关键词: La₂Zr₂O ₇, 热物性能, 热障涂层, 稀土共掺杂, 化学沉淀法

Abstract: Dy and Ce co-doped lanthanum zirconate composite (La _1.7 Dy _0.3(Zr _0.8 CeZr _0.2 )₂ O ₇, LDCZ) ceramic powders were prepared by the chemical precipitation method. XRD, SEM, differential Scanning Calorimetry (DSC) and TG, were used to analyze the crystallogrphic phase, microstructure and the phase stability of LDCZ. High-temperature dilatometer, DSC and laser thermal diffusivity methods were used to analyze its thermal expansion coefficient (TEC), specific heat and thermal diffusivity. The results show that the compositions of all prepared ceramic powders are in the range of the synthesis of La ₂ Zr ₂ O ₇ with pyrochlore structure, the ceramic powders are amorphous mixed oxide at 120℃, the amorphous mixed oxide is converted to composite oxide when temperature is increased to 900, and the composite oxide is converted to single La　₂　Zr　₂O　₇ with pyrochlore structure at 1200℃. The LDCZ powders keep the pyrochlore structure and there is no phase transformations for LDCZ at high temperatures (～1300℃). The thermophysical results indicate that the thermal expansion coefficient of the LDCZ ceramic is slightly higher than that of conventional Y₂O₃-8wt%ZrO₂ (8YSZ) and the thermal conductivity of the ceramic is 1.28--1.07W/m·K, it is 25% lower than preparing thermal barrier coatings.

Key words: La₂Zr₂O ₇, thermophysical properties, thermal barrier coating, rare-earth co-doped, chemical precipitation method