Recent Developments in Piston-Ring Materials 390127
THE importance of the material of the piston ring has too long been relegated to the background as compared with such design factors as ring proportions, ring loadings, circularity, point pressure, and so on; therefore, this paper concentrates on the material factors - such as composition, structure, and surface finish - which should go into the modern piston ring. The causes of piston-ring wear are analyzed and classified under three headings - abrasion, corrosion, and erosion.
Various types of coating materials, both metallic and non-metallic, employed to reduce the severity of scuffing or scoring, are considered. Test results are revealed that indicate that superficial coatings reduce piston-ring wear from scuffing and erosion, and that a very thin coating of tin was more effective than other types of metallic and non-metallic coatings.