三价铬镀液中的络合-缔合作用  

Coordination and Association of Trivalent Chromium in plating Bath

作　　者：沈慕昭[1] 刘艳[1] 胡志彬[1] 

机构地区：[1]北京师大化学系

出　　处：《电镀与精饰》1989年第3期3-9,共7页Plating & Finishing

摘　　要：自1856年Geuter首次用K₂Cr₂O₇和H₂SO₄沉积出金属铬层以来,尽管配方有些改变,但都是采用六价铬进行电镀生产,由于六价铬镀液毒性大、污染环境、影响工人健康,而三价铬镀液毒性小,电流密度范围宽,深镀能力和分散能力均比六价铬镀液好,所以人们很早就开始研究三价铬镀液。经过一百多年的历史,也未能得到理想的三价铬镀液,其主要原因是Cr（H₂O）₆³⁺The authors have made use of ultraviolet and visible spectrophotography, potentiostatic eleotrolysis, Hull cell experiments, cyclovoltammetry and paper electrophoresis to study the existence states of component electrolytes of three typical baths of tri-valent Cr plating. From these studies it was likely to con- clude that formic acid was proved not to be a ligand of Cr (Ⅲ) coordination but showed good plating charateristics, while EDTA and oxalic acid have been proved respectively to be strong Ligand in Cr (Ⅲ) coordination and moderately strong ligand but both are rather poor additives in Cr (Ⅲ) plating. Hence, it seems reasonable to suggest that formic acid ion plays the role of association with Cr(Ⅲ) ion as well asthe role of preventing the formation of higher valent state of Crions. Italso seems reasonable to suggest that the presence of sulfate ion might have done something good for association with Cr (Ⅲ) and liberation of Cr (Ⅲ) at thecathode.

关 键 词：电镀 镀铬 镀液 络合 缔合 

分 类 号：TQ153.11[化学工程—电化学工业]