High Temperature Oxidation Properties of Plasma Sprayed MCrAlY Coatings

Two MCrAlY (MCrAlY-CrO and MCrAlY-AlO) coatings with different oxide (Cr₂O₃ and Al₂O₃) ceramic compositions were prepared by atmospheric plasma spraying (APS) equipment, and the microscopic morphology, phase compositions and hardness of the coatings were analyzed by optical microscope, scanning electron microscope, X-ray diffractometer and microhardness tester. The high temperature oxidation tests were carried out on the two coatings. The results show that the two MCrAlY coatings prepared by APS contained Cr₂O₃, Ni₃Al, Al₂O₃ and some amorphous phases. The structure of the two coatings was a layered structure parallel to the bonding surface of the coating and the substrate. There were semi melted particles, micro cracks and grey oxides in the coatings. During the high temperature oxidation test, both MCrAlY-CrO coating and MCrAlY-AlO coating showed good high temperature oxidation resistance, because the oxidation products of chromium and aluminum which could protect the coatings, were formed on the surface of the coatings at high temperature.