新型酸性无氰镀镉工艺的开发研究

Development research on novel acidic cyanide-free cadmium plating process

开发了酸性无氰镀镉新工艺NCC-617。镀液组成为：氯化镉35-40 g/L,配位剂120-160 g/L,氯化钾140-180 g/L,光亮剂1.5-2.5 m L/L,辅助剂25-35 m L/L,p H 6.0-7.0。工艺条件为：挂镀──温度15-35℃,阴极电流密度0.5-1.5 A/dm^2;滚镀温度15-30℃,槽电压4-7 V,滚筒转速3-5 r/min。在电流密度1 A/dm2下,镉的沉积速率为0.33μm/min。NCC-617镀液的电流效率为73%,均镀能力为41%-52%,深镀能力为9.2。镀镉层经低铬彩色钝化后中性盐雾试验2 000 h仍无白锈生成,其耐蚀性实现了重大突破。镀层的氢脆性和结合力合格。总之,NCC-617镀镉工艺具有镀液稳定,镀层性能优良,电镀废水容易处理的优点,具有较好的应用前景。

A novel cyanide-free cadmium plating process coded as NCC-617 was developed. The plating bath composition are as follows： cadmium chloride 35-40 g/L, coordination agent 120-160 g/L, potassium chloride 140-180 g/L, brightener 1.5-2.5 m L/L, auxiliary agent 25-35 m L/L, and p H 6.0-7.0. The process conditions for rack plating are temperature 15-35 ℃and cathodic current density 0.5-1.5 A/dm^2, and for barrel plating, temperature 15-30 ℃, tank voltage 4-7 V and barrel rotation speed 3-5 r/min. The cadmium deposition rate is 0.33 μm/min at a current density of 1 A/dm2. The NCC-617 bath features a current efficiency of 73%, a throwing power of 41%-52% and a covering power of 9.2. No white rust generates on the cadmium coating treated by iridescent low-chromium passivation after neutral salt spray test for 2 000 h, which is a great breakthrough for the corrosion resistance of cadmium coating. Both hydrogen embrittlement and adhesion strength of cadmium coating are qualified. The NCC-617 cadmium plating process has a favorable application prospect due to its advantages of stable plating bath, excellent coating performances, and easy treatment of electroplating wastewater.