具有高梁微观结构多孔SiC的制备与表征

Preparation and Characterization of Biomorphic Silicon Carbide from Durra

高粱经高温热解转化为碳模板,再经液相渗透技术与熔融硅反应,生成具有高粱微观结构的多孔SiC材料.采用XRD、SEM和压汞技术对样品的物相、微观结构以及孔分布进行了研究.结果表明,最终的产物主要由β-SiC组成,且很好地复制了碳模板的微观结构.SiC的平均孔径和孔隙率分别为91.4μm和76.6%,与碳模板的88.5μm和71.2%相似.SiC的比表面积为33.7m^2/g,与碳模板的比表面积59.4m^2/g相比明显降低.二者相近的表面分维数(SiC为2.73,碳模板为2.70)也表明SiC很好地保持了碳模板的微观结构.高粱转化的SiC具有颗粒直径大、孔隙率高等特点.

Durra was firstly transformed into carbon template by high-temperature pyrolysis and then converted into biomorphic SiC by infiltration of liquid Si in Ar atmosphere at 1600℃. The purified SiC sample was characterized by X-ray diffraction, scanning electron microscope and mercury intrusion. The results suggest that the sample mainly consist of β-SiC and perfectly replicate the microstructure and morphology of the carbon template. The durra-derived SiC has a mean pore diameter of 91.4μm and porosity of 76.6%, and both of them are similar to those of the carbon template, 88.5 μm and 71.2%, respectively. The specific surface area of SiC is 33.7m^2/g, which is less than that of the carbon template, 59.4m^2/g. The surface fractal dimension is 2.73 for the SiC sample and 2.70 for the template by analyzing the mercury intrusion data. The durra-derived SiC has characteristics of large grain size and high porosity.