Solid carbon active screen plasma nitrocarburizing of AISI 316L stainless steel in cold wall reactor: influence of plasma conditions

Abstract

Low temperature plasma nitrocarburizing processes are widely used surface treatment techniques to improve the surface hardness and wear resistance of stainless steels without loss of their excellent corrosion resistance. In the present study, plasma nitrocarburizing based on the active screen technology was applied in an industrial-scale cold wall reactor for the treatment of AISI 316L. Different technological aspects of a cold wall active screen plasma nitrocarburizing (ASPNC) reactor are addressed. The current study compiles recent achievements for the ASPNC treatment using an active screen made of carbon fibre-reinforced carbon under varying plasma conditions. In addition, it is shown that utilizing an active screen made of carbon opens up the possibility to control the structural properties of expanded austenite by the variation of the plasma conditions. It is revealed that for the ASPNC treatment using an active carbon screen, the high reactivity of the generated plasma at the carbon surface suppresses the requirement to apply a bias discharge.