Electrochemical and elemental characteristics of nano-cornposite MAO coatings on the AZ۳۱B substrate fabricated in different times and current densities

Micro-Arc Oxidation (MAO) also called Plasma Electrolytic Oxidation (PEO), Anodic SparkDeposition (ASD) is a relatively modern surface treatment providing elevated corrosion and wearresistance especially for light weight active metals Electrochemical Impedance Spectroscopy (EIS) ofnano-composite Micro Arc Oxidation (MAO) coatings containing graphene nanoparticles wasinvestigated. Elemental analysis of coatings via Energy-Dispersive X-ray Spectroscopy (EDS)technique was also performed. The relation between the results of these two tests is explai in thispaper. The parameter of current density was changed to fabricate two different types of ceramiccoatings. Regarding Scanning Electron Microssopy (SEM) cross images of coatings, equivalentcircuits were drawn for each Electrochemical Impedance Spectroscopy (EIS) tested sample andcorresponding values of the circuits’ element were estimated. It was found that increasing currentdensity of coating process resulted in the composition of the outer layer of the coatings change and itsresistance against crossing electrolyte increase; on the other hand its capacity property enhanced property enjamcedbecause of increasing the surface area.

Keywords:

MAO coating , AZ۳۱B alloy , EIS , EDS , V-t diagram