Effect Of Rare-Earth On Ornamental Ti-Alloy Anodic Oxidation

Anodic oxidation coatings with bright colour and high corrosion resistance can be obtained on titanium using anodic oxidation technology. Different colors could appear on anodic oxidation coatings through changing anodic oxidation voltage in anodic oxidation process of titanium alloy. In this thesis, the influence of Ce(SO4)2 on ornamental Ti-alloy colorful anodic oxidation coatings in the vitriol electrolyte was researched.Firstly, the technological conditions of anodic oxidation coatings fabricated in basic electrolyte on titanium alloys were researched. The optimal technologcial conditions of anodic oxidation coatings fabricated in basic electrolyte were: 10 g/L vitriol acid, 3 g/L ammonium sulfate, the oxidation time was 20 min, the temperature was about 15℃.The effect of Ce(SO4)2 on Ti-alloy anodization was studied based on the research of basic electrolyte and technological conditions. The influence of Ce(SO4)2 on the appearance and corrosion resistance was evaluated. The oxidation process of the anodic oxidation coatings was analyzed by anodic polarization curves and potential-time curves. The corrosion resistance of the anodic oxidation coatings was evaluated by polarization curves,electrochemistry impendence spectrum and immersion test. The results showed that the oxidation coating formed in the electrolyte containing rare earth salt Ce(SO4)2 was better in the appearance and corrosion resistance than that formed in the electrolyte without rare earth salt. The optimum content of Ce(SO4)2 was 0.75 g/L. The surface morphology and phase composition of anodic oxidation coating were analyzed by SEM, XRD and EDX. The surface morphology was analyzed by SEM, it was shown that the surface by using rare-earth anodization was smoother and more symmetrical; With the EDS analysis of the film, it was shown that the oxidation of Ti-alloy surface was more sufficient by using rare-earth anodization than by the traditional oxidation, and there was not Ce element in the oxide film.;The structure of the oxide film was analyzed by means of XRD. The phase composition of oxidation film was TiO2。...