| Abstract Scope |
The Navy has a long history of research in ultra-high temperature materials, dating back to the early 1960s. Early investigations into boride materials studied the CrB2, NbB2, and CrB2-Al2O3 systems before moving to the Group IV borides and carbides. The chemical vapor codeposition of HfB2-SiB4 and HfB2-SiC was successfully accomplished, and UHTCMC processing studies were undertaken. Oxidation studies centered on ZrB2-SiC materials, and included work on the formation of immiscible glasses. A wide array of boride, carbide, nitride, mixed, and substoichiometric compositions were exposed in an arcjet in order to understand the response of materials at hypersonic flight temperatures, while furnace and rocket nozzle exposures helped to elucidate the role of system pressure and shear on the oxidation reactions. More recently, NSWCCD scientists have studied UHTC-based cermets, as well as the use of entropic stabilization techniques to investigate 2, 3, 4, 5, and 6 component diborides and silicides. |