Research On Controllable Preparation Process Of Highly Dispersive Micro/Nano Silver Powder

Micro-nano silver powder is widely used in electronic devices,biomedicine,catalysis,sensing and other fields because of its excellent electrical,thermal,optical,catalysis,antibacterial and other properties,and has become a hot research material.Studies have found that the performance and application of micro-nano silver powder are closely related to its surface morphology,powder size,particle size distribution,and dispersibility.Therefore,it is of great significance to deeply study the growth mechanism of micro-nano silver powder and realize the controllable preparation of micro-nano silver powder.In this paper,the liquid phase chemical reduction method is adopted,and gelatin and gum arabic powder are selected as surfactants to achieve high dispersion preparation of silver powder with a median particle size of 1.05?m.Studies have shown that when gum arabic powder is used as a surfactant to prepare silver powder,the silver powder prepared by"one-time addition"as a solution addition method uses coagulation and growth as the main growth method.The surface smoothness is poor,but the sphericity is high,and the particle size can be With strong controllability,highly dispersed spherical silver powder with specific dimensions can be prepared.Using gelatin as the main surfactant,the solution addition method is"dropwise addition"to prepare a spherical-like silver powder with a smooth surface with crystal growth as the main growth method.On this basis,when gum arabic powder is added to prepare a double dispersion system The uniformity of the particles can be further enhanced,and the prepared nano-silver can play a gap-filling effect on the secondary silver balls with rough surfaces during the preparation process of the silver conductive paste.When preparing silver powder,silver nitrate is used as the precursor of silver,and ascorbic acid is used as the reducing agent.Explore the mixing sequence of silver source solution and reducing solution,mixing speed,length of water bath,p H of the reaction solution and other factors.The impact of the trail.And to achieve the preparation of micron silver powder with good dispersibility,uniformity and sphericity,the particle size range of 0.71-1.72?m,and the median particle size of 1.05?m.Spherical micron silver with a median particle size of 1.05?m is used as the main conductive phase to prepare silver conductive paste.The silver powder and the organic carrier are uniformly mixed in a certain proportion and uniformly coated on the strontium titanate and leveled on the ceramic substrate.sintering.As the sintering temperature increases,the electrode surface porosity decreases,but too high sintering temperature will cause the sintering pores to become coarser,and the sample resistivity will first decrease and then increase.The silver powder with a median particle size of0.21?m prepared by the double dispersion system was added to the conductive phase to prepare binary silver powder conductive pastes with different filling ratios.After sintering,it was found that the electrode performance was greatly improved when the filling ratio was 5%,and the sample resistance rate and surface porosity are 1.97×10^-6?·cm and 11.79%,respectively.