大电流启镀下镀锡层覆盖度的研究

Study on coverage of tin coating with high current at initial plating stage

以不同粗糙度的钢板为基体,采用弗洛斯坦镀锡液在赫尔槽中电镀锡。先采用扫描电子显微镜观察了电镀初始阶段的锡镀层形貌,并通过赫尔槽试验研究了钢板粗糙度对镀层覆盖度的影响。在总电量相等的前提下,采用前期大电流后期小电流的方式电镀锡,以研究大电流启镀对镀锡层覆盖度的影响。结果表明,电镀初期锡晶核优先在原板表面轧制纹的凸起处生成并持续生长,导致镀层分布不均匀、覆盖度较低。采用大电流启镀可有效提高镀层覆盖度、均匀性和致密度。

Tin plating was carried out from Ferrostan tin plating bath in Hull cell using steel plates with different roughness as substrates. The morphology of tin coating obtained at initial plating stage was observed by scanning electron microscopy. The effect of roughness of steel plate on the coverage of tin coating was studied by Hull cell test. In order to study the effect of high current strike at initial plating stage on the coverage of tin coating, the plating process using high current at early stage followed by low current was proceeded under the precondition of equal total electric quantity. The results showed that tin tends to nucleate preferentially at micro-bumps of rolled stripes on the substrate surface and grow continually, leading to non-uniform distribution and low coverage of coating. High- current strike at initial plating stage is beneficial to improve the coverage, uniformity, and compactness of tin coating.