Na_2O对高铝粉煤灰合成莫来石的影响

Effect of Na_2O on the Mullite Synthesized from High-aluminium Fly Ash

本文研究了Na2O添加量和烧结温度对粉煤灰合成莫来石材料性能、晶体结构和显微形貌的影响。结果表明,Na2O可较大辐度降低粉煤灰合成莫来石的温度。在1300℃,Na2O添加至2%时,生成的莫来石细小,含量较高,但试样强度不高;Na2O添至4%时,莫来石发育为长柱状,长径比约8～12,并且相互交错成网状,材料的机械强度较高,抗折强度为97.71MPa,莫来石相对含量为76.1%;Na2O添加至8%时,莫来石含量明显减少,晶形变为不规则状。在一定范围内,材料的体积密度、烧成线收缩率和抗折强度均随温度的升高而增大,莫来石含量也相应增多。

In this work, the influence of Na2O and temperature on the properties, crystal structure, micrography of the mullite materials synthesized from high-aluminium fly ash were investigated in detail by SEM, XRD. The results showed that the Na2O exhibit efficiently side in reducing sintering temperature. The mullite crystal develope into fine and small shape with high yield when the batch containing 2 % Na2O is heated at 1300℃, and the attained mullite material own a relative low strength; when Na2O content reachs 4%, the mullite in the materials grows acrossly well into long-quadrel with the aspect ratio of 8-12, which results in the highest flexural strength of 97.71 MPa, and the mullite content in the sample reachs to 76.1% ; Na2O improved to 8 %, mullite content reduces in the sample and the crystal grows irregularly. The density, sintering liner shrinkage, bending strength and mullite content become higher with the sintering temperature rising in a certain range.