溶胶—凝胶法制备纳米碳化硅粉的几种影响因素

SOME FACTORS ON PREPARING NANOMETER-SIZED

以蔗糖和正硅酸乙酯（TEOS）为前驱体，对溶胶—凝胶法制备纳米碳化硅粉工艺中的几种影响因素：pH值、去离子水量、蔗糖加入先后顺序等进行了研究。XRD分析结果表明，过量水导致Si(OR)4的充分水解，并形成高度交联的水解聚合物。由于交联程度高使得1400℃反应时只能得到大粒径的无定型二氧化硅，不能得到β－SiC。适量水与TEOS反应时，无论是在酸碱条件下都能得到粒径为15～20nm左右的β－SiC粉。其中二氧化硅含量以先用适量水水解，再加入去离子水溶解之蔗糖的样品为最少。SEM和TEM分析表明，在酸性环境中水解后制得的纳米碳化硅粉分散性好，粒度均匀；而在碱性环境中水解制得的碳化硅粉团聚程度高。

With the precursors of tetraethoxysilane (TEOS) and saccharose (C12H22O11), we studied some important factors on the synthesis of nanometer-sized silicon carbide by sol-gel technique. These factors included the pH value of solutions, the amount of ionized water, and the sequence of adding saccharose into systems. The results of XRD indicated that excessive water led Si(OR)4 to hydrolyze completely and form highly cross-linked polymers. Consequently, only large-sized amorphous SiO2 particles could be obtained at 1 400 ℃ without (－ SiC. When TEOS reacted with moderate water, the β － SiC with the size of about 15～ 20 nm could be synthesized under both of the acid and basic conditions. For the samples prepared by adding mixture of saccharose and water into solutions after the hydrolysis of TEOS with moderate water, the amount of amorphous SiO2 was lower than all other samples. The analysis of SEM and TEM showed the β － SiC particles synthesized in acid solutions dispersed well and had the similar size; those prepared under basic conditions trended to agglomerate together.