Integral colour anodizing of aluminium and its alloys in organic and mixed acid baths

Abstract

A study of the integral colour oxidation, under potentiostatic conditions, in the (5-30)% v/v m-cresolsulphonic acid and (1-20)% w/v g resorcylic acid alone and when mixed with (0.1-5)% v/v sulphuric acid, has been carried out using aluminium and some of its alloys. In the mixed baths of 2,6-Dihydroxy benzoic acid and sulphuric acid, or m-cresolsphonic acid and sulphuric acid, integral colour coatings are obtained below 20°C and c.d. 2A/dm2, whereas in g-resorcyclic acid i.e. 2-6, dihydroxy benzoic acid, alone coloured films can be produced at any temperature from room temperature to the boiling point of the electrolyte. Curves were plotted showing the inter-dependence of voltage, current and bath temperature. The structure of the composite, films and base metal is depicted in the photomicrographs. (Retired scientist)