电磁屏蔽导电涂料用镀银铜粉的制备

采用置换反应法制备镀银铜粉时,铜粉还原银氨溶液中的Ag+生成的Cu2+与NH3形成络合物[Cu(NH3)4]2+,它吸附于铜粉表面而阻碍还原反应的继续进行,使制备的镀银铜粉表层的银含量降低。用氨水提高银氨溶液的pH,可增加制备的镀银铜粉表层的银含量,提高其抗氧化性能。当用氨水调节银氨溶液的pH至11.50时,可制得表层银的质量分数高达47.91%且具有常温抗氧化性能的镀银铜粉。研究了pH、AgNO3用量、AgNO3浓度和反应温度对镀银铜粉的抗氧化性能的影响。

Preparation of Silver-coated Copper Powder Used in Electromagnetic Shielding Conductive Adhesives

The silver-coated copper powder was prepared with substitution reaction method.It was found that copper powder reduced Ag~ by producing [Cu(NH_3)_4]~2 that was absorbed onto the surface of the copper powder in the ammoniacal silver solution,which prevented the reduction reaction from proceeding.Therefore,as-prepared silver-coated copper powder has less silver content.Raising the pH value of ammoniacal silver solution with ammonia solution could increase the silver content of the prepared silver-coated copper powder and improve its oxidation-resistant performance.Thus,silver-coated copper powder with silver content of 47.91% could be prepared by adjusting the pH value of the ammoniacal silver solution to 11.50.The influences of pH value,AgNO_3 dosage,AgNO_3 concentration and reaction temperature on oxidation resistance of the silver-coated copper powder were studied.