硫酸盐三价铬镀液中次磷酸钠浓度对不锈钢阳极电化学溶出的抑制作用

Inhibition Effect of Sodium Hypophosphite on Electrochemical Stripping of Stainless Steel Anode in Trivalent Chromium Sulfate Plating Bath

为了进一步完善以316不锈钢为阳极的硫酸盐三价铬镀铬新工艺,考察了镀液中次磷酸钠等对316不锈钢阳极电化学溶出的抑制作用。利用Hull槽试验、能量射散谱(EDS)和扫描电子显微镜(SEM)研究了次磷酸钠浓度对镀层外观、组分和表面形貌的影响。结果表明,次磷酸钠可以有效地抑制316不锈钢阳极的电化学溶出:当其浓度为0.020 mol/L时,316不锈钢阳极的电化学溶出量由无次磷酸钠时的116.7 mg/(A.h)下降到13.1mg/(A.h);浓度低于0.040 mol/L时,Hull试样外观没有变化;浓度低于0.060 mol/L时,镀层表面形貌无明显变化;镀层中含磷量随次磷酸钠浓度的提高而逐渐增加。

The inhibition function of sodium hypophosphite for electrochemical stripping of 316 stainless steel anode in trivalent chromium sulfate plating bath was investigated by highlighting the effects of concentration of sodium hypophosphite on the appearance,composition and surface morphology of the coatings based on Hull cell test,energy dispersive spectrometry and scanning electron microscopy.Results show that sodium hypophosphite can effectively inhibit the anodic electrochemical stripping of 316 stainless steel.The introduction of 0.020 mol/L sodium hypophosphite led to the decrease of anodic stripping amount from 116.7 mg/(A·h) to 13.1 mg/(A·h).The appearance of Hull cell panel kept unchanged at a sodium hypophosphite concentration of 0.040 mol/L and below.The surface morphology of the coating also kept unchanged as the concentration of sodium hypophosphite was lower than 0.060 mol/L.The content of phosphorus in the coating increased with increasing concentration of sodium hypophosphite.