Abstract: Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Abstract: Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Abstract: Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

Abstract: Methods for manufacturing porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's). Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, a thin coating of nuclear fuel may be deposited inside of a highly porous skeletal structure made, for example, of reticulated vitreous carbon foam.

Abstract: A coated carbon body having improved resistance to high temperature oxidation and a method for producing the coated carbon body are described. The coated carbon body comprises a carbon body, an intermediate glass forming coating within said converted layer, and an outer refractory coating on the intermediate coating. The body has a converted porous layer formed by etching and reacting the body with gaseous boron oxide and the resulting converted layer contains interconnecting interstices and boron carbide formed by the reaction of the boron oxide and the carbon body. The method comprises contacting a carbon body with boron oxide at an elevated temperature sufficient to cause the reaction between the carbon body and boron oxide to form a converted porous layer which contains interconnecting interstices in the body and boron carbide and then applying the intermediate glass forming coating over the converted layer and an outer refractory coating over the intermediate coating.

Abstract: A coated carbon body having improved resistance to high temperature oxidation and a method for producing the coated carbon body are described. The coated carbon body comprises a carbon body, an intermediate glass forming coating within said converted layer, and an outer refractory coating on the intermediate coating. The body has a converted porous layer formed by etching and reacting the body with gaseous boron oxide and the resulting converted layer contains interconnecting interstices and boron carbide formed by the reaction of the boron oxide and the carbon body. The method comprises contacting a carbon body with boron oxide at an elevated temperature sufficient to cause the reaction between the carbon body and boron oxide to form a converted porous layer which contains interconnecting interstices in the body and boron carbide and then applying the intermediate glass forming coating over the converted layer and an outer refractory coating over the intermediate coating.

Abstract: A method for making a lightweight structure having a high stiffness to weight ratio comprising providing a substrate defining at least a pair of outer surfaces spaced from each other, boring at least one hole through the structure to provide at least one void passage extending through the substrate between the outer surfaces, coating the outer surfaces of the substrate and the surfaces of the passage with a chemical vapor deposited material to a thickness of about one millimeter, plugging the void passage with a plug of a substrate material, and further coating the coated outer surfaces of the substrate and the ends of the plugs with a chemical vapor deposited material to form a continuous monolithic structure thereon.

Abstract: A composite structure having a high stiffness to weight ratio includes a substrate, e.g. graphite, defining at least a pair of outer surfaces which are spaced from each other and having a volume or void passages extending through the substrate between the outer surfaces. At least one stiffening element extends between the outer surfaces within this volume. The stiffening element defines a volume and has at least one wall intersecting each of the outer surfaces. The stiffening element and the outer surfaces are made up of a chemically vapor deposited material having the desired high stiffness to weight ratio and being formed as a monolithic structure having a thickness of at least about 1 millimeter. These structures have such diverse uses as aircraft parts and skis.

Abstract: The invention relates to an method of producing a titanium aluminide coating on a substrate by producing a flow of hydrogen and gaseous aluminum monochloride over a titanium surface to react to form a gaseous flow of titanium trichloride and aluminum monochloride and contacting the substrate with the flow of titanium trichloride and aluminum monochloride at a temperature of 800.degree. to 1200.degree. C., said substrate being a temperature below the temperature of the gases.

Abstract: A hard fine-grained internally stressed material of tungsten and carbon or tungsten, carbon and oxygen is described which is produced by thermochemical deposition. The material consists primarily of a two phase mixture of pure tungsten and an A15 structure, is free of columnar grain distribution, and has a hardness of greater than 1,200 VHN. The average grain size is less than 0.1 micron.