莫来石晶须的制备及其生长机理

Synthesis and Growth Mechanism of Mullite Whiskers

以Al2O3和SiO2为原料、AlF3·3H2O为添加剂，采用原位反应法经1373～1873K反应5h后制备莫来石晶须。研究了添加剂含量及反应温度等对莫来石晶须合成的影响，探讨了莫来石晶须的生长机理。结果表明：AlF3·3H2O的最佳添加量为4％（质量分数）时，莫来石晶须的长度和长径比均随合成温度的升高（1373-1873K）先增大后减小，当合成温度为1673K时，样品中莫来石晶须的长径比最大（约为54）。莫来石晶须的生长是由气一固反应机理控制。

Mullite whiskers were synthesized at 1 373-1 873 K for 5 h by an in-situ solid-reaction method using Al2O3 and SiO2 as raw materials, and AlF3·3H2O as an additive. The effects of additive content and reacting temperature on the synthesis of mullite whiskers were investigated, and the growth mechanism of mullite whiskers was discussed. The results show that the length and aspect ratio of mullite whiskers with an optimal content of 4% （in mass fraction） AlF3·3H2O firstly increase, and then decrease with increasing the synthesized temperature from 1373 to 1 873 K, and they have the greatest aspect ratio of 54 at 1 673 K. Mullite whiskers are formed based on the vapor-solid reaction mechanism.