Effects of Ta2O5 content on mechanical properties and high-temperature performance of Zr6Ta2O17 thermal barrier coatings

Zr6Ta2O17/YSZ double ceramic top coat thermal barrier coatings (TBCs) with different Ta2O5 content are prepared by atmospheric plasma spraying (APS). The effects of Ta2O5 content on mechanical properties and high-temperature performance of Zr6Ta2O17 TBCs are investigated. With the decrease in Ta2O5 content, the hardness and fracture toughness of the Zr6Ta2O17 coating increases from 12.833 to 15.117 GPa and from 3.3592 to 3.7753 MPa m(1/2), respectively. The Zr6Ta2O17 coating specimens with different Ta2O5 content do not delaminate from the substrate except the edge peeling after 180 h of oxidation or 2000 thermal cycles at 1150 degrees C. The Zr-12Ta specimen (the molar ratio of ZrO2/Ta2O5 of 0.88:0.12) presents the more excellent mechanical properties and high-temperature performance. The reduction in Ta2O5 content will improve the mechanical properties, high-temperature oxidation, and thermal cycle performance of Zr6Ta2O17/YSZ double ceramic top coat TBCs.