Plasma-assisted nitriding and nitrocarburizing of steel and other ferrous alloys

The fundamentals of plasma nitriding and nitrocarburizing are described, including the direct current (DC) and pulse glow discharge plasma, generation of the active nitrogen species and mechanism of the process. The hollow cathode discharge is also discussed. The role of sputtering with its research and practical aspects is thoroughly investigated. Plasma nitriding is defined as a low-nitriding potential type process, leading to the formation of thin compound layers in steels. The best applications of plasma nitriding include products made of stainless steels, especially those with requirements for selective hardening and highly polished surfaces, sintered low-density metal products, and production parts requiring a well-controlled nitrided layer with simultaneous selective hardening. Other good candidates for plasma nitriding include large gears for the power industry and metal-forming tools such as stamping dies. All of those applications have requirements for a high-quality nitrided case and selective hardening.