Advantages of thermal spraying process:

1. When spraying, the temperature rise of the workpiece is small, which does not affect the matrix structure and does not change the matrix hardness;

2. There is no need to preheat or post weld heat treatment before and after spraying, which improves the production efficiency;

3. After spraying, it can grind and polish directly without machining, which improves the efficiency;

4. Using supersonic spraying equipment, through the adjustment and control of various parameters, the coating has high bonding strength with the substrate, high surface hardness and low porosity, which meets the requirements of API 6A gas seal, low friction resistance, good wear resistance, wear resistance and erosion resistance, and reduces the valve switching torque.

The spraying process includes the following steps: workpiece cleaning, surface sandblasting, spraying, rough grinding, visual inspection, fine grinding, grinding, polishing, inspection and warehousing. The workpiece needs to be sandblasted before spraying, and the workpiece after sandblasting should avoid touching;

The workpiece is clamped by fixture before spraying, and the surface can be sheltered without spraying. Tungsten carbide alloy powder is selected with particle size of 15-45um, kerosene flow rate is controlled at 5.5-6.5gph, powder feeding flow rate is 20-30scfh, and each spraying interval is controlled at 20 minutes.