Si含量对反应烧结SiC陶瓷热电性能的影响

Effect of Si content on the thermoelectric properties of sintered SiC ceramics

采用可控溶渗反应烧结法制备了致密SiC陶瓷，研究了不同Si含量对反应烧结SiC陶瓷热电性能的影响。经研究发现，反应烧结SiC陶瓷中Si的存在使SiC陶瓷的电阻率急剧下降，大大改善了SiC陶瓷的电学性能；同时Si也改变了SiC陶瓷塞贝克系数随温度的变化趋势，即没有添加Si元素的SiC陶瓷的塞贝克系数随温度的升高逐渐增大，而添加Si元素的SiC陶瓷的塞贝克系数随温度的升高逐渐减小；总的来看，随着Si含量的增加，SiC陶瓷的塞贝克系数扣电导率不断增大，因此Sic陶瓷的功率因子不断提高，而且随着温度的升高，Si含量对SiC陶瓷热电优值的影响越来越明显，当含量为15％时，材料的热电优值是SiC烧结体的30倍。

The SiC ceramics was prepared by macromolecule pyrogenation combined with reaction bonging methods. The effect of Si content on the thermoelectric properties of sintered SiC ceramics was studied. The results show that the electric resistivities of sintered SiC ceramics decrease drastically by Si addition and the electric properties are improved greatly; meanwhile, temperature dependence of Seebeck coefficient of sintered SiC ceramics is changed also. As temperature increases, the Seebeck coefficient of pure sintered SiC ceramics increases, but it decreases with temperature when Si is added to SiC ceramics. Wholly speaking, Seebeck coefficient of SiC ceramics and the electric conductivity both increase when Si content increases, which results in a great improvement of the power factor of the materials. Moreover, the effect of Si content on the thermoelectric figure of merit of sintered SiC ceramics become stronger as temperature increases. The figure of merit of sintered SiC ceramics with 15%Si is 30 times that of sintered SiC ceramics at 873K.