Abstract
An engine must operate at an appropriate working temperature, the wear resistance of the engine parts must be increased, and frictional loss of energy must be reduced to increase performance and reduce exhaust pollution. This study determines the effect of cylinder temperature and different coatings for piston rings on engine characteristics. Ni-W alloy and Ni-W-BN(h) composite coatings are applied to the compression ring, and the dynamometer test is performed over 50 h using different operating parameters. The experimental data are analyzed by curve fitting for engine performance with cylinder temperature (Tsc) and the concentration of exhaust pollution particles. The experimental results show that a Ni-W alloy plating increases the wear resistance of piston rings. A Ni-W-BN(h) composite coating contains self-lubricating particles, which increases the wear resistance and lubricating properties. In terms of engine performance, Ni-W-BN(h) coated piston rings give the best brake mean effective pressure (BMEP) and fuel conversion efficiency (ηf), and low fuel consumption reduces HC and CO emissions. Therefore, Ni-W-BN(h) is the best coating material for a piston ring.