Ca_3Co_4O_9/Ag陶瓷复合材料的制备及其热电性能

Preparation and thermoelectric properties of Ca_3Co_4O_9/Ag ceramic composites

利用高分子网络凝胶法和放电等离子烧结技术(SPS)制备出高致密的Ca3Co4O9/Ag热电陶瓷复合材料。采用X射线衍射法表征了材料的相组成及其织构化程度,用SEM观察了粉体形貌和陶瓷断口的显微结构,并研究了Ag复合量对材料的室温热电性能的影响。研究结果表明,利用高分子网络凝胶法和SPS相结合的工艺有利于单质Ag在基体中的分布,使得基体中Ag相的粒径更小,分布更均匀。陶瓷复合材料的致密度均达到98%以上。虽然Ag颗粒的加入使Ca3Co4O9/Ag复合材料的Seebeck系数降低,但由于电导率显著提高,从而使材料的功率因子提高。

Ca3Co4O9/Ag polycrystalline samples were prepared by a polyacrylamide gel method, and followed by the spark plasma sintering （SPS）process. The formation of phase and the degree of texture were characterized by XRD. Microstructure of powers and the fracture of ceramics were observed by SEM. Effects of Ag content on the thermoelectric properties of Ca3 Co4 O9/Ag ceramics were studied at room temperature. The results indicate that Ag disperses evenly and the sizes of Ag particles are smaller by the polyacrylamide gel method and SPS process. The relative densities of the SPS samples are all over 98%. Though the addition of Ag decreases the Seebeck coefficient,the power factor of Ag composites is improved due to the obvious increase of electrical conductivity.