Ion nitriding is a chemical heat treatment process in which nitriding is carried out in a low vacuum of nitrogen-containing gas by means of a glow discharge generated between the mould (cathode) and the anode. This method has the advantages of clean working environment, fast infiltration speed and small deformation compared with the traditional gas nitriding, so it is widely used to improve the surface hardness and wear resistance of materials. Especially in the application of heavy mechanical parts such as toothed ring, ion nitriding can significantly improve the surface hardness, wear resistance and fatigue strength of the toothed ring, and at the same time reduce the distortion, to ensure the accuracy of the gear, and sometimes even can be directly assembled and used without the subsequent grinding process.

Specifically to the ring of ion nitriding process, including heat treatment, nitriding temperature control, nitriding layer thickness requirements, etc., are to meet the specific working environment and performance requirements. For example, according to the different working environment of the gear, the general requirements to obtain the nitriding layer depth is also different, the general gear nitriding layer requirements for 0.15-0.3mm, but for the impact load is particularly large or on the deformation, toughness requirements of the case, the nitriding layer may be in the 0.1mm or less, and for the impact load is large, large gears, the nitriding layer can reach 0.5-0.8mm.

The ion nitriding process also involves some special requirements, such as corrosion resistance, compound layer thickness, etc., which can be achieved by adjusting the process parameters or increasing the post-oxidation process. For example, one patent describes in detail a deep ion nitriding process for wind turbine gear rims, which achieves improved surface hardness and enhanced wear resistance of the rims by controlling the temperature and atmosphere.