烧结方式对ZnO-Bi_2O_3压敏瓷Bi_2O_3挥发的影响

Influence of sintering process on Bi_2O_3 vaporization of ZnO-Bi_2O_3 based varistor ceramics

采用裸烧、盖烧和埋烧等不同的烧结方式制备ZnO-Bi2O3压敏瓷,通过XRD和SEM等方法对压敏瓷的物相和显微组织进行研究,探讨烧结方式对氧化锌压敏瓷电性能和显微组织的影响。结果表明:烧结方式和烧结温度对压敏瓷的显微组织和电性能产生明显的影响。对于裸烧、盖烧和埋烧来说,1100℃均为最佳的烧结温度;1000℃时埋烧得到的压敏瓷的电性能较好,1100℃和1200℃时裸烧得到的压敏瓷的电性能较好;烧结方式对于Bi2O3挥发控制的强弱顺序为埋烧、盖烧、裸烧。

ZnO-Bi2O3 based varistor ceramics were sintered by using different sintering processes, open sintering, sintering inside a closed crucible and sintering within a powdered bed. The phases and microstructures of the varisotr ceramics were investigated by XRD and SEM. The effects of sintering process on electrical properties and microstructures of ZnO-Bi2O3 based varistor ceramics were discussed. The results show that the sintering process and sintering temperature have obvious effect on the microstructure and electrical properties of the samples. Optimal values for the electrical characteristics of the varistor ceramics by three kinds of sintering processes are obtained when the sintering is conducted at 1 100 ℃. At 1 000 ℃, the samples sintered within a powdered bed show better electrical properties than those subjected to the other two processes, while at 1 100 ℃ or 1 200 ℃, the open sintering samples exhibit better electrical properties. These results also show that Bi2O3 vaporization in three sintering processes is in the order from strong to weak as follows： sintering within a powdered bed, sintering inside a closed crucible, open sintering.