Abstract: The influence of defects on the oxidation, hot corrosion and thermal shock properties of sputtered Co-30Cr-6Al-0.5Y coatings was investigated.The results indicated that the nodular defects reduced the properties of the coatings.For the oxidation,the nodular defects resulted in the severe internal oxidation of aluminium,as a result,the pure alu mina scale could not form at very high temperature such as at 1 100℃.For the hot corrosion,the nodular defects served as the short-path for the diffusion of sulfur into the coating and the substrate,and caused the sulfidation,of the specimen.Moreover,the nodular defects became the crack source during the thermal shock test and decreased the thermal shock resistance.

Key words: CoCrAlY coating, defect, oxidation, hot corrosion, thermal shock