Salt Spray Corrosion Performance of NiCoCrAlY Coating

The corrosion performance of NiCoCrAlY coating obtained by LPPS (low pressure plasma spray) on low expansion GH907 superalloy was investigated by 500 h neutral salt spray testing in comparison with NiCr coating.The results showed that NiCoCrAlY coating lost its gloss,a few corrosion pits were observed and most coating remained to be integral and smooth.Its corrosion grade only reduced to the 9th grade after 500 h testing.On the other hand,the integrity and uniformity of NiCr coating was damaged and some cracks appeared in the coating,and the corrosion grade was lowed to the 4th grade after testing for 500 h.The corrosion products were mainly composed of oxides of Ni,Fe,Co etc.The NiCoCrAlY coating exhibited fairly good neutral salt spray corrosion resistance.