Enhanced protective coatings on Ti-10V-2Fe-3Al alloy through anodizing and post-sealing with layered double hydroxides

Abstract

Anodic oxidation is a prevalent technique to introduce superior corrosion and wear resistance upon the surface of titanium (Ti) alloys, in which the selection of appropriate electrolytes and defect-sealing strategies is a key. This study aims to address such issues through anodizing Ti-10V-2Fe-3Al alloy in malic acid, followed by a post-sealing treatment with Mg-Al layered double hydroxides (LDHs). The characteristics of the samples were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). SEM micrographs reveals that the anodic coating had a surface full of bulges and cracks, and was almost sealed by the following LDHs treatment. XRD pattern indicate that the anodic coating was mainly consisted of amorphous TiO2 with a small fraction of anatase, but its crystallization degree was increased through the post-sealing. Moreover, electrochemical and tribological measurements demonstrate that corrosion current density was 2.8 × 10−6, 2.0 × 10−7, 5.9 × 10−9 A cm−2, and wear rate was 1.45 × 10−3, 1.30 × 10−4 and 6.90 × 10−5 mm3 N-1 m-1 for respective bare Ti-10V-2Fe-3Al alloy substrate, anodized specimens without and with the LDHs post treatment. Finally, a plausible wear mechanism was proposed.