hidrógeno de amonio, la urea y el almidón de tapioca, el cuerpo humano puede absorber residuos que podrían producir algunos problemas. Las partículas de NaCI tienen la ventaja de que sus residuos no causan problemas al cuerpo humano (no son tóxicos) y son fácilmente removibles por el proceso de disolución en agua. Por su parte, el empleo de bicarbonato de amonio como material espaciador presenta las ventajas de no reaccionar con el titanio durante el proceso y se elimina por el aporte del calor durante la sinterización, debido a su descomposición al ser sometido a temperatura sobre los 35ºC, produciendo vapores de amoníaco de acuerdo a la reacción: A simple solid state process to obtain foams with a distribution of pores and type of porosity (open and closed pores) is the "spacers" method. This method allows to control the shape, size and distribution of porosity through sintering temperature, time and dissolution temperature (if the spacer is salt). Spacers commonly used to synthesize Ti foams are: carbamide, ammonium hydrogen carbonate (NFI4FICO3), tapioca starch, salt (NaCl), magnesium, ACRAWAX® (AW), PMMA, sucrose and urea. The spacer should be selected based on the following criteria: i) size and shape, ii) cost, iii) reactivity of the Ti with the support, iv) presence of left residues, v) easy processability and vi) non-toxic element. In the case of biomedical foams, the residues must be bio-inert or biocompatible, that is, in the case of ammonium hydrogen carbonate, urea and tapioca starch, the human body can absorb residues that could cause some problems. The NaCI particles have the advantage that their residues do not cause problems to the human body (they are not toxic) and they are easily removable by the process of dissolution in water. For its part, the use of ammonium bicarbonate as a spacer material has the advantages of not reacting with titanium during the process and is eliminated by the contribution of heat during sintering, due to its decomposition when subjected to a temperature above 35ºC, producing ammonia vapors according to the reaction:

NH4HCO3 → CO2 + NH3 + H2O NH 4 HCO 3 → CO 2 + NH 3 + H 2 O

La porosidad resultante del método de preparación y las propiedades mecánicas obtenidas para las espumas dependen en gran medida de la mezcla de partículas del soporte del espacio de polvo metálico. The porosity resulting from the preparation method and the mechanical properties obtained for the foams are highly dependent on the particle mixture of the support of the metal powder space.

Pulvimetalurgia Powder metallurgy

La Pulvimetalurgia (PM) o metalurgia de polvos es un proceso de fabricación que toma polvos metálicos con ciertas características como tamaño, forma y empaquetamiento para crear una figura de alta dureza y precisión. Una de las ventajas de la Pulvimetalurgia es la habilidad de fabricar piezas de formas complejas y dimensiones cercanas a las del producto final, con excelentes tolerancias, alta calidad y a un costo relativamente bajo, es decir, se obtienen piezas con una mayor homogeneidad y control del tamaño de los granos, logrando la formación de enlaces fuertes entre las partículas y, por ende, incrementos en la dureza y tenacidad de los materiales. Este proceso es adecuado para la fabricación de grandes series de piezas pequeñas con una gran precisión, para materiales puros o mezclas poco comunes y para controlar el grado de porosidad o permeabilidad, además existe una reducción en los costos debido a la posibilidad de eliminar los procesos de acabado, en comparación con otros métodos de fabricación como forja o fundición. Powder metallurgy (PM) or powder metallurgy is a manufacturing process that takes metallic powders with certain characteristics such as size, shape and packaging to create a figure of high hardness and precision. One of the advantages of Powder Metallurgy is the ability to manufacture parts with complex shapes and dimensions close to those of the final product, with excellent tolerances, high quality and at a relatively low cost, that is, parts are obtained with greater homogeneity and control of the size of the grains, achieving the formation of strong bonds between the particles and, therefore, increases in the hardness and toughness of the materials. This process is suitable for the manufacture of large series of small parts with great precision, for pure materials or unusual mixtures and to control the degree of porosity or permeability, in addition there is a reduction in costs due to the possibility of eliminating the processes of finishing, compared to other manufacturing methods such as forging or casting.

La Figura 1 muestra un esquema general de las etapas del proceso básico de Pulvimetalurgia. La fabricación de los componentes PM comienza con la mezcla de los polvos, aditivos y lubricantes. Esta mezcla es compactada como pieza dentro de un molde que tiene la forma deseada, mediante la aplicación de presiones. Después de la compactación, la mezcla toma las propiedades de un sólido, cuyo estado se denomina “en verde”. Posteriormente, el compacto es sinterizado a temperaturas por debajo del punto de fusión, bajo una atmósfera controlada, logrando una unión metalúrgica entre las partículas. Las operaciones básicas de compactar y calentar pueden combinarse en diversas formas en los procesos para la fabricación de polvos de metal. Figure 1 shows a general diagram of the stages of the basic powder metallurgy process. The manufacture of PM components begins with the mixing of powders, additives and lubricants. This mixture is compacted as a piece inside a mold that has the desired shape, by applying pressure. After compaction, the mixture takes on the properties of a solid, whose state is called "green". Subsequently, the compact is sintered to temperatures below the melting point, under a controlled atmosphere, achieving a metallurgical bond between the particles. The basic operations of compacting and heating can be combined in various ways in processes for the manufacture of metal powders.

Aleaciones de titanio Titanium alloys

Las adiciones de elementos de aleación al titanio puro producen un rango de posibles microestructuras en aleaciones de titanio. Es decir, la adición de otros elementos al titanio se puede obtener: Aleaciones Alpha (a), Aleaciones Alpha-beta (a-b) y Aleaciones beta (b). Estas aleaciones se caracterizan por las fases (estructuras cristalinas) que existen en la aleación cuando se encuentran cerca a una temperatura ambiente y poseen diferentes propiedades tal como se observa en la Figura 2. Las temperaturas a las que pueden existir las fases alfa y beta se alteran a medida que se agregan elementos de aleación al titanio. En función de su influencia sobre las proporciones de las fases alfa y beta por debajo del beta trans, los elementos de aleación se dividen en tres grupos: Additions of alloying elements to pure titanium produce a range of possible microstructures in titanium alloys. That is, the addition of other elements to titanium can be obtained: Alpha alloys (a), Alpha-beta alloys (a-b) and beta alloys (b). These alloys are characterized by the phases (crystalline structures) that exist in the alloy when they are close to room temperature and possess different properties as shown in Figure 2. The temperatures at which the alpha and beta phases can exist are they alter as alloying elements are added to the titanium. Depending on their influence on the proportions of the alpha and beta phases below the beta trans, the alloying elements are divided into three groups:

