Patent Application
20230366098
Conventional supersonic cold spray technology includes the deposition of a wide variety of metals from aluminium to titanium, and mixed metal/ceramic powders, and more recently a variety of polymeric materials. Metal and polymeric material cold spray technology is based on the use of malleable particles which individually splat and deform, then build up and knit together when they impact a surface at supersonic velocity. While ceramic and other brittle material particles have been added into the powder mix to produce high quality surface protection coatings, the fundamental process remains anchored to the deformability, or malleable nature of the metal or polymer components in the powder mix that act as a binder for the brittle material. Malleable binder material contents of 20-50 wt.% have been required to anchor the brittle material particles together.
Particles used in conventional cold spray applications are normally spherical in shape with a diameter of 5-70 microns depending on the cold spray equipment type, the material being sprayed, and the end use. Non-ductile or brittle material particles made from functional materials such as semiconductors, glassy and crystalline optical materials, hard and soft magnetic materials and hard ceramic structural coating materials such as silicon carbide, alumina, and zirconia that are greater than several tens of microns in size, however, do not adhere to each other or deposit into thick layers when they hit a surface at near supersonic or supersonic velocity, but instead they shatter or bounce off after sandblasting or eroding the surface.
Recent innovations by the inventor have shown that rapid cold spray deposition of 100% non-ductile, crystalline, or brittle material particles can be deposited onto both ductile and brittle substrates in both micron thick and centimetre thick material layers using a modified cold spray process which depends not on particle deformation at impact but primarily on the dense mechanical interlocking of different size brittle particles. By tailoring the powder particle size distribution and the cold spray equipment operational parameters, multiple categories and functional classes of brittle materials have been successfully deposited on both ductile and brittle substrates in thin to thick layers ranging from 20 µm to 2 cm in thickness or greater. This branch of cold spray deposition technology is now referred to as BPCS or Brittle Particle Cold Spray.
A fundamental difference between both metal cold spray and thin layer brittle material technology when compared to Brittle Particle Cold Spray (BPCS) technology comes from the shapes and the range of sizes of the particles required for material deposition. Thick or bulk layer cold spray deposition of non-malleable or brittle materials is not controlled by particle deformation or a partial melting process, but instead the material deposition begins and builds up as a result of mechanical interlocking of different size particles initially with small surface irregularities in the substrate which is then followed by particles of widely different sizes and irregular shapes impacting the material on the surface and mechanically interlocking with each other. For this interlocking and densification process to occur requires a wide distribution of particle sizes and the average particle size used in BPCS powders must be much smaller and the particles irregular in shape than those commonly used for traditional metal cold spray, polymer material cold spray and micron thick ceramic coating cold spray methods. Determination of the size and size distribution of very small particles as referenced in this application was done using a laser diffraction measurement system. Laser diffraction measures particle size distributions by measuring the angular variation in intensity of light scattered as a laser beam passes through a dispersed particulate sample. Large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles. The angular scattering intensity data is then analyzed to calculate the size of the particles responsible for creating the scattering pattern, using the Mie theory of light scattering The particle size is reported as a volume equivalent sphere diameter. All references to the size of irregular shaped particles in this application are equivalent spherical diameters when measured using this measurment technique.
Brittle Particle Cold spray (BPCS) deposition testing spanning a wide range of brittle material compositions and material functional types has shown that supersonic cold spray deposition of brittle material particles in greater than 20 to 100 microns in thickness requires both nano-meter and micrometer size particles in the powder mix and specific particle size distributions within the range from 100 nm to 15 µm in equivalent spherical size when measured using a laser diffraction technique.
Even small percentages of brittle material particles which exceed 20-30 micrometres in equivalent spherical size have been shown to disrupt the thick layer deposition process by cratering and eroding already deposited material.
The brittle particle cold spray (BPCS) process has been used to deposit a wide range of semiconductor materials including Bismuth and Antimony Tellurides, silver antimony telluride, germanium telluride (TAGS) materials, tetrahedrite formulations and other semiconductor copper sulfosalts. Ferroelectric materials including Barium Titanate in addition to magnetic materials including neodymium iron boride and praseodymium iron boride have also been successfully deposited using BPCS technology.
