Classifications

• • 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
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
• • 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
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
  • C22C1/1047—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/062—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on B4C
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
  • C22C32/0052—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides
  • C22C32/0057—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides based on B4C

Definitions

• the present invention relates to the field of synthesis of metal matrix composite materials and ceramic particulate reinforcements.
• the invention relates to a method for preparing a composite material having an aluminum matrix having dispersed therein reinforcements Al3B 4 8C 2.
• This process can notably be applied in the fields of aeronautics and the automobile.
• CMM metal matrix materials
• metal matrix materials which comprise a metal matrix (metal or metal alloy) in which are incorporated reinforcements (particles, fibers or other) metal or ceramic
• CMM metal matrix materials
• the advantage of CMM compared to light alloys (based on aluminum, magnesium or titanium) is that they have ratios E / p (elastic modulus / density) and ⁇ / ⁇ (limit of elasticity / density) very high.
• the composite material AI / B 4 C which is a particularly useful composite material that boron carbide is one of the most known hard material, it is lightweight and has a higher melting temperature at 2400 ° C.
• the chemical reactivity must also be controlled. Indeed, the equilibrium between the phases in the Al-BC system indicates that Al and B 4 C are not in equilibrium below a temperature which is not precisely known, but which is estimated in the literature to be superior at 1400 ° C.
• any synthesis based on the mixture of precursor powders of Al and B 4 C and carried out at a temperature below 1400 ° C therefore leads to the decomposition of the reinforcement B 4 C by Al and the formation of carbide AI3BC3.
• the latter although less sensitive to hydrolysis in the presence of moisture than the carbide AI 4 C3, still remains subject to this phenomenon which leads to the release of large amounts of CH 4 gas.
• the gas produced at the core of the composite material then generates stresses that lead to the ruin of the composite material (return to the powder state).
• other phases such as borides AIB 2 and AIB12 can also be formed during the interaction between Al and B 4 C. The fragility of these phases then induces embrittlement of the composite material.
• the first solution which will be called the cryogenic method, was developed by Julie Schoenung at the University of California, Davis. This method encounters the difficulty of implementing high energy grinding in liquid nitrogen for large quantities of material. The change of scale from laboratory to industrial production seems difficult. Moreover, this method can not ignore a consolidation step that must be carried out hot.
• the second solution is to minimize the duration of the hot consolidation step to limit as far as possible the progress of the reaction between Al and B 4 C.
• the main difficulty lies again in the amount of usable material. Indeed, the hot forming requires that the matrix Al is brought to a temperature sufficient to be subject to plastic deformation by creep. However, in the case of a large volume of material, the standardization of the temperature da ns the entire volume requires a significant temperature maintenance time also.
• the inventors have therefore set themselves the goal of designing a process for producing an alternative composite material to the composite AI / B 4 C, which has properties similar to those of the composite AI / B 4 C, while being able to be produced industrially. .
• the graphite element for closing the cavity is a graphite piston.
• the AIB 2 powder When placed in the graphite crucible in step a), the AIB 2 powder may be in various forms. According to a first variant, the powder is placed in the crucible in a compressed form, for example in the form of one or more pellets. According to a second variant, the powder is placed in the crucible in a powder form and step b) further comprises a compression of the powder. It is preferred to use the powder in powder form and compress it in the cavity of the crucible, since the AIB 2 diborure is weakly ductile, obtaining a compact is difficult.
• step b) when the powder is placed in the crucible in pulverulent form, step b) further comprises the compression of the powder.
• the compression of the powder and the closing of the cavity of the crucible are obtained by the use of a graphite piston.
• the piston is dimensioned so as to slide in the opening of the crucible in order to compress the powder and to close this opening.
• the crucible is heated at a temperature ranging from 1000 ° C. to 1400 ° C. for a period ranging from 5 minutes to 30 minutes.
• the descent in temperature in step d) is fast. This makes it possible to limit the decomposition reactions of the phases formed at high temperature.
• the cooling in step d) comprises a descent in temperature with a speed greater than or equal to 10 ° C / s until reaching 600 ° C.
