Sm_2Ce_2O_7-Gd_2Zr_2O_7复合材料制备及热导率

Preparation and Thermal Conductivity of Sm_2Ce_2O_7-Gd_2Zr_2O_7 Composite Materials

目的探讨了Gd_2Zr_2O_7的颗粒度和含量对(Sm_2Ce_2O_7)1-x(Gd_2Zr_2O_7)x复合材料热导率的影响。方法用纳米级和微米级粉体制备了两个系列的(Sm_2Ce_2O_7)1-x(Gd_2Zr_2O_7)x复合材料。用X射线衍射技术分析了材料的相组成,用扫描电镜观察了复合材料的显微形貌,用纽曼科普定律计算了复合材料的比热,用激光脉冲法测试了材料的热扩散系数。根据比热、密度和热扩散系数计算了复合材料的热导率,并根据最终热导率结果,分析了Gd_2Zr_2O_7颗粒度和含量对复合材料热导率的影响。结果所合成的粉体均具有单一的萤石晶体结构,纳米级Gd_2Zr_2O_7粉体最大比表面积为15.413 m^2/g,微米级Sm_2Ce_2O_7粉体最小比表面积为0.226 m^2/g。所制备的两个系列的(Sm_2Ce_2O_7)1-x(Gd_2Zr_2O_7)x复合材料也表现出单一的萤石晶体结构,但晶粒大小不均匀。结论当x=0.5时,纳米粉体制备的复合材料存在明显的纳米晶。微米级Gd_2Zr_2O_7对复合材料声子热导率抑制不明显,但可以抑制高温光子热导率;纳米级Gd_2Zr_2O_7的引入可明显降低复合材料的声子热导率,但对高温光子热导率抑制不明显。两个系列复合材料的热导率均低于YSZ。

The work aims to study the influence of content and particle size of Gd2Zr2O7 on the thermal conductivity of(Sm2Ce2O7)1?x(Gd2Zr2O7)x composite materials.Two series of(Sm2Ce2O7)1?x(Gd2Zr2O7)x composite materials were prepared by nano and micron powders.The phase-structure of composite materials was identified by X-ray diffraction method.The microstructure of composite materials was observed by scanning electron microscope.The specific heat capacity of composite materials was computed by Neumann-Kopp rule,and the thermal diffusivity of composite materials was measured by laser-flash method.Finally,the thermal conductivity of composite materials was obtained in light of the density,specific heat capacity and thermal diffusivity.The influence of particle size and content of Gd2Zr2O7 on thermal conductivity of composite materials was analyzed according to the final thermal conductivity results.The synthesized powders show single defect-fluorite structure.The largest specific surface area of nano-scale Gd2Zr2O7 is about 15.413 m2/g and the minimum specific surface area for micro-scale Sm2Ce2O7 is about 0.226 m2/g.These two series of(Sm2Ce2O7)1?x(Gd2Zr2O7)x composite materials also exhibit single fluorite crystal-lattice,while the grain size is not uniform.When x=0.5,the typical nano-scale grains are found in the composite materials prepared by nano-powder.The addition of micron-scale Gd2Zr2O7 does not influence the phonon-thermal conductivity obviously,but inhibits the photon thermal conductivity.The introduction of nano-scale Gd2Zr2O7 can reduce the phonon thermal conductivity of composite materials,while cannot inhibit the photon thermal conductivity obviously.The thermal conductivity of two series of composite materials is lower than YSZ.