Composited MAO coating with SiO2 particles on TA2 alloy by laser treatment

In order to decrease defects and improve protective performance, micro-arc oxidation (MAO) coating was modified by adding SiO 2 particles to form a composite coating on TA2 alloy via laser treatment. The microstructural morphology, phase structure, cohesive strength and corrosion resistance of the composite coatings were investigated and analyzed by using SEM, XRD , thermal cycle, and electrochemical testing, respectively. The results showed that SiO 2 particles were firstly adsorbed onto the MAO surface with the aid of ultrasonic treatment and then sealed micro-pores of the MAO coating after laser treatment. The composite coating mainly consisted of R-TiO 2 , A-TiO 2 and SiO 2 phases and exhibited a dense multilayer structure with a rich Si element in the outer layer. After subjecting the coatings to 300 thermal cycles, clacking or marked spalling zones could not be observed in the composite coating; nevertheless, an obvious destruction appeared in the single MAO coating without SiO 2 particles. The corrosion potential ( E corr ) and pitting potentials ( E pit ) of the composite coating were −0.303 V and 1.765 V compared to that of −0.682 V and 1.401 V for the single MAO coating. Additionally, the corrosion rate decreased to 1.40 × 10 −4 A·cm −2 with the highest resistance (76,788.67 Ω·cm 2 ) from2.19 × 10 −4 A·cm −2 , indicating a stronger corrosion resistance in the composite coating. The results of simulation from Comsol Multiphysics demonstrated that a laser power as 80 W was appropriate for melting SiO 2 particles into the MAO coating to form a dense and cohesive composite coating.