Effect of Titanium Nanoparticles in Electrolyte on the Properties of Micro-Arc Oxidation Coatings on AZ91D Magnesium Alloy Surface

Abstract

MAO coatings were prepared on AZ91D magnesium alloy surface in the phosphate electrolyte containing different concentrations of titanium nanoparticles.The effects of titanium nanoparticle concentration on the morphology,composition and properties of the as-prepared coatings were studied.Scanning electron microscope,energy dispersive spectrometer,X-ray diffractometer and X-ray photoelectron spectroscopy were employed to characterize the morphology and composition of such coatings.The corrosion resistance of coatings was tested by an electrochemical workstation,and the light absorption performance of the coatings was evaluated by a spectrophotometer.Results showed that the added titanium nanoparticles in electrolyte had little influence on voltage variation.However,the titanium nanoparticles in electrolyte could form Mg2TiO4in the micro-arc oxidation coatings.With the increase of the concentration of titanium nanoparticles,the small micropores on the surface of the coatings decreased first and then increased,so the corrosion resistance increased first and then decreased;furthermore,the coating's color changed from gray to light blue and then dark blue,leading to a gradual decrease of the reflectivity to simulated sunlight

Keywords

• micro-arc oxidation coating|titanium nanoparticle|az91d magnesium alloy|corrosion resistance|reflectance