Abstract: A process for recovering oxygen from carbon dioxide is disclosed which is an improvement over the conventional process of utilizing an iron carbide catalyst in such reclamation process. As with the conventional processes the carbon dioxide is reacted with hydrogen to form a mixture of methane and water. The methane produced is then passed over a high temperature stable glass surface heated to about 1000.degree. C.-1200.degree. C. to produce hydrogen gas and a high density carbon, i.e. having a density greater than about 2 grams per cubic centimeter. This results in lessening of the storage problem for the carbon material because of its high density. The hydrogen gas produced is also recycled back to the incoming carbon dioxide for reaction.

Abstract: Carbon-carbon composites are prepared to receive a subsequent protective coating by having a thin coating (0.1 to 5 mils) of chemically vapor deposited (CVD) SiC applied to its surface. The SiC layer improves the performance of subsequent protective coatings (especially pack produced SiC conversion coatings), especially in the case of carbon-carbon composites having a negative coefficient of thermal expansion.

Abstract: A spar for use in a helicopter is produced by a three step process including first a low temperature low pressure step, second a high pressure high temperature step for a short time and third a low pressure (atmospheric) medium temperature step for a relatively long time.

Abstract: A method of producing high density carbon at relatively low temperatures is described. By flowing methane gas over glass rods or tubes at flow rates of 10 to 1300 cc per minute and temperatures of 1000.degree. to 1200.degree. C., carbon having a density greater than 2 grams per cubic centimeter and hydrogen gas are produced. An inert gas such as argon can be intermittently pulsed through the system to sweep the system free of low density carbon deposits and heating preferably takes place by means of induction coil heated graphite susceptors or resistance heaters.

Abstract: Silicon carbide coated carbon fibers and composite materials incorporating these fibers are disclosed. The silicon carbide coating provides electrical insulation and improved resistance to environmental degradation. The coated fibers may be embedded in organic, metal or glass matrices to form useful composite materials.

Abstract: Novel fine grained pyrolytic silicon nitride is produced by adding a substantial amount of methane to the normal reactant gases. Silicon tetrafluoride and ammonia in ratios of 60:40 to 10:90 may be employed with additions of methane in amounts equal to from 50 to 500% of the sum of silicon tetrafluoride and ammonia. When these reactant gases are passed over a heated substrate at a low pressure pyrolytic silicon nitride with a grain size of less than about 10 microns results.

Abstract: A method is described for increasing the impact properties of dense silicon nitride articles. The method includes the application of a slurry composed predominately of silicon powder to the surface of the dense silicon nitride article. The slurry coated article is then nitrided at an elevated temperature to partially convert the silicon powder to silicon nitride and to bond the particles together and to the substrate. About 15 to 45 volume percent of the silicon powder is not converted to silicon nitride but remains as elemental silicon.

Abstract: Processes of forming amorphous boron-carbon alloy in bulk form without crystallization are disclosed. Such products can be produced in thicknesses well in excess of ten mils by employing Reynolds number gas reactant flow conditions of 40 to 120. The resultant products of such processes having grain sizes preferably less than 30 A are also disclosed.

Abstract: Silicon nitride coated carbon fibers and composite materials incorporating these fibers are disclosed. The silicon nitride coating provides electrical insulation and improved resistance to environmental degradation. The resultant coated fibers may be embedded in organic or metal matrices to form composite materials.

Abstract: A process for producing continuous filaments from polyamic acid suitable for conversion to polyimide filaments comprising providing a starting solution consisting essentially of equimolar amounts of P,P-diaminophenyl ether and bis-(3,4-dicarboxyphenyl) sulfone dianhydride, the remainder a solvent selected from the group consisting of dimethylformamide, methyl pyrrolidone and mixtures thereof, said starting solution having a viscosity ranging from 500 to 5,000 centipoises preferably 1,500 to 3,000 centipoises, and forming the starting solution into filaments by extruding it in a coagulating bath consisting essentially of a liquid selected from the group consisting of propanol, methyl alcohol, ethyl alcohol, butyl alcohol, a mixture of ethyl alcohol and propanol and a mixture of methyl alcohol and acetone.

Abstract: The low pressure braze bonding of members comprised of, for example, titanium and zirconium alloys is accomplished with the use of foil-type braze alloy preforms. The braze alloy preforms comprise a titanium-zirconium foil which has been coated on at least one side with a layer of nickel which functions as a eutectic depressant alloying agent. Upon heating, at a temperature below the beta transus of titanium, a liquid phase will form and the nickel will partially alloy with and migrate into the foil and workpieces and solidification of the resulting joint may thereafter be obtained.

Abstract: The diffusion brazing of members comprised of materials which are characterized by embrittlement as a result of exposure to excessive temperatures is accomplished with the aid of preforms consisting of a titanium-zirconium alloy foil coated with a plurality of eutectic depressant alloying agents. The depressant agents, in a preferred embodiment, are applied as layers and consist of beryllium and nickel. The preforms are sandwiched between surfaces to be joined and the resulting assemblies are heated in a non-reactive environment with light pressure loading whereby a liquid phase will result and diffusion of metal from the preform into the base metals will occur.