The mechanical interlocking and densification process that occurs during the supersonic cold spray of brittle material particles that have a specific particle size distribution from approximately 100 nanometers to 15 µm and irregular particle shapes enables a significant expansion of the applications for cold spraying brittle materials. Experiments have shown that the particle size distribution for brittle particle cold spray powders can be expanded to include particles down to 5 nm in size. In addition, the BPCS mechanical interlocking deposition process is not primarily controlled by the material type but instead deposition is enabled by the distribution of the particle sizes of the materials. This significantly expands the applications of BPCS beyond spraying a brittle material powder material composed of a single chemical compound and expands the applications of brittle particle cold spray to include materials whose properties can be enhanced or changed by the addition of very small nanoparticles of the same or different materials.
BPCS technology has been used for the sequential deposition of interlocking layers of different brittle materials with different chemical structures and functional properties because it is the particle size distribution in the individual material powders which primarily controls the deposition process. This mechanical interlocking process, therefore, also enables the deposition of graded composition materials where a gradual compositional transition from one brittle material type to another is made that is beneficial to the functional performance of the entire deposited material. As an example, the transition from one type of thermoelectric semiconductor material to another can be made. Specific nanoparticle dopants in the size range from 5-100 nm can also be added in order to optimize the net figure of merit for the cold spray deposited thermoelectric semiconductor elements and to cover a wider temperature operational range for electrical energy generation.
In addition, layered materials that gradually transition between 100 % brittle material particles to 100% metal or other malleable materials can be fabricated using the cold spray process by mixing micron sized metal or other ductile material particles in different weight percentages into the brittle material powders. This gradual transition in the makeup of the powder from 100% brittle particles to 100% malleable or deformable particles can occur because the deposition process gradually changes from a process that is dominated by the mechanical interlocking of brittle particles to the standard metal cold spray process which is determined by the deformation of the malleable particles. This compositional layering from brittle to ductile materials can, as an example, be utilized to reduce thermal stresses at material interfaces caused by thermal expansion differences between the cold sprayed brittle material and a metal or polymer substrate material. The ability to transition from a 100% brittle semiconductor to a 100% metal conducting layer and/ or transition from 100% metal conducting layer to a 100% brittle material layer also enables the complete cold spray additive manufacturing of functional mechanical or electrical devices that require both brittle functional materials and metallic or other ductile material elements.
Since the primary factors which determine the successful cold spray deposition of thick layers of brittle materials are the particle sizes, the particle size distribution, and the particle shapes, and to a lesser degree the type of functional material and the substrate compositions, it has been demonstrated by the inventor that the powder material used in the cold spray process can be composed of more than one chemical compound, and that those compounds can be from the same or different functional material groups. The cold spray deposited material can therefore be a mixture of two or more material compounds with different chemical compositions, and, therefore, different mechanical, electrical, chemical, and optical properties. Each component material can have different particle size ranges and particle size distributions that when mixed together create the particle size distribution required for the deposition of thick layers of brittle materials. By expansion of the particle size range that can be cold sprayed down to five nanonmeters, then specific material thermal, electrical, structural, and optical properties can be controlled or modified. As an example, brittle particle semiconductor and magnetic materials have been cold sprayed with the addition of up to 20 volume percent of five nanometer synthetic diamond particles and up to 20 volume percent of carbon nanoparticles in the 30 nm size range.
This ability to combine and mix materials with different particle sizes and particle size distributions allows for the cold spray deposition of ceramic matrix composite materials for use in high temperature thermal protection system applications which incorporate high temperature glass, ceramic, or carbon fibers and carbon nanotubes in the powder mix. Micro-fiber reinforced composite brittle materials have been cold sprayed with amorphous silica fiber with a diameter of approximately 1.5 µm and fiber aspect ratios of 100 in volume percentages up to 20%. Composite materials have been cold sprayed using carbon nano tube contents of 20 volume percent or higher.
While the primary applications of these innovative methods and products apply to cold spraying micro and nanostructured brittle materials, the process of the mechanical interlocking of particles spanning the range from 5 nm to 15 microns during the cold spray process also applies to metals, and polymer materials, Ductile material powders can be composed of different ductile materials, and reinforcing micron sized ceramic fibers can be added to the ductile material powder mix.
