Construction and Performance Study of Superhydrophobic Coatings on the Surface of the Titanium Alloy Welded Joint

Abstract

In order to improve the corrosion resistance of welded joints of Titanium(Ti) alloy, using TA2 welded joints as the substrate, a combination of micro-arc oxidation and low-energy modification methods was used to prepare superhydrophobic coatings in the base metal zone, weld zone and heat affected zone, respectively. The microstructure, morphologies and chemical composition of the sample were characterized by metallographic microscopy, scanning electron microscopy(SEM), X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FTIR). Moreover, the corrosion resistance of the sample in a 3.5%(mass fraction) NaCl solution was tested by electrochemical impedance spectroscopy(EIS). Results showed that the substrate treated by micro-arc oxidation obtained a brain shaped micron groove structure, and its phase composition became anatase type TiO2. After low-energy modification, the water contact angles of the three regions were 154.5°, 152.3° and 153.6°, and the rolling angles were 2.9°, 4.4° and 3.2°, respectively, which exhibited good superhydrophobicity. In EIS testing, the capacitance arc radius of superhydrophobic coatings was the largest, followed by micro-arc oxidation coatings. Both types of which improved the corrosion resistance of the substrate. Among them, the charge transfer resistance of the superhydrophobic sample in the heat affected zone increased by nearly 7 times compared to the substrate, exhibiting the optimal corrosion inhibition performance.

Keywords

• titanium alloy; welded joints; superhydrophobic coating; corrosion resistance