燃烧条件对自蔓延高温合成Al_2O_3/AlB_(12)复相陶瓷粉体特性的影响

Effects of Combustion Conditions on the Characteristics of Al_2O_3/AlB_(12) Composite Powders Produced by Self-Propagation High-Temperature Synthesis

以铝、B2O3为原料，利用自蔓延高温合成（SHS）制备了Al2O3／AlB12复相陶瓷粉体，研究了燃烧条件对粉体特性的影响．结果发现，经球磨处理后，复相陶瓷粉体中Al2O3的平均粒径为3～4μm，AlB12的粒度为亚微米级．粉体的比表面积为～1m2／g．燃烧过程中B2O3易于挥发，并在合成产物的表层生成B2O3和9Al2O3·2B2O3副产物相．在较低压力的氩气中进行合成，可以减少副产物相，获得纯度较高的复相陶瓷．与实际测量的燃烧温度对比发现，按照化学反应式13Al＋6B2O3＝6Al2O3＋AlB12，通过热力学计算得到的绝热燃烧温度明显偏高．

Al2O3/AlB12 composite powders were produced by self-propagation high-temperature synthesis (SHS) employing Al and B2O3 as initial reactants. The effects of combustion conditions on the characteristics of the powders were discussed. The results show that, Al2O3 has an average particle size of 3~4μm, while the size of AlB12 is in the submicron range. The composite powders have an average specific surface of ~1 m2/g. Impurities of B2O3 and 9Al2O3.2B2O3 can be observed at the surface of the products because of the evaporization and condensation of B2O3. By decrease the argon pressure in the reactor, Al2O3/AlB12 powders of high purity can be obtained. The adiabatic temperature of the reaction 13Al+6B2O3=6Al2O3+AlB12 obtained from thermodynamic calculations is significantly higher than the measured combustion temperature.