Traditional thermal spray processes are based on this principle: heat fast – spray fast, with the idea being that the faster process is completed, the less oxidation will occur and the coating we will get will be better. Sometimes it works, however, fast heating requires higher gas temperatures, which may cause quite the opposite results: material evaporation, higher oxidation levels and coating material degradation.
While Kermetico are developing HVAF equipment, they continuously keep to one principle: heat slow, spray fast. A large diameter combustion chamber and a comparatively low gas combustion temperature allows the delivery of powder materials axially, directly to the combustion zone, where they are heated gradually and evenly.
The guns have a large diameter, flow optimized nozzle and narrow powder jet and these factors minimize any nozzle wall influence on particle velocity. Multiple gun designs and configurations let us spray materials with different melting points without overheating them.
Depositing the same feedstock using different technologies results in different coating properties. The Kermetico HVAF process lets you spray well-known materials with more desirable properties: higher hardness, ductility and deposition efficiency, with lower porosity and cost.
Coating Properties for a Protective Coating
- Gas permeability.
- Fracture toughness.
- Corrosion resistance in the given environment.
- Tribological properties in contact with a given material.
- Electrical conductivity.
- Bond strength.
- Coefficient of thermal expansion.
- Residual stress.
- Spray rate.
- Deposition efficiency.
- Cost of the feedstock spray material.
- Cost of the applied coating.
HVAF Coating Materials Include:
- Amorphous steel.
- Chromium carbide.
- Hastelloy coatings.
- Non-stick coatings.
- Stainless steel.
- Tungsten carbide.