Tungsten carbide HVOF coating is a coating technique that uses propane, propylene and other hydrocarbon gases and high-pressure oxygen to burn high-temperature and high-speed combustion flame flow in the combustion chamber or in a special nozzle, and the combustion flame speed can reach more than Mach 5 (1500m/s). 
By adding the powder axially into the flame, the sprayed particles can be heated to a molten or semi-molten state and accelerated to a speed of 300-500m/s or even higher to obtain high quality, high density and high stability coatings. The supersonic flame speed is very high, but the temperature is relatively low, about 3000 °C, when it’s used for WC-Co cemented carbide spraying, the decomposition of WC during the spraying process can be effectively suppressed. The coating not only has high bonding strength, but also has compactness and excellent wear resistance,which greatly exceeds that of plasma sprayed coatings. Therefore, Tungsten carbide HVOF coating is widely used.
The process and characteristics of supersonic spraying: high flame speed and low temperature make its coating performance and spraying process have many characteristics:
1. High flame and spray particle velocity. The flame speed reaches above 1800m/s, and the particle speed reaches 300-650m/s.
2. The particles are evenly heated. The injected powder is injected axially or radially into the combustion chamber so that the powder stays in the flame for a considerable time and melts sufficiently to produce a concentrated jet.
3. The contact time between the powder and the surrounding air is short, the flying speed of the powder particles is fast, the contact time with the surrounding atmosphere is short, and there is little reaction with the atmosphere. The active elements in the sprayed material are unlikely to burn, which is very important for avoiding decomposition and desorption. Carbide materials of carbon are particularly advantageous.
4. Fine spray powder, smooth coating The particle size of the powder used for high-velocity flame spraying is generally 10-45μm, which belongs to fine-grained powder. At the same time, the sprayed particles have high speed and melting, and the coating deformation is enough to form the coating surface. Small roughness.
5. Dense coating with high bonding strength The porosity of the high-speed flame sprayed coating is less than 2%, and the bonding strength is greater than 70MPa.
Oston Carbide provides a variety of surface strengthening technologies, including PTA surfacing, HVOF spraying, gas shielded welding, flame cladding, vacuum cladding, solid/salt bath boronizing, thermal diffusion hardening, etc.
