Effects of surface oxide species and contents on SiC slurry viscosity

摘要

The disadvantageous effects of colloidal SiO2 layer and micro-content of metal oxide adsorbed on SiC powdersurface on SiC slurry stable dispersion were studied, and the novel method to avoid this disadvantage was proposed. Byacidwashing, on the one hand, because the maximum Zeta potential of SiC powder increases to 72.49 mV with the decreas-ing content of metal oxide adsorbed on the SiC powder surface, the repulsion force between SiC powders that dispersed inslurry is enhanced, thus the SiC powder can be fully dispersed in slurry. On the other hand, after HF acidwashing, with theOH- group adsorbed on SiC powder surface destroyed and replaced by the F- ion, the hydrogen bond adsorbed on the OH-group is also destroyed. Therefore, the surface property of the SiC powder is changed from hydrophilic to hydrophobic;H2O that adsorbed on SiC powder surface is released and can flow freely, and it actually increases the content of the effec-tive flow phase in the slurry. These changes of SiC powder surface property can be proved by XPS and FTIR analysis. Fi-nally, the viscosity of SiC slurry is decreased greatly, and when the viscosity of the slurry is lower than 1 Pas, the solidvolume fraction of SiC powder in the slurry is maximized to 61.5 vol.%.