Abstract: An aluminum burning rocket engine lining. The lining material is or includes one or more transition metal carbides of tantalum, niobium or vanadium. Applicants have determined that in aluminum burning rocket engines molten Al2O3 coats the inside surface of the throat of the rocket nozzle protecting certain transition metal carbides from oxidizing reactions at temperatures below a specific temperature that Applicants call the reaction initiated temperature (RIT). Applicants have proven through calculations and tests that a variety of transition metal carbide compositions as good as or better than tungsten as an engine liner material for aluminum burning rocket engines.

Abstract: An underwater torch with a metal infiltrated ceramic electrode for cutting and machining. The electrode has a composition with an empirical formula MB2-z+N, wherein 0<z<0.10 and M is selected from the group consisting of Zr, Hf and Ti, wherein N is selected from a group consisting of Cu, Au and Ag and wherein the MB2-z defines a ceramic structure formed with ceramic and defining a volume with void spaces comprising at least 10 percent of the volume of the matrix structure and the N occupies a portion of the void spaces. A preferred electrode material is ceramic matrix of ZrB2 slightly enriched in Zr that is infiltrated with copper. Preferred methods of making the composition involves at least two step: First, ZrB2 (which preferably is slightly enriched in Zr) is formed into a ceramic matrix having a density of up to 96 percent. Second, the ceramic matrix is heated in a pool of copper at a vacuum and at an infiltration temperature of about 1700 degrees C.