Hard Anodizing Process of Super-high Strength Aluminum Alloy and Its Salt Spray Corrosion Resistance

ZHANG Haiyan; JIA Pengxiang; DU Dongxing

doi:10.7643/issn.1672-9242.2025.08.002

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Equipment Environmental Engineering ›› 2025, Vol. 22 ›› Issue (8) : 14-23. DOI: 10.7643/issn.1672-9242.2025.08.002

Special Topic—Application and Collaborative Evaluation Technology of Light Weapons in Complex Environments

Hard Anodizing Process of Super-high Strength Aluminum Alloy and Its Salt Spray Corrosion Resistance

ZHANG Haiyan¹, JIA Pengxiang², DU Dongxing^3,*

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Abstract

The work aims to effectively extend the service life of 7A19 ultra-high strength aluminum alloy structural components and equipment in coastal corrosive environments and investigate the corrosion behavior of hard-anodized films during salt spray testing. Single factor experiments were conducted to examine the effects of current density and oxidation time on film properties. Subsequently, 240 h and 480 h salt spray tests were performed, and corrosion resistance was evaluated using electro-chemical impedance spectroscopy (EIS). The results indicated that the thickness and roughness of the hard-anodized film increased with higher current density and longer oxidation time. However, oxidation times reaching 60 min severely compromised film uniformity. While film hardness generally exhibited a positive correlation with thickness, specimens anodized at 1 A/dm² and 2 A/dm² failed to meet the hardness requirements specified by the national standard. Following salt spray exposure, corrosion resistance did not increase monotonically with greater film thickness. The diameter and depth of pores significantly influenced the integrity of bonding between the chromium-rich sealing layer and the film. With the exception of films formed with a 60 min oxidation time, all other samples maintained good corrosion resistance after 480 h of salt spray exposure, exhibiting no significant corrosion products. The oxide film formed under the process parameter range of hard anodizing in this paper can significantly extend the corrosion resistance of 7A19 ultra-high strength aluminum alloy in the salt spray-accelerated corrosion environment.

Key words

aluminum alloy / hard anodizing / neutral salt spray test / corrosion resistance / electro-chemistry / AC impedance spectrum

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ZHANG Haiyan, JIA Pengxiang, DU Dongxing. Hard Anodizing Process of Super-high Strength Aluminum Alloy and Its Salt Spray Corrosion Resistance[J]. Equipment Environmental Engineering. 2025, 22(8): 14-23 https://doi.org/10.7643/issn.1672-9242.2025.08.002

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Funding

Talent Introduction Project of Mianyang Polytechnic (MZ22RC01); Mianyang Philosophy and Social Sciences Key Research Bas-Mianyang Vocational Education Center Funding Project (MYZJ2023ZC002)