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WO2025049973A1 - Impression 3d à base d'aérosol de nanoparticules - Google Patents

Impression 3d à base d'aérosol de nanoparticules Download PDF

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Publication number
WO2025049973A1
WO2025049973A1 PCT/US2024/044763 US2024044763W WO2025049973A1 WO 2025049973 A1 WO2025049973 A1 WO 2025049973A1 US 2024044763 W US2024044763 W US 2024044763W WO 2025049973 A1 WO2025049973 A1 WO 2025049973A1
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WIPO (PCT)
Prior art keywords
printing
solvent
particles
nozzle
furnace
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WO2025049973A9 (fr
Inventor
Shalinee Kavadiya
Pratim Biswas
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University of Miami
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University of Miami
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Publication of WO2025049973A9 publication Critical patent/WO2025049973A9/fr
Pending legal-status Critical Current
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Classifications

    • 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
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/22—Direct deposition of molten metal
    • 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
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/50—Means for feeding of material, e.g. heads
    • B22F12/53—Nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • 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
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/90—Means for process control, e.g. cameras or sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing

Definitions

  • State-of-the-art three-dimensional (3D) printing techniques include: 1) extrusion and melting of a wire filament (for polymers, no metals) and printing on a surface; 2) photocuring a liquid polymer with light or a laser; 3) melting a bed or pile of metal powder with a laser or electron beam; or 4) extruding a viscous ink.
  • each of these technologies has at least one of the following limitations: i) lack of versatility (i.e., inability to print a broad variety of materials and/or on a wide range of surfaces); ii) lack of speed (i.e., inability to print quickly, considering the post-processing of the printed structure); and iii) lack of resolution and precision (i.e., poor resolution and ability to control the properties of the printed structure).
  • powder bed fusion the primary technique for 3D printing of metals, is highly complex, uses a powder bed that is difficult to manage, uses a high-energy laser that increases the process energy demand, and has a resolution of only 50 micrometers (pm) as it uses large particles (45 pm), and having a bed of small nanoparticles is very challenging. Additionally, it is difficult to print composite polymeric materials with the powder bed fusion technique.
  • Embodiments of the subject invention provide novel and advantageous systems and methods for aerosol-based three-dimensional (3D) printing (A3DP).
  • A3 DP can be used for layer- by-layer (i.e., additive manufacturing) printing of polymers, metals, metal oxides, and composite materials by melting their nanoparticles.
  • a solution of materials to be printed that can contain soluble materials or nanoparticles or their precursors
  • is atomized e.g., using a collison nebulizer to produce droplets of the material (solvent and precursor/nanoparticles).
  • the solvent can then be evaporated using a dryer (e.g., a diffusion dryer) and/or a furnace (e.g., an electric furnace), and particles can be fed into a 3D printing nozzle.
  • the nozzle can be heated to melt the particles and translated over the printer bed according to the 3D model file to deposit molten or semi-molten nanoparticles and print the structure.
  • A3DP can be used to print polymers, metals, and composite materials at high resolution with fine details.
  • the systems and methods are simple to use and capable of printing nearly any material with speed, resolution, and accuracy.
  • a method for A3 DP can comprise: dissolving a first material in a first solvent to give a first solution; atomizing the first solution to produce first droplets comprising the first solvent and the first material; evaporating the first solvent by providing the first droplets to at least one of a dryer and a furnace to leave first particles comprising the first material; feeding the first particles into a 3D printing nozzle; heating the 3D printing nozzle to melt the first particles and give heated particles that are molten or semi-molten; and using the 3D printing nozzle to deposit the heated particles on a substrate, thereby printing a structure using a deposited material.
  • the deposited material can comprise the first material or the first material can be a precursor of the deposited material.
  • the first solvent can be evaporated by, for example, providing the first droplets to the dryer or by providing the first droplets to the furnace.
  • the dryer can be a diffusion dryer, and the furnace can be an electric furnace.
  • the first material can comprise first soluble materials dissolved in the first solvent and/or suspended nanoparticles dispersed in the first solvent (e.g., only nanoparticles, only dissolvable (i.e., soluble) material, or both).
  • the first material can be or comprise a polymer, a metal, a metal oxide, or a combination thereof (including multiple polymers, multiple metals, or multiple metal oxides).
  • Atomizing the first solution to produce the first droplets can comprise using a collision nebulizer.
  • a size of the first droplets can be in a range of from 1 micrometer (pm) to 5 pm.
  • a resolution of the A3DP can be, for example, 40 pm or less (e.g., 10 pm or about 10 pm).
  • the first solution can further comprise a second material different from the first material; the deposited material can be a composite material of a third material and a fourth material; the first material can be the same as the third material or can be a precursor of the third material; and the second material can be the same as the fourth material or can be a precursor of the fourth material.
  • the second material can comprise second soluble materials dissolved in the first solvent and/or suspended nanoparticles dispersed in the first solvent (e.g., only nanoparticles, only dissolvable (i.e., soluble) material, or both).
