Lubricity of Low-Viscosity Aviation Fuel JP-10 and Tribological Behaviors of Silver (Ag) Films in JP-10

Abstract

To increase the thrust-to-weight ratio and reliability of gas turbine engines, conventional oil-lubricated bearings are desired to be replaced by fuel-lubricated bearings in fuel pumps. The present study aimed to examine the lubricity of low-viscosity aviation fuel JP-10 with ball-on-disc (Si3N4 ball/M50 steel disc) friction tests at ambient temperature and evaluate the tribological performance of self-lubricious silver (Ag) films while sliding in JP-10 against an Si3N4 ball. Four hundred–nanometer-thick Ag film was deposited on M50 steel by magnetron sputtering and high-current pulsed electron beam (HCPEB) was employed to alloy the as-deposited Ag film. Coefficients of friction (COFs) and wear topographies indicate that JP-10 had decent boundary and hydrodynamic lubrication performance, which was significantly better than that of deionized water but far weaker than that of professional lubricant. In JP-10, the counterpart almost immediately tore the as-deposited Ag film down from the M50 steel substrate, but the wear of the exposed steel surface was slight compared to that of bare M50 steel. Transferred Ag on the friction interface was probably responsible for the significant wear reduction but cannot effectively decrease the COF. The HCPEB-treated Ag film exhibited low friction (0.12) and effective wear protection in JP-10, but it can only function in a relatively short time in low-load conditions because of rapid wear. After wear-out, the COF rapidly rose higher than 0.2. The present work suggests that both types of Ag films are potential tribological surface modification approaches to raceways of fuel pump hybrid bearings for short-range applications.