Microstructure and corrosion resistance of pure titanium surface modified by double-glow plasma surface alloying

In this paper, the TiO2 alloyed layer was successfully formed on pure titanium surface using the double glow plasma surface alloying technology. The microstructure and phase composition of the alloyed layer were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). The micro-hardness of the alloyed layer was investigated by nano-indentation test. The surface roughness was decreased after the treatment. Measuring the anodic polarization curves in Tyrode’s solution, the corrosion rates of the untreated and treated samples were compared. The results indicated that the uniform dense TiO2 alloyed layer was obtained on the pure titanium surface. As compared with pure titanium, the free corrosion potential of TiO2 alloyed layer increased and the free corrosion current density decreased, which corresponded to a decreased corrosion rate. It led to the improvement of corrosion resistance of the pure titanium surface.