Tribological behavior of sintered steel under starved lubrication in R600A environment

This study aims to develop and characterize wear resistant and low coefficient of friction material pairs at hermetic compressors bearings, compatible with new environmentally acceptable R600a (Isobutane) refrigerant. However, the long term wear and durability of compressors using R600a is unknown. The tribological behavior of 100Cr6 steel pin running against untreated and steam treated sintered steel under starved lubrication in air and R600a environments were investigated. Tests were conducted at a constant load of 50 N and the sliding speed of 0.8 m/s. Mineral oil was misted into the sample at the beginning of the each wear test. Energy dispersive X-ray analysis and SEM were carried out on pin and plate samples after wear tests. The concept of durability distance had been established for starved lubrication sliding; it was expressed as the distance necessary for the generation of the very first wear track marking, as correlated to the first fluctuation of the corresponding friction curve. It was found that durability distance is lower for the tests in R600a than those of in air. Adverse effect of R600a on wear is thought to be due to change in viscosity and foaming characteristics of the oil in the presence of R600a.