Effect of the actual environment present in hermetic compressors on the tribological behaviour of a Si-rich multifunctional DLC coating

Friction and wear control can be achieved primarily by considering the nature of the counter faces, together with the environmental conditions. In most cases, a transfer film is found on the sliding surfaces. The environment plays a crucial role on the kinetics of formation and on the composition of the transfer film, and thus strongly influences friction level and wears rates. In this paper, the effect of the actual environment (refrigerant) present in hermetic compressors on the tribological behaviour of a Si-rich multifunctional DLC coating deposited on 1020 steel and tested against 52100 steel pins was analyzed. Unlubricated reciprocating pin-on-disk tests were performed using a high pressure tribometer (HPT) under different atmospheres (air, CO2 and R600a). The tribological behaviour (friction coefficient and wear rate results) was analyzed using laser interferometry, scanning electron microscopy and micro-Raman spectroscopy. Samples tested in R600a environment presented the lowest friction coefficient and the lowest wear rate for both body and counter-body.