• Estabilizadores alfa (estabiliza la fase alfa a temperaturas más altas) • Alpha stabilizers (stabilizes the alpha phase at higher temperatures)

• Estabilizadores beta (estabiliza la fase beta a temperaturas más bajas)• Beta stabilizers (stabilizes the beta phase at lower temperatures)

• Aditivos neutros (tienen una influencia menor en la estabilización de estas fases) • Neutral additives (they have a minor influence on the stabilization of these phases)

Las Aleaciones Alpha (a) se caracterizan por su resistencia, tenacidad, esfuerzo a la fluencia y soldabilidad. Los solutos estabilizadores de alfa son aquellos que, como una función de concentración, elevan la temperatura del (a + b) / a transus. Dichos solutos generalmente no son metales de transición (es decir, "metales simples", SM). Alpha (a) Alloys are characterized by their strength, toughness, yield stress and weldability. Alpha stabilizing solutes are those that, as a function of concentration, raise the temperature of the (a + b) / a transus. Such solutes are generally not transition metals (ie "simple metals", SM).

En el caso de las Aleaciones Beta (b), los solutos de transición (metal) son estabilizadores de la fase bcc. Por lo tanto, todas las aleaciones b generalmente contienen grandes cantidades de uno o más de los llamados " b-isomorfos" formando adiciones: vanadio, niobio, tántalo (grupo V Metales de transición) y molibdeno (grupo VI metales de transición). Las aleaciones beta son metaestables; es decir, tienden a transformarse en un equilibrio o balance de estructuras. Las aleaciones beta generan resistencia a partir de la resistencia intrínseca de la estructura beta y la precipitación de las fases alfa y otras de la aleación a través del tratamiento térmico después del procesamiento. El beneficio más significativo proporcionado por una estructura beta es el incremento de formabilidad de tales aleaciones en relación con los tipos de estructura cristalina hexagonal (alfa y alfa- beta). La formabilidad puede definirse como una medida de la cantidad de deformación que un material puede experimentar en un proceso de formado sin que falle, tal como adelgazamiento localizado o fractura. Otras características de la aleación beta son: ser tratable térmicamente a niveles de alta resistencia, excelente resistencia a la tracción hasta 370°C, poca resistencia a la fluencia por encima de 370°C, buena soldabilidad como solución tratada, buena tenacidad, lenta tasa de crecimiento de grietas por fatiga y contiene suficiente estabilizador beta para retener una estructura completamente beta a temperatura ambiente, la cual aumenta la ductilidad. In the case of Beta Alloys (b), the transition solutes (metal) are stabilizers of the bcc phase. Therefore, all b-alloys generally contain large amounts of one or more of the so-called "b-isomorphs" forming additions: vanadium, niobium, tantalum (group V transition metals) and molybdenum (group VI transition metals). Beta alloys are metastable; that is, they tend to transform into a balance or balance of structures. The Beta alloys generate strength from the intrinsic strength of the beta structure and the precipitation of the alpha and other phases of the alloy through heat treatment after processing. The most significant benefit provided by a beta structure is the increased formability of such alloys relative to the hexagonal crystal structure types (alpha and alpha-beta). Formability can be defined as a measure of the amount of deformation that a material can undergo in a forming process without failure, such as localized thinning or fracture. Other characteristics of beta alloy are: being heat treatable at high strength levels, excellent tensile strength up to 370 ° C, low creep resistance above 370 ° C, good solderability as solution treated, good toughness, slow rate fatigue crack growth and contains sufficient beta stabilizer to retain a fully beta structure at room temperature, which increases ductility.

Las aleaciones a + b son tales que, en el equilibrio, generalmente a temperatura ambiente, admiten una mezcla de fases a y b. Aunque muchas aleaciones binarias estabilizadas b en equilibrio termodinámico son de dos fases, en la práctica las aleaciones a + b generalmente contienen mezclas de estabilizadores a y b. Las aleaciones a + b generalmente exhiben una buena capacidad de fabricación, así como también una alta resistencia a temperatura ambiente y una resistencia moderada a temperatura elevada. Pueden contener entre 10 y 50% de fase b a temperatura ambiente; si contienen más del 20%, no son soldables. Las propiedades de las aleaciones a + b pueden controlarse mediante tratamiento térmico, que se utiliza para ajustar los estados microestructurales y precipitaciones del componente b. Las aleaciones están formuladas de modo que tanto la fase alfa (hcp) como la fase beta (bcc) existen a temperatura ambiente. Estas aleaciones, hasta cierto punto, comprometen algunas de las características de las aleaciones alfa y beta. The alloys a + b are such that, in equilibrium, generally at room temperature, they admit a mixture of phases a and b. Although many stabilized binary alloys b in thermodynamic equilibrium are two-phase, in practice alloys a + b generally contain mixtures of stabilizers a and b. A + b alloys generally exhibit good workability, as well as high room temperature strength and moderate elevated temperature strength. They can contain between 10 and 50% phase b at room temperature; if they contain more than 20%, they are not weldable. The properties of alloys a + b can be controlled by heat treatment, which is used to adjust the microstructural states and precipitation of component b. The alloys are formulated so that both the alpha phase (hcp) and the beta phase (bcc) exist at room temperature. These alloys, to some extent, compromise some of the characteristics of alpha and beta alloys.

Aplicaciones Biomédicas de Aleaciones de Titanio Biomedical Applications of Titanium Alloys

Se han desarrollado dos generaciones de aleaciones de Ti para aplicaciones biomédicas. La primera generación de aleaciones a y (a + b) que tienen un alto módulo de Young (110 GPa aprox.) y la segunda generación son aleaciones b con módulos de elasticidad más bajos (entre 55-90 GPa). Las aleaciones de Ti de bajo modulo, como por ejemplo la aleación a + b con la composición Ti-35Nb-7Zr-5Ta se desarrollaron especialmente para el hueso humano (cortical: 3-30 GPa). Sin embargo, incluso las aleaciones de Ti de bajo módulo son significativamente más rígidas que el hueso esponjoso (ver Figura 4). Para resolver estos problemas y mejorar aún más las propiedades biológicas y mecánicas, se han desarrollado muchas nuevas aleaciones de Ti para la aplicación biomédica. Por ejemplo, el diseño de aleaciones de Ti de fase b única, que permite reducir el módulo elástico. Sin embargo, existe una contradicción entre el módulo elástico y otras propiedades mecánicas en esas aleaciones de Ti. Cuando se reduce el módulo elástico, la resistencia de la aleación de Ti también disminuye. Two generations of Ti alloys have been developed for biomedical applications. The first generation of alloys a and (a + b) that have a high Young's modulus (110 GPa approx.) and the second generation are b alloys with lower modulus of elasticity (between 55-90 GPa). Low modulus Ti alloys, such as the a + b alloy with the composition Ti-35Nb-7Zr-5Ta were developed especially for human bone (cortical: 3-30 GPa). However, even low modulus Ti alloys are significantly stiffer than cancellous bone (see Figure 4). To solve these problems and further improve the biological and mechanical properties, many new Ti alloys have been developed for biomedical application. For example, the design of single-phase Ti alloys, which allows to reduce the elastic modulus. However, there is a contradiction between the elastic modulus and other mechanical properties in these Ti alloys. When the elastic modulus is reduced, the strength of the Ti alloy also decreases.

