Abstract: A thermal spray method for the fabrication of ceramic/metal and ceramic/ceramic hardcoating for wear applications. The method makes use of feedstock powder, composed of micron-scale aggregates of hard phase material particles that are either mixed or coated with a readily fusible nano-scale binder phase material. Thus, during thermal spraying, the nanostructured material undergoes rapid melting while the aggregated material is heated but not necessarily melted. A dense coating is formed when the molten nano-material fills the available pore spaces between the heated and softened aggregates, providing a strong and tough matrix for the consolidated material. Optimal wear properties are achieved when the volume fraction of aggregated particles is high, typically in the range of 0.5-0.9. Aggregated material may be composed of one, two or more particles of difference sizes and/or compositions, with particle size distribution that gives high packing density for the hard phase.

Abstract: This invention relates to methods whereby nanoparticle liquid suspensions are used in conventional thermal spray deposition for the fabrication of high-quality nanostructured coatings. Ultrasound is used for disintegration of the as-synthesized particle agglomerates, nanoparticle dispersion in liquid media, and liquid precursor atomization.

Abstract: This invention relates to methods whereby nanoparticle liquid suspensions are used in conventional thermal spray deposition for the fabrication of high-quality nanostructured coatings. Ultrasound is used for disintegration of the as-synthesized particle agglomerates, nanoparticle dispersion in liquid media, and liquid precursor atomization.

Abstract: A chemical synthetic route for nanostructured materials that is scalable to large volume production, comprising spray atomization of a reactant solution into a precursor solution to form a nanostructured oxide or hydroxide precipitate. The precipitate is then heat-treated followed by sonication, or sonicated followed by heat treatment. This route yields nanostructured doped and undoped nickel hydroxide, manganese dioxide, and ytrria-stabilized zirconia. Unusual morphological superstructures may be obtained, including well-defined cylinders or nanorods, as well as a novel structure in nickel hydroxide and manganese dioxide, comprising assemblies of nanostructured fibers, assemblies of nanostructured fibers and agglomerates of nanostructured particles, and assemblies of nanostructured fibers and nanostructured particles. These novel structures have high percolation rates and high densities of active sites, rendering them particularly suitable for catalytic applications.

Abstract: A hot pressing method involves the simultaneous application of high pressure (1.5-8 GPa) at a relatively low temperature (0.2-0.6 Tm) High compaction pressure causes particle deformation, such that the green density increases with pressure up to a maximum at about 8 GPa. Low sintering temperature mitigates grain growth during the consolidation process. Another factor that promotes densification is the occurrence of a pressure-induced phase transformation (typically from a metastable structure to a more stable structure), accompanied by a significant reduction in free volume for example greater than about 1 to about 2 vol. %. Such transformation-assisted consolidation has been successfully applied to produce sintered oxide and non-oxide bulk nanocrystalline ceramics having a grain size less than 100 nm, starting with even finer-scale ceramic nanopowders. Under appropriate high pressure conditions, a sintered grain size can be realized that is actually smaller than the original powder particle size.

Abstract: This invention relates to methods whereby nanoparticle precursor solutions are used in conventional thermal spray deposition for the fabrication of high-quality nanostructured coatings. The method allows combining nanoparticle synthesis, melting, and quenching into a single operation.

Abstract: This invention relates to methods whereby nanoparticle precursor solutions are used in conventional thermal spray deposition for the fabrication of high-quality nanostructured coatings. The method allows combining nanoparticle synthesis, melting, and quenching into a single operation.

Abstract: A method for fabricating a triphasic composite such as a WC/Co/diamond composite with a high volume fraction of diamond in a WC/Co matrix. The method involves sintering of a WC/Co powder compact to develop a porous preform, which displays some rigidity and strength, infiltrating the porous preform with a controlled distribution of carbon, and high pressure/high temperature treatment of the carbon-containing WC/Co preform to transform the carbon to diamond. The distribution of diamond in the composite can be functionally graded to provide a WC/Co core and a diamond-enriched surface, wherein all three phases form an interconnected structure in three dimensions. Such a tricontinuous structure combines high strength and toughness with superior wear resistance, making it attractive for applications in machine tools and drill bits.

