Plasma nitrosulfurizing techniques for low friction coefficient with H2S and C3H8 gas addition

AISI 1045 steels were plasma nitrosulfurized with C3H8 gas to enhance surface hardness as well as tribological properties. During the plasma nitrosulfurizing, 100 sccm of C3H8 gas was added to the mixture of N2, H2 and H2S. The process was carried out under 2 torr pressure at 550 °C for 2 h. When C3H8 gas was added to the gas mixture, surface hardness was higher than that of conventional plasma nitrosulfurizing layer. FeS was observed on the plasma nitrosulfurized layers and sulfur concentration increased as H2S gas flow rate increased. Friction coefficient of AISI 1045 steels has been reduced to 0.4 by adding 100 sccm of C3H8 gas during plasma nitrosulfurizing. Wear rate also lowered from 5.3 × 10− 6 to 1 × 10− 6 mm3/Nm when C3H8 gas was added.