Corrosion Study of NIP and NIP Composite Plated Piston Ring

Piston rings are used to seal the cavity formed between the piston and cylinder in order to allow the engine to operate efficiently. The Piston rings wear out due to constant rubbing action with cylinder wall and also have to withstand very high temperature. The top compression ring is the closest to combustion gases and is exposed to the greatest amount of chemical corrosion and highest operating temperature. This has lead to development of new coatings to piston ring with good wear and corrosion resistance. One such coating is Nickel Phosphorus (Ni-P) and Nickel Phosphorus composite coating (Ni-P SiC) used in automotive industry. Reinforcement of ceramic particle not only enhances the tribological property but also the corrosion resistance behavior. The electroplated Ni-P & Ni-P metal matrix with ultra-fine SiC particles of 0.6 microns to a coating thickness of 30 microns minimum. Our work aims to study the corrosion property of Ni-P with different range of phosphorus percentage and Ni-P reinforced with ultra-fine SiC particles with different weight percent (10, 50 and 100 gms/lt) using potentiostat instrument. Results were also compared with conventional chrome plated piston rings.