不锈钢电化学着金黄色及其耐蚀性研究

Process for Golden Coloring on Austenitic Stainless Steel via Electrochemical Route and Corrosion Resistance of the Coloring Film

通过正交试验研制了一种奥氏体不锈钢低温、无铬环保型电化学着色新工艺,获得了其最佳配方及工艺参数为:硼酸8g/L、柠檬酸三铵10g/L、硫酸亚铁铵25g/L、添加剂ZH-L4.0mL,电位-600～-700mV,温度60～70℃,时间3～5min,pH值8.0。所得到的不锈钢着色膜光亮美观、呈金黄色,具有优越的耐蚀性。采用电化学方法研究了不锈钢表面着色膜在3.5%NaCl溶液中的动电位极化曲线,结果表明,不锈钢着色显著提高了膜的电化学稳定性,经封闭处理后其耐点蚀能力大为提高,腐蚀电流密度较小。

A new environmentally acceptable and Cr-free technology for the chemical coloring of stainless steel at low temperature was established based on orthogonal test.Thus the optimal formulation and parameters for coloring of the stainless steel were determined.The potentiodynamic polarization curve of the coloring film on the stainless steel in 3.5% NaCl solution was measured using electrochemical method.As the results,the optimal formulation for the coloring of the stainless steel was determined to be composed of 8 g/L boric acid,10 g/L tri-ammonium citrate,25 g/L iron-ammonium sulfite,4.0 mL additive ZH-L,while the optimal coloring parameters were determined to be potential of-600～-700 mV,temperature of 60～70 ℃,duration of 3～5 min,and pH value of 8.0.The resulting coloring film was bright and golden and had good corrosion resistance.The electrochemical stability of the stainless steel was greatly increased by electrochemical coloring,while the resistance to pitting of the coloring film was significantly increased by sealing and its corrosion electric current density was low.