Effect of DyCl ₃ doping on micro-arc oxidation of TC11 alloys

To investigate the effect of DyCl 3 addition on the properties of micro-arc oxidation (MAO) coatings formed on TC11 titanium alloy, this study conducted MAO treatment in a silicate-phosphate composite electrolyte system with the introduction of DyCl 3 at different concentrations. By means of analytical equipment including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and an electrochemical workstation, the variations in the microstructure, phase composition, and corrosion resistance of the MAO coatings were studied. Results showed that with the addition of DyCl 3 , the final oxidation voltage was increased, the pore size of the MAO film was deceased, the surface roughness of the films was reduced, which means the denser and smoother MAO films. Dy 3 + participates in the film formation process in the form of the hard Dy 2 O 3 phase, which enhances the hardness and corrosion resistance of the coatings. Further analysis reveals that the MAO coating prepared when the DyCl 3 concentration is 0.15 g/L exhibits the optimal performance in key properties: its hardness and thickness reach 490.8 HV and 34.1 μm, respectively; in a 3.5% NaCl corrosive solution, it has the lowest corrosion rate of 2.9421 × 10 − 3 mpy, thus showing the best overall properties among all the prepared MAO coatings.