Surface treatment of powder metallurgy parts

The main purpose of the surface treatment of powder metallurgy parts are below: 
1. Improve the wear resistance (2) to improve the corrosion resistance (3) improve the fatigue strength.
Applied to the powder metallurgical parts surface treatment can divide five basic categories:
1. The coating on the surface of treated parts covered with a layer of other material without any chemical reaction;
2. The surface chemical treatment: the surface of the processed parts and the chemical reaction between reactants;
3. The chemical heat treatment, other elements such as C and N spread to be processed parts surface;
4. Surface treatment: through the cycle of temperature change and phase change, the microstructure changes on the surface of the processed parts;
5. Mechanical deformation method: the surface is able to produce body deformation, is mainly compressive residual stress, and at the same time improve the surface density.