High- and Ultra-High-Purity Aluminum, a Review on Technical Production Methodologies

Aluminum and aluminum-based alloys have been used for many years. In view of the increase in material purity requirements of advanced technology products, research regarding high-purity aluminum has gained significant attention in recent years. In this review, we seek to describe the fundamental purification principles and the mechanisms of various segregation techniques used to produce high-purity aluminum. Moreover, we aim to provide an overview of high-purity aluminum production, with particular emphasis on: (a) principles on how to produce high-purity aluminum by layer- and suspension-based segregation methods; (b) discussion of various influencing process parameters for each technique, including three-layer electrolysis, vacuum distillation, organic electrolysis, suspension-based segregation, zone melting, Pechiney, Cooled Finger, and directional solidification; as well as (c) investigations of fundamental working principles of various segregation methods and corresponding reported end-purification for the production of HP-Al. Eventually, the end-reported product purity, and advantages and disadvantages of various purification methods and technologies are summarized. By analyzing and comparing the characteristics of different methods, we put forward suggestions for realizing efficient and environmentally friendly production of high-purity aluminum in the future.

Анодный оксид алюминия, сформированный в водных растворах хелатных комплексных соединений цинка и кобальта

The galvanostatic anodizing results of specially prepared high-purity aluminum in aqueous solutions of complex compounds K3[Co(C2O4)3] and K2[Zn(edta)] of various concentrations in the current density ranges 1.5–1.10·102 and 1.5−30 mA·сm−2, respectively. The kinetic features of anodizing have been established, indicating the occurrence of an oscillatory electrochemical process. Morphological features of a flaky and loose nature for K2[Zn(edta)] and monolithic for K3[Co(C2O4)3], uncharacteristic for anodic aluminum oxide, were revealed. The elemental composition, IR spectroscopic and photoluminescent characteristics of the formed oxides are shown.