Effect of Hard Chromium Coating on the Frictional Behavior of Piston Ring Material

Hard chromium coatings are widely used as a potential coating material for ferrous materials. The superior tribological properties and corrosion resistance are the main properties of the hard chromium coatings. In an IC engine, the reduction in the friction between the tribopairs improves efficiency by reducing the fuel energy and lowering the emissions. In this work, the piston rings material was electroplated using the hard chromium and tribological tests were performed using a reciprocating tribometer with pin and plate specimens. The piston ring material was used as a pin and cylinder wall as a plate. The experiments were performed between (i) uncoated pin and plate, (ii) coated pin and plate and, and (iii) coated pin and uncoated plate. A linear reciprocating test rig was used for the experimentation at frequency values of 25, 30 Hz at 30 N, and 45 N load. A controlled temperature of 180̊ C was maintained and SAE 15W40 lubricating oil was used. It is found the chromium coating has proven to improve the friction behavior of the piston rings material; however, coating on both the mating parts (piston ring and cylinder) is not useful. Also, with an increase in frequency, the friction force decreases thereby decreasing the coefficient of friction and with an increase in load the friction force value increases.