Study On The Modification Of SiC Particle And Its Dispersing Stablity

Recrystallized silicon carbide (RSiC) is a promising structural and functional material due to its high temperature strength, outstanding oxidation resistance and ecxcellent electrical and thermal performances, thus it draws more and more reseacher’s attention. However, RSiC is not a dense material because there is no densification in the sintering process by evaporation-agglomeration mechanism. Its porosity is determined by its density of green body, and influence its properties such as high temperature strength, resistence of oxidation, and conduction rate of heat and electricity. In order to improve the density of RSiC green body, the key is to lower the water content in SiC slurry by the modification of SiC particles.This paper systematically studied the effect of the adsorption of three cationic surfactants (polyethyleneimine, cetyl pyridinium bromide, polyvinylpyrrolidone) onto the silicon carbide surface on its green density. UV-Vis, FTIR, and other means was used to study the adsorption behavior and the adsorption mechanism of surfactants in the surface of silicon carbide powder. The zeta potential analyzer, Washburn, and other means was used to study the effect of surfactant adsorprion on the surface of the silicon carbide powder on the surface zeta potential and its water contact angle.After cationic surfactant was added, the addition of silicon carbide slurry rheology was characterized by rotational viscometer. Silicon carbide green body density measured by water displacement method.The results showed:1The adsorption of cationic surfactant on the silicon carbide powderis mainly because of the negative charge effect, hydrogen bonding.2With the surfactant adsorbed on the silicon carbide powder surface, the surface zeta potential of silicon carbide powders had significantly improved, and the water contact angle decreased, which indicated that the hydrophilicity of the modified silicon carbide powder was improved.3cationic surfactants changed the silicon carbide slurry spindle thixotropic ring. Cationic surface active agent could reduce the area of the ring, indicating that the silicon carbide slurry thixotropy became smaller, while destruction of the thixotropic structure of the silicon carbide slurry of energy was also reduced. Cationic surface active agent could improve the density of green silicon carbide, and lowering the slurry water content.