ITSS Groups

High Velocity Oxygen Fuel (HVOF) coating

What is High Velocity Oxygen Fuel(HVOF)

- High Velocity Oxygen Fuel (HVOF) coating is a thermal spray coating process, which is used to improve or restore a component's surface (properties or geometry).
- This surface engineering technique better enables life extension of equipment by increasing erosion and wear resistance, and corrosion protection.
- HVOF spraying was developed in the 1980s and is a subset of thermal spraying. HVOF spraying works by mixing fluid fuel and oxygen, which is fed into a combustion chamber and ignited.
- The resultant gas has an extremely high temperature and pressure, which is ejected through a nozzle at supersonic speeds. To the high velocity gas stream, powder is injected, which partially melts.
- The stream of hot gas and powder is directed towards the surface to be coated. The resulting dense coating has low porosity and high bond strength, providing many benefits such as corrosion resistance

Advantages of Using a HVOF Coating

Advantages of HVOF spraying over other thermal spray processes primarily relate to improved coating quality, such as
  • Higher density (lower porosity) due to greater particle impact velocities
  • Higher strength bond to the underlying substrate and improved cohesive strength within the coating
  • Lower oxide content due to less in-flight exposure time
  • Retention of powder chemistry due to reduced time at temperature
  • Smoother as-sprayed surface due to higher impact velocities and smaller powder sizes
  • Better wear resistance due to harder, tougher coatings
  • Higher hardness due to less degradation of carbide phases
  • Improved corrosion protection due to less through thickness porosity
  • Thicker coating due to less residual stresses