MODALIDADES PREFERIDAS DE LA INVENCIÓN PREFERRED MODALITIES OF THE INVENTION

La presente invención se dirige a una espuma de aleación en base a titanio de fórmula Ti-13Ta-XSn, en donde X = 3, 6, 9 y 12 %atómico. The present invention is directed to a titanium-based alloy foam of the formula Ti-13Ta-XSn, where X = 3, 6, 9 and 12 atomic%.

En una modalidad preferida de la invención, la espuma de aleación en base a titanio es Ti-13Ta-3Sn. In a preferred embodiment of the invention, the titanium-based alloy foam is Ti-13Ta-3Sn.

En otra modalidad preferida de la invención, la espuma de aleación en base a titanio es Ti-13Ta-6Sn. In another preferred embodiment of the invention, the titanium-based alloy foam is Ti-13Ta-6Sn.

Aún en otra modalidad preferida de la invención, la espuma de aleación en base a titanio es Ti-13Ta-12Sn. In yet another preferred embodiment of the invention, the titanium-based alloy foam is Ti-13Ta-12Sn.

En una modalidad de la invención la espuma de aleación en base a titanio tiene una porosidad de hasta un 50%. In one embodiment of the invention, the titanium-based alloy foam has a porosity of up to 50%.

En otra modalidad de la invención la espuma de aleación en base a titanio tiene un módulo elástico de hasta a 30 GPa. In another embodiment of the invention, the titanium-based alloy foam has an elastic modulus of up to 30 GPa.

En otra modalidad de la invención la espuma de aleación en base a titanio tiene límite elástico superior a 200 MPa. In another embodiment of the invention, the titanium-based alloy foam has an elastic limit greater than 200 MPa.

Adicionalmente, la presente invención se refiere a un método de preparación de una espuma de aleación en base a titanio, que comprende las siguientes etapas: i. preparación de la aleación Ti-13Ta-XSn (X = 3, 6, 9 y 12 %at.); ii. preparación de probetas verdes a partir de la aleación; y mediante compactación; y iii. sinterización de las probetas verdes. Additionally, the present invention relates to a method of preparing a titanium-based alloy foam, comprising the following steps: i. preparation of the Ti-13Ta-XSn alloy (X = 3, 6, 9 and 12 at.%); ii. preparation of green specimens from the alloy; and by compaction; and iii. sintering the green specimens.

En una modalidad preferida de la invención, la etapa de preparación de la aleación se realiza mediante aleado mecánico. In a preferred embodiment of the invention, the alloy preparation step is carried out by mechanical alloying.

En otra modalidad preferida de la invención, la etapa de preparación de las probetas verdes se realiza por compactación de la aleación. In another preferred embodiment of the invention, the step of preparing the green specimens is carried out by compacting the alloy.

En otra modalidad preferida de la invención, la etapa de preparación de las probetas verdes se emplea un material espaciador. In another preferred embodiment of the invention, the step of preparing the green specimens uses a spacer material.

En una modalidad aún más preferida de la invención el material espaciador es bicarbonato de amonio. In an even more preferred embodiment of the invention the spacer material is ammonium bicarbonate.

En una modalidad preferida de la invención, la etapa de sinterización de las probetas verdes compactadas se realiza en un horno tubular. In a preferred embodiment of the invention, the sintering step of the compacted green specimens is carried out in a tube furnace.

En una modalidad aún más preferida de la invención la etapa de sinterización se realiza a 1300°C. In an even more preferred embodiment of the invention the sintering step is carried out at 1300 ° C.

Por último, la presente invención se dirige al uso de la espuma de aleación en base a titanio como biomaterial. Finally, the present invention is directed to the use of the titanium-based alloy foam as a biomaterial.

En una modalidad preferida de la invención el biomaterial es un implante óseo. In a preferred embodiment of the invention the biomaterial is a bone implant.

EJEMPLO EXAMPLE

Se sintetizaron diferentes espumas de acuerdo a la presente invención. Different foams were synthesized according to the present invention.

I. Materiales v Aparatos I. Materials and Apparatus

Se preparó la aleación Ti-13Ta-12Sn mediante aleado mecánico (molienda), empleando como materia prima polvos metálicos de titanio, tantalio y estaño. Como agente controlador del proceso de aleado mecánico (molienda) se empleó ácido esteárico triple (CH3(CH2)i6COOH) en un 2% en peso. The Ti-13Ta-12Sn alloy was prepared by mechanical alloying (grinding), using titanium, tantalum and tin metal powders as raw material. What controlling agent of the mechanical alloying process (grinding), triple stearic acid (CH3 (CH2) i6COOH) was used at 2% by weight.

Se utilizó como material espaciador (space holder) bicarbonato de amonio ((NH4HCO3). Como medio de molienda se utilizaron bolas de óxido de zirconio YSZ (ZrÜ2 estabilizado con itria). Se usaron bolas de 5 y 10 mm de diámetro, en una razón en masa de bolas con respecto al polvo de 10:1. Ammonium bicarbonate ((NH4HCO3) was used as spacer material ((NH4HCO3). Zirconium oxide balls YSZ (YSZ stabilized ZrÜ2) were used as grinding medium. Balls of 5 and 10 mm in diameter were used, in a ratio in mass of balls with respect to the powder of 10: 1.

Para la molienda de los polvos se utilizaron dos recipientes de óxido de zirconio YSZ (ZrÜ2 estabilizado con itria). Se usó Argón (Ar) ultra puro en la cámara de guantes para evitar la oxidación de los polvos. Two YSZ zirconium oxide vessels (YSZ stabilized ZrÜ2) were used for grinding the powders. Ultra pure Argon (Ar) was used in the glove box to prevent oxidation of the powders.

Se utilizó estearato de zinc como lubricante sólido en la compactación de la probeta en verde. Zinc stearate was used as a solid lubricant in the compaction of the green specimen.

El manejo, llenado y vaciado de los contenedores se realizó en una cámara de guantes (ver Figura 5). The handling, filling and emptying of the containers was carried out in a glove box (see Figure 5).

