Study of dispersion mechanisms of modified SiC powder: electrostatic repulsion and steric hindrance mechanism
Surface modification technology was used to increase the dispersion of SiC powder. The slurry with high stability was fabricated using modified SiC powder with high dispersibility. The relative settlement height (RSH) of slurry was maintained at 72.5% after 30 hours, indicating high stability of SiC powder co-modified with polyvinylpyrrolidone (PVP) and tetramethyl ammonium hydroxide (TMAH) in water medium. Meanwhile, minimum viscosity of 0.322 Pa.s was obtained under 45 Vol% solid content, and the maximum solid content of slurry was 64.6 Vol%. In addition, the maximum Zeta potential of modified SiC powder was -58.5 mV, indicating strong electrostatic repulsion among particles. Therefore, the modified SiC powder shows high dispersion. More important is that the effect of dispersion mechanism on performance of modified SiC powder was investigated in depth. TMAH, as one of excellent dispersants, can increase the electrostatic repulsion among particles significantly, facilitating preparing the slurry with low viscosity and high solid content. However, PVP, as one of neutral polymers with hydrophilic, plays an important role in maintaining the stability of slurry.