Abstract: A family of extremely fine-grained alloys are used to make coatings or free-standing bodies having desirable properties for use as a heat-resistant and wear-resistant material. In an illustrative embodiment, the alloys are comprised of a multiplicity of alternate, microcrystalline or nanocrystalline films of tungsten metal and tungsten compound. The tungsten compound film may be comprised of a tungsten carbide or a tungsten boride. The tungsten films are the primary films. Their desirable characteristics, in addition to their very fine crystalline habit, per se, are the high strength, high hardness, high resilience, and high fracture energy which these fine crystallites foster. They may be manufactured by a chemical vapor deposition process in which reactive gas flows are rapidly switched to produce alternate films with abrupt hetero-junctions and thereby to produce the useful micro-crystalline habit. The unique synthesis method allows effective control of critical flaw size.

Abstract: A process for producing a single-crystal silicon wafer, comprises the following steps: producing a layer on the front surface of the silicon wafer by epitaxial deposition or production of a layer whose electrical resistance differs from the electrical resistance of the remainder of the silicon wafer on the front surface of the silicon wafer, or production of an external getter layer on the back surface of the silicon wafer, and heat treating the silicon wafer at a temperature which is selected to be such that an inequality (1) [ O ? ? i ] < [ O ? ? i ] eq ? ( T ) ? exp ? ? 2 ? ? SiO ? 2 ? ? r ? ? k ? ? T is satisfied, where [Oi] is an oxygen concentration in the silicon wafer, [Oi]eq(T) is a limit solubility of oxygen in silicon at a temperature T, ?SiO2 is the surface energy of silicon dioxide, ? is a volume of a precipitated oxygen atom, r is a mean COP radius and k the Boltzmann constant, with the silicon wafer, during the heat treatment, at least pa

Abstract: An SOI wafer, includes a substrate made from silicon, an electrically insulating layer with a thermal conductivity of at least 1.6 W/(Km) and a single-crystal silicon layer with a thickness of from 10 nm to 10 ?m, a standard deviation of at most 5% from the mean layer thickness and a density of at most 0.5 HF defects/cm2. A process is for producing an SOI wafer of this type, in which a substrate wafer made from silicon is joined to a donor wafer via a layer of the electrically insulating material which has previously been applied. The donor wafer bears a donor layer of single-crystal silicon, with a concentration of vacancies of at most 1012/cm3 and of vacancy agglomerates of at most 105/cm3. After the wafers have been joined, the thickness of the donor wafer is reduced in such a manner that the single-crystal silicon layer having these properties is formed from the donor layer, this single-crystal silicon layer being joined to the substrate wafer via the layer of electrically insulating material.

Abstract: A family of extremely fine-grained alloys are used to make coatings or free-standing bodies having desirable properties for use as a heat-resistant and wear-resistant material. In an illustrative embodiment, the alloys are comprised of a multiplicity of alternate, microcrystalline or nanocrystalline films of tungsten metal and tungsten compound. The tungsten compound film may be comprised of a tungsten carbide or a tungsten boride. The tungsten films are the primary films. Their desirable characteristics, in addition to their very fine crystalline habit, per se, are the high strength, high hardness, high resilience, and high fracture energy which these fine crystallites foster. They may be manufactured by a chemical vapor deposition process in which reactive gas flows are rapidly switched to produce alternate films with abrupt hetero-junctions and thereby to produce the useful micro-crystalline habit. The unique synthesis method allows effective control of critical flaw size.

Abstract: A process for producing a single-crystal silicon wafer, comprises the following steps: producing a layer on the front surface of the silicon wafer by epitaxial deposition or production of a layer whose electrical resistance differs from the electrical resistance of the remainder of the silicon wafer on the front surface of the silicon wafer, or production of an external getter layer on the back surface of the silicon wafer, and heat treating the silicon wafer at a temperature which is selected to be such that an inequality (1) [ O ? ? ? i ] < [ O ? ? ? i ] eq ? ( T ) ? exp ? ? ? 2 ? ? SiO ? 2 ? ? r ? ? ? k ? ? ? T is satisfied, where [Oi] is an oxygen concentration in the silicon wafer, [Oi]eq(T) is a limit solubility of oxygen in silicon at a temperature T, ?SiO2 is the surface energy of silicon dioxide, ? is a volume of a precipitated oxygen atom, r is a mean COP radius and k the Boltzmann constant, with the silicon wafer, during the heat treatment, at least part

Abstract: An SOI wafer, includes a substrate made from silicon, an electrically insulating layer with a thermal conductivity of at least 1.6 W/(Km) and a single-crystal silicon layer with a thickness of from 10 nm to 10 &mgr;m, a standard deviation of at most 5% from the mean layer thickness and a density of at most 0.5 HF defects/cm2.

