助剂用量对反应烧结碳化硅结构及力学性能的影响

Effect of additive dosage on the structure and mechanical properties of silicon carbide prepared by reaction sintering

以碳化硅、碳黑和石墨为原料,聚乙烯吡咯烷酮K90、K30为分散剂,聚甲基丙烯酸铵CE-64为减水剂,采用注浆成型工艺制备碳化硅素坯,并在1700℃下对素坯进行反应烧结制备碳化硅成品,研究了分散剂、减水剂用量对浆料黏度、素坯密度、素坯孔隙率和成品微观组织及力学性能的影响。结果表明:随着助剂用量的增加,浆料黏度总体上呈现下降趋势,素坯密度呈先降后升趋势,素坯孔隙率呈先升后降趋势。当K90、K30、CE-64的质量分数分别为3.8%、2.0‰、4.3‰时,所得素坯的孔隙分布均匀,素坯中碳化硅分布较为疏松,渗硅通道较多,有利于碳和硅粉的充分反应,获得的烧结制品性能优良。

The green silicon carbide was prepared by slip casting using silicon carbide, carbon black, and graphite as the raw materials, polyvinylpyrrolidone K90 and K30 as the dispersant, and ammonium methacrylate CE-64 as the superplasticizer. Subsequently, the final product of silicon carbide was subjected by reaction sintering at 1700 ℃. The influences of additive dosage on the slurry viscosity, green density, biscuit porosity, and the microstructure and mechanical performance of silicon carbide product were investigated. In the results, with the increase of additive dosage, the slurry viscosity shows a downward trend, the density of the green silicon carbide first decreases and then increases, and the porosity of the green silicon carbide first increases and then decreases. As the additive dosages of K90, K30, and CE-60 are 3.8%, 2.0‰, and 4.3‰ by mass, the pore distribution of the green is uniform, and the properties of the sintered products obtained are excellent. The loosen distribution of silicon carbide in the green offers more channels for silicon permeation, which is beneficial for the reaction between carbon and silicon.