Study Of Plasma Nitriding Technology

The research field of this thesis belongs to heat treatment in metal materials. Ionic nitriding is a universal applied technique, which involves lots of marginal subjects such as discharge physics, Vacuum, Chemistry, Electronics and Materials science. Plasma nitriding technique is developing quickly and has been widely applied to machine, metallurgy, traffic, light industry, electron, aviation etc. At present, this technique has made a quite profit.The thesis focuses on the manufacture practice and the characteristic of ionic nitriding. The emphasis is placed on the research of plasma nitriding principle, nitriding technics and operation, test on the microstructure and performance of the nitrification layer.Plasma nitriding is an application way to metal surface and heating treatment based on the formed plasma by glow discharge. Nitriding is a way of heating treatment, namely, metal accessory is put into activate nitrogen and the gas of low light pressure is ionized into energy electrons, high energy ions and high energy neutral atoms by the action of the electric field under a definite temperature and the time of the heat preservation. It is these particles that can change nitriding layer microstructure and that accelerates the layer formation. Nitrogen is infiltrated through the surface of metals and it changes the chemical components. As a result, the surface of metal has good performance with high hardness, high resistant attrition, high fatigue strength, high resistant erode and resistant die burn. Strengthening mechanism of ion nitriding is different from surface quenching and cementation, which makes surface strengthen by quenching to get martensite. Ionic nitriding is the way to make materials strengthen, which result from the steady compound formed on the surface of the metal. There is no need for quenching after treatment.In recent years, mould industry is quickly developing and more and more surface engineering are popular. Surface hardness is strengthened by use of plasma nitriding technique to change microstructure of mould surface. On the basis of that, the major research works accomplished in this paper are as follows.Hardness, resistant attrition, fatigue strength, resistant erode and resistant die burn of the materials are enhanced and the life of the mould is increased by five to ten times. Through recent two years practice, the author has explored the technics parameters of ionic nitrding on the surface of the mould and has furthered the study on microstructure and performance of nitriding. In the end, good effect has been obtained.