A historical, statistical and electrochemical approach on the effect of microstructure in the anodizing of Al alloys: a review

Abstract

Anodizing is a well-documented surface treatment that is inserted in a complex protection system against corrosion applied to Al alloys. In the scientific literature, there are many works about this topic, which are concentrated on: (1) anodic aluminum oxide (AAO) growth mechanism; (2) anodized alloys corrosion behavior, or (3) the influence of anodizing parameters on the following steps of corrosion protection of the anodized layer. However, the effect of the microstructure on the AAO formation is not yet well established. This paper aims to review the effect of the microstructure of Al and its alloys on the anodizing process by a historical, statistical, and electrochemical approach, considering the advantages in understanding the influence of intermetallics in this process. Besides, this review brings a comparison among the number of publications and the types of alloys studied by statistical analyses. Finally, it emphasizes the importance of anodizing in the aeronautical industry, in which a great number of studied alloys are applied, mainly the 2XXX (Al-Cu) and 7XXX (Al-Zn) series alloys.

Graphical Abstract

Keywords:

• Anodizing
• Al alloys
• microstructure
• aeronautical industry
• corrosion protection
• statistical analysis

Acknowledgments

The authors thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), [Process 2019/18388-1, 2022/06935-0], for the grant of João Victor de Sousa Araujo. Acknowledgments are also due to the library staff of the Nuclear and Energy Research Institute (IPEN), Aston University, Technical University of Denmark, and Illinois University for the support in the search for some research papers, and to Mr. Michael Tang, for providing the doctoral theses published at University of Manchester.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), [Process 2019/18388-1, 2022/06935-0].