添加剂和升温速度对Si_3N_4陶瓷显微结构的影响

EFFECTS OF ADDITIVES AND HEATING RATE ON MICROSTRUCTURE OF Si 3N 4 MATERIALS

研究了添加剂组合与升温速度对气压烧结Ｓｉ３Ｎ４显微结构的影响。第二添加剂使晶体粒径整体增大，长径比降低。同时加入Ｓｃ２Ｏ３和ＺｒＯ２，并慢速升温，可有效提高长径比。放慢升温速度利于形成双峰粒度分布。

The effects of additives and heating rates on microstructure of gas pressure sintered Si 3N 4 were investigated. Addition of secondary additive increases the overall β Si 3N 4 grain growth, but the average aspect ratio of β Si 3N 4 grains is smaller. Low heating rate develops a bimodal grain size distribution, resulting in the microstructure with large elongated β Si 3N 4 grains embedded in a finegrained β Si 3N 4 matrix. When Sc 2O 3 and ZrO 2 are both added, the average aspect ratio in low heating rate is much greater than that in high heating rate.