Abstract: A thermal protection system (TPS) comprising a mixture of silicon carbide and SiOx that has been converted from Si that is present in a collection of diatom frustules and at least one diatom has quasi-periodic pore-to-pore separation distance d(p-p) in a selected range. Where a heat shield comprising the converted SiC/SiOx frustules receives radiation, associated with atmospheric (re)entry, a portion of this radiation is reflected so that radiation loading of the heat shield is reduced.

Abstract: The present invention relates to an improved process to produce an essentially carbon-free nitrate of an alkali metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, metal, or mixtures thereof, which process comprises:Contacting an anhydrous composition of an alkali metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, or mixtures thereof substituted with an organic or an inorganic carbon-containing substitute with flowing nitrogen dioxide, dinitrogen tetroxide or mixtures thereof at a temperature of between about 40.degree. to 150.degree. C. under anhydrous conditions for a time and at a pressure effective to form the nitrate of the alkaline metal, alkaline earth metal, transition metal, lanthanide metal, actinide metal, or mixtures thereof, essentially free of any carbon containing contaminant. Materials produced by this improved process are useful as electrical superconductors, e.g. YBa.sub.2 Cu.sub.3 O.sub.

Abstract: Production of carbide shapes of silicon, titanium or vanadium by reaction of carbon with the metal in liquid phase such being carried out by heating a mixture of particles of carbon and particles of the metal rapidly to the melting point of the metal, thereby minimizing solid state reaction, and holding at a temperature and for a time sufficient to cause reaction. The metal and carbon particles are about 0.05 to 10 mm in diameter. An organic binder is used which volatilizes or dissociates upon heating.