甲醛还原碳酸银制备单分散超细银粉的研究

Study on Preparation of Monodisperse Ultra-fine Silver Powder by Reduction of Silver Carbonate from Formaldehyde

以PVP K30为分散剂,碳酸钠和乙酸混合溶液为pH调节剂在水溶液中使用甲醛还原硝酸银制备得到单分散银粉。研究PVP K30添加量、初始反应温度对银粉形貌和物性的影响。研究发现,当PVP K30添加量小于3%时得到的银粉团聚严重,形貌不规则;当PVP K30添加量在4%时,银粉由微晶银粉变为类球形银粉;添加PVP K30在5%~6%时,所得银粉均匀性变差。最优条件为初始反应温度30℃,添加硝酸银质量4%~5%的PVP K30时所得的银粉比表面为0.36 m2/g,振实密度为4.5 g/cm3,其物性可以满足烧结银浆用类球形银粉要求。

Silver powders are chemically precipitated by formalin in the presence of PVP K30 as dispersing agent,acetic acid and carbonate sodium mixture solution as pH modifier.The effect of PVP K30 dosage,initial temperature are investigated.It is found that when the dosage of PVP K30 is below 3%,the aggregated silver particles with irregular shape are obtained.When the dosage of PVP K30 is increased 4%to 5%and the initial temperature is 30℃,the sphere like silver powders with uniform particle size are obtained.With the addition of PVP 30K increasing to 5%~6%,the particle uniformity deteriorates.When the most silver powders have a surface area of 0.36 m2/g and tap density 4.5 g/cm3,they can be used for thick film paste.