Investigation on the influence factors for preparing mullite-whisker-structured porous ceramic
Investigation on the influence factors for preparing mullite-whisker-structured porous ceramic
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DOI：
10.1016/j.jallcom.2015.07.154
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发表时间：
2015-11
影响因子：
6.2
通讯作者：
Linfeng Xu;Xiuan Xi;Wenli Zhu;Anze Shui;W. Dai
中科院分区：
文献类型：
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作者：
Linfeng Xu;Xiuan Xi;Wenli Zhu;Anze Shui;W. Dai
以六氟铝酸铵（AHA）或玉米粉为造孔剂，可制得低密度莫来石晶须结构多孔陶瓷。AHA还用作硅蚀刻剂和铝源。研究了硅线石晶须的形成机理及其向莫来石晶须的转化。研究了多孔陶瓷中玉米粉掺杂量和粒度对陶瓷体密度和晶须生长的影响。实验结果表明，硅线石晶须是由气相反应和固相反应两种过程生成的，并有莫来石晶须生成。莫来石转变在1250 °C开始，在1450 °C完成。玉米粉燃烧产生的气孔会促进气生硅线石晶须的生长，降低多孔陶瓷的体积密度和导热系数。玉米粉的最佳添加量为50%，最佳粒度为120-160目。同时，所制备的莫来石晶须结构多孔陶瓷在高于1250 °C的温度下表现出较低的热导率。
Low-density mullite-whiskers-structured porous ceramic can be obtained through ammonium hexafluoroaluminate (AHA) or corn flour adopted as pore-forming agents. The AHA was also used as silicon etchant and source of aluminum. The formation mechanism of sillimanite whiskers and their transformation into mullite whiskers were investigated. The effects of amount and granularity of corn flour doping in the porous ceramic on the bulk density and whisker growth were also investigated. The experimental results demonstrated that sillimanite whiskers were formed by a gas phase reactionviatwo solid phase processes and mullite whiskers occurred. The mullite transformation starts at 1250 °C, completes at 1450 °C. Pores from burning out of corn flour will promote the growth of gas-derived sillimanite whiskers with the bulk density reduction of the porous ceramic as well as the heat conductivity coefficient. The optimal amount and granularity of corn flour is 50 wt% and 120–160 mesh, respectively. Meanwhile, the prepared mullite-whisker-structured porous ceramic showed low thermal conductivity at the temperature higher than 1250 °C.