Dispersing SiC powder and improving its rheological behaviour

The surface properties of silicon carbide powder was investigated by zeta potential measurements and compared with silicon oxide powder. The quantitative adsorption behaviour of polyethylene imine onto silicon carbide powder in aqueous solution is measured with UV adsorption spectrum at three pH ranges. In acid and neutral pH ranges, the adsorption isotherms belong to Langmuir type and reach the maximum value around 0.038 mg/m2. In basic range, the adsorption amount is more than 10 times that in the low pH range, as high as 0.456 mg/m2. The FTIR spectra are presented to verify this adsorption. Improved rheological properties of slurries are obtained through addition of PEI. An optimum amount of dispersant is given as 1.0 dwb% when the solid content is kept as 40 vol%.