Properties of Carbon-Based Coatings in High Temperature Applications

摘要

Carbon-based coatings, usually called DLC for diamond-like carbon, are widely used in tribological systems under high load and/or high pressure to reduce friction and wear. However, DLC starts to graphitize at temperatures higher than about 300°C which significantly limits the application to operating temperatures below this value in order to preserve the good tribological properties of these coatings in terms of low friction against steel and high wear resistance. While graphitization limits the application of DLC, it also allows the great running-in properties of carbon-based coatings. The degradation of DLC was investigated with a SRV test set-up (reciprocating sliding wear test) under dry running conditions. The results for friction and wear were completed by measurements of the depth-dependent coating hardness and the analysis of the structural properties by means of Raman Spectroscopy. In addition, the effect of DLC on the tribological properties of a lubricated contact was investigated on a disc-on-disc tribometer and compared to other coating materials. This analysis was completed by measurements of the thermal conductivity of the different coatings.