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 wt. % NiCr binder, 20 wt. % Cr203 hardener, and 10 wt. % each Ag and BaF2ICaF2 lubricants. For evaluation, the coating is plasma spray deposited onto test journals which are slid against a superalloy partial arc foil bearing. The test load was 10 KPa (1.5 psi) and the bearings were run under start/stop cyclic conditions. The data show good wear performance of the bearing especially at temperatures above 25 °C. Bearing friction was moderate (μ ≤≈0.4) over the entire temperature range. Based upon the results obtained, the PS304 coating has promise for high temperature, oil-free turbomachinery applications. Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999
The Effect of Compositional Tailoring on the Thermal Expansion and Tribological Properties of PS300: A Solid Lubricant Composite Coating
This paper describes a research program in which the goal is to alter the thermal expansion coefficient of a composite solid lubricant coating PS300, by compositional tailoring. PS300 is a plasma-sprayed coating consisting of chrome oxide, silver and barium fluoride/calcium fluoride eutectic in NiCr binder. By adjusting the composition, the thermal expansion coefficient can be altered, and hence chosen, to more closely match a selected substrate preventing coating spallation at extreme temperatures. Thermal expansion coefficients (CTEs) for a variety of compositions were measured from 25° to 800°C using a commercial dilatometer. The CTEs ranged from 7.0 to 13 × 10−6/°C depending on the binder content. Subsequent tribological testing of a modified composition indicated that friction and wear properties were generally comparable, and for some operating conditions superior, to the original composition. Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997
The camel in Somali oral traditions
The relationship between the camel and the Somali people has traditionally been reflected in Somalia's oral literary forms: Poems, proverbs, work songs, metaphores and tales of wisdom. The author h ...