Journal of Xi'an Jiaotong University

Study of SiC Slurry Viscosity Affected by Surface Oxide Content
Ning Shufan,Li Hongyan,Chen Wei,Liu Bin,Chen Shoutian
(State Key Laboratory of Electrical Insulation for Power Equipment,Xi'an Jiaotong University,Xi'an 710049,China)

Abstract:The influences of surface oxide content on SiC slurry viscosity are investigated. To avoid the disadvantage of SiC slurry stable dispersion affected by surface SiO₂ layer and micro-content of metal oxide, it is necessary for SiC powder to be leached by acid. With the decrease of contents of SiO₂ and metal oxide adsorbed on SiC powders surface by acid treatment, Zeta potentials of SiC-1 and SiC-2 powders increase from 60.71 mV to 72.49 mV and from 55.728 mV to 63.546 mV respectively,and OH^-group adsorbed on SiC powders surface is destroyed and replaced by F^-.With the breakdown of OH^-group, hydrogen bond adsorbed on OH^-group is removed. Therefore the surface state of SiC powders is changed from hydrophilic to hydrophobic.The change of SiC powders surface state can be proved by XPS and FT-IR analysis. The repulsion force between SiC powders that dispersed in slurry is enhanced due to the increase of Zeta potential,thus the SiC powders can be dispersed fully in slurry.H₂O that adsorbed on SiC powders surface is released and flows freely as hydrogen bond is removed.These two changes of SiC surface state result in the viscosity of SiC slurry being decreased and the solid volume fractions of SiC-1 and SiC-2 powders in slurry being increased to 62% and 51% respectively.
Keywords:SiC;metal oxide;Zeta potential;hydrophobic;slurry viscosity