硫酸-ジカルボン酸電解液によるアルミニウムの硬質陽極酸化

Abstract

It has been required for long years to produce aluminum coating of abrasion resistant oxide film. However, in the conventional process, abrasion resistant oxide layer was produced only by anodizing in electrolyte at low temperatures, or in the range of -10-0°C. Such process had disadvantages for setting up expensive refrigerating plant in order to maintain the low temperature.This report relates to the hard anodizing of aluminum in the electrolytes of sulfuric acid-dicarboxylic acids, whereby efficiency of the formation of oxide film, and hardness and abrasion resistance of the film were improved.The most excellent results were obtained with the electrolyte containing 15% (by wt.) of sulfuric acid+1-5% (by wt.) of malonic acid. The film produced with the above electrolyte at 20°C had almost so high impact abrasion resistance as that produced with the electrolyte of 15% (by wt.) of sulfuric acid alone at 5°C.The above mixed electrolyte could be operated at temperature of about 10°C higher than the case of sulfuric acid alone and no reduction of abrasion resistance was observed. The results of this study dissolved the problem of disposing of refrigerating plant.