Growth of mixed anodic films on combinatorial Al-Gd alloys and their superimposed potential-pH diagrams

Abstract

• Ultra-thin anodic films are grown on the surface of an Al-Gd combinatorial library. • Thermodynamic calculations identify electrolytes for the growth of anodic films. • Different compositions and pH electrolytes can be used for efficient anodization. • Electrolyte species incorporation in anodic films extend their applications range. • Impedance analysis shows uniform growth of anodic films for all electrolytes. Growth of ultra-thin anodic films on alloys of aluminium and gadolinium having mixed chemistries is demonstrated in aqueous phosphate and borate electrolytes using scanning droplet cell microscopy. The present study reveals that electrolytes having different compositions and pH can be used for the efficient growth of anodic films. Consequently, the applications of anodic films can be extended owing to the modification of film properties by incorporation of various electrolyte species. Dielectric characteristics of films are examined by using electrochemical impedance measurements, which disclose a linear increase in inverse capacitance with formation voltage suggesting the uniform growth of anodic films irrespective of electrolyte selection. Oxide formation factor, k , greater than unity was obtained in selected electrolytes.