INFLUENCE OF CALCIUM IONS ON ELECTROPHORETIC DEPOSITION OF GLASS PARTICLES

Charge of glass particles in ethanol was changed from negative to positive by introducing calcium ions into suspension,which resulted in co-deposition of the glass particles and hydroxyapatite particles in ethanol subsequently. Changes of deposition yield and depositing current in the suspension with different concentration of calcium ions were studied. The role of Ca~(2+) in electrophoretic deposition was analyzed. Results show that Ca~(2+) in the suspension is either absorbed onto the glass particles to change the charge properties, or retained in the suspension as primary current carrier in the electrophoretic deposition process. The concentration of Ca~(2+) has much influence on electrophoretic deposition and defects appear in the coating prepared in the suspension with too high or too low concentration of Ca~(2+). Defects of the coating are also described.