High temperature lubrication of various ceramics and metal alloys via directed hydrocarbon feed gases

High temperature lubrication via the in situ deposition of lubricous carbon surface films from the pyrolytic decomposition of hydrocarbon feed gas has been confirmed on a variety of self-mated ceramic and metal alloy sliding contacts. Pin-on-disk tests were performed at 520 degrees C in an atmosphere purged with nitrogen at 3 l/min, with a directed acetylene admixture supplied at 0.2 l/min, and compared to tests in nitrogen alone or air. Friction coefficients of Less than mu approximate to 0.08 were recorded for all metal alloys tested-AISI M50, 52100, 440C and 1018 steel, as well as K-Monel (500) and Hastalloy C276. Friction coefficients of less than mu approximate to 0.10 were found for alumina, silicon nitride, tungsten carbide, and zirconia. Only soda lime glass showed no friction coefficient reduction upon acetylene admixture. In general, acetylene admixture also significantly reduced wear volume, with wear reductions of multiple orders of magnitude in many instances. (C) 1998 Elsevier Science S.A.