氧化锆—莫来石纳米复相陶瓷的制备  

Preparation of ZrO_2—mullite nano-composite ceramics

作　　者：谭小平[1] 梁叔全[1] 李少强[1] 唐艳[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2005年第5期790-794,共5页Journal of Central South University:Science and Technology

基　　金：国家"863"计划资助项目(2003AA332040)

摘　　要：通过选择合适的SiO2-Al2O3-ZrO2(SAZ) 配方和添加剂, 在1 620～1 700 ℃熔成均匀的SAZ熔体, 经超快速冷却凝固得到大块透明非晶体, 再经二步热处理制得白色氧化锆-莫来石纳米复相陶瓷. 用差式扫描量热分析、 X射线衍射和扫描电镜等技术研究SAZ系非晶的原位受控晶化过程. 研究结果表明: 在900～950 ℃时, SAZ系非晶中开始析出四方氧化锆(t-ZrO2);在1 000 ℃左右时, 莫来石晶相开始形成;在1 100 ℃时, 晶化基本完全, 其显微结构致密, 粒子大小均匀, 呈球状, 平均粒径为20～50 nm;当温度继续升高至1 150 ℃时, 有少量单斜氧化锆(m-ZrO2)生成, 这说明在1 100～1 150 ℃时, 已有部分t-ZrO2发生马氏体相变;当温度高达1 250 ℃时, m-ZrO2含量明显增加, 还有堇青石相析出, 其粒子迅速长大, 到1 350 ℃时少数莫来石晶体长度达5 μm;加入添加剂TiO2, 并未改变初晶相t-ZrO2的形成, 但显著降低了SAZ系非晶的晶化温度, 促进其整体晶化.With the reasonable composition design of basic component SiO2-Al2O3-ZrO2 （SAZ） and additions, the SAZ homogeneous melt was prepared at 1 620 - 1 700 ℃ and then the transparent amorphous bulk material was obtained after quenching. The bulk material was heat-treated at 900- 1 000 ℃ for 2 h to nucleate and at 1 100 - 1 200℃ for 1 h to crystallize, and then ZrO2- mullite nano-composite ceramics were prepared. The crystallization behaviors of SAZ amorphous bulk materials were investigated by differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy. The results show that the SAZ amorphous bulk materials start devitrifying at 900 - 950℃ and t-ZrO2 phase forms first. With the temperature up to 1 000℃, mul- litization appears and mullite becomes the major phase at 1 100 ℃. Above 1 100 ℃, a small amount of t-ZrO2 changes into m-ZrO2, and the m-ZrO2 content is more than 50% for the samples heat-treated at 1 250 ~C when cordierite is formed. There is no change of the crystal phase formed first through adding TiO2, which greatly decreases the crystallization temperature and promotes the crystallization of the SAZ amorphous bulk. And the sample heated at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with the size of ball-like grains of about 20 - 50 nm. With the temperature up to 1 350 ℃, the grains grow quickly and some grow into platelike grains with a few grains of about 5μm.

关 键 词：SiO2-Al2O3-ZrO2系非晶 二步热处理 晶化行为 

分 类 号：TQ171[化学工程—玻璃工业]