Influences of Sr(OH)2 on the Structure and Corrosion Resistance of Micro-Arc Oxidation Coatings Formed on TC4 Titanium Alloy

In order to improve the comprehensive properties of TC4 titanium alloy, micro-arc oxidation (MAO) coating is prepared on the surface of a TC4 substrate in a basic electrolyte with varying concentrations of Sr(OH)(2). The surface morphology, phase composition, element distribution, and corrosion resistance of MAO coatings are analyzed by scanning electron microscopy, X-ray diffraction, an energy-dispersive spectrometer, the electrochemical test, and the erosion-corrosion test. The results show that the voltage of the MAO process increases and then decreases; the surface morphology and density of the coatings are greatly improved after doping Sr(OH)(2). When the concentration of Sr(OH)(2) is 0.6 g L-1, the thickness, hardness, and adhesion strength of the coating reach the maximum values of 37.04 mu m, 836.2 HV, and 21.8 N, respectively. At this time, the wear resistance and corrosion resistance are the best, and the friction coefficient and the corrosion rate are the lowest: 0.3352 and 1.04 x 10(-10) mm a(-1), respectively.