Alloy family in which M stands for nickel, cobalt or both, combined with chromium, aluminum and a small yttrium addition. On exposure to hot gas the aluminum forms a slow-growing, adherent alumina scale that protects the metal, and yttrium helps it stay attached. MCrAlYs serve as standalone oxidation coatings and as the bond coat under ceramic thermal barriers, applied by VPS, HVOF or HVAF.
Vanes get NiCoCrAlY by HVOF, a vacuum diffusion cycle, then the 8YSZ top coat.
Also heard as
- MCrAlY bond coat
- NiCoCrAlY
- CoNiCrAlY
- NiCrAlY
Related terms
Bond coat
The first layer sprayed on a substrate to help the following coat stick and sometimes protect the metal.
TGO
Thermally grown oxide: the alumina layer that grows between bond coat and ceramic in hot service.
VPS
Vacuum plasma spray: plasma spraying inside a low-pressure inert chamber to make oxide-free metal coatings.
Thermal barrier coating
A ceramic coating system that insulates hot-section metal parts from combustion gas temperatures.