Surface engineering and interface chemistry of two-step sandblasted and dual acid-treated Ti6Al4V alloy for superior corrosion resistance and photocatalytic degradation

Ti6Al4V has excellent mechanical strength and broad passivation behavior, although it has limited photocatalysis and is susceptible to specialized corrosion under challenging acidic conditions. In this study, Ti6Al4V alloys were treated with sandblasting (SB)/ plasma (PT) treatment and were treated again with double acid etching (DAE) to demonstrate the surface improvements. The Ti6Al4V was tested with the primary etching mixture containing H2SO4, HCl and DI water and then with the oxidizing mixture of H2SO4 and H2O2. The XRD and FTIR analysis showed that the composition consisted mostly of α-Ti with low intensity, followed by Ti-O and Ti-OH phases of TiO2 functional groups formed after both treatments. UV-DRS examination indicated that the band gap energy of the SB-DAE Ti6Al4V decreased dramatically from 3.05 to 2.18. SEM images revealed that leaf-like porosity regions, plate-like patterns, rose-like patterns, and circular microstructures were formed in the Ti6Al4V alloy after the treatments. From the corrosion analysis, the SB-DAE rendered an increase in Ecorr of Ti6Al4V by 87.71% and decreased Icorr by 93.38%, whereas PT-DAE increased the Ecorr by 7.94% and decreased Icorr by 87.40%. Furthermore, the SB-DAE-treated Ti6Al4V exhibited 79% photocatalytic efficiency under UV–visible radiation, which is higher than untreated Ti6Al4V (48%). The surfaces of Ti6Al4V treated with SB and DAE improve their hardness, charge-transfer behavior, and oxygen vacancies of functional performance by incorporating controlled morphologies and structures onto defective TiO2, all of which are improved for photocatalysis and corrosion performances.