Tribological behavior of DLC films in space and automotive oil under boundary lubrication

Abstract

The extremely hardness, high elastic modulus, excellent wear and corrosion resistance, high thermal and chemical stability, and the low-friction nature of the diamond-like carbon (DLC) coatings open further possibilities in improving tribological performance and reliability of different machine components. However, despite of the low friction coefficients normally observed for DLCcoated surfaces under dry sliding conditions, only a few DLC-coated tribological components are likely to be operated completely without a lubricant. In this paper, it was investigated the tribological behavior of DLC films in space and automotive oil under boundary lubrication. DLC films was grown over 316L stainless steel disks using plasma enhanced chemical vapor deposition. The tribological performance of the DLC film under Fomblin and 5W30 oil was investigated. Transferred materials on the DLC surface was examined using Raman Spectroscopy and contact angle. The combined effect of the transferred layer and the water content on oils might contribute to the effective improvement of the frictional and wear rate behaviors, which depends on the chemical structure and end groups in the lubricating oil.