Improving the Properties of the Piston Surface by Optimized Nitriding Parameters

Abstract

Pistons of internal combustion engines are subjected to high fatigue loadings and high temperatures during operation. A progressive loss of the material may occur to the weakest areas of the piston resulting in a premature failure. A surface modification is required to lengthen its life. Nitriding is one of the surface treatments which can be used to enhance the surface properties. In this work, the processing parameters of nitriding process of the piston surface were investigated to to obtain the highest hardness. The optimized parameters were used to produce the treated product which subsequently tested using wear test, surface roughness test, and corrosion test. The samples were cut from a piston crown to form a 3 mm thickness and 13 mm width. The process of plasma nitriding was done in a DC glow discharge plasma nitriding machine with a flow of N2 gas. The processing parameters of the nitriding were pressures, time and temperature. The result shows that the highest hardness was obtained in the sample nitrided by a pressure of 1.2 mbar, a time of 3 hours, and a temperature of 175 C. However, the sample nitrided by the same parameters produces a highest value in the surface roughness and corrosion rate. The use of optimized parameters therefore can be used to lengthen the life of piston.