Replacing Hexavalent Chrome Passivation
六价铬钝化的环保替代体系
标签：六价铬, 钝化, 环保替代, 三价铬, RoHS
黄铜件传统铬酸盐钝化含六价铬，已被 RoHS 与 REACH 严格限制。现行三条替代路线：①三价铬钝化——30–45 °C、pH 3.5–4.0、浸 60–120 s，干膜蓝色调、耐中性盐雾 96–168 h，约为六价铬工艺的 60–80%；②BTA 系苯并三氮唑钝化（1–2 g/L、50–60 °C、2–5 min），最适合铜与仿古件，不改变做旧色；③硅烷-硅唑复合成膜，可作涂装底层。切换要点：三价铬槽液寿命短（约 20–40 Ah/L），须按通电量补加而非按时间。
Conventional chromate passivation of brass contains Cr(VI) and is tightly restricted by RoHS and REACH. Three routes now replace it: trivalent chrome (30–45 °C, pH 3.5–4.0, 60–120 s) giving a bluish film with 96–168 h neutral salt spray — roughly 60–80% of hexavalent performance; BTA inhibition (1–2 g/L, 50–60 °C, 2–5 min), best for copper and antique finishes since it leaves patina color untouched; and silane-triazole hybrid films as paint primers. Key switch note: trivalent baths exhaust in ~20–40 Ah/L — replenish by ampere-hours passed, not by time.
