Mechanical and Corrosion Behavior of Plasma Electrolytic Oxidation Coatings on AZ31B Mg Alloy Reinforced with Multiwalled Carbon Nanotubes

Plasma electrolytic oxidation (PEO) is an effective surface modification technique. The PEO technique has been widely used to grow protective oxide layers into materials with lower corrosion resistance properties. In this study, a new technique was used for synthesizing AZ31B magnesium alloy reinforced with multiwalled carbon nanotubes (MWCNTs). After the synthesis, the composites were coated by PEO in a solution of sodium metasilicate pentahydrate (Na2SiO3 center dot 5H(2)O) and potassium hydroxide (KOH). The microstructure morphology and composition in the interface were characterized by scanning electron microscopy and energy-dispersive x-ray spectroscopy. The hardness, the elastic modulus and adherence of the coatings were studied by nanoindentation tests. Finally, the samples were subjected to corrosion tests by electrochemical impedance spectroscopy. The microstructure and mechanical analysis shows that the PEO coating morphology has a dependency on the MWCNTs content into the metal matrix and exhibited good mechanical properties and high corrosion resistance.