Cyanide-free Sulfite Gold Plating
无氰亚硫酸盐镀金
标签：无氰镀金, 亚硫酸盐, 环保安全, pH控制, 首饰电镀
亚硫酸盐镀金浴（以亚硫酸金钠计 Au 5–8 g/L、游离亚硫酸钠 40–60 g/L、pH 8.5–9.5、45–55℃、0.3–0.8 A/dm²）不含氰化物，废水处理简单，适合首饰与文创车间。浴液对氧敏感：需氮封液面或每日补亚硫酸钠 1–2 g/L，防止金还原出现紫色"金雾"；pH 低于 8 同样析金。挂具用钛材，工件入槽前 5% 硫酸活化 30 s 以保证结合力。镀层 18–23K 可调、厚度 0.25–1 μm，光泽与氰化物浴相当。
Sulfite gold baths (5–8 g/L Au as sodium gold sulfite, 40–60 g/L free sulfite, pH 8.5–9.5, 45–55℃, 0.3–0.8 A/dm²) run cyanide-free with easy wastewater handling—ideal for jewelry and craft shops. The bath is oxygen-sensitive: blanket with nitrogen or add 1–2 g/L sodium sulfite daily to prevent a purple "gold haze"; below pH 8 it decomposes too. Use titanium racks and activate in 5% sulfuric acid for 30 s before entry. Deposits tune 18–23K at 0.25–1 μm, matching cyanide-bath brightness.