Supersonic spraying process:

Supersonic spraying WC alloy process for airtight sealing valve plate: spraying cemented carbide on the sealing surface of valve plate not only meets the scratch resistance and corrosion resistance of valve plate, but also does not change the matrix structure, the matrix hardness is not affected, and does not need preheating and post weld heat treatment, which is convenient for large-scale production and improves the production efficiency.

Using Praxair jp8000 supersonic spraying equipment, the sealing surface of valve plate is sprayed with tungsten carbide alloy. The density of the sprayed tungsten carbide alloy coating meets the requirements of gas seal, and the hardness of the coating is HV ≥ 1250; Porosity of coating: ≤ 1%; The bonding strength of the coating is not less than 10000psi (70MPa); The coating thickness is more than or equal to 0.10 mm.

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.

Process advantages:

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.