HVOF (HIGH VELOCITY OXYGEN FUEL)
HVOF (High Velocity Oxygen Fuel) is a high-resistant coating formed by formed by High Velocity Oxygen Fuels, such as chromium(II) carbide in nickel and chromium matrix, tungsten carbide in cobalt matrix and others.
The obtained layer reaches a thickness of 0.3 -0.4 mm, at a hardness of about 1000HV0.3. The coating is characterized by high resistance to abrasion and erosion, low porosity (below 1%) and low amount of oxides. The spraying process is carried out with a special gun in which the aviation fuel is burned and the exhaust gases reach supersonic speeds. Particles of the coating material are accelerated to supersonic speed and thanks to high kinetic energy are pushed into the surface of the modified part. As the particles stay in the flame itself for a short time, the surface contains small amounts of oxides and other inclusions, and thanks to the high speed, high adhesion of the layer to the surface is obtained. The process itself does not heat the component surface to high temperatures (below 200°), thus prevents the introduction of tension.
These coatings can be used on valve closing surfaces, pump impellers and other surfaces exposed to water or steam, as well as factors such as coal dust and ash.
The HVOF method can be used to cover new elements as well as to regenerate used ones. In case of damage in the nitride layer, it is necessary to remove the whole layer and apply the HVOF layer.
To ensure consistent application, we use robots that are able to apply the HVOF layer precisely. The layer applied in this way is characterized by uniform thickness over the entire surface, and thus evenly distributed tension. In addition, the robot ensures a constant distance between the burner and the surface of the coated part, which results in an homogenous layer over the entire surface.