Growth, corrosion and wear resistance of SiC nanoparticles embedded MAO coatings on AZ31B magnesium alloy

Resumo

In this research, nanocomposite coating was deposited on magnesium matrix AZ31B alloy using the micro arc oxidation (MAO) method. MAO was carried out in SiC-nanoparticles containing suspension using the sodium silicate and sodium aluminate bases at constant current density. The effect of nanopowder addition and MAO periods were also investigated in the present work. Using the Scanning electron microscopy (SEM), the thickness and surface morphology of the coatings were studied. The coefficient of friction and abrasion rate curves were used to analyze nanopowder addition on resistance to abrasion, while the potentiodynamic curves were used for assessing the resistance to corrosion in the ceramic nanocomposite coating deposited on surface of alloy AZ31B. The morphological studies on surface of coatings revealed that the cavitation level and size increases with the increasing coating duration. Besides, Energy Dispersive X-Ray Diffraction (EDS) analyses from cross section and surface of the prepared coatings revealed that nanopowder distribution on interface of coating with matrix and boundaries of the cavities is almost uniform. The cross section studies of the coatings revealed that their thickness increases, as coating duration prolongs. Furthermore, the corrosion behavior of the samples indicated that presence of nanopowder does not significantly affect the resistance to corrosion of the coatings; however, coefficient of friction and abrasion rate of coatings indicates a respective rise and drop in presence of these nanopowders.