Properties Of Multi-oxide Stabilized Zirconia Tbcs Produced By Electron Beam-physical Vapor Deposition

Thermal barrier coatings (TBCs) were used to improve the durability of aircraft gas turbine, which increases the component lifetime as well as allows higher engine temperature and better efficiency. A major disadvantage of the currently 6⁸ wt% Y₂O₃ (YSZ) TBCs is the t-m phase transformation. This limits the TBCs works at temperatures below 1200℃. Therefore, it is important to develop novel ceramics for TBCs.Ta₂O₅ doped yttrium stabilized zirconia (Ta-YSZ) and yttrium partially stabilized zirconia (YSZ) ceramics for thermal barrier coatings (TBCs) were synthesized by the solid state reaction. The phase compositions, microstructures, thermal expansion coefficient and thermal conductivity of the materials were investigated using XRD, SEM, DIL and LFA method, respectively. Ta-YSZ is solely composed with tetragonal phase, while YSZ is composed with tetragonal and monoclinic phases. The microstructure of Ta-YSZ is better than that of YSZ. The thermal expansion coefficient of Ta-YSZ is higher than that of YSZ. The thermal conductivity of Ta-YSZ is lower than that of YSZ.Ta-YSZ TBCs was deposited by the electron beam-physical vapor deposition method (EB-PVD). The phase compositions, microstructure, isothermal oxidation behaviors and thermal cycling behaviors of Ta-YSZ TBCs were investigated. The phase compositions of Ta-YSZ coatings are t/t′phases. The crystal morphology of Ta-YSZ TBCs is columnar, which is the typical morphology for the EB-PVD coatings. The Ta-YSZ coating is destroyed when isothermal oxidized at 1100℃for 1200h or thermal cycled 600 times. The main reasons for this destroy are that the decomposition of t/t′and Ta₂O₅ and the spallation.