Properties of Al₂O₃/ZrO₂ Composite Structural Thermal Barrier Coating Prepared by Plasma Spraying Method

Three kinds of thermal barrier coating were prepared on the surface of 304 stainless steel by plasma spraying method with NiCrAlY served as metal bonding layer material and Al₂O₃ and ZrO₂ served as the ceramic layer materials. The microscopic morphology and crystalline phase of the coating was characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD). The high temperature oxidation resistance and thermal shock resistance of the coating were also studied. The results show that NiCrAlY/Al₂O₃/ZrO₂ composite structural thermal barrier coating surface did not have any hole and crack, and there were Mg₂Zr₅O₁₂ and (Fe, Mg) (Cr, Fe)₂O₄ crystalline phase in the coating after high temperature oxidation. NiCrAlY/ZrO₂ coating had the best high temperature oxidation resistance because of the oxygen barrier effect of Al₂O₃. The thermal expansion coefficient of interlayer material in NiCrAlY/ZrO₂ coating had a gradient trend and the coating exhibited the best thermal shock resistance.