无氰电镀黄铜工艺研究

Study on technology of cyanide-free brass plating

针对三步法钢丝电镀黄铜工艺复杂、冗长,维护和管理难度高,以及热扩散工序耗能高等问题,研究出一步法焦磷酸盐无氰直接电镀黄铜工艺。介绍电镀工艺配方以及测试方法,给出镀层中Cu与Zn的质量分数计算公式。通过试验得出:电流密度在0.5～1.2A/dm2时,随着电流密度的增加,镀层中铜含量下降,锌含量不断提高,电流密度超过1.2A/dm2时,镀层中铜含量随电流密度的提高而增加,锌含量不断减少;辅助络合剂质量浓度为60g/L时,镀层中Cu,Zn质量比基本达到60∶40,满足产品结合力的要求;当起始电流密度大于临界电流密度(0.28A/dm2)时镀层结合力良好,小于0.28A/dm2时镀层的结合力较差。试验表明,用一步法工艺配方电镀黄铜钢丝,镀层结合力好,合金成分稳定,沉积速度快,生产线容易改造,且能达到清洁生产,节能降耗的目的。

Aiming at the problems of complex, too long, difficult maintenance and management of three steps steel wire brass plating technology, and high energy consumption of thermal diffusion, the one step pyrophosphate cyanide-free brass plating technology was researched. The plating technology ingredient and testing method were introduced. The mass fraction calculating formula of Cu and Zn in coating is given out. Experiments show that with the amplifying of current density when the value of current density is 0.5 - 1.2 A/dm^2 , Cu content in coating decreases and Zn content increases. When the current density is larger than 1.2 A/dm^2 , Cu content in coating increases with the amplifying of current density, Zn content decreases. When the mass concentration of accessory complexing agent is 60 g/L, the mass ratio of Cu to Zn in coating is 60 to 40, which meets the requirements of product adhesion. When initial current density is higher than critical current density（0.28 A/dm^2）, the adhesion of coating is well. When it is lower than critical current density, the adhesion of coating is poor. Experiments show that using one step technology to plate brass steel wire, the adhesion of coating is well, alloy composition is stable, and deposition rate is high, production line can be reformed easily. And it can attain the aim of cleaning production and energy saving and consumption reducing.