Self-Lubricating Materials for High Temperature Ring/Cylinder Application

In support of development efforts for advanced heat engines, self-lubricating materials were evaluated for their friction and wear characteristics above 260 C. The work focused on the ring/cylinder interface and tested self-lubricating ring or cylinder specimens against plasma-sprayed chromia or other ceramic materials. Three materials were chosen for the evaluation. Two of them were solid lubricant compacts, and one was a self-lubricating coating. The compacts were the Westinghouse (Boes) compact and a commercially available molybdenum disulfide-based composite. The coating consisted of a wear-resistant matrix filled with solid lubricating materials to reduce friction. The Boes compact resulted in high temperature friction and wear results that were in some cases equal to or better than those of earlier tests run with liquid lubrication. The other compact and the coating both had much higher wear and coefficients of friction than the Boes compact. The work showed the potential of solid lubricants to lubricate the ring/cylinder interface in low-heat-rejection engines effectively.