INFLUENCE OF DEFECTS ON PROPERTIES OF SPUTTERED CoCrAIY COATINGS

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