Cyclic high temperature oxidation behaviour of sputtered Cr/Al multilayer coatings on superalloy

The cyclic high temperature oxidation behaviour of sputtered Cr/Al multilayer coatings fabricated by direct current magnetron sputtering on the superalloy substrate has been studied in the present work. The microstructural features of the as deposited coatings were characterised by field emission scanning electron microscopy, atomic force microscopy and X-ray diffraction. The weight change measurements were made to calculate the cyclic oxidation kinetics of the coatings, in air at 900 degrees C. It was observed that the corrosion rate of sputtered Cr/Al multilayer coated superalloy is lower than that of the uncoated superalloy due to the formation of continuous, dense, adherent and protective oxide scale over the surface of the coatings. The protective oxide scales are basically the thin layer of Cr2O3 and Al2O3, which has formed over the Cr/Al multilayer coated superalloy substrate exposed to air at a temperature of 900 degrees C.