No abstract

The Stirling space power machine incorporates a linear alternatm to generate electrical power. The alternator is a reciprocating device that is driven by a solar or nuclear-powered Stirling engine. The power piston and cylinder are made of titanium 6Al-4V (Ti6-4) alloy, and are designed to be lubricated by a hydrodynamically generated gas jilm. Rubbing occurs during starts and stops and there is the possibility of an occasional high speed rub. Since titanium is k n o k to have a seuere galling tadeng in sliding contacts, a "backup," self-lubn'cating coating on the cylinder and/or the piston is needed. This report describes the results of a research program to study the lubrication of Ti6-4 with the following chromium carbide based materials: plasma-sprayed PS212 coatings and sintered PM212 counterfaces. Program objectives are to achieue adherent coatings on Ti6-4 and to measure the friction and wear characlerirtics of the following sliding combinations under conditions simulative of the Stirling-driven space power linear alternator: Ti6-4/Ti6-4 baseline, Ti6-4/PS212-coated Ti6-4, and PS212-coated Ti6-4/PM212.