Se utilizó un molino planetario para realizar la síntesis de la aleación (ver Figura 6). A planetary mill was used to carry out the synthesis of the alloy (see Figure 6).

II. Procedimiento Se pesaron los polvos de titanio, estaño, tantalio y ácido esteárico (2%) de acuerdo a la siguiente Tabla 1. II. Procedure Titanium, tin, tantalum and stearic acid (2%) powders were weighed according to the following Table 1.

Tabla 1

Figure imgf000013_0001
Se realizó el aleado mecánico con un tiempo de molienda de 50 h efectivas a una velocidad de 250 RPM (ver Figura 7). Table 1
Figure imgf000013_0001
The mechanical alloying was carried out with a milling time of 50 h effective at a speed of 250 RPM (see Figure 7).

Una vez finalizado el tiempo de molienda, se recuperaron los polvos aleados. Luego se prepararon las probetas en verde. En esta etapa se compactan los polvos en la máquina de compactación. After the grinding time was over, the alloyed powders were recovered. The green test tubes were then prepared. At this stage the powders are compacted in the compaction machine.

Las muestras con una microestructura bimodal se obtuvieron mezclando el 25% del peso de los polvos molidos con el 75% del peso de los polvos sin moler. La microestructura bimodal (+BM) se define como una mezcla de 25% de partículas nanométricas y 75% de partículas micrométricas. Se obtuvieron muestras sin microestructura bimodal (-BM) con polvos sin moler. Además, se agregó una cantidad de material espaciador de acuerdo al porcentaje de porosidad que se quiso obtener en las probetas (0%, 30%, 40% y 50%). Samples with a bimodal microstructure were obtained by mixing 25% of the weight of the ground powders with 75% of the weight of the raw powders. The bimodal microstructure (+ BM) is defined as a mixture of 25% nanoparticles and 75% micrometric particles. Samples without bimodal microstructure (-BM) were obtained with raw powders. In addition, an amount of spacer material was added according to the percentage of porosity that was wanted to obtain in the test tubes (0%, 30%, 40% and 50%).

La Tabla 2 muestra la masa de cada uno de los elementos. Tabla 2

Figure imgf000014_0001
Table 2 shows the mass of each of the elements. Table 2
Figure imgf000014_0001

La sinterización se llevó a cabo en un horno tubular (ver Figura 9) mediante atmosfera controlada de argón. Se introdujeron las probetas en verde a sinterizar. El ciclo posee dos isotermas, la primera corresponde a la volatización del material espaciador el cual se realiza a 180°C por una hora y media. La segunda isoterma corresponde a la sinterización de la aleación metálica, la cual se realiza a 1300°C por 3 h. Luego del enfriamiento, las probetas se retiraron del horno. Sintering was carried out in a tube furnace (see Figure 9) using a controlled argon atmosphere. The green specimens to be sintered were introduced. The cycle has two isotherms, the first corresponds to the volatilization of the spacer material, which is carried out at 180 ° C for an hour and a half. The second isotherm corresponds to the sintering of the metal alloy, which is carried out at 1,300 ° C for 3 h. After cooling, the specimens were removed from the oven.

III. Caracterización de las espumas III. Characterization of the foams

La morfología de los polvos y espumas obtenidas se estudiaron mediante microscopía electrónica de barrido (SEM). The morphology of the powders and foams obtained were studied by scanning electron microscopy (SEM).

La porosidad de las espumas se midió mediante un software de análisis de imágenes obtenidas mediante un microscopio óptico acoplado a una cámara Leica MC170 HD. The porosity of the foams was measured using image analysis software obtained using an optical microscope coupled to a Leica MC170 HD camera.

Las mediciones ultrasónicas del módulo elástico se realizaron mediante transductores ultrasónicos. El protocolo de medición y cálculo se basa en la norma ASTM D2845-08. The ultrasonic measurements of the elastic modulus were carried out using ultrasonic transducers. The measurement and calculation protocol is based on the ASTM D2845-08 standard.

La medición de la densidad se realizó con un picnómetro de 20 mi y una balanza con una sensibilidad de 0,001 g, basada en la norma ASTM D792-08. Los ensayos de compresión se realizaron con una máquina Zwick-Roell a una velocidad de carga de 0,02 mm/min según la norma BS ISO 14317:2015. Density measurement was performed with a 20 ml pycnometer and a balance with a sensitivity of 0.001 g, based on the ASTM D792-08 standard. Compression tests were carried out with a Zwick-Roell machine at a loading speed of 0.02 mm / min according to BS ISO 14317: 2015.

IV. Resultados IV. Results

Caracterización de polvos aleados mecánicamente mediante MicroscopíaCharacterization of mechanically alloyed powders by Microscopy

Electrónica de Barrido (SMEB) Scanning Electronics (SMEB)

La Figura 10 muestra imágenes SEM de polvos aleados mecánicamente durante 50 h a magnificación de a) 1000X, b) 5000X, c) 7500X y d) 10000X de la aleación de titanio (Ti-13% Ta-12%Sn (%at.)). Se observó una morfología irregular, con algunas partículas aglomeradas, bordes redondeados y otras dispersas. Además, se apreció una distribución de tamaño poco homogénea, con formación de una morfología esférica. Cabe señalar que los procesos de soldadura en frío y fractura coexisten durante el proceso de molienda, sin embargo, existe la predominancia de soldadura en frío, ya que se observó que las partículas poseen una morfología esférica. Figure 10 shows SEM images of mechanically alloyed powders for 50 h at magnification of a) 1000X, b) 5000X, c) 7500X and d) 10000X of the titanium alloy (Ti-13% Ta-12% Sn (% at.)) . An irregular morphology was observed, with some agglomerated particles, rounded edges and others scattered. In addition, a not very homogeneous size distribution was observed, with the formation of a spherical morphology. It should be noted that the cold welding and fracture processes coexist during the grinding process, however, there is the predominance of cold welding, since it was observed that the particles have a spherical morphology.

Caracterización con EPS Characterization with EPS

Se le realizó un microanálisis por energía dispersiva a los polvos aleados mecánicamente, los resultados se muestran en la Figura 11 , en donde a) corresponde al área de los polvos probeta donde se realizó el EDS y b) los elementos que se encuentran presentes cada uno con un color característico y coloreado en el área donde se encuentra presente. Se observó que en todas las áreas la distribución de los elementos es homogénea, como se esperaba, los elementos que predominan son el Ti, Ta y Sn, seguido por el oxígeno. A las 50 h se observó que cada partícula contiene sustancialmente todos los elementos de partida, en la proporción en que se mezclaron entre sí. A microanalysis by energy dispersive was carried out on the mechanically alloyed powders, the results are shown in Figure 11, where a) corresponds to the area of the test tube powders where the EDS was carried out and b) the elements that are present each one with a characteristic and colored color in the area where it is present. It was observed that in all areas the distribution of the elements is homogeneous, as expected, the predominant elements are Ti, Ta and Sn, followed by oxygen. At 50 h it was observed that each particle contains substantially all the starting elements, in the proportion in which they were mixed together.

