Study On Ultrafine Ag Powder Of Controllable Morphology And Particle Size Prepared By Liquid Chemical Reduction Method

In order to prepare spherical high-quality ultrafine silver powder, liquid-phase chemical reduction method was used to research the preparation of morphology and particle size controllable ultrafine silver powder, and different raw materials were compared, then the process conditions of silver powder were studied in this paper. The main contents are as follows:1. The influences of different silver source, reducing agent, and dispersing agent on sliver powder's morphology and particle size have been studied and compared respectively. Results show that AgNO3, ascorbic acid and PVP(K30) are the best materials to prepare highly dispersed ultrafine spherical silver powder in this study.2. The effects of process conditions on the ultrafine silver powder's morphology and particle size have been studied and results show: with the increase of PVP amount, silver powder morphology changes from amorphous to the spherical and then to the petal-shaped, particle size decreased as the morphology varies. As reaction temperature increases, silver powder agglomeration increases, and the particle size also increases, but the morphology broadly unchanged. With the increase of pH value, the degree of particle agglomeration increase, and the average particle size becomes larger; the average particle size of the silver particles becomes larger as the AgNO3 concentration increases; fast drip rate conducive to give a uniform spherical silver powder with narrow particle size distribution range and good dispersibility; organic solvents help to improve the dispersibility of silver powder.3. Analysis of the factors affecting the morphology and particle size of ultrafine of silver powder have been made by combining the experimental and theoretical methods. Results show that silver powder nucleation mainly affect silver particle size distribution and particle size;controlling the silver growth process can control themorphology and particle size of silver in a certain range; nucleation and growth method of silver while the silver atom concentration rapidly rise is advantageous for obtaining spherical silver powder with a uniform particle size; the agglomeration of silver particles mainly appeared as "connection" and "bridging".4. Using Silver nitrate as raw materials, PVP(K30) as a dispersing agent, ascorbic acid as a reducing agent, when AgNO3 concentration is 0.2mol / L, m(PVP) / m(AgNO3) is 0.6, pH value is 7, the reaction temperature is 40 ?, the drip rate is 5ml / s, and using ethanol to separate and dry the silver, highly dispersed ultrafine spherical silver powder can be prepared with smoothsurface, high sphericity, average size of 0.8?m and a particle size concentrated distribution in0.45 ~ 1.3?m.This paper can provide some technical and theoretical guidance to the preparation of high quality superfine micron / submicron silver powder with specific and morphology.