The effects of pore widening and calcination on anodized aluminum oxide prepared from Al6082

• Published in: Surface & coatings technology 2020-02, Vol.383, p.125234, Article 125234
• Main Authors: Kozhukhova, A.E., du Preez, S.P., Bessarabov, D.G.
• Format: Article
• Language: English
• Subjects: Al6082; Aluminum; Aluminum base alloys; Aluminum oxide; Anodized aluminum; Anodizing; Calcination; Diameters; Morphology; Oxalic acid; Pore–widening; Roasting; Thickness; Widening
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.125234

In this study, semi-organized anodized aluminum oxide (AAO) is prepared by two-step anodization in oxalic acid using a low-purity aluminum (Al) alloy (Al6082) as the source material. Obtaining ideally ordered AAO layers from Al alloys is confounded by the presence of impurities and requires specialized post-anodization treatment. Here, a process is proposed for obtaining an AAO layer with a semi-ordered pore arrangement by means of calcination and pore-widening procedures. Calcination temperatures of 400–600 °C and pore–widening times of 15–120 min were explored. It was found that calcination improved the pore order of AAO layers from disordered to semi-ordered (defined as being near ideally ordered—one pore surrounded by six neighboring pores). In addition, it was found that calcination at 600 °C resulted in suitable pore widening of the AAO layer. The morphology of the AAO layers was characterized using scanning electron microscopy, which was applied to determine pore diameter, inter-pore distance, pore density, and AAO layer thickness. We found that calcinated and pore-widened AAO layers with pore diameters of 48.7 nm, inter-pore distances of 80.6 nm, and pore densities of 178 pores/μm2 could be prepared. The AAO preparation method proposed here is an economically attractive process suitable for the preparation of AAO layers due to the utilization of an inexpensive Al source. •AAO layer preparation from low cost Al sources is economically attractive.•Non-Al elements present in Al alloys perplexes AAO layer preparation.•Pore arrangement of AAO layers prepared from Al alloys is generally disordered.•AAO layer calcination and pore widening improves pore arrangement.