The evaluation of a modified chrome oxide based high temperature solid lubricant coating for foil gas bearings

This paper describes the friction and wear performance of PS304, a modified chrome oxide based coating,for foil gas bearings. PS304 contains 60 Mit. % NiCr binder; 20 wt. % Cr2O3 hardener, and 10 wt. % each Ag and BaF2/CaF2 lubricants. For evaluation, the coating is plasma spray deposited onto test journals which are slid against a superalloy partial are foil bearing. The test load was 10 KPa (1.5 psi) and the bearings were I run under start/stop cyclic conditions. The data show good wear performance of the bearing especially at temperatures above 25 degrees C. Bearing friction was moderate (mu less than or equal to approximate to 0.4) over the entire temperature range. Based upon the results obtained, the PS304 coating has promise for high temperature, oil-free turbomachinery applications.