Piston Ring Coatings for Internal Combustion Engines

Since the inception of the first internal combustion engine, the designers of engines and engine components have sought to improve piston ring wear resistance and to minimize cylinder liner wear. This paper describes and summarizes the work which has been done in our research laboratory towards this objective over a fifteen year period. The work encompasses aspects of coating design and metallurgical considerations, bench test data, laboratory engine test results and field engine results. Comparisons showing engine and laboratory test results of piston rings coated with hard chromium plate, molybdenum, compositions containing molybdenum and metallic oxides are presented.