Abstract: A chemical synthetic route is disclosed for nanostructured materials that is scalable to large volume production, comprising spray atomization of a reactant solution into a precursor solution to form a nanostructured oxide or hydroxide precipitate. The precipitate is then heat-treated followed by sonication, or sonicated followed by heat treatment. This route yields nanostructured doped and undoped nickel hydroxide, manganese dioxide, and ytrria-stabilized zirconia. Unusual morphological superstructures may be obtained, including well-defined cylinders or nanorods, as well as a novel structure in nickel hydroxide and manganese dioxide, comprising assemblies of nanostructured fibers, assemblies of nanostructured fibers and agglomerates of nanostructured particles, and assemblies of nanostructured fibers and nanostructured particles. These novel structures have high percolation rates and high densities of active sites, rendering them particularly suitable for catalytic applications.

Abstract: A method for fabricating a triphasic composite such as a WC/Co/diamond composite with a high volume fraction of diamond in a WC/Co matrix. The method involves sintering of a WC/Co powder compact to develop a porous preform, which displays some rigidity and strength, infiltrating the porous preform with a controlled distribution of carbon, and high pressure/high temperature treatment of the carbon-containing WC/Co preform to transform the carbon to diamond. The distribution of diamond in the composite can be functionally graded to provide a WC/Co core and a diamond-enriched surface, wherein all three phases form an interconnected structure in three dimensions. Such a tricontinuous structure combines high strength and toughness with superior wear resistance, making it attractive for applications in machine tools and drill bits.

Abstract: This invention relates to methods whereby reprocessed nanoparticle powder feeds, nanoparticle liquid suspensions, and metalorganic liquids are used in conventional thermal spray deposition for the fabrication of high-quality nanostructured coatings. In one embodiment of this invention, the nanostructured feeds consist of spherical agglomerates produced by reprocessing as-synthesized nanostructured powders. The method is applicable to as-synthesized nanostructured powders made by a variety of liquid chemical processing methods. In another embodiment of this invention, a fine dispersion of nanoparticles is directly injected into a combustion flame or plasma thermal spray device to form high-quality nanostructured coatings.

Abstract: A low pressure combustion flame method for the production of nanophase powders, coatings and free-standing forms. The process involves controlled thermal decomposition of one or more metalorganic precursors in a flat-flame combustor unit in which both temperature distribution and gas phase residence time are uniform over the entire surface of the burner. It is this feature that makes the combustion flame reactor such a versatile tool for (1) high rate production of loosely agglomerated nanoparticle powders with controlled particle size and distribution, (2) uniform deposition of shape conformal nanophase coatings, and (3) net-shaped fabrication of nanocrystalline free-standing forms such as sheets, rings and drums. Applications for this new nanomaterials processing technology include electrical, thermal, optical, display, magnetic, catalytic, tribological and structural materials.

Abstract: A new carbothermic reaction process is described for the thermochemical processing of nanophase WC-Co powders. The process permits shorter reaction times, reduced temperatures, and finer microstructures compared to conventional processing methods.The process builds on our experience with spray conversion processing [1], but involves 1) chemical vapor infiltration reaction of the carbon infiltrant and particle substrate to from WC-CO; and 2) removal of any excess (unreacted) carbon by controlled gasification. A feature of the carbothermic reaction process is its adaptability to conventional WC-Co processing technology, as well as to spray conversion processing technology.The resulting power particles consist of a network of fine grains, (less than 100 nm) of WC and Co with interconnected fine porosity. Powder particles suitable for subsequent handling and consolidation are readily produced with diameters greater than 10 microns.