Caracterización por difracción de rayos X (DRX) Characterization by X-ray diffraction (XRD)

En la Figura 12 se presentan los patrones de difracción de rayos X de los polvos de aleación Ti-13Ta-12Sn (%atómico) molidos a diferentes horas. Se observó la formación de una nueva fase con estructura fcc a medida que pasa el tiempo y simultáneamente la disminución de la fase beta con el pasar de las horas. La mayor cantidad de titanio alfa se reportó a las 5 h, luego, con el transcurso del tiempo su cantidad disminuyó hasta las 40 h, donde ya no se encuentra presente esta fase. Figure 12 shows the X-ray diffraction patterns of the Ti-13Ta-12Sn (atomic%) alloy powders ground at different times. The formation of a new phase with fcc structure was observed as time passed and simultaneously the decrease of the beta phase with the passing of the hours. The highest amount of alpha titanium was reported at 5 h, then, over time, its amount decreased until 40 h, where this phase is no longer present.

Caracterización óptica de las probetas sinterizadas Optical characterization of the sintered specimens

Se realizó el dimensionamiento y registro fotográfico de las probetas (ver Figura 13) posterior al proceso de sinterización. En todas existe una disminución de tamaño de altura y diámetro de aproximadamente 0,4 y 0,7 mm, respectivamente, siendo mayor para el caso de las espumas sin microestructura bimodal (0%, 30%, 40% y 50% porosidad). La contracción volumétrica promedio para las probetas con microestructura bimodal fue de 5%, en cambio para las probetas sin estructura bimodal fue 21%. La contracción volumétrica se obtuvo mediante la Ecuación 1 , esta relación conlleva el cálculo de volumen inicial y final de las probetas cilindricas descritas en las Ecuaciones 2 y 3.

Figure imgf000017_0001
The dimensioning and photographic registration of the specimens (see Figure 13) was carried out after the sintering process. In all of them there is a decrease in height and diameter size of approximately 0.4 and 0.7 mm, respectively, being greater in the case of foams without bimodal microstructure (0%, 30%, 40% and 50% porosity). The average volumetric contraction for the specimens with bimodal microstructure was 5%, whereas for the specimens without bimodal structure it was 21%. The volumetric contraction was obtained through Equation 1, this relationship entails the calculation of the initial and final volume of the cylindrical specimens described in Equations 2 and 3.
Figure imgf000017_0001

En general para ambas estructuras se observó una distribución no homogénea de los poros y constituyentes. Esta distribución no uniforme de los poros se puede explicar mediante la segregación del material espaciador durante el vaciado de los polvos en la matriz de acero en la compactación de los polvos. In general, for both structures an inhomogeneous distribution of pores and constituents was observed. This non-uniform distribution of the pores can be explained by the segregation of the spacer material during the emptying of the powders in the steel matrix in the compaction of the powders.

Principalmente se observaron dos tonalidades en la matriz, una clara y una oscura para ambas estructuras, posteriormente el análisis de EDS permitió determinar a cuáles elementos corresponden dichas tonalidades. Mainly, two tones were observed in the matrix, one light and one dark for both structures, later the EDS analysis allowed to determine which elements these tones correspond to.

En las muestras con microestructura bimodal se observó una tonalidad más oscura (en toda la matriz) respecto a las muestras sin microestructura bimodal, lo cual se atribuye a la adición de polvos aleados mecánicamente. In the samples with bimodal microstructure, a darker hue (throughout the matrix) was observed compared to the samples without bimodal microstructure, which is attributed to the addition of mechanically alloyed powders.

Finalmente, se aprecia que la distribución de tamaño de los poros varía significativamente, ya que es posible encontrar poros con tamaños de 40 prm a 770 miti, inclusive se observan pequeños puntos negros que corresponden a microporos formados, este fenómeno se aprecia notablemente en el bulk de la muestra con estructura bimodal (0% porosidad). La forma de los poros es completamente irregular, esto se puede explicar por la forma geométrica del material espaciador utilizado (bicarbonato de amonio). Finally, it is appreciated that the pore size distribution varies significantly, since it is possible to find pores with sizes from 40 prm to 770 miti, even small black dots are observed that correspond to formed micropores, this phenomenon is notably appreciated in the bulk of the sample with bimodal structure (0% porosity). The shape of the pores is completely irregular, this can be explained by the geometric shape of the spacer material used (ammonium bicarbonate).

Caracterización de espumas metálicas mediante Microscopía Electrónica deCharacterization of metallic foams by Electron Microscopy of

Barrido (SMEB) Sweep (SMEB)

La Figura 14 muestra las imágenes representativas a 200X de magnificación de las muestras con microestructura bimodal con a) 0% porosidad, b) 30% porosidad, c) 40% porosidad y d) 50% porosidad; y sin microestructura bimodal con e) 0% porosidad, f) 30% porosidad, g) 40% porosidad y h) 50% porosidad. Se observa la interconexión de los poros, la irregularidad de su forma y distinta distribución de tamaño de ellos, además de la existencia de dos tonalidades diferentes. Determinación de la Porosidad Figure 14 shows the representative images at 200X magnification of the samples with bimodal microstructure with a) 0% porosity, b) 30% porosity, c) 40% porosity and d) 50% porosity; and without bimodal microstructure with e) 0% porosity, f) 30% porosity, g) 40% porosity and h) 50% porosity. The interconnection of the pores, the irregularity of their shape and their different size distribution are observed, as well as the existence of two different shades. Determination of Porosity

Para medir la porosidad se usó el método de Arquímedes, los resultados se presentan en la Tabla 3. En el caso de la porosidad aparente y absorción de agua en valores porcentuales, volúmenes en cm3 y densidad en g/cm3. Tabla 3

Figure imgf000018_0001
To measure porosity, the Archimedes method was used, the results are presented in Table 3. In the case of apparent porosity and water absorption in percentage values, volumes in cm 3 and density in g / cm 3 . Table 3
Figure imgf000018_0001

