Effect of Surface-Treatment of Ultrasounic Impact Combined with Electrospark Deposition on Corrosion Resistance of TC4 Titanium Alloy

A dense modified layer in thickness about 11 μm was prepared on the surface of TC4 titanium alloy by surface-treatment of ultrasonic impact combined with electrospark deposition. The morphology, chemical composition, phase structure and corrosion resistance of the TC4 titanium alloy before and after modification were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical testing. The results show that the modified layer on TC4 titanium alloy surface was mainly composed of titanium oxide Ti₂O, aluminum oxide Al₂O₃ and titanium aluminum intermetallic compound Al₃Ti. Although the corrosion potential of the modified layer was slightly higher than that of the TC4 titanium alloy substrate, its corrosion current was significantly smaller than that of the TC4 titanium alloy substrate. At the same time, the charge transfer resistance of the modified layer was also larger than that of the TC4 titanium alloy substrate. So the modified layer had better corrosion resistance than that of the TC4 titanium alloy substate.