Gd2Zr2O7陶瓷的高温热物理性能及Gd2Zr2O7-8YSZ双涂层制备

通过高温固相合成方法制备了烧绿石结构Gd₂Zr₂O₇陶瓷材料,研究了其高温相稳定性和热物理性能。采用电子束物理气相沉积方法制备了Gd₂Zr₂O₇-8YSZ(8%Y₂O₃-ZrO₂)双陶瓷层结构热障涂层,分析了涂层顶层的晶体结构和原子数量比。结果表明,Gd₂Zr₂O₇在室温至1500℃范围内具有良好的相稳定性,比第一代热障涂层8YSZ的高温相稳定区间提高250℃以上。Gd₂Zr₂O₇块材的热膨胀系数在100~1500℃范围内介于8.8×10^-6~11.0×10^-6 K^-1之间,与8YSZ接近; 在1000~1400℃高温区间,热导率约为1.0 W(m·K)^-1,比8YSZ降低一半左右。沉积制得的Gd₂Zr₂O₇涂层化学成分符合化学计量比,为烧绿石结构,涂层呈现典型的柱状晶结构。

High temperature thermo-physical properties of and preparation of a novel thermal barrier coating Gd2Zr2O7-8YSE

Gd₂Zr₂O₇ was prepared by solid state synthesis and its phase stability and thermo-physical properties were investigated. The Gd₂Zr₂O₇-8YSZ(8%Y₂O₃-ZrO₂) double-ceramic-layer thermal barrier coatings was prepared by electron beam physical vapour deposition. The crystal structure and atomic number ratio of the top coating were analysed. Results reveal that Gd₂Zr₂O₇ powders show excellent phase stability up to 1500℃, 250℃ higher as compared to the conventional 8YSZ.The coefficients of thermal expansion of the Gd₂Zr₂O₇ bulk ranges from 8.8×10^-6-11.0×10^-6 K^-1 at the temperature from 100 to 1500℃, which are comparable to that of the 8YSZ bulk.The thermal conductivities of the Gd₂Zr₂O₇ bulk are in a level of 1.0 W(m·K)^-1 at 1000-1400℃ and about 50% lower than that of the conventional 8YSZ. The as-deposited Gd₂Zr₂O₇ coating with pyrochlore structure has a stoichiometrical composition and exhibits a typical columnar grain structure.