CeO_2和MgO助烧剂对矾土基莫来石合成料烧结的影响

Effects of sintering aids CeO_2 and MgO on sintering properties of bauxite based homogenized mullite grogs

以高铝矾土碎矿（w（Al2O3）为75%～84%）和煤矸石（w（Al2O3）约45%）为原料,按矾土基莫来石合成料的设计成分要求（w（Al2O3）为68%～72%）进行配比,于1500～1700 ℃分别保温3 h煅烧合成了矾土基莫来石,并分别研究了助烧剂CeO2和MgO单独加入,CeO2＋MgO复合加入,复合加入时CeO2与MgO的比例以及复合加入量对矾土基莫来石合成料烧结性能的影响.结果表明：加入CeO2＋MgO复合助烧剂比单独加入CeO2或MgO的促烧结效果要好,当CeO2＋MgO外加量为0.75%,CeO2与MgO质量比为1/1时,可使试样的烧结温度降至1600 ℃（不加助烧剂的为1700 ℃）,得到显气孔率0.9%,体积密度为2.84 g·cm^-3,荷重软化开始温度为1570 ℃的合成莫来石;显微结构分析表明,此合成料荷重软化温度较高的原因是发育良好的柱状莫来石构成了交错连锁的网络结构,同时TiO2大部分固溶在莫来石晶体中.

The bauxite based homogenized mullite grogs were prepared by using broken bauxite （ w（Al2O3 =75% - 84% ） and coal gangue（ w（ Al2O3 ）≈45% ） as starting materials according to the designed requirement of the grogs composition （ w（ Al2O3 ） =68% -72% ）, and firing at 1500 - 1700 ℃ for 3 h respectively. The effects of CeO2, MgO,the composite of CeO2 and MgO, the ratio of CeO2 and MgO, and the composite addition on the sintering properties were investigated. The results show that the composite of CeO2 and MgO has better sintering effect than the individual one. When the total addition of CeO2 and MgO is 0.75% and the mass ratio of CeO2 and MgO is I ：1 ,the sintering temperature is decreased to 1600 ℃ （that of specimen without sintering aid is 1700 ℃）,apparent porosity is 0.9% ,bulk density is 2.84 g · cm^-3 and the refractoriness under load is 1570 ℃. The grogs have higher refractoriness under load because its microstructure is characterized by continuous interlocking net structure of well developed columnar mullite crystals,and most of TiO2 enters mullite crystals as solid solution.