前驱体法制备碳化硅/硅氧碳陶瓷复合材料

Synthesis of SiC/SiOC Ceramic Composites by Pyrolysis of Precursor

采用含氢聚硅氧烷、环四甲基硅氧烷和超细硅粉为主要原料,在氩气保护下热解制得了碳化硅/硅氧（SiC/SiOC）碳陶瓷复合材料。结果表明：在1000~1200℃热解,制得了致密的硅氧碳陶瓷材料,硅粉颗粒均匀分布在基体中。当热解温度为1400℃时,硅氧碳陶瓷发生相分解,生成少量无定形碳化硅,添加硅粉后无定型碳化硅转变为有序晶体结构,且有少量孔洞随机分布在碳化硅/硅氧碳陶瓷复合材料中。提高热解温度至1500℃,生成的碳化硅量增加,但仍为无定型结构;添加硅粉后促进硅氧碳陶瓷中生成大量有序结构的碳化硅,产物中碳化硅衍射峰最强;生成的碳化硅/硅氧碳陶瓷复合材料的微观形貌表现为多孔结构,且基体内均匀分布着大量的孔洞,孔径约3μm。

In an argon atmosphere furnace, SiC/SiOC ceramic composites were fabricated by pyrolysis using polymethylhydrosiloxane, tetramethyl tetravinyl cyclotetrasiloxane and ultrafine silicon powders as raw materials. The result shows that the SiOC ceramic with dense structure was fabricated by pyrolysis in 1000- 1200 ℃, and Si particles were uniformly distributed in the matrix. When the pyrolysis temperature was 1400 ℃, the phase separation of SiOC ceramic resulted a small amount of amorphous SiC synthesized. The amorphous SiC was converted into an ordered crystal structure after adding silicon powders, and a small amount of pores were randomly distributed into SiOC ceramic. With the pyrolysis temperature increased to 1500 ℃, the amount of prepared SiC was increased, but the SiC was still amorphous structure. Addition of Si powders promoted large amount of crystalline SiC fabricated, and the diffraction peak intensity of SiC in the product was the strongest. The SiC/SiOC ceramic composites had a porous structure with large numbers of holes in a aperture of 3 μ m distributed uniformly into the matrix.