Thermal Spray in Aerospace
Thermal sprayed coatings, especially using APS or HVOF spray are widely used in Aero engines. The fan,compressor, combustion chamber, and turbine must be protected with coatingsagainst oxidation, hot gas corrosion, erosion, and wear. Hundreds of componentsare now sprayed in an aero engine usedforindustrial turbine engine units worldwide. Their main role is to reduce wear,corrosion, and thermal flux, improve the engine efficiency, and promote lifeextension.
Typical materials and processes used to realize the functions are as follows:
Typical materials and processes used to realize the functions are as follows:
- Adhesive wear:
- WC–Co and Cr3C2–NiCrAlY by high-velocity oxyfuel spraying
- Al2O3 or Cr2O3 by air-plasma spraying (APS)
- The duplex thermal barrier is usually ZrO2 stabilized with 8 wt% Y2O3 by air-plasma spraying onto an NiCrAlY bond coating.
- High-temperature corrosion resistant coatings, such as those sprayed by a plasma:
- NiCrAlY
- NiCoCrAlYTa
- Abradable coatings, such as:
- Al+6 wt% Si sprayed by a flame
- A composite of Al–Si+polyester by air-plasma spraying
- A composite of CoNiCrAlY with BN and a polyester by air-plasma spraying
- CoNiCrAlY by plasma spraying
- Some examples of parts on which thermally sprayed coatings are applied in aero-engines include
- Adhesive wear:
- Fan blade clappers
- Stator blades
- Flame tube locations
- Duplex thermal barriers:
- Combustion cans
- Combustion vanes
- Turbine blades
- Corrosion-resistant coatings:
- Turbine vanes
- Turbine blades
- Abradable coatings:
- Sectors of turbine rings