A specific application for both ceramic and metal materials is the addition of up to 20% of Johns Manville amorphous silica Q-Fiber to the cold sprayed powder. A unique aspect of this fiber resulting from its initial manufacturing process is that it exhibits shrinkage when exposed to high temperatures. Incorporating this fiber into a ceramic or metal matrix cold sprayed powder results in the material being held in compression by the fiber shrinkage which occurs during the cold spray process or during post cold spray deposition thermal processing. This produces a prestressed composite material.
By the use of the mechanical interlocking and densification process that occurs when using a range of particle sizes and specific particle size distributions required for the cold spray deposition of non-malleable, brittle functional material particles, multi compound, nano-structured and micro-structured brittle material compounds can be deposited using Brittle Particle Cold Spray (BPCS) deposition technology. Layers of brittle materials composed of two to ten or greater chemical compounds ranging in thickness from 20 micrometres to several centimetres can be deposited using a cold spray deposition method where the deposited material in any one layer is composed of multiple chemical compounds consisting of the same or different functional material types.
Layers of mixed material compounds can be cold spray deposited where each individual chemical compound in the mix is composed of particles which span the entire 5 nanometer to 15 micrometer size range, or the cold spray powder can be produced with the particles of each material constrained to a specific particle size range or discrete particle size ranges. For example, but not limited to, compound one is composed of particles of a first brittle material compound with a D(10) to D(90) volumetric size range from 5 nm to 100 nm, a second composition material with particles for an example limited to a D(10) to D(90) volumetric size range from 100 nm to 500 nm, a third brittle material compound with particles in a D(10) to D(90) size range from 500 nm to 1.5 µm and one or more additional materials which cover a volumetric particle size range from D(10 to D(90) of 1.50 -15 µm.
[The resulting cold spray deposited mix of material types and chemical compositions produces a nano-structured and micro-structured material with nanometer and micrometer sized compound particles. The compounds which have been included within the powder mix having different chemical compositions and atomic structures, and which exhibit a wide range of chemical composition, chemical reactivity, and structural, thermal, electrical, optical and magnetic properties. The mixed-compound powder used in the supersonic cold spray process is controlled to volumetrically have greater than 95% of the particles with a maximum particle size not greater than 15 micrometers, and a controlled volumetric particle size distribution over the nominal particle size ranges from 5-100 nm, 0.10-1.0 micrometers; 1.0-2.0 micrometers; 2.0-5.0 micrometers; and 5-10 micrometers in major dimension, and the powder can be composed of but not limited to from 2-10 different composition materials.
Materials with a very narrow particle size range, such as 5-10 nm can be added to the powder mix to modify a specific chemical, thermal, electrical or structural or other property of the cold sprayed material. Multi compound material powders composed of 100% brittle materials can be cold sprayed, and the presence of metallic, organic or any ductile material binder materials is not required within the mix of compounds. Metals and other malleable material powders such as polymers, however, may be added to the powder mix to achieve specific electrical, magnetic, chemical, optical or structural characteristics of the deposited material. High temperature ceramic and carbon micro and or nano fibers with aspect ratios of 100 or greater can be incorporated into the cold spray powder to produce high temperature ceramic composite materials.
Material types which can be incorporated into the powder mix include, but are not limited to, n-type and p-type semiconductors, hard and soft magnetic materials, ferroelectric materials, optical materials, metallic materials, superconductors, ionic semiconductors, high temperature ceramic materials such as fused quartz, mullite, zirconia, silicon carbide, boron carbide, and polymeric materials. Using this process, the mixed-compound powder material, which has been partitioned into specific particle size domains for each different compound can be deposited onto flat as well as complex shaped surfaces in both thin and thick layers, and from individual small pellet sized spots to large continuous areas, thus enabling coatings and bulk material depositions which exhibit functional properties that are specifically tailored to the application.
