化学镀液中NiSO_4·6H_2O浓度对镀速及镀层硬度的影响

The Influence of the NiSO_4·6H_2O Concentration in Electroless Plating Solution on the Deposition Rate and Hardness of Electroless Coating

在TC4钛合金表面制备了Ni-P低磷化学镀层,研究了镀液中NiSO4.6H2O浓度对镀层沉积速度及镀层硬度的影响。采用紫外可见光分光光度计、扫描电镜及能谱仪、显微硬度仪分别对镀液中的NiSO4.6H2O浓度,镀层的表面形貌和化学成分,镀层的硬度进行测定。结果表明:化学镀液最佳施镀周期为60min。镀液中NiSO4.6H2O浓度对化学反应速率有重要影响,当浓度差达到临界值4.77g/L,沉积速度显著降低。随着反应进行,晶胞尺寸逐渐增大,晶粒粗化;同时镀层磷含量逐渐升高,镀层结构由晶态向微晶态转化,塑性变形抗力降低,硬度降低。

The electroless nickel coating with low-phosphorus content was carded out on the TC4 titanium alloy. The influence of NiSO4 ·6H2 O concentration in the electroless plating solution on the deposition rate and hardness of the electroless coating was studied. NiSO4·6H2O concentration of low-phosphorus electroless plating solution, the morphology, ele- mental composition and hardness of the coating were characterized by the ultraviolet-visible spectrophotometer, scanning electron microscopy （SEM）, energy dispersive spectroscopy （ EDS ）, micro-hardness testing machine. The results showed that the best plating cycle was 60 min for electroless plating solution. And NiSO4·6H2O concentration of electroless plat- ing solution had a very important influence on the reaction rate. When the concentration difference reached critical value of 4.77g/L, the deposition rate significantly decreased. The size of the cell gradually increased and the grains coarsened with the reaction progress. At the same time, the phosphorus content of the coating gradually increased. However, thestructure of the coating translated from crystalline state into micro crystalline state. The mi- croyield strength against microplastic deformation and hardness of the coating decreased.