Optimized Fabrication and Characterization of TiO 2 -Nb 2 O 5 -ZrO 2 Nanotubes on β-Phase TiZr 35 Nb 28 Alloy for Biomedical Applications via the Taguchi Method.

The nanostructured surface modification of metallic implants is increasingly gaining attention for biomedical applications. Among such nanostructured surfaces, oxide nanotube (NT) structures have received significant consideration in the biomedical and clinical fields, particularly because of their unique biological characteristics. This experimental study is based on the optimization and characterization of TiO ₂ -Nb ₂ O ₅ -ZrO ₂ nanotubes (NTs) on newly developed β phase TiZr ₃₅ Nb ₂₈ alloy. The effects of the anodization process parameters on the inner diameter ( D _i ) of the NTs were investigated. The experiment was conducted using the Taguchi experimental design with an L ₉ (3 ³ ) orthogonal array, with three control factors targeted for optimization: (i) applied voltage, (ii) water content of the electrolyte solution, and (iii) anodization time. The chemical composition, morphology, and hydrophilic properties of TiO ₂ -Nb ₂ O ₅ -ZrO ₂ NTs after optimization were characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. The results showed that a large D _i of NTs was achieved using an applied voltage of 40 V, water content of 5%, and anodization time of 120 min, with the applied voltage identified as the most effective parameter for the growth of TiO ₂ -Nb ₂ O ₅ -ZrO ₂ NTs based on signal-to-noise (S/N) ratio analysis. The Pareto ANOVA and confirmation test results showed that the Taguchi method was successful in optimizing the larger D _i for NTs; moreover, the optimized nanotubular surface exhibited the highest surface roughness and an increased hydrophilic nature. The above findings may contribute to the development of high-performance nanostructured coatings for biomedical applications.