High-Temperature Oxidation Resistance of CoCrAlY Protective Coating Strengthened by Laser Peening

Abstract:

The CoCrAlY coating was deposited on the surface of the nickel-based superalloy by Air plasma spraying (APS). And on this basis, electron beam vacuum deposition (EBVD) method was used to deposit aluminum film on the coating surface in order to increase the Al content. The above two coatings were reinforced by laser peening (LP) technique. X-ray diffraction (XRD) and scanning election microscope (SEM) were used to compare the phase structure, morphology and composition of the CoCrAlY coating before and after LP treatment. The results of microstructural analysis showed that the surface roughness of APS-CoCrAlY coating was decreased, and the microstructure became more compact after LP treatment. The surface Al content of CoCrAlY coating deposited with Al film after LP impact was increased significantly, and the content of β-CoAl phase was increased. The grain size was refined concurrently. The results of high-temperature oxidation test at 1050 °C showed that the oxide film formed on the surface of LP treated coating became smoother and denser than that of the original one, and the thickness of the oxide film was significantly thinner. In addition, the aluminized CoCrAlY coating after LP treatment achieved optimal performance of high-temperature oxidation resistance.