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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 CleanFleet project was a 24-month demonstration of five alternative motor fuels and a control gasoline in 111 FedEx delivery vans. Delivery vans from Chevrolet, Dodge, and Ford were operated on compressed natural gas (CNG), M-85 (methanol containing 15 percent RFG), propane gas, and California Phase 2 reformulated gasoline (RFG). Control vans for each fleet were operated on gasoline. Electric vans on loan from Southern California Edison were also used by FedEx. Data were gathered on vehicle emissions, fleet operations, and facility and vehicle capital and operating costs. This paper focusses on vehicle reliability and maintenance. Maintenance experience is described, vehicle utilization is discussed, the results of oil analysis are presented, and future engine teardown and inspection plans are described.

In support of efforts to apply ceramics to advanced heat engines, a study was performed of the wear mechanisms of ceramics at the ring/cylinder interface. A laboratory apparatus was constructed to reproduce most of the conditions of an actual engine, but used easily prepared ring and cylinder specimens to facilitate their fabrication. Plasma-sprayed coatings of Cr2O3 and hypersonic flame-sprayed coatings of cobalt-bonded WC performed particularly well as ring coatings. Similar performance was obtained with these coatings operating against SiC, Si3N4, SiC whisker-reinforced Al2O3, and Cr2O3 coatings. The study demonstrated the critical need for lubrication and evaluated the performance of two available lubricants. SIGNIFICANT EFFICIENCY IMPROVEMENTS have been predicted resulting from the practical application of low-heat-rejection engines (1,2).