Study on Dispersion Behavior of ZnO-Al2O3 Powders Aqueous Suspension

The stability and fluidity of ZnO-Al2O3 mixed powders suspension in aqueous solution adding with polyacrylic acid and polyethylene glycol were investigated. The Zeta potential of ZnO and Al2O3 were measured respectively in absence and presence of polyacrylic acid and polyethylene glycol. The influences of milling time, pH value, mass fraction of the additive and solid volume fraction on the stability and fluidity of ZnO-Al2O3 powders aqueous suspension were investigated by experiments of viscosity and sedimentation etc. It is noted that ZnO and Al2O3 powders have absolute value of zeta potential bigger than 45mV in pH value from 8 to 10.3 with adding polyacrylic acid. It is found that the suspension has the lowest viscosity and the best stability when the pH value is around 9 and the additive amount of polyacrylic acid is about 0.2wt%, in which the 55vol% solids content of slurry is obtained with the apparent viscosity less than 400mPa ¤s. The saturation absorption amount of polyacrylic acid for ZnO-Al2O3 mixed powders could be 0.2wt% in which the apparent viscosity is lower and the suspension stability is good in the pH range from 9 to 10.3. With the additive amount of polyethylene glycol increasing, the viscosity of suspension increase and the stability of suspension decease. The optimized milling time is 40h.