  • the second material can be or comprise a polymer, a metal, a metal oxide, or a combination thereof (including multiple polymers, multiple metals, or multiple metal oxides).
  • a size of the first particles can be in a range of from 450 nanometers (nm) to 2.5 pm.
  • the first material can be a water-soluble polymer (for example, polyethylene glycol (PEG)).
  • the method can further comprise: dissolving a second material in a second solvent to give a second solution; atomizing the second solution to produce second droplets comprising the second solvent and the second material; evaporating the second solvent by providing the second droplets to at least one of the dryer and the furnace to leave second particles comprising the second material; and feeding the second particles into the 3D printing nozzle.
  • Heating the 3D printing nozzle can melt the second particles; the heated particles can comprise the second material; the deposited material can be a composite material of a third material and a fourth material; the first material can be the same as the third material or can be a precursor of the third material; and the second material can be the same as the fourth material or can be a precursor of the fourth material.
  • a size of the second particles can be in a range of from 450 nm to 2.5 pm.
  • a system for A3DP can comprise: a solvent-evaporating device that comprises at least one of a dryer and a furnace; a 3D printing nozzle connected to an exit of the solvent-evaporating device; a tube connecting the 3D printing nozzle to the exit of the solvent evaporating device; a heating element disposed around the 3D printing nozzle and configured to heat the 3D printing nozzle during use; and a platform disposed below an exit of the 3D printing nozzle and configured for 3D printing thereon.
  • the device can further comprise an atomizer configured to atomize a solution to produce droplets to be provided to the solvent-evaporating device.
  • the atomizer can comprise or be, for example, a collison nebulizer.
  • the system can further comprise a container connected to an entrance of the solvent-evaporating device and configured to have droplets contained therein.
  • the system can further comprise a first chamber having the container and the solvent-evaporating device disposed therein.
  • the solventevaporating device can comprise the dryer, the furnace, or both.
  • the dryer can be a diffusion dryer, and the furnace can be an electric furnace.
  • a resolution of the A3DP of the system can be, for example, 40 pm or less (e.g., 10 pm or about 10 pm).
  • a system for A3DP of in situ synthesized materials can comprise: a device (e.g., an atomizer, a nebulizer, a vaporizer, etc.) generating vapors and/or droplets of a precursor of the in situ synthesized materials; a solvent-evaporating device that comprises at least one of a dryer and a first furnace; a high-temperature furnace connected to an exit of the solvent-evaporating device and configured to decompose the precursor; a first tube connecting the high temperature furnace to the exit of the solvent-evaporating device; a 3D printing nozzle connected to an exit of the high-temperature furnace; a second tube connecting the 3D printing nozzle to the exit of the high temperature furnace; a heating element disposed around the 3D printing nozzle and configured to heat the 3D printing nozzle during use; and a platform disposed below an exit of the 3D printing nozzle and configured for 3D printing thereon.
  • a device e.g., an atomizer, a n
  • the device can further comprise a container connected to an entrance of the solvent-evaporating device and configured to have droplets contained therein.
  • the device can further comprise a first chamber having the container and the solvent-evaporating device (and the high-temperature furnace) disposed therein.
  • the solvent-evaporating device can comprise the dryer, the first furnace, or both.
  • the dryer can be a diffusion dryer, and the first furnace can be an electric furnace.
  • a resolution of the A3 DP of the system can be, for example, 40 pm or less (e.g., 10 pm or about 10 pm).
  • Figure la shows a schematic view of a system for aerosol-based three-dimensional (3D) printing (A3DP), according to an embodiment of the subject invention.
  • Figure lb shows images of structures printed using the system for A3DP as shown in Figure la.
  • the middle image is a microscopic image with a scale bar of 50 micrometers (pm).
  • Figures 2a-2c show scanning electron microscope (SEM) images of microstructures of polyethylene glycol (PEG) printed at different nozzle temperatures.
  • Figures 2a-2c show images or a nozzle temperature of 50 °C, 75 °C, and 100 °C, respectively. The scale bar for each image is 100 pm.
  • Figure 3a shows an electron microscope image of microstructures of PEG printed using an A3DP system.
  • the scale bar is 10 pm.
  • Figure 3b shows an electron microscope image of microstructures of a composite of PEG and lignin printed using an A3DP system.
  • the scale bar is 500 nanometers (nm).
  • Figure 3c shows an electron microscope image of microstructures of a composite of carbon particles and PEG printed using an A3DP system.
  • the scale bar is 1 pm.
  • Figure 3d shows an electron microscope image of a functionally graded material comprising lignin and PEG.
  • the scale bar is 100 pm.
  • Figure 4 shows an overview of development of an A3 DP system.
  • Figure 5a shows different nozzles that may be used with an A3DP system, according to embodiments of the subject invention.
  • Figure 5b shows structure shapes that can be printed with an A3DP system, according to embodiments of the subject invention.
  • Figure 6 shows a schematic view of a system for A3 DP, according to an embodiment of the subject invention.
  • Figure 7 shows a chart comparing A3DP technology of embodiments of the subject invention to other types of 3D printing.