Abstract: A family of extremely fine-grained alloys are used to make coatings or free-standing bodies having desirable properties for use as a heat-resistant and wear-resistant material. In an illustrative embodiment, the alloys are comprised of a multiplicity of alternate, microcrystalline or nanocrystalline films of tungsten metal and tungsten compound. The tungsten compound film may be comprised of a tungsten carbide or a tungsten boride. The tungsten films are the primary films. Their desirable characteristics, in addition to their very fine crystalline habit, per se, are the high strength, high hardness, high resilience, and high fracture energy which these fine crystallites foster. They may be manufactured by a chemical vapor deposition process in which reactive gas flows are rapidly switched to produce alternate films with abrupt hetero-junctions and thereby to produce the useful micro-crystalline habit. The unique synthesis method allows effective control of critical flaw size.

Abstract: A process for the heat treatment of a silicon wafer, during which the silicon wafer is at least temporarily exposed to an oxygen-containing atmosphere, the heat treatment taking place at a temperature which is selected in such a way that the inequality [ Oi ] < [ Oi ] eq ⁢ ( T ) ⁢ exp ⁢ ( 2 ⁢ σ SiO 2 ⁢ Ω rkT ) is satisfied, where [Oi] is the oxygen concentration in the silicon wafer [Oi]eq(T) is the limit solubility of oxygen in silicon at a temperature T, &sgr;SiO2 is the surface energy of silicon dioxide &OHgr; is the volum

Abstract: A process for the heat treatment of a silicon wafer, during which the silicon wafer is at least temporarily exposed to an oxygen-containing atmosphere, the heat treatment taking place at a temperature which is selected in such a way that the inequality 1 [ Oi ] < [ Oi ] eq ⁢ ( T ) ⁢ exp ⁢ ( 2 ⁢ σ SiO 2 ⁢ Ω rkT )

Abstract: A family of extremely fine-grained alloys are used to make coatings or free-standing bodies having desirable properties for use as a heat-resistant and wear-resistant material. In an illustrative embodiment, the alloys are comprised of a multiplicity of alternate, microcrystalline or nanocrystalline films of tungsten metal and tungsten compound. The tungsten compound film may be comprised of a tungsten carbide or a tungsten boride. The tungsten films are the primary films. Their desirable characteristics, in addition to their very fine crystalline habit, per se, are the high strength, high hardness, high resilience, and high fracture energy which these fine crystallites foster. They may be manufactured by a chemical vapor deposition process in which reactive gas flows are rapidly switched to produce alternate films with abrupt hetero-junctions and thereby to produce the useful micro-crystalline habit. The unique synthesis method allows effective control of critical flaw size.

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 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 and an outer refractory coating on the intermediate coating. The body has a converted porous layer formed by etching and reacting the body with 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 glass forming coating over the converted layer. Preferably an outer refractory coating is applied over the glass forming coating.

Abstract: A structural article for high temperature applications comprises a body formed of at least partially consolidated, particulate silicon nitride, a conformal outer coating of silicon nitride or silicon carbide on the body, and a conformal intermediate layer of a silicon, oxygen and nitrogen-containing compound, i.e. silicon oxynitride, chemically bonded to both the body and the outer coating. The method for making such an article comprises providing a body formed of at least partially consolidated, particulate silicon nitride, oxidizing the surface of the body, removing silicon dioxide from the oxidized surface of the body; and chemically vapor depositing a conformal outer coating of silicon nitride or silicon carbide. The conformal outer coating provides a protective envelope around and assists in high temperature isostatic pressing of the body and hence permits one to use the structural article in isostatic pressing processes.

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 method of forming a coated article is described. The article is composed of a carbon body having a thermochemically deposited coating which renders the body resistant to oxidation at high temperatures. A volatile gaseous halide of silicon is partially reduced to form a lower halide in a first reaction zone having a first pressure and separated from the body. The lower halide is flowed into a second reaction zone maintained at a pressure lower than the pressure in the first reaction zone. A gaseous alloying agent is introduced into the second reaction zone. The agent includes one or more elements selected from the group consisting of carbon, oxygen, aluminum, and nitrogen. As a consequence, a liquid phase intermediate compound is deposited on the substrate body which is thereafter thermochemically reacted to produce a coating of the silicon alloy.

Abstract: A coated article and method of forming the same. The article is composed of a carbon body having a thermochemically deposited coating which renders the body resistant to oxidation at high temperatures. The coating is formed of a silicon alloy having a non-columnar grain distribution with substantially equiaxial grains of an average diameter of less than one micron. The amount of silicon in the coating is in excess of the alloy stoichiometry, producing infusion of silicon, with such at or above its melting temperature, into the cracked mosaic of the coating, to form an oxidative resistant glass filler.

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.