Plasma Nitriding (nitriding) is a surface hardening method applied in ferrous materials. The Plasma Nitriding process, which is carried out in vacuum furnaces specially designed for the process, is realized by ionizing the process gases and directing them to the work pieces by means of electric current.
When the diffusion temperature is reached in the slowly heated parts with the plasma phase that surrounds the work pieces homogeneously, nitrogen atoms begin to diffuse inward from the surface.
Plasma Nitriding process temperature can be between 350-580 °C depending on the type of material, the heat treatments it has undergone before and the desired surface properties. Processing time, on the other hand, can take from 15 minutes to 120 hours depending on the desired features.
Common applications include: Gears, crankshafts, camshafts, cam followers, valve parts, clamping screws, die casting molds, forging molds, cold forming molds, injectors and plastic injection molds, long shafts, axles, clutch and engine parts. Where surface masking is desired, plasma nitriding and plasma nitro-carburization are often preferred over other gas processes. Plasma nitriding can be applied to all iron-based materials, even highly porous sintered steels, cast irons and high alloy tool steels with a chromium content exceeding 12%. Stainless steels and nickel-based alloys can be plasma nitrided and retain most of their corrosion resistance in low temperature applications. Plasma nitriding of titanium and aluminum alloys are special applications. For heavy loads on large machine parts such as shafts and axles, special chrome and aluminum alloy nitriding steels provide as much benefit as plasma nitriding, as they have a surface hardness of over 1000 HV.