  • Figure 8 shows a chart of example materials that can be printed using an A3 DP system according to embodiments of the subject invention.
  • Figure 9a shows an electron microscope image of a top view of PEG printed using an A3DP system.
  • the scale bar is 200 pm.
  • Figure 9b shows an electron microscope image of a side view of PEG printed using an A3DP system.
  • the scale bar is 100 pm.
  • Figure 9c shows an electron microscope image of a top view of PEG printed using an A3DP system.
  • the scale bar is 50 pm.
  • Figure 9d shows an electron microscope image of a cross section of PEG printed using an A3DP system.
  • the scale bar is 20 pm.
  • Figures lOa-lOh show images of different shapes and structures of PEG printed using an A3DP system.
  • Figures 10a and lOd show a square structure with a length of 5 millimeters (mm), a width of 5 mm, a height of 1 mm, and a line width of 0.2 mm.
  • Figures 10b and lOe show an equilateral triangle structure with each side having a length of 5 mm and the line width being 0.2 mm.
  • Figures 10c and lOf show a circle structure with a diameter of 5 mm and a line width of 0.2 mm.
  • Figures 10g and lOh show a pentagon structure and a hexagon structure, respectively.
  • Figure Ila shows a grid that can be printed using an A3DP system. Though certain dimensions are shown in Figure I la, these are for exemplary purposes only and should not be construed as limiting. Images of a grid printed using PEG and a lignin/PEG composite are shown in the left side and the right side, respectively, of Figure lb.
  • Figure 11b shows an electron microscope image of a grid as shown in Figure I la, printed with a lignin/PEG composite using an A3DP system.
  • the scale bar is 500 pm.
  • Figure 13 shows images of a lignin/PEG graded composite material printed using an A3DP system.
  • the righthand image shows an enlarged version of the box in the lefthand image. From left to right in each image, the lignin concentration is graded from 2.5 mg/ml lignin to 0 mg/ml of lignin.
  • Figure 15 shows images of a titanium dioxide (TiChj/PEG composite printed using an A3DP system.
  • the top righthand image shows an enlarged version of the box in the lefthand image.
  • the solution that was used to print the composite had 0.5 mg/ml of TiCh and 100 mg/ml of PEG.
  • the scale bar for the lefthand, top righthand, and bottom righthand images are 100 pm, 10 pm, and 10 pm, respectively.
  • Figures 16a-16d shows fluid flow through the four different nozzles, respectively, shown in Figure 5a.
  • Figure 17 shows different nozzles that may be used with an A3 DP system, according to embodiments of the subject invention.
  • Figure 19a shows a plot of focusing ratio versus aerosol flow velocity (in meters per second (m/s)) for nozzle 1 from Figure 17, and Figure 19b shows a plot of focusing ratio versus ratio of aerosol flow rate to sheath flow rate for nozzles 2-4 from Figure 17.
  • An aerosol flow of 2.35 m/s was used to obtain the results in Figure 19b.
  • a particle size of 500 nm, a nozzle size of 0.4 mm, and a nozzle-to-printing surface distance of 0.5 pm was used to obtain the results for both Figure 19a and Figure 19b.
  • Figure 20a shows a plot of collection efficiency versus aerosol flow velocity (in m/s) for nozzle 1 from Figure 17, and Figure 20b shows a plot of collection efficiency versus ratio of aerosol flow rate to sheath flow rate for nozzles 2-4 from Figure 17.
  • An aerosol flow of 2.35 m/s was used to obtain the results in Figure 20b.
  • a particle size of 500 nm, a nozzle size of 0.4 mm, and a nozzle-to -printing surface distance of 0.5 pm was used to obtain the results for both Figure 20a and Figure 20b.
  • Figures 21a-21c show SEM images of microstructures of poly vinylidene fluoride (PVDF) printed at different nozzle temperatures.
  • Figures 21a-21c show images for a nozzle temperature of 170 °C, 200 °C, and 220 °C, respectively. The scale bar for each image is 5 pm.
  • PVDF poly vinylidene fluoride
  • Embodiments of the subject invention provide novel and advantageous systems and methods for aerosol-based three-dimensional (3D) printing (A3 DP).
  • A3DP can be used for layer- by-layer (i.e., additive manufacturing) printing of polymers, metals, and composite materials by melting their nanoparticles.
  • a solution containing soluble materials or nanoparticles (of the material(s) to be 3D printed or their precursors) is atomized (e.g., using a collison nebulizer) to produce droplets of the material (solvent and precursor/nanoparticles).
  • the solvent can then be evaporated using a dryer (e.g., a diffusion dryer) and/or a furnace (e.g., an electric furnace), and particles can be fed into a 3D printing nozzle.
  • the nozzle can be heated to melt the particles and translated over the printer bed according to the 3D model file to deposit molten or semi-molten nanoparticles and print the structure.
  • A3DP can be used to print polymers, metals, metal oxides, and composite materials (e.g., composites of polymers, composites of metal oxide and polymers, and composites of metals and polymers) at high resolution with fine details.