La porosidad aparente es la relación del volumen de los poros abiertos de la muestra con su volumen exterior y que no considera el volumen de los poros cerrados. En todas las probetas se obtuvo un valor superior respecto a la porosidad teórica (ver Figura 15), el aumento de la porosidad se puede explicar no sólo por la porosidad introducida mediante el material espaciador, sino que también por la generada con la propia sinterización entre las partículas, es decir, se formaron microporos que aumentan el porcentaje de porosidad. Además, se observa que la porosidad en las espumas con estructura bimodal es levemente superior a las sin microestructura bimodal, por lo que es posible concluir que la adición de microestructura bimodal promueve la generación de porosidad interconectada. Sin embargo, cabe señalar que a medida que aumenta la porosidad teórica, disminuye el porcentaje de error absoluto respecto a la porosidad aparente llegando desde un 24% a un 5%. Las probetas con microestructura bimodal presentan valores levemente superiores respecto a las probetas sin microestructura bimodal con la misma tendencia. The apparent porosity is the ratio of the volume of the open pores of the sample with its external volume and does not consider the volume of the closed pores. In all the specimens a higher value was obtained with respect to the theoretical porosity (see Figure 15), the increase in porosity can be explained not only by the porosity introduced by the spacer material, but also by that generated with the sintering itself between the particles, that is, micropores were formed that increase the percentage of porosity. Furthermore, it is observed that the porosity in foams with bimodal structure is slightly higher than those without bimodal microstructure, so it is possible to conclude that the addition of bimodal microstructure promotes the generation of interconnected porosity. However, it should be noted that as the theoretical porosity increases, the percentage of absolute error with respect to the apparent porosity decreases, reaching from 24% to 5%. The specimens with bimodal microstructure present slightly higher values compared to the specimens without bimodal microstructure with the same tendency.

Respecto a la densidad (ver Figura 16) se obtiene una relación lineal inversa respecto a la porosidad teórica, es decir, a medida que aumenta el porcentaje de porosidad, disminuye la densidad con un coeficiente de determinación (R2) de 0,99 aproximadamente. Esta tendencia se observa en ambas microestructuras. Cabe destacar que a partir de un 30% de porosidad, la densidad de las probetas sin microestructura bimodal es levemente superior. Regarding the density (see Figure 16), an inverse linear relationship is obtained with respect to the theoretical porosity, that is, as the percentage of porosity increases, the density decreases with a coefficient of determination (R 2 ) of approximately 0.99 . This trend is observed in both microstructures. It should be noted that from 30% porosity, the density of the specimens without bimodal microstructure is slightly higher.

Módulo de elasticidad Modulus of elasticity

El módulo de elasticidad se obtuvo mediante el ensayo de ultrasonido, los resultados se muestran en la Tabla 4 y graficados en la Figura 17. Se obtiene una relación lineal inversa respecto a la porosidad teórica, es decir, a medida que aumenta el %porosidad, disminuye el módulo de elasticidad. Esta relación es esperable, ya que el módulo de elasticidad de un material poroso disminuye a medida que la porosidad aumenta. Por otro lado, si se comparan los módulos obtenidos en ambas estructuras es posible apreciar que en el caso de la microestructura bimodal se obtuvieron valores menores respecto a sin microestructura bimodal; sin embargo, a medida que aumenta el %porosidad, disminuye la diferencia entre ambas rectas, y en donde el módulo de elasticidad se modifica de acuerdo al %porosidad. The modulus of elasticity was obtained through the ultrasound test, the results are shown in Table 4 and graphed in Figure 17. An inverse linear relationship is obtained with respect to the theoretical porosity, that is, as the% porosity increases, decreases the modulus of elasticity. This relationship is to be expected, since the modulus of elasticity of a porous material decreases as the porosity increases. On the other hand, if the modules obtained in both structures are compared, it is possible to appreciate that in the case of the bimodal microstructure, lower values were obtained compared to without bimodal microstructure; however, as the% porosity increases, the difference between the two lines decreases, and where the modulus of elasticity is modified according to the% porosity.

Tabla 4

Figure imgf000019_0001
Esfuerzo de fluencia Table 4
Figure imgf000019_0001
Yield stress

Se evidenció el aumento de los valores de microdureza de las muestras con microestructura bimodal respecto a las muestras sin microestructura bimodal, esto se debe a la presencia de granos finos producidos en la molienda y su endurecimiento por deformación. The increase in the microhardness values of the samples with bimodal microstructure with respect to the samples without bimodal microstructure was evidenced, this is due to the presence of fine grains produced in grinding and their deformation hardening.

CONCLUSIONES CONCLUSIONS

Mediante la caracterización por DRX se puede señalar que en el caso de las espumas con microestructura bimodal predomina la presencia de una solución sólida base Ti con microestructura beta y algunos compuestos intermetálicos como SnTa3. Mientras que en el caso de las espumas sin microestructura bimodal predomina la presencia una solución sólida base Ti con microestructura. By means of XRD characterization, it can be pointed out that in the case of foams with bimodal microstructure, the presence of a solid solution base Ti with beta microstructure and some intermetallic compounds such as SnTa3 predominates. While in the case of foams without bimodal microstructure, the presence of a solid Ti-based solution with microstructure predominates.

Respecto a los resultados de % porosidad aparente, en todas las probetas se obtuvo un valor superior respecto a la porosidad teórica. Las probetas con microestructura bimodal presentan valores levemente superiores respecto a las probetas sin microestructura bimodal. Regarding the results of% apparent porosity, in all the specimens a higher value was obtained with respect to the theoretical porosity. The specimens with bimodal microstructure show slightly higher values compared to the specimens without bimodal microstructure.

Las probetas con microestructura bimodal presentan menor valor de módulo de Young respecto a las probetas sin microestructura bimodal; sin embargo, a medida que aumenta el %porosidad, disminuye la diferencia entre ambas rectas. The specimens with bimodal microstructure have a lower value of Young's modulus compared to the specimens without bimodal microstructure; however, as the% porosity increases, the difference between the two lines decreases.

Al considerar que el módulo de elasticidad reportado, el hueso humano no supera los 30 GPa, las probetas que cumplen con este valor para su implantación en el cuerpo humano corresponderían a las espumas con una porosidad de 30%, 40% y 50% con y sin microestructura bimodal. Considering that the modulus of elasticity reported, human bone does not exceed 30 GPa, the specimens that meet this value for implantation in the human body would correspond to foams with a porosity of 30%, 40% and 50% with and without bimodal microstructure.

La adición de microestructura bimodal mejora considerablemente el esfuerzo de fluencia. The addition of bimodal microstructure considerably improves yield stress.