• step e) The elimination of the crucible in step e) can be obtained separating the ingot of composite material obtained at the end of step d) (and which forms the composite material part to obtain) crucible or by proceeding to a turning operation that will destroy the crucible.
• the composite material AI / Al3B 4 8C 2 is made according the method of the invention is a good alternative to the composite material AI / B 4 C.
• the ternary compound T3-Al3B 4 SC 2 which form the reinforcement is in equilibrium with the Al matrix according to the literature.
• it has properties similar to those of B 4 C, as can be seen from the table below, and is therefore a credible alternative to B 4 C for the production of a ceramic matrix composite and reinforcement of carbide type rich in boron.
• the matrix and the reinforcement are formed at high temperature and in-situ, which has several advantages.
• the reinforcements of the composite are obtained during the decomposition of the AIB 2 particles by germination / growth in the liquid phase.
• the matrix / reinforcement interface is therefore chemically clean (no impurities, oxides or other) and thus leads to optimum resistance of the interface.
• the reinforcements are formed in situ and have not had to undergo a grinding cycle, grinding which is often likely to induce defects which are then starting points for the cracking of the composite material.
• the method which is the subject of the invention also has the advantage of the simplicity of its implementation.
• it makes it possible to obtain a dense ingot directly from the internal geometry of the graphite crucible, since the ingot is shaped in the liquid state in the graphite crucible.
• the single figure is an image obtained by scanning electron microscopy of an ingot obtained according to a first embodiment according to the method which is the subject of the invention.
• the method which is the subject of the invention is based on a so-called reactive synthesis method.
• the matrix and the reinforcement of the composite material are obtained in situ by a reaction between two precursors.
• the precursors chosen are aluminum diboride (AIB 2 ) and graphite (C).
• AIB 2 is in the form of a powder and is placed in a crucible which is made of graphite.
• the same graphite element preferably a graphite piston, is used to compact the powder and to seal the cavity of the crucible.
• the whole is then heated to high temperature.
• the heating is performed at a temperature above the decomposition temperature of AIB 2 , that is to say the temperature from which one begins to have a liquid phase.
• the decomposition temperature of AIB 2 i.e. at 960 ° C, two phases are obtained, a liquid phase and a solid phase.
• the heating is carried out at a temperature of between 1000 ° C. and 1400 ° C., preferably between 1200 ° C. and 1400 ° C., for a period of time. which can be variable, but will generally be between 5 and 30 minutes. In fact, the duration of heating at a given temperature is adjusted according to the desired microstructure: the longer the heating time, the larger the size of the reinforcing particles.
• the two phases AIB 2 and C is not in equilibrium, they react together to form the mixed carbide and Al Al3B 4 8C 2.
• the climbs and descents in temperature are fast, in order to limit both the size of the reinforcing particles and their decomposition during cooling.
• the graphite crucible can be removed by simple machining, releasing the ingot of CMM composite material contained therein. Since this was obtained at a temperature higher than the Al fusion, the presence of the matrix in the liquid state makes it possible to directly obtain a composite with a relative density greater than 99.5%.
• the microstructure of the AI / Al3B 4 sC 2 composite thus obtained is observed under SEM (single figure).
• the white phase corresponds to the aluminum matrix and the black particles correspond to the reinforcement phase Al3B 4 sC 2 . It is found that the reinforcements are homogeneously dispersed in the matrix and have a size of between 200 nm and 5 ⁇ (average size of about 700 nm).
• the method of the invention makes it possible to create an interface between a matrix and a reinforcement which is mechanically strong, but without leading to the decomposition of the reinforcement and the creation of deleterious secondary phases for the properties of the composite. Indeed, during the reactive synthesis between AIB 2 and graphite (C), there are very few minor phases are formed and the composite thus essentially comprises a phase of Al (the matrix) and a phase of Al3B 4 8C 2 (reinforcement), the minor phases being present in minimal amounts.
• the process according to the invention provides a new synthetic route for producing, in a simple manner and in quantity, Al-matrix composite materials reinforced with particles of a mixed boron (B) and aluminum (Al) carbide. whose properties are close to those of a B 4 C reinforcement.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

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Cited By (1)

Citations (3)

• 2015
  • 2015-07-20 FR FR1556859A patent/FR3039169B1/fr not_active Expired - Fee Related
• 2016
  • 2016-07-19 RU RU2018106104A patent/RU2018106104A/ru not_active Application Discontinuation
  • 2016-07-19 EP EP16741604.9A patent/EP3325681B1/fr not_active Not-in-force
  • 2016-07-19 WO PCT/EP2016/067116 patent/WO2017013087A1/fr not_active Ceased
  • 2016-07-19 US US15/745,927 patent/US20180209016A1/en not_active Abandoned

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