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Scuffing of Area Contacts Under Starved Lubrication Conditions

The scuffing behavior of 390-T6 and DHT3 aluminum alloys, Si-Pb brass and gray cast iron, sliding against 1018 carburized steel, is experimentally studied under starved lubrication conditions. The major emphasis of the study is on the 390-T6 aluminum alloy. All tests are conducted in a high pressure tribometer (HPT) under RI34a (tetrafluoroethane) environment with polyalkylene glycol (PAG) and polyolester (POE) lubricants to simulate failures of critical tribocontacts in refrigerant compressors. An area contact, pin-on-disc geometry, is used to examine the effects of degree of lubricant starvation, sliding velocity, materials, and lubricant/refrigerant mixtures on scuffing. The scuffing transitions characteristics of 390-T6 aluminum as a function of lubricant supply rate are also examined. The processes leading to scuffing and failure mechanisms are studied by examination of scuffed surfaces and subsurfaces. Based on the experimental observations, it is hypothesized that bulk material failure during scuffing is due to plastic shearing or smearing. Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2000