Hardening Technology of Rotary Seal Valve

Rotary seal valve hardening technology: laser cladding technology and supersonic flame spraying

Laser cladding technology
Laser cladding is used to melt the coating materials and the substrate surface at the same time by laser irradiation and solidify quickly to form a surface coating that combines with the matrix metallurgy. It can improve the wear resistance, corrosion resistance, heat resistance, oxidation resistance and electrical properties of the base surface remarkably. Compared with the surfacing, spraying, electroplating and gas phase deposition, laser cladding has the characteristics of small dilution, compact structure, good combination of coating and matrix, suitable for multi coating material, large change of size and content. Because of the small loss of the coating material, the special process of laser cladding can save a large amount of material. Although the performance of the valve seal surface with laser cladding hardening is superior to the plasma surface and manual arc surface, the high price of the laser cladding equipment restricts its application on the hardening of the valve.

Supersonic flame spraying
Supersonic flame spray, a high energy density spray method developed by American Browning Company in the early 80s, is a supersonic flame that uses propane, propylene and other hydrocarbon gas or hydrogen and high-pressure oxygen in the combustion chamber, or burning in a special nozzle. The high temperature and high speed combustion flame flow (speed 21500) M/s) heats the sprayed particles to melt or semi molten state and accelerates up to 300-500m/s, resulting in high quality and compact coating with high bonding strength. The supersonic flame velocity is very high, but the temperature is relatively low (about 3000 C) for WC-Co system of cemented carbide, it can effectively inhibit the decomposition of WC in the spraying process. The coating has high bonding strength, superior wear resistance, which is much higher than that of the ionic spraying layer and is equivalent to the explosive coating layer. It also exceeds the hard chromium coating and spray coating, so it is widely used.