  • the systems and methods are simple to use and capable of printing nearly any material with speed, resolution, and accuracy.
  • A3 DP advances the field of additive manufacturing, along with the aerospace, healthcare, energy, automotive, and defense industries.
  • Figure la shows a schematic view of a system for A3DP, according to an embodiment of the subject invention; and Figure lb shows images of structures printed using the system for A3DP as shown in Figure la.
  • the A3 DP system combines the continuous aerosol process for particle synthesis with 3D printing capabilities.
  • a solution of material to-be-printed can be aerosolized (e.g., using a nebulizer), which generates droplets ranging, for example, from 1 pm to 5 pm in size.
  • a smooth printing operation requires that the solution is stable - the solute (material to-be-printed) is either soluble or well dispersed within the solvent.
  • the droplets are then carried by a carrier gas into a dryer (e.g., diffusion dryer), heater, and/or furnace to evaporate and remove the solvent, producing dry particles.
  • the particle size can be controlled through the material concentration in the solution and can be measured online using aerosol instruments, such as a scanning mobility particle sizer (SMPS) and a GRIMM® device, and offline with a scanning electron microscope (SEM).
  • the dry particles can subsequently be introduced into the printing nozzle inside a customized printing chamber.
  • the printing nozzle can be heated, and as the particles pass through the nozzle, they undergo melting because the particles (with size on the order of nanometers or at least sub pm) melt rapidly during the short residence time in the nozzle.
  • the molten/partially molten particles deposit on the printing surface or a previously printed layer, adhere, and solidify.
  • the coordinated movement of the nozzle and the printing surface dictated by the 3D model, facilitates the sequential layer-by-layer construction of a 3D structure.
  • the resolution of the printer is defined as the smallest dimension it can print in the x, y, and z directions. Printing precision is defined as the accuracy in printing dimensions (x, y, and z) compared to the 3D model.
  • the structures can be printed onto any flat surface and can also be detached from the surface post-printing.
  • Figure 7 shows a table comparing A3DP (embodiments of the subject invention, far right column) to related state of the art 3D printing technologies, showing the advantages of A3DP.
  • Figure 8 shows a table of example materials that can be printed using A3DP and how the aerosol can be produced before supplying to the printer.
  • the particle deposition on the printing surface occurs through inertial impaction.
  • a gaseous stream containing particles flows through a nozzle with a small orifice, the flow is choked, with the upstream pressure much higher than the downstream pressure. Meanwhile, the particle experience heat from the heated nozzle and melts. Upon exiting the nozzle, the flow expands, and molten particles accelerate toward the printing surface.
  • the particles experience the following forces: 1) drag force, which represents friction between the particle and carrier gas; 2) Basset force, which represents a non-steady viscous gradient force; 3) inertia; 4) gravity force; 5) Saffman force, which represents a steady lift force induced by the local shear flow of a viscous fluid; and 6) thermophoretic force, representing temperature gradient between the nozzle and printing surface.
  • Basset force is negligible due to the very low viscosity of the carrier gas.
  • the Saffman force can be disregarded due to the low viscosity of the carrier gas and the limited gradient of gas velocity within the nozzle cross-section. Therefore, the predominant forces to consider are drag, inertia, gravitational, and thermophoretic forces.
  • the gravitational force is low for small particles.
  • thermophoretic force is small
  • fc I + 0.15 e P ° 687 is the correction factor to account for Reynolds number (Re) higher than unity.
  • the large particles with high inertia, and hence, high Stk number deviate from the gas flow and impact on the surface, whereas small particles that have low inertia and low Stk number follow the gas trajectory and deposit around the printing line in a broadened deposition pattern, which is called overspray (can be seen on the microscopic image in Figure lb). While the overspray is significantly smaller than the printed structure dimensions, its elimination is crucial for enhancing precision and resolution. Apart from particle size, the process parameters that affect the Stk number and/or influence the overspray can be crucial.
  • a smaller nozzle diameter minimizes overspray and enhances precision and resolution due to the higher particle velocity coming from the smaller nozzle, which improves the direct impaction of the particle on the surface.
  • smaller nozzles are also susceptible to clogging issues.
  • the particle impaction theory serves as a fundamental principle to various deposition techniques, such as cold spray or aerosol impaction-driven deposition and aerosol instrumentation.
  • overspray can occur in 3D printing if droplets on the order of 1 pm - 5 pm are deposited on the printing surface at lower flow rates (such as less 200 standard cubic centimeters per minute (seem)). Although the droplets are much larger to directly impact the surface, having a size distribution of droplets and low flow rates decreases the Stk number, leading to overspray.
  • A3DP utilizes particles that are much smaller (e.g., less than 2 pm) and prints molten particles. Smaller particles have a low tendency to deviate from the gas flow and impact the surface but are required to achieve high resolution.
  • Systems and methods of the subject invention can attain a resolution of no more than 40 pm in the x-y directions and no more than 100 nm in the z-direction using a simple converging orifice nozzle.
