A (Co,Mn)3O4 spinel coating was obtained by thermal conversion from the Co–Mn3O4 composite coating electroplated on E-brite ferritic stainless steel substrate. The effects of pH, stirring speed, and cathodic current density on Mn content of the composite coating were studied. The optimal bath composition and process parameters were determined as follows: CoCl2?6H2O 50 g/L, CoSO4?7 H2O 300 g/L, H3BO3 30 g/L, sodium dodecyl sulfate 0.03 g/L, Mn3O4 120 g/L, pH 5.0, room temperature, cathode-to-anode distance 30 mm, stirring speed 500 r/min, cathodic current density 20 mA/cm2, and time 10 min. The Co–Mn3O4 composite coating was converted to be (Co,Mn)3O4 spinel coating after being heated in atmosphere at 800 °C for 4 hours. The (Co,Mn)3O4 spinel coating had a stable structure even after being kept at 800 °C for 100 hours. It was smooth, compact, and able to hinder the volatilization of Cr from the substrate efficiently.%以E-brite铁素体不锈钢为基体,先复合电镀制备了Co–Mn3O4,再热转化得到(Co,Mn)3O4尖晶石涂层.研究了镀液pH、搅拌速率和阴极电流密度对复合镀层中 Mn 含量的影响,得到复合电镀的较优配方和工艺条件为:CoCl2?6H2O 50 g/L, CoSO4?7H2O 300 g/L,H3BO3 30 g/L,十二烷基硫酸钠0.03 g/L,Mn3O4 120 g/L,pH 5.0,室温,极间距30 mm,搅拌速率500 r/min,阴极电流密度20 mA/cm2,时间10 min.在800 °C的空气中氧化4 h后,Co–Mn3O4复合镀层热转化为(Co,Mn)3O4尖晶石涂层,氧化100 h后结构稳定,表面平整致密,能够有效阻隔Cr元素向外挥发.
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