电瓷烧结过程中显微结构和表面特征变化规律

Qantitative Pattern of the Change in Microstructure and Surface Properties of Electric Ceramic During Sintering Processes

烧结过程直接影响陶瓷坯体的比表面积、显微结构、孔隙结构以及其它多种表界面性质,从而对陶瓷性能产生重要影响。本文系统研究了常用电瓷在烧结过程中表界面性质的变化规律,分别测试并获得原样和5个不同烧结温度样品的N2吸附-脱附等温线数据,计算获得了样品的比表面积、孔体积、孔径分布、表面分维值等数据,并讨论了上述表面特征和显微结构与烧结温度的关系。研究结果表明:在700℃以下,比表面、孔体积以及表面分维值变化不大;当温度达到1000℃时,表面分维值达最大值;比表面积和孔体积在1340℃时最低。结合扫描电镜观察结果,认为上述变化与脱水作用、矿物相转变、表面融熔、晶界移动、晶粒长大等过程有关。

Sintering process directly influences the specific surface area, microstructure, pore size distribution and other interface properties of the ceramic, which influence its material characteristics and practical performance crucially. In this paper, the changes in surface and interface properties and pore structure of the electric ceramic for power-transmission equipments during high strength sintering process were studied systematically. Original sample and five of different sintering temperatures were prepared and their N2 adsorption-desorption isotherms were measured. Based on the adsorption and desorption data, the specific surface area,pore volume, pore size distribution by BJH method and surface fractal dimension by FHH method were calculated. In addition, the microstructures of these samples were observed using scanning electronic microscopy. Furthermore, the coincidence relation between the observed phenomena and sintering temperature was discussed. Results show that soecific surface area. pore volume and surface fractal dimension are nearly not changed before 700℃. At 1000℃, surface fractal dimension reaches the summit value, while the specific surface area and pore volume decrease sharply at 1340℃. Combined with the SEM observation results, it is indicated that these changes are directly related to the dehydration, mineral phase transformation, movement of crystal boundaries and the growing of crystal grain.