ABSTRACT
Nitriding is a ferritic thermochemical treatment, which introduces atomic nitrogen into the ferrite phase of ferrous materials. It is a case-hardening technique operating in the temperature range of 500°C–590°C, 590°C being the eutectoid temperature in the binary iron-nitrogen system. Industrially, the gas-nitriding technique is most commonly practiced to case-harden ferrous materials. Plasma nitriding operates under the glow discharge conditions. Accordingly, it is also known as glow discharge nitriding or simply ionitriding. A gas discharge is generated by establishing a voltage across two electrodes in soft vacuum. Plasma heat treatment can handle the entire range of ferrous materials—from cast irons and low carbon steels to alloy steels and stainless steels. The plasma nitriding of titanium and titanium alloys has drawn much interest. Titanium has a strong affinity for nitrogen, and it has been established that the golden TiN nitride takes only a few minutes to form.