Supersonic cold-spray deposition of mixed compound brittle material powders, inlcuding a wide range of thermoelectric semiconductors, piezoelectric materials hard and soft magnetic materials, synthetic diamond, fused quartz, borosilicate glass, silicon carbide, carbon.boron carbide, boron nitride, and metallic elements such as alumium and nickel have been demonstrated, and these processes can apply to all classes of functional materials. Unique powder material compositions, particle shape and sizes, and control of the cold-spray process parameters and equipment design allow the uniform cold spray deposition to a surface of nano structured and microstructured materials where both different compound compositions and particle size ranges are used to control the deposited material’s electrical, magnetic, optical, and structural properties and chemical reactivity.
In addition, brittle material powders constructed from one or more brittle materials can be further modified by the addition of high temperature micro and/or nano-fibers and/or hollow microspheres and nanospheres and then cold spray deposited to produce fiber reinforced high temperature composite materials, and high temperature syntactic foams. This ability to add high temperature nano and microfibers into the ceramic or brittle particle powder mix allows the gradual transition within the deposited cold spray material from a random high temperature ceramic fiber reinforced brittle material to a random ceramic fiber reinforced, high temperature capable metallic material. Random ceramic fiber reinforced metallic and other ductile materials can also be cold sprayed.
Successful cold spray deposition of brittle materials requires a wide range of particle sizes and three dimensional shapes for the mechanical interlocking process to yield high density and mechanically rigid deposits. Brittle particles with large aspect ratios such as ceramic or carbon fibers can be included in the powder mix, and the powder then cold sprayed into a random fiber reinforced composite material.
The brittle particle cold spray process occurs as a result of the mechanical interlocking and impact densification of the varius size and shaped particles. Successful deposition of many different functional classes of brittle materials has been achieved when the particles are irregular in shape and the particle sizes are in a specific volumetric distribution that spans the size range from approximately 100 nm to 15 µm in equivalent spherical dimension. A unique aspect of the process is that some or all of particles below 1 µm in size do get through the supersonic shock layer above the deposition surface and are not all swept away by the expanding gas stream. SEM analysis of cold spray deposited brittle materials clearly show that particles as small as 100 nm are part of the deposited materials and that those nominally 100 nm sized particles fill the gaps between the larger particles, and contribute to the mechancial strength of the deposited material.
Recent research has demonstrated that brittle material particles as small as 5 nm can be added into the brittle material powder and the mixed powder can then be successfully cold spray deposited into layers from 20 µm to centimeters in thickness that incorporate those nanoparticles within the body of the parent single compound or multicoumpound brittle material. Very narrow size range nano particles of different chemical compounds ranging from 5-70 nm in particle size have been demonstrated in weight concentrations from less than 1% up to 20% of the total powder weight.
Recent innovations as described in the referenced patents have expanded the application of supersonic cold spray technology to enable the thick layer or bulk material deposition of brittle or non maleable materials without the need for a metal or any binder materials in the powder mix. This branch of cold spray technology is now generally referred to as Brittle Particle Cold Spray or BPCS. Supersonic cold spray of 100 percent pure brittle material particles has been demonstrated on a wide variety of thermoelectric semiconductor materials, hard and soft magnetic materials, and ferroelectric materials, and research has shown that BPCS technology applies to brittle materials in all functional material groups with a wide range of chemical compositions and material properties.
Research covered within this application significantly expands the applications and technology for brittle particle cold spray technology by demonstrating that muticompound brittle materials composed of from two or greater different chemical compounds, random fiber composite ceramic materials where high aspect ratio ceramic or other fibers are incorporated into the brittle material powder mix, and single compound and multicompound brittle materials incorporating nanoparticles as small as 5 nm can be deposited using supersonic cold spray technology.
Single component powder materials that have been used used successfully in Brittle Particle Cold Spray or (BPCS) are composed of irregular shaped particles with equivalent spherical sizes ranging from approximately 100 nanometers to 15 micrometers in size when measured using a Mastersizer 2000/3000 Laser Diffraction system with a dry dispersion technique or when viewed using high power SEM imaging.
The BPCS process requires specific particle size distributions to enable a tight mechanical interlocking of the brittle material particles of different sizes and subsequent densification upon impact of additional particles as the buildup process proceeds from micron level thickness up to centimeters in material thickness. Research has shown that specific amounts of both 100 nanometer to 1 µm sized particles are required, and that particles in the 5-10 µm particle size are also required for near theoretical density depositions.
