Radical nitriding of cast iron

An investigation was carried out to determine the effects of hydrogen plasma etching for radical nitriding of cast iron. Nitriding reaction was inhibited by free carbon on the surface of cast iron. Therefore, cast iron substrates were pretreated by hydrogen plasma etching before radical nitriding. The Vickers hardness of the nitrided samples pretreated by hydrogen plasma etching with an applied voltage of -600 V was harder than that of similar samples with an applied voltage of -380 V. In addition, estimation on tribological properties indicated that the friction coefficients of all nitrided samples were almost the same as that of the untreated cast iron substrate.