微波烧结制备碳化硅晶须的影响因素

Preparation of SiC whisker by microwave sintering

将干燥后的硅溶胶-活性炭作为反应物,在不加入任何金属催化剂的情况下,利用微波加热碳热还原法合成碳化硅晶须,研究反应温度和时间及坩埚部位对产物的影响。结果表明:30 min时,温度由1300℃升高到1600℃,产物中物相β-SiC越来越多;1500℃条件下,合成产物在坩埚的上部和中部主要分别为分散的SiC晶须和团聚在一起的SiC晶须;坩埚底部的产物主要为表面光滑的SiO2颗粒。1600℃条件下,合成产物在坩埚的上部和中部主要分别为分散的SiC晶须和等轴状β-SiC颗粒,底部为晶须和颗粒的混合物。1500℃×30 min得到的SiC晶须产率和直晶率优于1600℃×30 min得到的SiC晶须产率和直晶率。

Silicon carbide whiskers were synthesized by microwave heating carbothermic method using dried silica sol and active carbon as reactants under the condition of no adding any metal catalysts. The effects of heating temperature and time on products were studied. The results show that as the sintering temperature rises from 1300℃ to 1600 ℃ under the heating time of 30 min, the amount of B-SiC phase in the product increases. Different products are observed at different positions of the crucible. The products of dispersal SiC whisker and agglomerated SiC whisker at the top part and the center part of the crucible, and smooth surface SiO2 particles at the bottom of the crucible are obtained at the sintering temperature of 1500℃ for 30 min. Under the condition of heating temperature at 1600℃, the synthetic products are mainly composed of dispersal SiC whisker and equiaxia113-SIC particles at the top part and the center part of the crucible, and a mixture of whiskers and particles at the bottom of the crucible. It is found that higher yield and straight whiskers ratio can be obtained for synthesizing silicon carbon whiskers by microwave sintering at 1500℃ for 30 min.