Corrosion Behavior of Ta-10W Coatings on CP-Ti and TC4 Substrates

Abstract

The corrosion resistance of commercial purity titanium (CP-Ti) and Ti-6Al-4V (TC4) alloys coated with Ta-10W via multi-arc ion plating is investigated. The coating with uniform thickness exhibited silvery, dense, and continuous surface without apparent defects. The interface between the Ta-10W coating and substrate was dense with light elemental diffusion. The coating x-ray diffraction profile was body-centered cubic, α-Ta. The corrosion current density of the coated samples was reduced by one order of magnitude in 3.5% HCl solution, compared to that of the substrates. Electrochemical impedance spectroscopy showed that the Ta-10W coating improved the substrate metal corrosion resistance by slowing down the corrosion tendency and rate, increasing the charge transfer resistance and dielectric property of the double layer. Electrochemical corrosion testing showed that the Ta-10W coating improved the substrates’ corrosion resistances. After immersion in 5% HCl solution for 168 h, the uncoated substrates exhibited severe corrosion, whereas the CP-Ti and TC4 substrates coated by Ta-10W were still intact and dense. Point scanning of the immersed corrosion demonstrated that the Ta-10W coating reduced the relative oxygen content from 5.17 to 0.78% of the TC4. These results indicated that the Ta-10W coating was efficient in protecting the CP-Ti and TC4 from corrosion.