银-纳米SiO2脉冲复合电镀工艺条件的优化与性能研究

采用正交试验,以镀层显微硬度为评价标准,得到银-纳米SiO2脉冲复合电镀的最佳工艺条件为：6 mg/L的阳离子表面活性剂,100mg/L的非离子表面活性剂,15g/L的纳米SiO2,脉宽0.5ms,占空比40%,脉冲平均电流密度0.8～1.1A/dm2.正交试验结果表明,纳米SiO2含量对镀层的影响较大.该镀液分散能力（采用远近阴极法测定）为61%,覆盖能力近似为100%,镀层硬度为246.5HV,钎焊性较好。经研究发现,空气搅拌较机械搅拌更有利于纳米微粒在镀层中的分散.XRD测试得出,复合镀层在（111）面上的择优取向得到显著加强,进一步证实该镀层结晶致密,耐蚀性较纯银镀层好。

Optimization of Ag-nano-SiO2 pulse composite electroplating process and properties of bath and deposits

By orthogonal test and using the micro-hardness of deposit as evaluation criterion, the process conditions of Ag-nano- SiO2 pulse composite electroplating were optimized as follows:6 mg/L of a cationic surfactant, 100 mg/L of a nonionic surfactant,15 g/L of nano-SiO2 particles, pulse width of 0.5 ms, duty ratio of 40% , pulse average current density of 0.8 - 1. 1 A/dm2. The results of orthogonal test show that the content of nano-SiO2 particles in bath has a great influence on the deposit. The bath has a throwing power (determined by far and near cathode method) of 61% and a covering power of near to 100% , and the deposit has a micro-hardness of 246.5 HV and good solderability. Moreover, air agitation is found to be more favourable to the dispersion of nano-particles in the deposit than mechanical agitation. XRD test demonstrates that the composite deposit has a obviously stronger preferred orientation of (111) surface, which further proves that the deposit has dense crystal structure and better corrosion resistance than pure silver deposit.