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

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.