Preparation of highly dispersed ultrafine silver powders with polyacrylic acid as dispersant

In order to improve the dispersivity of silver powders,highly dispersed ultrafine silver powders were prepared from silver nitrate by chemical reduction method with ascorbic acid as the reducing agent and polyacrylic acid as the dispersant.The effects of pH value,temperature and dispersant dosage on the mean particle size and morphology of the ultrafine silver powders were studied.The results show that the pH value of the reaction solution shows significant effect on the morphology of the ultrafine silver powders.Dendritic,sphere-like and spherical silver powders are respectively obtained when the pH values of the reaction solution are 2,4 and 8.The dispersant dosage has the most significant effect on the particle size of the ultrafine silver powders,and the mean particle size of the silver powders decreases rapidly with increasing dispersant dosage.The optimized preparation condition is: the pH value equals to 8,the temperature is 50 ℃,and the mass ratio of dispersant to silver nitrate is 0.005.The silver powders prepared under the optimized condition show the best dispersivity with a mean particle size of 1.41μm.