Effect of gliding arc discharge plasma on surface characteristics and biocompatibility of titanium alloy

This study developed a system for generating gliding arc (GA) discharge and investigated the oxidation treatment of Ti-6Al-4V alloy surfaces using GA discharge, focusing on surface characterization and biocompatibility assessment. The results indicate that increasing the power output and reducing the working gas flow rate enhance the stability of the arc and plasma generated by GA discharge. The addition of water vapor to the working gas promoted the generation of OH, H, and O radicals during the discharge process. The electrode wear powder did not significantly affect the biocompatibility of the surface treated by GA discharge. An amorphous titanium oxygen compound layer with fine surface irregularities and high hardness was formed on a Ti-6Al-4V alloy exposed to GA discharge. An oxygen diffusion layer was also created beneath the compound layer. Scanning electron microscopy, energy-dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy analyses indicated that more calcium phosphates precipitated on the GA discharge-exposed specimen during the Hanks’ liquid immersion test. The MTT assay results after cell culture on the specimens indicated that the number of mouse calvarial-derived osteoblast cells on the specimens exposed to GA discharge was higher than that on untreated specimens. The results demonstrate that GA discharge treatment significantly enhances the bioactivity and cytocompatibility of Ti-6Al-4V alloy surfaces.