Effects of H2O in EtOH-H2O disperse medium on the electrophoretic deposition of CaSiO3 fine powder

The effects of H2O in the EtOH-H2O disperse medium on the electrophoretic d eposition (EPD) of CaSiO3 fine powder were investigated. Fine CaSiO3 powder with average diameter of 1.7 mu m was prepared by the coprecipitation meth od. It was deposited on a stainless steel substrate by EPD in the disperse media with various H2O concentrations (0-20.2 mass%) under a DC field of 50 V. The amount of the CaSiO3 deposition increased with increasing H2O up to 11.2 mass% but decreased rapidly beyond this concentration. The surface po tential of the powder showed a similar trend as the amount of deposition ag ainst H2O concentration. The effect of H2O was summarized as follows: (I) t he addition of positive charge on the surface of CaSiO3 particles (2) the n eutralization of the surface charge by OH- caused by the dissolution of CaS iO3 in the H2O. (C) 1998 Elsevier Science Limited All rights reserved.