A Thermodynamic Approach for Selection of Anodizing Electrolytes in AluminiumHolmium System

In this paper, an approach is described for the electrolyte selection to grow optimally anodic films on thermally coevaporated aluminium and holmium combinatorial alloys. This method based on thermodynamic and electrochemical principles proves that electrolyte selection for anodizing of alloys having different microstructures and electrochemical behaviour of individual constituents can be decided by superimposing potentialpH diagrams of individual constituents of the alloy. For the application of this approach, the most widely investigated valve metal, aluminium, and a nonvalve metal rare earth, holmium, have been chosen as a model case. Based on selfconstructed EhpH diagrams and solubility data, suitable electrolytes and pH range leading to the formation of barriertype anodic films on aluminium and holmium as well as on their alloys are proposed.(VLID)4844497Version of recor