Oxidation resistance of thermal barrier coating with vacuum heat treated double-layer bond coating

Abstract:

The lifetime of traditional thermal barrier coating with one layer bond coating is limited by the insufficient oxidation resistance. A thermal barrier coating with a double-layer bond coating was prepared by HVOF and APS. Vacuum heat treatment was carried out prior to the top coating. Oxidation resistance of the thermal barrier coating was researched. The results show that the content of β-(Co, Ni)Al phase is raised from 13.91% to 27.78% by the 1050℃×3h vacuum heat treatment, and the distribution is more homogeneous. The roughness of HVOF sprayed bond coating is decreased by vacuum heat treatment. The roughness of vacuum heat treated bond coating is raised from Ra 7.2μm to Ra 10.4μm by the introduction of APS layer, and the bonding strength of thermal barrier coating is up to 39.4MPa. The wight gain rate of thermal barrier coating is 0.1719g/m_².h after oxidized at 1050℃ for 200h, which is consistent with antioxidant level of aviation industry standard. The bond coating sprayed by APS is sacrificed to oxidize prior to HVOF layer. The stress tolerance of bond coating/top coating interface is improved, and the lifetime will be extended.