  • Composite materials have several advantages over single materials, as they can be tailored to specific requirements, allowing for the incorporation of desired properties such as stiffness, thermal conductivity, and electrical conductivity.
  • One example is a composite of polymer and carbon materials for manufacturing parts of flexible electronics, where the polymer provides flexibility to the structure and the carbon material provides desired thermal and electrical conductivity.
  • Existing methods for printing composite materials are limited in their ability to print as-synthesized customized particles.
  • Embodiments of the subject invention can print materials synthesized in situ from their precursors and use any type of aerosol-based material synthesis process prior to the printing process. This allows an advantage in printing any type of material.
  • Figures 3a-3d show several materials printed via A3DP, including a polymer (polyethylene glycol (PEG)), a composite of polymers (lignin and PEG), a composite of metal and polymer (in situ synthesized carbon particles from lignin decomposition and PEG), and functionally graded material of lignin and PEG in Figures 3a-3d, respectively.
  • the A3DP process offers a distinct capability to integrate aerosol synthesis processes into the A3DP printing system, thereby facilitating the printing of customizable materials with specific properties (mechanical, thermal, and electrical properties) and offering unprecedented versatility. This will provide many advantages in the field of additive manufacturing.
  • Embodiments of the subject invention can print any 3D printing material, including low-melting point water-soluble materials (polymer), composites of low-melting water-soluble and water-insoluble materials (polymers), and composites of a high-melting point non-soluble (metal oxides particles) and a low melting point soluble material (polymers).
  • polymer low-melting point water-soluble materials
  • polymers composites of low-melting water-soluble and water-insoluble materials
  • A3DP process parameters can control other properties of the printed structure, such as morphology (porous vs. dense), porosity, mechanical strength, conductivity, and other application- specific properties. Morphology of the printed structure is a direct function of the rate of melting of the particles, the residence time of the particle in the nozzle and between the nozzle and the printing surface, and the rate of solidification. These can be controlled via process parameters. Several of these parameters are interdependent; for example, the nozzle throat diameter affects the nozzle temperature required to melt the particles. A larger diameter widens the flow inside the nozzle and raises the required nozzle temperature to melt the particles.
  • a porous structure will be produced compared to the structure printed with a smaller nozzle throat diameter at the same nozzle temperature.
  • the particle size will affect the total mass of material for printing and impact the internal porosity at a microscopic scale.
  • Parameters such as nozzle temperature, printing surface temperature, and nozzle-to- printing surface distance, are also externally accessible and influence structure porosity.
  • a higher nozzle-to-printing surface controls the solidification of the molten particles, with a larger distance providing more time for solidification, therefore, depositing semi-molten to solid particles, leading to increased structural porosity.
  • Extensive experimentation has been conducted to study all these parameters to obtain a wide range of morphology based on parameters (see also Figures 16a-16d, 17, and 18).
  • the morphologies ofthe printed structures have been analyzed using an SEM.
  • a comprehensive parameter-property map of printed structures have been developed, and correlations between the process parameters and the printing characteristics have been established that enable the successful application of these relationships to the printing of various single polymeric materials.
  • Embodiments can print composite structures comprising two polymers of different melting points and water solubilities.
  • PVDF poly vinylidene fluoride
  • the structures in Figures 5b can be printed using any of the nozzles shown in Figures 5a or 17.
  • one of the following methods can be used: 1) preparing a stable solution of the two polymers mixed together and aerosolizing the mixed solution, which will generate composite particles; and/or 2) preparing two individual solutions of each polymer, aerosolizing each of them and mixing the polymer particles in-flight to the printer nozzle.
  • Insolubility of the second polymer in water requires preparing a solution in an organic solvent, which alters the dynamics of solvent evaporation and capture. In order to dissolve them together, another solvent (e.g., dimethyl formamide (DMF)) can be used. While a change in the solvent affects droplet dynamics, solvent evaporation, solvent capture, and generation of dry particles, the process does not require large modifications.
  • the nebulizer can spray a DMF solution, and the diffusion dryer can be replaced with a high-pore-size inert molecular sieve to adsorb DMF.
  • the residence time of aerosolized droplets in the diffusion dryer can be extended to ensure the evaporation of DMF. This reinforces the capability to print materials that cannot be dissolved in water, opening a window of a range of polymers for printing with A3 DP technology.
  • Aerosolizing the mixed polymer solution will produce droplets containing both polymers in the same composition as the solution.
  • the primary parameter for printing is the nozzle temperature as it melts the particles, which can be categorized in two different regimes - 1) temperature lower than the melting point of the composite polymer (Tnozzie ⁇ T me itin g , composite), and 2) temperature higher than the melting point of (Tnozzie > Tmeiting, composite)- It is important to note that the melting point of a composite polymer would lie between the melting points of each polymer and will be a function of the composition of the first polymer (Pl) and the second polymer (P2).
  • composite particles will either remain solid or partially soften as they pass through the nozzle, and as they deposit, they will partially sinter with previously deposited particles and form a porous structure. When the particles do not melt, the adhesion or sintering between them is due to high-velocity impaction on the printing surface.