La microestructura bimodal y porosidad adecúan (favorece la disminución) el módulo de elasticidad y esfuerzo de fluencia de espumas de aleaciones de Ti- 13Ta-XSn (X = 3, 6, 9 y 12 %atómico) necesarias para estar en el cuerpo humano, siendo la porosidad la más influyente. Las probetas con microestructura bimodal y con porosidad cumplen los requerimientos mecánicos para servir como implantes biomédicos, módulo elástico menor a 30 GPa y esfuerzo de fluencia en compresión sobre 120 MPa. The bimodal microstructure and porosity adapt (favor the decrease) the modulus of elasticity and yield stress of Ti- 13Ta-XSn alloy foams (X = 3, 6, 9 and 12 atomic%) necessary to be in the human body, being porosity the most influential. Specimens with bimodal microstructure and porosity meet the mechanical requirements to serve as biomedical implants, elastic modulus less than 30 GPa and yield stress in compression over 120 MPa.

La sección anterior se considera únicamente ilustrativa de los principios de la invención. El alcance de las reivindicaciones no debe estar limitado por las realizaciones a modo de ejemplo expuestas en la sección anterior, sino que se les debe dar la interpretación más amplia congruente con la memoria descriptiva como un todo. The preceding section is considered only illustrative of the principles of the invention. The scope of the claims should not be limited by the exemplary embodiments set forth in the preceding section, but should be given the broadest interpretation consistent with the specification as a whole.

Claims

REIVINDICACIONES 1. Espuma de aleación en base a titanio, CARACTERIZADA porque la aleación es: 1. Alloy foam based on titanium, CHARACTERIZED because the alloy is: Ti-13Ta-XSn en donde X = 3, 6, 9 y 12 %atómico. Ti-13Ta-XSn where X = 3, 6, 9 and 12 atomic%. 2. La espuma de aleación en base a titanio de acuerdo a la reivindicación 1 , CARACTERIZADA porque la aleación es Ti-13Ta-3Sn. 2. The titanium-based alloy foam according to claim 1, CHARACTERIZED in that the alloy is Ti-13Ta-3Sn. 3. La espuma de aleación en base a titanio de acuerdo a la reivindicación 1 , CARACTERIZADA porque la aleación es Ti-13Ta-6Sn. 3. The titanium-based alloy foam according to claim 1, CHARACTERIZED in that the alloy is Ti-13Ta-6Sn. 4. La espuma de aleación en base a titanio de acuerdo a la reivindicación 1 , CARACTERIZADA porque la aleación es Ti-13Ta-12Sn. 4. The titanium-based alloy foam according to claim 1, CHARACTERIZED in that the alloy is Ti-13Ta-12Sn. 5. La espuma de aleación en base a titanio de acuerdo a las reivindicaciones 1 a 3, CARACTERIZADA porque tiene una porosidad de hasta un 50%. 5. The titanium-based alloy foam according to claims 1 to 3, CHARACTERIZED in that it has a porosity of up to 50%. 6. La espuma de aleación en base a titanio de acuerdo a las reivindicaciones anteriores, CARACTERIZADA porque tiene un módulo elástico de hasta a 30 GPa. 6. The titanium-based alloy foam according to the preceding claims, CHARACTERIZED because it has an elastic modulus of up to 30 GPa. 7. La espuma de aleación en base a titanio de acuerdo a las reivindicaciones anteriores, CARACTERIZADA porque tiene límite elástico superior a 200 MPa. 7. The titanium-based alloy foam according to the preceding claims, CHARACTERIZED in that it has an elastic limit greater than 200 MPa. 8. Método de preparación de una espuma de aleación en base a titanio de acuerdo a la reivindicación 1 , CARACTERIZADO porque comprende las siguientes etapas: iv. preparación de la aleación Ti-13Ta-XSn (X = 3, 6, 9 y 12 %at); v. preparación de probetas verdes a partir de la aleación; y mediante compactación; y vi. sinterización de las probetas verdes. 8. Method of preparing a titanium-based alloy foam according to claim 1, CHARACTERIZED because it comprises the following steps: iv. preparation of the Ti-13Ta-XSn alloy (X = 3, 6, 9 and 12 at%); v. preparation of green specimens from the alloy; and by compaction; and I saw. sintering the green specimens. 9. El método de acuerdo a la reivindicación 7, CARACTERIZADO porque la etapa de preparación de la aleación se realiza mediante aleado mecánico. 9. The method according to claim 7, CHARACTERIZED in that the alloy preparation step is carried out by mechanical alloying. 10. El método de acuerdo a la reivindicación 7, CARACTERIZADO porque la etapa de preparación de las probetas verdes se realiza por compactación de la aleación. 10. The method according to claim 7, CHARACTERIZED in that the preparation stage of the green specimens is carried out by compacting the alloy. 11. El método de acuerdo a la reivindicación 7, CARACTERIZADO porque en la etapa de preparación de las probetas verdes se emplea un material espaciador. 11. The method according to claim 7, CHARACTERIZED in that a spacer material is used in the preparation stage of the green specimens. 12. El método de acuerdo a la reivindicación 10, CARACTERIZADO porque el material espaciador es bicarbonato de amonio. 12. The method according to claim 10, CHARACTERIZED in that the spacer material is ammonium bicarbonate. 13. El método de acuerdo a la reivindicación 11 , CARACTERIZADO porque el material espaciador 13. The method according to claim 11, CHARACTERIZED in that the spacer material 14. El método de acuerdo a la reivindicación 9, CARACTERIZADO porque la etapa de sinterización de las probetas verdes compactadas se realiza en un horno tubular. 14. The method according to claim 9, CHARACTERIZED in that the sintering stage of the compacted green specimens is carried out in a tube furnace. 15. El método de acuerdo a la reivindicación 10, CARACTERIZADO porque la etapa de sinterización se realiza a 1300°C. 15. The method according to claim 10, CHARACTERIZED in that the sintering step is carried out at 1300 ° C. 16. Uso de la espuma de aleación en base a titanio de acuerdo a la reivindicación 1 , CARACTERIZADO porque sirve como biomaterial. 16. Use of the titanium-based alloy foam according to claim 1, CHARACTERIZED because it serves as a biomaterial. 17. El uso de la espuma de aleación en base a titanio de acuerdo a la reivindicación 16, CARACTERIZADO porque el biomaterial es un implante óseo. 17. The use of the titanium-based alloy foam according to claim 16, CHARACTERIZED in that the biomaterial is a bone implant.
PCT/CL2019/050140 2019-12-13 2019-12-13 Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial Ceased WO2021113999A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CL2019/050140 WO2021113999A1 (en) 2019-12-13 2019-12-13 Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CL2019/050140 WO2021113999A1 (en) 2019-12-13 2019-12-13 Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial

