微波合成片状β-SiC的工艺研究

On the Microwave Synthesis of Flaky β-SiC

片状β-SiC可通过使用石墨纸(C)作为碳源、正硅酸乙酯水解制得的SiO2溶胶.凝胶作为硅源、经微波加热合成。本文根据加热过程中微波炉加热温度、输入功率和反射功率的变化曲线,探讨了微波合成片状β-SiC过程中微波加热热效应。分别选择1100°C、1200°C、1300°C、1400°C和1500°C五个微波烧结温度,研究了相同保温时间下不同加热温度对微波合成片状β-SiC的影响。在烧结温度1300°C下,选取保温时间分别为0min、10min、30min和60min,探索了同一合成温度下不同保温时间对微波合成片状β-SiC的影响。采用XRD,SEM技术对样品进行了表征。结果发现,烧结温度为1100°C时,产物中合成了片状β-SiC;当烧结温度为1400°C时,片状β-SiC转化为β-SiC颗粒。过高的烧结温度和过长的保温时间都将导致β-SiC的氧化。在1300°C保温30min条件下得到的片状β-SiC生长最好。

The flaky β-SiC can be synthesized by microwave sintering, using graphite paper (C) as a carbon source and SiO2 prepared by hydrolysis of ethyl orthosilicate as a silicon source. According to the change curve of the heating temperature, input power and reflected power of the microwave oven during the heating process, the microwave heating effect in the process of microwave synthesis of flaky β-SiC was discussed. Five microwave sintering temperatures (1100°C, 1200°C, 1300°C, 1400°C and 1500°C) were selected to study the effects of heating temperatures on the microwave synthesis of flaky SiC at the same holding time. At the synthesis temperature of 1300°C, the effects of holding time at the same synthesis temperature on the microwave synthesis of flaky SiC were investigated at 0 min, 10 min, 30 min and 60 min. The samples were characterized by XRD and SEM. It was found that, when the sintering temperature was 1100°C, the flaky β-SiC was synthesized. When the sintering temperature was 1400°C, the flaky β-SiC was converted into β-SiC particles. The higher sintering temperature and longer holding time will lead to the oxidation of β-SiC. The best sintering condition of flaky β-SiC is 1300°C for 30 min.