Thermal Spray in Aerospace
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Thermal Spray in Aerospace
Thermal spray coatings, particularly those applied by APS (Atmospheric Plasma Spray) or HVOF (High Velocity Oxy-Fuel) methods, are extensively utilized in aircraft engines. Critical engine components such as the fan, compressor, combustion chamber, and turbine require protective coatings to guard against oxidation, corrosion from hot gases, erosion, and wear. Currently, hundreds of engine parts in industrial turbine units worldwide receive these thermal spray coatings. Their primary functions include reducing wear and corrosion, managing thermal load, enhancing engine efficiency, and extending component lifespan. Common materials and processes employed to achieve these protective functions include:
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 (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