稀土元素对酸性化学镀镍的影响*

在酸性化学镀镍磷合金镀液中添加稀土元素(La、Pr、Nd),研究了其对镀速的影响。对镀层进行了XRD分析,用SEM观测表面形貌,EDX分析镀层组成,并进行了耐腐蚀极化曲线测定。结果表明在镀液中添加稀土离子能显著降低镀速,甚至完全终止Ni-P的沉积。镀液中添加稀土时,镀层中不含稀土元素,镀层仍为非晶态结构,但P含量略有降低,镀层的表面形貌发生了变化。镀液中含稀土(La、Pr、Nd)时,所得镀层在3.5%NaCl溶液中的自腐蚀电位降低,腐蚀电流密度增大,耐腐蚀性降低。

Effect of Rare Earth Elements on Electroless Plating of Ni with Acidic Bath

Rare earth elements(La, Pr, and Nd) were added into the acidic bath for electroless plating of Ni, and the effect of its ion on the deposition rate was investigated. XRD measurement was taken with the deposits, the surface morphology was observed by scanning electron microscopy(SEM), and the composition was measured by EDX. The corrosion resistance of the deposits was measured with polarization curves. The results show that the deposition rate is sharply depressed by adding rare earth ions into the bath, which even completely halts the deposition. Although rare earth element was added into the bath, the deposits obtained were still in an amorphous state without rare earth detected in them, but the phosphorus content of the deposits appreciably decreased, and the surface morphology of the coatings changed. When the rare earth(La, Pr, and Nd) was added into the bath, the corrosion potential of the obtained deposits in 3.5% NaCl solution decreased compared with that of the deposits from the rare earth free bath, the corrosion current density increased, and the corrosion resistance of the deposits was deteriorated.