Three-Dimensional Porous Ti-15ta Alloy Surface Dual Passivation Mechanism: Synergy of Alkaline Heat Treatment and Biomineralization

Abstract

To address the contradiction between mechanical adaptability and biological corrosion in existing titanium alloy implants, this study fabricated Ti-15Ta alloys with macro-micro-nano hierarchical porous structures using polyvinyl alcohol (PVA)-template-assisted powder metallurgy, with titanium and tantalum as raw materials. Alkaline heat treatment and biomineralization were applied to form a dual passivation layer of TiO2/Ta2O5 and hydroxyapatite on the surface. Results showed that the sample with 15 wt% PVA had a porosity of 51.5%, a compressive strength of 151.1 MPa, and an elastic modulus of 18.8 GPa, demonstrating good mechanical matching with cortical bone. After surface modification, the self-corrosion current density was as low as 5.15×10-6 A·cm-2, and the polarization resistance reached 9.2×103 Ω·cm2, representing a decrease in self-corrosion current by approximately two orders of magnitude compared to the original sample. The passivation potential range expanded to 0.1–1 V, significantly enhancing corrosion resistance. This study proposes a dual-function strategy of "porous mechanical adaptation - dual passivation layer anti-corrosion" to ensure the long-term physiological stability.

Keywords: Ti-15Ta alloy, Hierarchical porous structure, Surface modification, Dual Passivation, Corrosion resistance