High Velocity Air/Oxygen Fuel, HVAF/HVOF
High Velocity Air Fuel (HVAF) refers to a thermal spray coating technique for the deposition of high-performance coatings. This coating is deposited from cemented carbide and metal powders. It protects machine parts against wear, corrosion, abrasion and erosion.
HVAF provides many benefits, such as:
- Low operating cost
- High material throughput
- High coating quality
HVAF can produce High Velocity Oxygen Fuel (HVOF)-like coatings. It is also capable of producing coatings similar to those produced by using cold spray.
HVAF coatings can be compared to coatings that are produced by HVOF and cold spray. HVAF is a "thermal spray" process that is less warm than HVOF, but warmer than cold spray.
This process utilizes axial powder injection into an air-fuel jet at 3452–3542°F (1900–1950°C). As a result, the process is used in applying carbide-based materials effectively. Since the air-fuel jet produces fewer oxides in comparison to high-temperature oxy-fuel jets, the HVAF process is also suitable for applying metals with little or no oxidation, resembling to cold spray. Therefore, all common thermal spray powder materials can be applied with HVAF—but only ceramics.
Some advantages of HVAF include:
- Compressed air is used instead of oxygen
- Higher spray rates and deposit efficiency
- Economic, faster spraying and lower application cost
- Quality coating; harder, better-performing coatings
- Spray gun is used for surface preparation
HVAF has many industrial uses; some are:
- Aerospace dimensioning
- Chemical tank protection
- Oil refining and drilling
- Pulp and paper industries
- Maritime corrosion resistance
- Auto engine part repairs