稀土Dy和Ce共掺杂La2Zr2O7新型热障涂层用陶瓷材料

Dy and Ce Co-doped La_2Zr_2O_7 Ceramic Powder used for Thermal Barrier Coating

用化学沉淀法制备了稀土Dy和Ce共掺杂La_2Zr_2O_7新型热障涂层用陶瓷粉末La_(1.7)Dy_(0.3)(Zr_(0.8)CeZr_(0.2))_2- O_7(LDCZ).通过X射线衍射、扫描电镜、高温膨胀仪、DSC和激光热导仪对粉末相结构、不同煅烧温度下的相组成、微观结构、高温相稳定性、热膨胀系数和导热系数进行了分析.结果表明,稀土共掺杂的La_(1.7)Dy_(0.3)(Zr_(0.8)CeZr_(0.2))_2O_7保持了烧绿石结构,120℃时粉末为无定形的混合氧化物,900℃时转化为复合氧化物,1200℃时转变为单一的烧绿石相;高温下LDCZ无明显相变;添加Dy和Ce不仅可提高锆酸镧的热膨胀系数,使其高于8YSZ的热膨胀系数,并可使其导热系数较La_2Zr_2O_7降低25%以上,达到1.28～1.07W/m·K.

Dy and Ce co-doped lanthanum zirconate composite （La1.7Dy0.3（Zr0.8CeZr0.2）2O7, 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 La2Zr2O7 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 La2Zr207 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 that of La2Zr2O7, which indicates that LDCZ may be an excellent material for preparing thermal barrier coatings.