ANODIZING OF ALUMINUM AT ELEVATED-TEMPERATURES

In most decorative and engineering applications of anodized aluminium it is necessary that the film be reasonably hard and be wear or abrasion resistant. However, this leads to brittleness and low ductility in practice. It has long been known that by using higher temperatures during anodizing softer more ductile films result. This investigation reports the result of studies in this field using conventional sulphuric acid electrolytes at temperatures up to 60°C and current densities up to 15 A/dm2 (equivalent voltages up to 35V). Substantial changes in film properties and anodizing behaviour have been found.