LAUSR

The friction and wear properties, as well as the scuffing resistance, of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated. Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating (GDC) and diamond-like coating (DLC). The results indicated that the DLC coating had outstanding tribological properties (small coefficient of friction and wear loss) at 150 °C, while the GDC coating exhibited better performance at an elevated temperature (240 °C). The DLC coating had a better scuffing resistance; no material adhesion occurred for 70 min under the unlubricated condition. The interrupted wear behaviors revealed that the scuffing process of the GDC coating involved the consumption of lubricant oil with relatively stable wear, a reduction in the friction force, and the occurrence of scuffing, in sequence. In contrast, although the friction force also increased after a short period of weak friction, no scuffing was observed. This is attributed to the formation of a mixed oxide and graphitic C tribolayer.