PVD is a physical coating, which has a relatively low temperature. Compared with PVD coating, PVD has little influence on reducing the substrate's own strength. The principle is that high-speed particles bombarding the target produce refractory atoms deposition on the blade surface. CVD is a chemical coating, the coating temperature is relatively high, will have a certain impact on the substrate, but the adhesion with the substrate is good, the principle is to use a variety of chemical gases in the coating furnace reaction to generate refractory deposition on the surface of the blade.