Low-tin Cu-Sn alloy coatings with a thickness of 20 μm above were prepared on low-carbon steel wafers by barrel plating from a cyanide-free bath. The effects of mass concentrations of Sn2P2O7 and K4P2O7, dosage of additive JZ-1, cathodic current density, and bath temperature on the composition and properties of Cu-Sn alloy coating were studied. The results showed that all factors studied have certain influence on composition, properties, and continuous thickening of the coating. The bath composition and process conditions for continuous thickening of Cu-Sn alloy coating are as follows: K4P2O7 350-400 g/L, Cu2P2O7·-4H2O 20-25 g/L, Sn2P2O7 1.5-2.0 g/L, K2HPO4·3H2O 60 g/L, additive JZ-1 0-0.5 ml/L, temperature 30-35 ℃, pH 8.5, cathodic current density 0.34-0.46 A/dm2, and rotation rate 15 r/min. The Cu-Sn alloy coating obtained by barrel plating under the optimal conditions for 4 h features a thickness of not less than 20 μm, 12-26wt% Sn, strong adhesion to steelrnsubstrate, excellent corrosion resistance, and good mechanical and physical properties.%以低碳钢圆饼为基体,在焦磷酸盐溶液体系中滚镀制备厚度为20 μm以上的低锡铜锡合金.研究了Sn2P2O7的质量浓度、K4P2O7的质量浓度、添加剂JZ-1的用量、阴极电流密度及镀液温度对铜锡合金镀层组成和性能的影响.结果表明,这些因素对镀层的组成、性能和持续增厚都有一定的影响.低锡铜锡合金镀层可持续增厚的镀液组成与工艺条件为:K4P2O7 350～400 g/L,Cu2P2O7·4H2O 20～25 g/L,Sn2P2O7 1.5～2.0 g/L,K2HPO4·3H2O 60 g/L,添加剂JZ-1 0 ～ 0.5 mL/L,pH 8.5,阴极电流密度0.34～0.46 A/dm2,镀液温度25～35℃,滚筒转速15 r/min,循环过滤.在上述条件下对钢铁基体滚镀4h可获得平均厚度为20 μm以上、锡的质量分数为12％～ 16％的铜锡合金镀层,该镀层与钢铁基体之间的结合力良好、耐蚀性能好,具有较好的机械性能与物理性能.
展开▼