  • the second regime Tetizzie > Tmeiting, composite
  • the nozzle temperature is sufficient to melt the composite particles, molten particle deposition and solidification will result in a dense structure. If the temperature is too high, composite particles will melt and retain a high temperature. The delayed solidification upon printing will cause the printed material to deform and deteriorate the precision.
  • the porosity of the structure can also be controlled by changing the total concentration and P1/P2 concentration ratio.
  • a lower P1/P2 ratio will result in a more porous structure due to faster solidification. Because one droplet produces one particle and the droplet size is independent of the nozzle temperature, particle size distribution in all three temperature regimes is the same. A high total concentration of the polymers will produce larger particles and an increased porosity within the structure at low nozzle temperature.
  • Another strategy is to aerosolize both polymers separately, using different solutions for each of them. This eases up the formulation of the polymer solutions; the solution of the water- soluble polymer (Pl (e.g., PEG)) in water and the solution of water-insoluble polymer (P2 (e.g., PVDF)) in solvent (e.g., DMF).
  • Pl water-soluble polymer
  • P2 water-insoluble polymer
  • solvent e.g., DMF
  • the droplets of each polymer can be passed through separate diffusion dryers, and dry polymer particles can be mixed in flight to the printer nozzle.
  • a schematic diagram of the A3 DP process for two aerosol feeds is presented in Figure 6. Because the aerosolization of each polymer solution generates the same number of droplets, the aerosol number concentration will be higher than during the aerosolization of a mixed polymer solution.
  • the nozzle temperature in this case, can be categorized in three different regimes - 1) temperature lower than the melting point of both the polymers (Tnozzie ⁇ T rae itm g ,pi and T m eiting,P2), 2) temperature higher than the melting point of Pl but lower than the melting point of P2 (Tmeiting,Pi ⁇ Tnozzie ⁇ meitin g ,P2), and 3) temperature higher than the melting point of Pl and P2 (Tnozzie > T me iting,pi and T m eiting,p2).
  • the polymers will deposit on the printing surface as discrete particles or molten material droplets and will solidify.
  • Figure 6 shows a schematic view of a system for A3DP according to an embodiment of the subject invention.
  • Figure 6 shows with dotted lines the example where two different polymer solutions are used (the top solution and then the section polymer solution), as well as the example where a metal oxide precursor solution is used in combination with one or more polymer solutions to make a polymer-metal composite.
  • A3DP printing can be used to print composites of a soluble low melting point material and a non-soluble high melting point material.
  • A3DP can be used to print a composite of a polymer and a material comprising a metal or a metal oxide.
  • a composite of PEG and TiO can be printed using A3DP. This is shown in Figure 6.
  • Metal oxide particles can be synthesized through an aerosol process using a precursor.
  • the precursor can be vaporized or nebulized, and the vapors can be passed through a furnace (e.g., a high-temperature tube furnace (500 - 1000 °C)) with a carrier gas.
  • the precursor decomposes in the furnace to form metal or metal oxide particles.
  • this second approach for printing a metal oxide-polymer composite involves the online synthesis of metal oxide particles using the aerosol process, followed by in-flight mixing of the metal oxide and polymer particles before introducing them into the printer, as depicted in Figure 6.
  • the entire process, from the synthesis of metal oxide and polymer particles to printing their composite, can be a continuous process.
  • the nozzle temperature, particle size, and metal oxide/polymer concentration ratio can affect the porosity of the structure.
  • Lower temperatures will yield structures with higher porosity, while a higher temperature that can effectively melt the polymer will lead to the formation of a dense and precise structure.
  • the size of the particles can be controlled. Larger particles and aggregate result in large pores in the structure compared to individual small particles.
  • TiC /PEG ratio a higher number of particles will create a more porous structure.
  • A3 DP can streamline the production of complex parts with intricate geometries and reduce the need for assembly and post-processing. This will improve manufacturing processes, enhance product performance, and reduce material waste.
  • the versatility of the A3DP technique allows printing of a variety of materials and integration with several material synthesis processes (spray-drying, spray pyrolysis, flame synthesis of particles, and electrospray), which will accelerate novel material development, including composite and functionally graded materials.
  • micro/nano-scale drug delivery vehicles e.g. nanorockets, Janus micromotors
  • micro/nano robots for precision surgery (e.g.
  • microdrills, micro-grippers, and microcannons allow doctors to perform a variety of minimally invasive procedures in difficult- to-access locations with high precision and control.
  • Environmental microrobots that can perform remediation tasks in hard-to-reach positions, such as surveillance of pollution, purification of water bodies, and elimination of explosives and heavy metal ions, will benefit from A3 DP technology.
  • this high-resolution 3D printing will enable exploration of efficient designs for wind turbines, designs for efficient light trapping in solar cells, and fabrication of highly efficient perovskite solar cells on the complex surface of silicon solar cells.
  • the increasing demand for high-performance and miniaturized electronics requires electronics to have a 3D form occupying z-axis space. Compared to the traditional photolithography techniques for fabrication, high-resolution and simple 3D printing will accelerate the advancement in these areas.
