Effect of Surface Coatings on the Tribological Properties of Sliding Contacts

The present work discusses the effects of Electrolytically deposited chromium coating on the Tribological behaviour of piston ring material. The frictional behaviours were evaluated using the linear reciprocating Tribometer under varying conditions of load and temperature. Test temperatures of 25, 50, and 100 degrees Celsius and loads of 20, 30, and 40N were applied during the tests to obtain the wear response of the coating under conditions similar to real piston cylinder/ring friction conditions. Tests were carried out with a constant sliding speed of 0.1 m/s. Optical micrographs and scanning electron microscope were used to analyze the nature of wear. It has been found that for lubricated or non-lubricated and coated or uncoated specimens, on increasing load, wear and surface roughness both increased for pins and plates. For dry conditions and a fixed load of 30N, wear of coated pins is found to be increasing with temperature from 25॰C to 100॰C, but plate wear shows a fully opposite variation in wear with increasing temperature thus wear decreased. Therefore, a substantial resistance to wear has been achieved by the hard chromium coating of pins.