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:

Thermally Sprayed Coatings

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 (Plasma Sprayed):

NiCrAlY
NiCoCrAlYTa

Abradable Coatings:

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 polyester by air-plasma spraying
CoNiCrAlY by plasma spraying

Examples of Parts in Aero-engines:

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

Thermal Spray in Aerospace