放电等离子烧结制备Ca3Co4O9陶瓷及其电学性能

采用化学共沉淀与放电等离子烧结相结合的方法制备了Ca3Co4O9陶瓷.通过X射线衍射,红外光谱仪,扫描电镜等表征手段,探讨了Ca3Co4O9的形成过程,研究了不同制备工艺对陶瓷的物相,显微结构和性能的影响.实验结果表明共沉淀前驱物800℃预烧6 h或8 h后,再经放电等离子850℃,压力30 MPa下烧结5 min,可以获得纯相Ca3Co4O9陶瓷;800℃预烧6 h的烧结体密度为4.53 g/cm3,800℃预烧8 h的烧结体密度为4.78 g/cm3;前驱物预烧8 h后再经放电等离子烧结的块体具有较好的电学性能.700℃时,电阻率为8.30×10-5 Ωm,Seebeck系数为182μV/K.电导率和Seebeck系数在目前Ca-Co-O材料中是较高的.

SYNTHESIS AND ELECTRICAL PROPERTIES OF Ca3Co4O9 CERAMICS BY SPARK PLASMA SINTERING

Ca3 Co4 O9 ceramics were prepared by combining a chemical coprecipitation and spark plasma sintering(SPS) technique. The formation process of Ca3 Co4 O9 and the influence of different process on the phase,microstructure and properties of the ceramics were investigated by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy.The results show that the single phase Ca3Co4O9 bulk ceramics can be obtained from the precursors pre-calcined at 800 ℃ for 6 h or 8 h and then sintered by spark plasma at 30 MPa, 850 ℃ for 5 min. The densities of the samples calcined at 800 ℃ for 8 h or 6 h are 4.78 g/cm3 and 4.53 g/cm3 respectively. The bulk ceramics sample sintered by SPS process and using the powders calcined at 800 ℃ for 8 h exhibits better electric properties. After calcined at 700 ℃ ,the electrical resistivity of the sample are at the high level in the Ca - Co - O ceramic materials.