Controllable Preparation Of Micro-sized Superfine Silver Powder

In this paper, with silver nitrate used as silver source, liquid phase reduction method was used to synthesize superfine silver powder, and the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and laser particle sizer.The effect of single factors on morphology, particle size as well as dispersion property of superfine silver powderthe were investigated such as reducing agent, dispersant, temperature of reaction system and the way of adding dispersant. The reaction system was determined as follows: ascorbic acid as reducing agent, PVP as protective agent and dispersant. Results show that the superfine silver powder with high sphericity and well dispersibility can be obtained when PVP addition is10%(wt%to silver nitrate), the reaction system temperature is40℃and the concentration of silver nitrate is0.2mol/L, and the particle size is around1μm. With further study, it can be found that the particle size of superfine silver powder between1.15μm～2.1μm were prepared controllably with the change of dispersant addition ways.Based on the research, the effect of induced crystal on silver powder was investigated. The crystal seeds of high sphericity, well dispersibility and uniform particle size were prepared in advance, then the crystal seed induced in reaction system, with the dropping silver nitrate, the silver atoms reduced by ascorbic acid were absorbed on the surface of crystal seeds. The results show that the particle size of silver powder grew in a linear mode with the increasing of the quality and dropping speed of silver nitrate. Under the conditions of dropping silver nitrate and reducing solution in cocurrent way with the speed of1mL/min, the superfine silver powder with high sphericity and well dispersibility were obtained, and the particle size was1.8μm.The paper provides an important experimental basis for particle size control of superfine silver powder.