Feb 27, 2008 - exhaust gas could lubricate high-temperature Si3N4 bearing surfaces through lubricous carbon deposition and replenish- ment. As graphitic ...
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Lubrication of Silicon Nitride in a Simulated Turbine Exhaust Gas Environment@ W. GREGORY SAWYER (Member, STLE), THIERRY A. BLANCHET (Member, STLE) a n d SALVADORE J. CALABRESE Rensselaer Polytechnic Institute Dcpartmcnt of Mechanical Engineering, Aeronautical Engineering a n d Mechanics Troy, New York 12180
7bti17.g hc~sbeen conducted on silicon nitride (Si3N4)i n simulated engine exlin~~st gas environnmzts i n four-ball rolling contacts and pi~n-o~r.-disk slidin,g contacts lo 590°C. Utilizing a steel race, the depth (fthe wenr tmck formed at the Si3N4/Si3N4 rolling contad i n the presence of exhnust gas rum roughly one-hay that formed i n the presntce of N2 alone. Deposition of lubricous microctystalline graphite c(~rl,onfrom CO ruithin the exhaust was conjrmed by Raman spectroscoj~y.I?emovnl of H 2 0 from the exhaust gas further reduced rolling ruear. I