Abstract: An apparatus of forming non-agglomerated nanostructured ceramic (n-ceramic) powders from metalorganic precursors combines rapid thermal decomposition of a precursor/carrier gas stream in a hot tubular reactor with rapid condensation of the product particles on a cold substrate under a reduced inert gas pressure of 1-50 mbar. A wide variety of metalorganic precursors is available. The apparatus is particularly suitable for formation of n-SiC.sub.x N.sub.y powders from hexamethyl-disilizane or the formation of n-ZrO.sub.x C.sub.y powders from zirconium tertiary butoxide. The n-SiC.sub.x N.sub.y compounds can be further reacted to form SiC or Si.sub.3 N.sub.4 whiskers, individually or in random-weave form, by heating in a hydrogen or ammonia atmosphere. The non-agglomerated n-ceramic powders form uniformly dense powder compacts by cold pressing which can be sintered to theoretical density at temperatures as low as 0.5 Tm.

Abstract: A process is described for the production of composite powders with ultrafine microstructures. The process involves three coordinated steps:1) preparation and mixing of an appropriate starting solution;2) spray drying to form a chemically homogeneous precursor powder; and3) fluid bed thermochemical conversion of the precursor into the desired nanophase composite powder.Both spray drying and fluid bed conversion are scaleable technologies, and together provide the means for producing bulk quantities of nanophase composite powders at low manufacturing cost. Processing parameters are controlled to ensure maintenance of chemical and microstructural uniformity at the nanoscale (less than 0.1 micron) level.Spray conversion processing is a versatile technology, which can be applied to a variety of metal--metal (e.g. W--Cu), ceramic-metal (e.g. WC--Co), and ceramic--ceramic (e.g. Al.sub.2 O.sub.3 --SiO.sub.2) nanophase composite powders ceramic-metal (e.g. WC--Co), and ceramic--ceramic (e.g. Al.sub.2 O.sub.3 --SiO.

Abstract: A new carbothermic reaction process is described for the thermochemical processing of nanophase WC-Co powders. The process permits shorter reaction times, reduced temperatures, and finer microstructures compared to conventional processing methods.The process builds on our experience with spray conversion processing but involves 1) chemical vapor infiltration reaction of the carbon infiltrant using a carbon source gas at a carbon activity greater than or equal to 1.0 with the particle substrate to form WC-CO; and 2) removal of any excess (unreacted) carbon by controlled gasification using a gas with carbon activity less than 1.0. A feature of the carbothermic reaction process is its adaptability to conventional WC-Co processing technology, as well as to spray conversion processing technology.The resulting power particles consist of a network of fine grains, (less than 100 nm) of WC and Co with interconnected fine porosity.

Abstract: The present invention relates to a novel process for producing silicon and/or aluminum containing iron alloy product as well as the material produced from same in either sheet or bulk structure form for electromagnetic circuit application. The process entails modifying an iron feedstock containing less than about 2.5 wt % silicon, aluminum or a combination thereof. The process further consists of diffusion of silicon or silicon and aluminum or aluminum into an iron feedstock by a pack diffusion or a chemical vapor deposition method in which the iron feedstock is heated to a temperature at which diffusion occurs in the presence of a pack containing silicon and/or aluminum sources, a reducing agent, a catalyst, and a filler, or in the presence of a flowing gas stream containing a volatile silicon compound. The resulting iron alloy product, which has a silicon content in the range of 0.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely, fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: A novel isotropically reinforced microcomposite is described. An entirely fluid-phase method has been devised for producing the net-shape filamentary structures. The process depends for its success on the ability to generate in situ, within a shaped mold, a three-dimensional random weave of carbon filaments by catalytic decomposition of a hydrocarbon feed. Almost any desired filament filler matrix combination can be produced by utilizing chemical vapor deposition to modify the surface and bulk properties of the filamentary structure. Infiltration of filler matrix materials can be achieved by adaptation of existing materials technologies.