铬铵矾电沉积铬中阻氢剂的阻氢作用

Study on Retardance of Hydrogen Evolution by Cationic Surfactant in Electrodeposition of Chromium from Chromium-Ammonium Alum

为阻止氢离子在电沉积铬过程中与三价铬离子竞争析出,提高金属铬电沉积效率,选用1631这种含氮的阳离子表面活性剂作为阻氢剂,在硫酸铵+硼酸介质中扫描极化曲线,利用极化曲线法研究1631在铬电极表面的阻氢作用,以析氢过电位为指标,选取1631浓度、溶液pH值、温度和搅拌速度为影响阻氢效果的4因素,设计L9(34)的正交试验。经优化,确定1631阻氢的最佳试验条件为:1631浓度20mg/L,温度45℃,pH值2.4,搅拌速度0.42mL/s。在该工艺条件下,对含有20mg/L1631的硫酸铬铵进行电沉积铬,金属铬沉积的电流效率提高了12.23%,1631起到了很好的阻氢作用。研究表明,1631是提高铬电沉积效率的有效阻氢剂。

N-containing cationic surfactant 1631 was used as the hydrogen-evolution retarding agent so as to prevent the competitive precipitation of H+ with Cr 3+ ions during the electrodeposition of chromium and increase the electrodeposition efficiency of chromium. The retardation action of the surfactant to the hydrogen-evolution was investigated via measuring the polarized curve in an ammonium sulfate-boric acid bath. The optimal condition for the hydrogen-evolution retardation of the surfactant was determined making use of orthogonal tests, with respect to the potential of hydrogen-evolution, the concentration of the surfactant 1631, the pH value of the electrolyte solution, temperature, and stirring velocity. As the results, the technological conditions at which the optimal hydrogen-evolution retardation of the surfactant was reached were suggested to be as follows: concentration of the 1631 surfactant 20 mg/L, temperature 45 ℃, pH value 2.4, stirring velocity 0.42 mL/s. The current efficiency was increased by 12.23% as 20 mg/L 1631 surfactant was added in the chromium-ammonium alum electrolyte, indicating that the surfactant was effective in retarding the hydrogenevolution during the electroplating of chromium from the chromium-ammonium sulfate bath.