Near theroetical density material depositions have been demonstrated for a wide range of multicomponent brittle material functional types with up to five different material compounds in the powder mix. Deposited material layers of multicomponent powders can vary from twenty micrometers to greater than a centimeter in thickness with material deposition rates exceeding centimeters in thickness per minute, and measured deposition efficiencies up to 30% and potentially higher. The weight percentages of each material in the brittle material powder mix can vary as long as the particle size distributions of each of those materials are similar and the volumetric particle size distribution of each component material within the powder spans the two orders of magnitude equivalent volumetric spherical size range from 100 nm to 10 µm. This ability to cold spray mixed powders of different chemical compounds and with different weight percentages as long as the particle size distributions are similar also enables the ability to cold spray brittle materials that gradually transition from one brittle material compound to another through the thickness of the material.
In addition it also allows the mixing of ductile materials such as metals or polymers into the powder mix and the gradual transition from a cold spray process which is controlled by mechanical interlocking of brittle particles to a cold spray deposition process that is controlled by the ductile behavior of the metal or polymer component of the powder mix.
Additional research has demonstrated that the Brittle Particle Cold Spray (BPCS) process can also be used to spray thick layer depositions of combined brittle material powders where the required total particle size distribution from 100 nm to 15 µm is determined by combining multiple brittle material chemical compounds and functional types, but with each material’s particles constrained to a specific particle size range and particle size distribution within the total particle size range required for the mechanical interlocking process and densification to proceed.
Achieving the specific particle size distributions (PSDs) 201202, 203 and 205 as shown on
Since materials with diverse material properties such as 600 a sulfur based semiconductor with particle sizes in the D10 to D90 range from approximately 2-15 microns, and synthetic diamond particle with particle sizes in the D10-D90 range from 0.05-2.0 microns can be mixed and then successfully sprayed using the BPCS process, this mix-and-match capability of combining both material types and particle size distributions enables the formation of cold sprayed material compounds with unique, thermal, electrical, chemical, optical and structural properties.
A specific but not inclusive application example of this mixing brittle material powders that individually fall within all or part of the required particle size distrubution range, is mixing two or more different thermoelectric semiconductor materials with the objective of widening the Seebeck coefficient versus temperature response curve of the compound material to improve the bulk material thermoelectric Figure of Merit for a particular thermal operating environment, or the combining of different functional material types such as a neodymium iron boride magnetic material powder with particle size distribtuion 310 and a bismuth telluride powder with the particle size distribution 320 to create a powder with the approximate particle size distribution or 325, so that the bulk material’s properties meet a set of specific required set of chemical, thermal, electrical and magnetic properties.
The ability to mix functional brittle material types, for example includes, but is not limited to, magnetic materials, thermoelectric semiconductor materials, ionic semiconductor materials, ferroelectric/ piezoelectric materials, superconducting materials, optical materials, and even structural materials such as silicon carbide and diamond used for surface hardened wear resistant coatings. In addition simulated or actual extraterrestrial soils such as Lunar and Martian soils, when mixed with other brittle materials to achieve a desired particle size distribution over the range of 100 nm to 15 µm can also be supersonic cold spray deposited.
Metal and other ductile material powders in the size range from five microns or below can also be added to the mix in weight percent concentrations not limited to from less than 0.1% to 10 % without disruption of the brittle material deposition process.
A unique attribute of this significant expansion of the process and applications for Brittle Particle Cold Spray (BPCS) technology described, therefore, is the ability to combine powders of different brittle functional material compounds and produce thick layer cold spray depositions as long as the the combined particle size distribution falls within a specific particle size distribution.
As described in the referenced patents, the primary factor in the brittle particle cold spray mechanical interlocking process has been shown to be the particle size distribution of irregularly shaped particles. In effect the various shapes and sizes of the particles mesh together and the smaller particles fill the gaps between larger particles. While regular and irregular shaped particles greater than 20 µm in equivalent spherical size have been demonstrated to disrupt that deposition process and scour or sandblast the surface as a result of their much greater kinetic energy at impact, micron sized and sub micron sized particles with very high aspect ratios such as fibers and nanotubes, however, can be added into the powder mix, and the composite mixture then cold sprayed.