Publications (1)

Publication Number Publication Date
WO2021113999A1 true WO2021113999A1 (en) 2021-06-17

Family

ID=76329273

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CL2019/050140 Ceased WO2021113999A1 (en) 2019-12-13 2019-12-13 Titanium-based alloy foam; method for preparing the alloy; and use thereof as biomaterial

Country Status (1)

Country Link
WO (1) WO2021113999A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2459686C2 (en) * 2010-07-15 2012-08-27 Государственное образовательное учреждение высшего профессионального образования Самарский государственный технический университет Method of making titanium nickelide-based porous biocompatible materials
WO2018009582A1 (en) * 2016-07-05 2018-01-11 Porosteon Development Llc Porous metal devices

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2459686C2 (en) * 2010-07-15 2012-08-27 Государственное образовательное учреждение высшего профессионального образования Самарский государственный технический университет Method of making titanium nickelide-based porous biocompatible materials
WO2018009582A1 (en) * 2016-07-05 2018-01-11 Porosteon Development Llc Porous metal devices

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
AGUIRRE, T.: "Efecto De La Estructura Biomodal Y Porosidad Sobre EI Modulo De Elasticidad Y Esfuerzo De Fluencia En Espumas De Ti-Ta-Sn. Tesis de pregrado para optar al titulo de ingeniero civil metalúrgico", TESIS DE PREGRADO PARA OPTAR AL TITULO DE INGENIERO CIVIL METALÚRGICO, March 2018 (2018-03-01), Universidad Tecnica Federico Santa Maria, Chile, XP055834675, Retrieved from the Internet <URL:https://repositorio.usm.cl/bitstream/handle/11673/24077/3560900258117UTFSM.pdf?sequence=1&isAllowed=y> [retrieved on 20200417] *
ARNALDI, C. ET AL.: "Analysis Of Synthesis And Mechanical Properties Of Ti-Ta-Sn Foams For Use In Biomedical Applications", XXVII INTERNATIONAL MATERIALS RESEARCH CONGRESS, 2018 *
ARNALDI, C.: "Análisis De Sintesis Y Propiedades Mecanicas De Espumas Ti-Ta-Sn Para El Uso En Aplicaciones Biomedicas. Tesis de pregrado para optar al tituio de ingeniero civil metalurgico", TESIS DE PREGRADO PARA OPTAR AL TITULO DE INGENIERO CIVIL METALÚRGICO, September 2019 (2019-09-01), Universidad Tecnica Federico Santa Maria, Chile, XP055834676, Retrieved from the Internet <URL:https://repositorio.usm.cl/bitstream/handle/11673/47205/3560900260918UTFSM.pdf?sequence=1&isAllowed=y> [retrieved on 20200416] *
PALKA, K. ET AL.: "Porous Titanium Implants", ADVANCED ENGINEERING MATERIALS, vol. 20, no. 5, May 2018 (2018-05-01), pages 1700648, XP055834677, DOI: 10.1002/adem.201700648 *
XIONG LI, WONG JIANYU, HODGSON CYNTHIA S, PETER D, CUI WEN, LI YUNCANG, PH D, XIONG JIANYU, ENG M, WONG CYNTHIA S, PH D, HODGSO: "Ti6Ta4Sn Alloy and Subsequent Scaffolding for Bone Tissue Engineering", TISSUE ENGINEERING: PART A, vol. 15, no. 10, 1 October 2009 (2009-10-01), pages 3151 - 3159, XP055834678 *

Similar Documents

Publication Publication Date Title
Brailovski et al. Bulk and porous metastable beta Ti–Nb–Zr (Ta) alloys for biomedical applications
Ehtemam-Haghighi et al. Microstructural evolution and mechanical properties of bulk and porous low-cost Ti–Mo–Fe alloys produced by powder metallurgy
Tan et al. Additive manufacturing of bio-inspired multi-scale hierarchically strengthened lattice structures
Yan et al. Improved mechanical properties of the new Ti-15Ta-xZr alloys fabricated by selective laser melting for biomedical application
Zhang et al. Superelastic behaviors of biomedical porous NiTi alloy with high porosity and large pore size prepared by spark plasma sintering
Mavros et al. Spark plasma sintering of low modulus titanium-niobium-tantalum-zirconium (TNTZ) alloy for biomedical applications
Li et al. Fabrication and characterization of porous Ti–10Cu alloy for biomedical application
Li et al. Fabrication of biomedical Ti-24Nb-4Zr-8Sn alloy with high strength and low elastic modulus by powder metallurgy
Ahn et al. Mechanical and microstructural characteristics of commercial purity titanium implants fabricated by electron-beam additive manufacturing
Bertheville Porous single-phase NiTi processed under Ca reducing vapor for use as a bone graft substitute
Hsu et al. Processing and mechanical properties of porous Ti–7.5 Mo alloy
Wang et al. Effects of Sn content on the microstructure, mechanical properties and biocompatibility of Ti–Nb–Sn/hydroxyapatite biocomposites synthesized by powder metallurgy
Yang et al. Mechanical properties of porous Ti-Mo and Ti-Nb alloys for biomedical application by gelcasting
Salvo et al. Mechanically enhanced novel Ti-based alloy foams obtained by hot pressing
Kaya et al. Microstructure characterization and biocompatibility behaviour of TiNbZr alloy fabricated by powder metallurgy
Kumar et al. Statistical modelling of mechanical properties and bio-corrosion behaviour of Mg3Zn1Ca15Nb fabricated using microwave sintering
Aguilar et al. Improving the mechanical strength of ternary beta titanium alloy (Ti-Ta-Sn) foams, using a bimodal microstructure
Topuz et al. Processing of Ti/(HA+ ZrO2) biocomposite and 50% porous hybrid scaffolds with low Young's modulus by powder metallurgy: Comparing of structural, mechanical, and corrosion properties
Lai et al. Effect of pore structure regulation on the properties of porous TiNbZr shape memory alloys for biomedical application
Awad et al. Physical, mechanical, and corrosion properties of Ti–12Mo and Ti–15Mo alloys fabricated by elemental blend and mechanical alloying techniques
Hsu et al. Structure and mechanical properties of as-cast Ti–5Nb–xCr alloys
Gao et al. Preparation and characterization of Ti-10Mo alloy by mechanical alloying
Bütev et al. Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions
Ansari et al. Fabrication and characterization of magnesium-based nanocomposites reinforced with Baghdadite and carbon nanotubes for orthopaedical applications
US20090088845A1 (en) Titanium tantalum oxygen alloys for implantable medical devices

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19955990

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19955990

Country of ref document: EP

Kind code of ref document: A1