Abstract: A process and apparatus for making high purity aluminum nitride from organometallic aluminum, such as an alkylaluminum compound. A gaseous alkylaluminum compound and gaseous ammonia are introduced into a heated reaction zone where the gases are mixed and high purity aluminum nitride is produced. The high purity aluminum nitride is collected in the form of a powder or deposited as a thick, dense layer on an appropriate substrate mounted in the reaction chamber. A carrier gas such as hydrogen gas, may be used to conduct the alkylaluminum compound from a suitable reservoir containing liquid alkylaluminum compound to the reaction chamber. A preferred alkylaluminum compound is triethylaluminum.

Abstract: An optical solar reflector comprising a layer of silicon nitride having a reflective metallic coating on one side thereof and an optional dielectric coating on the opposite side.

Abstract: A thermal insulating device for use as the exterior coating of a space vehicle which consists essentially of a rigid carbon-carbon foam having an elastomeric foam bonded to the rear surface thereof and having a chemically vapor deposited coating applied to the front and side surfaces thereof.

Abstract: A silicon solar cell having a coverplate made of .beta.-silicon carbide.

Abstract: A process and apparatus for making high purity aluminum nitride from organometallic aluminum, such as an alkylaluminum compound. A gaseous alkylaluminum compound and gaseous ammonia are introduced into a heated reaction zone where the gases are mixed and high purity aluminum nitride is produced. The high purity aluminum nitride is collected in the form of a powder or deposited as a thick, dense layer on an appropriate substrate mounted in the reaction chamber. A carrier gas such as hydrogen gas, may be used to conduct the alkylaluminum compound from a suitable reservoir containing liquid alkylaluminum compound to the reaction chamber. A preferred alkylaluminum compound is triethylaluminum.

Abstract: A process for preparing reflective pyrolytic graphite by the chemical vapor deposition of graphite on a suitable support from methane or other short chain hydrocarbons at a suitable pressure and temperature followed by annealing the pyrolytic graphite at a temperature in excess of 2600.degree. C. and pressure of 5 to 10 torr.

Abstract: A low-density, thermally insulating composite which is ablation resistant and impervious to gases and liquids. The composite is comprised of a carbon-carbon syntactic foam material which is covered and penetrated by pyrolytic carbon, in order to increase the strength of the foam material. Pyrolytic graphite is then deposited onto at least one surface of the pyrolytic carbon covered and penetrated foam material to improve the thermal insulation of the composite and render it impervious to gas or liquids.