Research has demonstrated that random fiber Ceramic Matrix Composite (CMC) materials can be made where ceramic material micro and/ or nanofibers or carbon microfibers or carbon nanotubes are incorporated as a specific component of the brittle particle powder material mix. Cold spray deposition of materials composed of greater than ninety-five percent of brittle material particles requires a specific particle size distribution, but part of that distribution can be made of materials with large length to diameter ratios such asfibers so that the high aspect ratio particles act as a structural reinforcement for the deposited brittle material. High temperature capable fibers such as fused quartz, mullite, zirconia, carbon fiber and carbon nanotubes can be used, and fibers with length to diameter ratios of greater than 100 have been demonstrated.
Similar cold spray deposition testing of random ceramic fiber reinforced materials has been performed successfully with other semiconductor and magnetic materials and other ceramic fiber compositions including zirconia fibers. Research is underway to expand that list to very high temperature capability fiber and higher temperature ceramic materials for advanced thermal protection system applications.
While the innovations described herein pertain primarily to brittle particle materials, the mechanical interlocking deposition process of particles in the 100 nm to 15 µm can also be applied to materials that are considered ductile in nature including pure metals, high entropy metal alloys, and high temperature capability polymer materials such as polyether-ether-ketone and polytetrafluoroethylene. Ceramic reinforcing fibers can also be added to these ductile material powders and deposited using the same process as described for brittle material cold spray deposition.
Johns Manville amorphous silica Q-Fiber is manufactured using a process that removes impurities from the fibers, and that process results in different levels of shrinkage of the fibers when exposed to temperatures from 500° C. to 1100° C. Cold spray deposited random fiber reinforced brittle materials 803 can be made using preshrunk Q-fibers 802 and/or Q-fibers that will shrink when exposed to temperatures greater than 500° C. Cold spray deposited random fiber reinforced materials fabricated using the non-preshrunk Q-fiber can therefore be exposed to temperatures during the cold spray deposition process or post the cold spray process that results in shrinkage of the fibers. Shrinkage of the randomly oriented fibers places the cold spray deposited composite material in compression and pre-stresses the deposited material. This fiber shrinkage process can be used to improve the structural capability of random fiber reinforced composite materials for some applications.
The mechanical interlocking process of the brittle particles during cold spray deposition has been demonstrated to enable the addition of a wide range of ceramic and other types of microfibers into the brittle particle powder mix which then are incorporated into the cold sprayed material during the cold spray process. Ceramic microfibers fibers such as fused quartz, mullite, and zirconia, carbon fibers, and carbon nanotubes can be used to create high temperature capable random fiber ceramic matrix composite materials for thermal protection and other applications.
Research by the inventor has shown that single compound and multicompound brittle particle material powders with particle size distributions which are substantially similar to 200 can be further modified by the addition of nanoparticles in the size range from 5 nm to 70 nm. Powders with added nanoparticles in the 5-70 nm size range can be cold spray deposited with up to but not limited to twenty weight percent of the same or different chemical composition nanoparticles being added into the brittle particle powder mix. The nanoparticles can be brittle ceramic materials, carbon, diamond, and/ or nano scale metal particles.
Various inter-particle forces cause agglomeration or loose sticking together of irregular shaped brittle particles in cold spray powders 200 where the brittle particle sizes vary from approximately 5 nm to 15 µm in equivalent spherical size. In
This ability to incorporate very small nanoparticles in the brittle particle cold spray powder mix enables nano-doping or nano-structuring of the cold spray deposited brittle material.
The present application claims the benefit of the earlier filing dates of priority to U.S. Provisional Application No. 63/342,462, filed on 16 May 2022 and U.S. Provisional Application No. 63/403,733, filed on 03 Sep. 2022, the entire contents of both which being incorporated by reference herein in their entirety. The present application also contains subject matter related to that in U.S. Pat. 9,306,146, U.S. Pat. 10,714,671, U.S. Pat. 10,957,840, U.S. Pat. 11,473,200, U.S. Pat. 11,617,291 filed 30-DEC-2020, the entire contents of which are being incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63403733 | Sep 2022 | US | |
| 63342462 | May 2022 | US |
