An improved method of quantification of effects of cathode polarizing and depolarizing agents inspired by the Winand diagram

摘要

The Winand diagram has been known in the literature for decades, and its widespread utility and applicability to electrodeposition have been demonstrated. Certain limitations have been discussed - for instance, quantitative problems when organic inhibitors are introduced. The conceptual complexities have confined its use to a limited number of technical specialists, and indeed, its main use has been by Winand's own group. This investigation focusses on the transition from bi-dimensional (2D) to tri-dimensional (3D) nucleation, appearing on the Winand diagram as an arc separating deposits of different morphology and grain size. A modified technique for determining the potential of 3D nucleation in any industrial electrolyte is proposed. This is found to give a new dimension to the Winand diagram, and to point to solutions to many of the earlier dilemmas. The method has so far been used extensively in studies on zinc electrodeposition. Correlations have been observed between deposit morphology and a pair of polarization parameters. This extended theory and modified methodology may form a future basis for (a) selection of cell additives for existing or new electrodeposition processes and (b) correction of deviations likely to affect deposit quality in routine industrial operations.