Rf plasma nitriding of pure iron and stainless steel

In r.f. inductively coupled plasma (r.f.-ICP) nitriding, the nitriding of iron is prevented by the addition of hydrogen. However, in this study, the r.f.-ICP nitriding of iron surface was achieved by the application of negative bias voltage even in the presence of hydrogen. It seems that the effect of bias voltage overcomes the additive effect of hydrogen. Furthermore, the r.f.-ICP nitriding of SUS304 in the presence of hydrogen was investigated. At 550 degrees C, the nitriding was suppressed by the addition of hydrogen, as well as the nitriding of iron. However, the nitriding was promoted by the addition of hydrogen at 350 degrees C, and a hard nitrided layer was obtained. On the contrary, SUS304 was not nitrided without hydrogen at 350 degrees C. (C) 1998 Elsevier Science S.A. All rights reserved.