Research on effect of Eu3+ doping on thermal insulation property and interfacial fracture toughness of YSZ thermal barrier coatings

Abstract:

Traditional YSZ coating and Eu3+ doped YSZ coating were prepared by APS method. SEM was used to observe and measure the morphology and porosity level of the two coatings. The thermal conductivity of the two coatings in the range of 100-1100°C was measured by using a flashlight heat conducting system. 30 cycles and 50 cycles of oxidation cycle treatment for both YSZ coating and YSZ:Eu coating were conducted by oxidation cycle test equipment at 1100°C, the interfacial fracture toughness of as-received and heat treated specimens were then calculated. The results show that the thermal conductivity of the YSZ:Eu coating is lower than that of the YSZ coating at the same temperature, indicating that 2mol% Eu3+ doping can effectively reduce the thermal conductivity of the YSZ TBCs. For both types of coating, interfacial fracture toughness decreases while the TGO thickness increases with the oxidation cycle number increasing. At the same heat treatment conditions, the interfacial fracture toughness of the YSZ:Eu coating is greater than that of the YSZ coating, and the TGO thickness is thinner, indicating that 2mol% Eu3+ doping inhibits the growth of TGO and improves the coating’s interfacial properties.

Key words:thermal barrier coatings; Eu3+ doping; thermal conductivity; oxidation cycle; fracture toughness