Corrosion and Biocompatibility Studies of Bioceramic Alumina Coatings on Aluminum Alloy 6082

Abstract

Recent advances in ceramic materials, particularly porous alumina (Al₂O₃), have significantly enhanced the safety and efficacy of medical implants by improving biocompatibility and modulating cellular behavior for biomedical applications. Variations in the surface structure and chemical composition of porous Al₂O₃ promote different biological responses and coating stability, underscoring the need for further biological and corrosion research. Traditional methods for producing alumina ceramics from powder are expensive, time-consuming, and limited in their ability to create complex shapes and large structures due to the brittleness of alumina. This study evaluates the biocompatibility of bioceramic-coated aluminum (Al) alloy 6082 as a lightweight and cost-effective alternative for bone osteosynthesis plates. Al₂O₃ coatings were achieved through anodization using phosphoric and sulfuric acids. The untreated and anodized alloys were analyzed for chemical stability and biocompatibility and compared with medical-grade titanium alloy. All specimens exhibited excellent biocompatibility, demonstrating high adhesion and viability of the fibroblast cell line. Corrosion resistance and metal ion release were assessed in simulated body fluid, with all specimens effectively suppressing the release of Fe and toxic Al ions. The untreated Al alloy exhibited a higher release of Mn ions than the coated specimens. Notably, the bioceramic coating obtained in sulfuric acid demonstrated 3 orders of magnitude higher corrosion resistance, indicating its potential suitability for biomedical applications. By addressing the limitations of traditional alumina ceramics, our approach enables the fabrication of products in diverse sizes and shapes, offering a practical solution for creating customized biomedical implants.

Keywords: cell adhesion; osteosynthesis plates; porous Al2O3; simulated body fluid; viability.

Figure 1

SEM topography (left) of the tested specimens under low and high magnifications and their water drop contact angles (right).

Figure 2

Grazing incidence X-ray diffraction (GIXRD) pattern of tested specimens (a). Pattern fragment (b) −shift of Al(111) peak after anodizing.

Figure 3

Indentation (top) and Vickers microhardness (bottom) of the tested specimens.

Figure 4

pH of SBF during the immersion experiments with the specimens.

Figure 5

Total ion release of tested specimens after immersion in SBF for 1 to 28 days, determined by ICP-OES.

Figure 6

SEM topography of tested specimens.

Figure 7

Tafel plots of (a) Al alloy, (b) Al₂O₃^P and (c) Al₂O₃^S before and after immersion in SBF for 1 to 28 days.

Figure 8

Bode (a, c, e) and Nyquist (b, d, f) plots of Al (a, b), Al₂O₃^P (c, d) and Al₂O₃^S (e, f) electrodes on exposure time in SBF solution.

Figure 9

Equivalent electrical circuits used for fitting of EIS spectra of Al alloy and Al₂O₃^P (a), and Al₂O₃^S (b).

Figure 10

SEM images of L929 cells cultured on Ti alloy, Al alloy, Al₂O₃^P, and Al₂O₃^S samples at various magnifications. Arrows indicate cells with low contrast.

Figure 11

Impact of alloy extracts on the relative viability of L929 cells: (a) overall growth (including adhesion and proliferation) and (b) proliferation alone (excluding adhesion) The mean relative viability (%) was calculated based on the untreated control group, with error bars indicating the standard deviation. No significant differences were observed between groups in both (a, b) (one-way ANOVA, p = 0.61 and p = 0.66, respectively).