The Study On The Preparation Of Silver Palladium Submicron Powder

In this work, A Liquid Chemical Reduction based on symmetric addition of silver nitrate and palladium nitrate to reducing agent was used to prepared the Silver-Palladium submicron powders. The obtained powders have potential application inthe conductive paste materials.Byoptimizing the reaction conditions, the morphology, size, size distribution, loose density and tap density could be easily and effectively controlled.. The morphology of Silver-Palladium powders was characterized by Scanning electronic microscope (SEM), the crystal structure was determined by analyzing the pattern of X-ray Diffraction (XRD), and the particle size distribution was recorded by centrifugal sedimentation method.The synthetic conditions, including the pH value of the solution, species and concentration of the dispersant, reducing agent, addition time and the concentration of the reactants, were optimized. The experiment results indicated that, comparing with other reducing agent(hydrazine hydrate or formaldehyde), ascorbic acid was more suitable to prepare high-purity, well dispersed, micron-sized or sub-micron-sized, sphere-like Silver-Palladium powders, with as reducer thanIn this approach, the morphology and the size of the Silver-palladium powder were greatly influenced by the pH value of the solution. The particle size of Silver-palladium powder decreased with the increasing of pH value. The optimum conditions were summed up as follows:reducing silver nitrate by ascorbic acid, silver nitrate concentration of0.083mol/L, the atomic ratio of silver and palladium is7:3, mass ratio of reducer to oxidant of1:2, gum Arabic is used as dispersant, pH value of the oxidation solution is2.0adjusted by sodium hydroxide, mixed with symmetric way.The products was high-purity, sphere-like, well dispersed Silver-palladium powder with the mean particle size range from0.3to0.1μm, the yield was98.67%, and this powders can be used as conductive paste material.