  • A3 DP according to embodiments of the subject invention was used to print a thermoplastic polymer, PEG.
  • a solution of PEG in water (100 mg/ml) was aerosolized using a nebulizer, which generated droplets ranging from 1 pm to 5 pm in size and yielded particles in size range from 450 nm to 2.5 pm upon solvent evaporation. The solvent was captured in the diffusion dryer, and dry particles were fed into the printing nozzle.
  • a simple orifice nozzle with a throat diameter of 400 pm was used for printing.
  • the particle residence time of particles within a 400 pm nozzle was 7.37 milliseconds (ms), while the approximate time for particle melting at 100 °C nozzle temperature was about 22 microseconds (ps), allowing the particles to melt inside the nozzle.
  • the printing surface temperature was kept at 30 °C, and as the particles deposited on the printing surface, they solidified. Consequently, layer-by-layer deposition of these particles created a 3D structure.
  • Figures 9a-9d show the PEG as printed.
  • the A3DP process involves several process parameters that influence both the underlying physics of the process and the properties of the printed structures, such as resolution, precision, morphology, and other application-specific properties. These parameters encompass both the aerosol process parameters and the printing parameters.
  • the aerosol process parameters are material properties, material concentration in the solution (which affects the particle size), flow rate, and particle number concentration generated from the nebulizer.
  • the printing parameters are nozzle temperature, printing surface temperature, nozzle-to-printing surface distance, nozzle design, and nozzle size (throat diameter).
  • Nozzle temperature determines the melting of particles
  • Figures 2a-2c depict the microstructure of a line of PEG printed at different nozzle temperatures. If the nozzle temperature is insufficient to completely melt the PEG, spherical solid or partially molten particles deposit, resulting in a porous structure ( Figure 2a). Conversely, a very high temperature ( Figure 2c) leads to complete particle melting and an elevated temperature of the molten particle, delaying their solidification time. In this case, the incoming gas flow from the nozzle deforms the structures. Achieving an optimal nozzle temperature is crucial for printing precise structures with specific morphology and density. These observations also demonstrate the potential of the A3DP process in manufacturing structures with diverse morphologies. Similarly, printing surface temperature affects the material solidification upon printing and particle deposition supported by thermophoretic force; therefore, the printing surface temperature lower than the nozzle temperature but higher than the room temperature is required to adhere and solidify the material on the surface.
  • Aerosol process parameters are other important sets of parameters that affect the printing properties.
  • the aerosol flow rate directly influences the nozzle temperature required to melt the particles and the velocity of the particle toward the printing surface; hence affects the printing properties - resolution, precision, and morphology. Additionally, it also affects the rate of material supplied to the printer.
  • the aerosol process for particle synthesis and printing process for their subsequent printing are independent, which means the amount of aerosol supplied does not change according to the desired printing parameters as happens in traditional printing techniques. Additionally, while the aerosol process is continuous, printing may require intermittent pauses in material flow as the nozzle travels between different locations on the printing surface.
  • A3DP according to embodiments of the subject invention was used to print a composite of PEG and lignin.
  • the process shown in Figure 6 was performed using the second polymer solution.
  • Figures l ib and 12 show images of the printed composite material.
  • A3 DP according to embodiments of the subject invention was used to print a graded composite of PEG and lignin.
  • Figures 13 and 14 show images of the printed graded composite material.
  • A3 DP according to embodiments of the subject invention was used to print a composite of PEG and TiCh.
  • the process shown in Figure 6 was performed using the top and bottom solutions shown on the lefthand side.
  • TiCh particles can be first synthesized (e.g., through an aerosol process using titanium(IV) isopropoxide (TTIP) precursors).
  • TTIP precursors can be vaporized, and the vapors can be passed through a high-temperature tube furnace (500 °C - 1000 °C) with a carrier gas. The precursor can decompose in the furnace to form metal oxide particles.
  • Figure 18 shows images of the printed composite material, which was obtained via A3 DP according to embodiments of the subject invention using purchased TiCh nanoparticles, which were mixed with PEG solution and aerosolized.
  • A3 DP according to embodiments of the subject invention was used to print a composite of PEG and PVDF and a composite of PEG and lignin.
  • the printed materials are shown in Figures 22a - 22f.
  • the process shown in Figure 6 was performed using a mixed solution of the two polymers.
  • the composite materials were easily printed by aerosolizing a mixed solution of multiple materials (i.e., PEG and PVDF, or PEG and lignin).
  • the nozzle temperature was adjusted such that only one polymer was melted and the molten polymer functioned as an adhesive between the unmelted polymer.
  • the particle was composed of a homogeneously distributed PVDF and PEG mixture (see Figures 22a and 22b).
  • the molten PEG might melt the small amount of PVDF, forming a dense morphology similar to pure PEG.
  • the microstructure resembles PVDF particles dispersed in PEG, leading to pore formation due to a high solid particle content compared to molten PEG (see Figure 22c).
