Effect of Additive on Dispersibility of Flake-Graphite in Aqueous Medium

The sedimentation rate and the dispersion rate of flake-graphite in aqueous medium were taken as evaluation criteria. The effects of individual addition of seven additives and composite addition on the dispersibility of flake-graphite in aqueous medium were investigated. The results show that sodium dodecyl benzene sulfonate and lauryl sodium sulfate have evident dispersion effect to flake-graphite in aqueous medium, achieving dispersion rates of 97.8% and 80.0%, the sedimentation rate of 92.0% and 94.0% in 0.5 hour, respectively, but stability of sedimentation was not ideal. The optimum formula of additive, lauryl sodium sulfate addition of 4.7% (mass), N-acetyl-L-proline addition of 3.7% (mass) and tributyl phosphate addition of 2.6% (mass), was obtained by orthogonal design. The dispersion rate was 99.2% and the sedimentation rate in 1 hour was 92.0% when using the optimum fomula. Flake-graphite in the silver-graphite composite coating prepared by the optimum formula dispersed uniformly.