A C Anodizing of Aluminium in Sulphuric Acid

Abstract

SummaryThe effect of various operating parameters has been examined for a c anodizing in sulphuric acid in the vicinity of commercial conditions. To obtain good quality films with maximum thickness and minimum variation, minimum burning tendency with no pitting, a 15% solution at low temperature with 20 g/l nickel sulphate as modifier is recommended. Such a solution is sensitive to aluminium build-up, which should be limited to 10 g/l. The modified solution gives improved consistency of coloration and compares favourably with the d c process. Electron probe microanalysis and Auger spectroscopy of the coatings show little difference as against the conventional anodized film.