  • the other composite was of PEG and lignin, which has a melting point ranging from 200 °C to 500 °C.
  • the micro structure resembles lignin particles dispersed in PEG as PEG cannot melt lignin.
  • COMSOL Multiphysics was used to create a finite element model of the A3DP system that directly relates the process parameters to u, T, and p.
  • the system modeled in COMSOL includes the printing nozzle (see also Figures 16a and 16b), printing surface, and the volume between the nozzle and printing surface.
  • a representative number of particles with lognormal size distribution were introduced to effectively mimic the A3DP while also reducing the computational time and complexity of the simulation.
  • the initial velocity and temperature of the particles are known from the experimental conditions. Particles encountering any surface are considered to be adhered to that specific position on the surface.
  • the time-dependent equations were solved to track the particles at each time step.
  • COMSOL does not include particle-particle interaction such as coagulation; therefore, the equations for particle dynamics were numerically solved, which provided particle size distribution as a function of particle position and time. The result was compared with results for particle trajectory from COMSOL to understand the effect of coagulation.
  • the computational results provide particle trajectory and particle position and temperature at each time step.
  • the particle position can be used to calculate resolution and precision, and the particle temperature can be used to understand the particle melting and solidification in the process.
  • FR is the ratio of the printed line width to the nozzle throat diameter; line width is the width that contains 90% of the particles that are deposited.
  • FR represents the printing resolution in x and y dimensions.
  • Resolution is the smallest x, y, and z dimensions that can be printed.
  • CE signifies the percentage of particles in the printer nozzle that is deposited within the desired line width.
  • CE relates to the precision in x and y; precision is the exact dimension to be printed in the x, y, and z dimensions.
  • precision is the exact dimension to be printed in the x, y, and z dimensions.
  • Process parameters were considered to assess their effect on FR and CE, hence on resolution and precision.
  • the nozzle is a part of the system modeled in the COMSOL, and other parameters can be changed easily in the model.
  • PEG was used as the material.
  • the particle size distribution can be directly measured using aerosol instrumentation in the lab. The flow rate was varied between 100 seem - 1 liter per minute (1pm); nozzle temperature was varied from T m - 25 °C to T m + 100 °C, where T m is the melting point of the bulk material; printing surface temperature was varied from 30 °C to T m - 100 °C; nozzle-to-printing surface distance was varied from 0.5 mm to 5 mm; and nozzle throat diameter was varied from 100 pm to 1 mm.
  • Nozzles with sheath gas surrounding the aerosol stream are more effective than those without sheath gas. These designs are primarily distinguished by the diameter of the aerosol nozzle at the intersection with the sheath gas and the length of the nozzle throat. The diameter at the junction of the sheath gas affects the mixing between the aerosol and sheath gas, thereby impacting the achievable resolution. The length of the nozzle throat determines the residence time for the particle. A longer length retains particles at high velocities, which will possibly increase the Saffman force on particles, focusing the particles toward the nozzle centerline. Additionally, for each of these designs, other variables design parameters are the nozzle throat diameter (100 pm - 800 pm) and the half-angle (30° - 60°) of the converging section before the nozzle throat.
  • Figures 19a and 19b show the FR results for the five nozzles shown in Figure 17, and Figures 20a and 20b show the CE results for the five nozzles. It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.

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Abstract

L'invention concerne des systèmes et des procédés d'impression tridimensionnelle (3D) à base d'aérosol (A3DP) et qui peuvent être utilisés pour l'impression couche par couche de polymères, de métaux et de matériaux composites par la fusion de leurs nanoparticules. Une solution contenant des nanoparticules (du ou des matériau(x) devant être imprimé(s) en 3D ou de leurs précurseurs) est atomisée pour produire des gouttelettes du matériau. Le solvant peut ensuite être évaporé à l'aide d'un séchoir et/ou d'un four, et des particules peuvent être introduites dans une buse d'impression 3D. La buse peut être chauffée pour faire fondre les particules et déplacée en translation par-dessus le lit d'imprimante selon le fichier de modèle 3D pour déposer des nanoparticules semi-fondues et imprimer la structure.
PCT/US2024/044763 2023-09-01 2024-08-30 Impression 3d à base d'aérosol de nanoparticules Pending WO2025049973A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040118309A1 (en) * 2002-07-03 2004-06-24 Therics, Inc. Apparatus, systems and methods for use in three-dimensional printing
US20170252974A1 (en) * 2014-10-29 2017-09-07 Hewlett-Packard Development Company, L.P. Three-dimensional (3d) printing method
US20210187843A1 (en) * 2019-12-18 2021-06-24 Krzysztof Wilk Print heads for 3d printers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040118309A1 (en) * 2002-07-03 2004-06-24 Therics, Inc. Apparatus, systems and methods for use in three-dimensional printing
US20170252974A1 (en) * 2014-10-29 2017-09-07 Hewlett-Packard Development Company, L.P. Three-dimensional (3d) printing method
US20210187843A1 (en) * 2019-12-18 2021-06-24 Krzysztof Wilk Print heads for 3d printers

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