粉煤灰资源化合成莫来石材料及其性能研究

以天然铝矾土和工业废物粉煤灰为原料,运用反应烧结合成了低成本的莫来石陶瓷材料。结果证明,刚玉与方石英相在1200～1300℃间通过固态反应生成二次莫来石,在温度高于1300℃时,刚玉相熔于短暂玻璃相中。二次莫来石化及莫来石晶体生长所导致的样品体膨胀大于液相烧结所引起的收缩,导致样品出现膨胀现象。1600℃烧结样品的平均热膨胀系数为5.40×10-6℃-1,平均抗弯强度186.19 MPa。莫来石在强酸强碱热溶液中表现出两个阶段:快速阶段(0～5h)和低速阶段(5～20h),这分别对应于样品的表面腐蚀和体腐蚀过程。

Synthesis and Performance Investigation of Mullite Materials by Recycling Waste Fly Ash

Low-cost mullite ceramics were synthesized by reaction-sintering with natural bauxite and industrial waste fly ash as starting materials.The results indicate that secondary mullite was produced at 1200～1300℃ by the solid state reaction of cristobalite and corundum,followed by the dissolution of corundum into transitory glassy phase at higher temperatures(≥1300℃).The formation of secondary mullite and its growth resulted in a volume expansion,which was higher than the shrinkage induced by liquid-phase sintering.The samples sintered at 1600℃ had average thermal expansion coefficient of 5.40×10-6℃-1 and average bending strength of 186.19 MPa.The sintered mullite exhibited two corrosion stages in hot strong acidic and alkaline solutions:fast stage(0～5h) and low-rate stage(5～20h),which respectively corresponded to the surface corrosion and bulk corrosion processes of the samples.