A review on preparation process and tribological performance of coatings for internal combustion engine piston ring

Abstract

Reducing the energy consumption and exhaust emission, and improving the combustion efficiency of internal combustion engine are important for solving the problems of climate change and environmental pollution. The piston ring-liner system is one of the most serious friction pairs in internal combustion engine, accounting for 26% of the total friction loss. Depositing strengthened coatings on the surface of piston rings is an effective method to reduce the friction coefficient and wear rate. This paper reviews the research progress of several representative technologies for preparing coatings, such as electroplating, physical vapor deposition (PVD), thermal spraying and chemical vapor deposition (CVD), and so on. Various coatings, such as Cr-Al2O3 coating prepared by representative electroplating process, CrN and DLC coatings prepared by physical vapor deposition, and Mo-based and C-based coatings prepared by thermal spraying process, are briefly discussed. Furthermore, the positive and negative aspects of commonly used piston ring coatings are compared, and their development trends are summarized.