THE EFFECT OF CURRENT DENSTY ON CORROSION BEHAVOR OF PULSE ELECTRODEPOSTED N-SCNANOCOMPOSITE COATING ON AZ91 MAGNESUMALLOY

Magnesium and its alloys are the lightest of structural metals, which makes them one of the most promising materials to minimize vehicle weight, but poor surface properties restrict the application of these alloys. Toimprove the surface properties of AZ91 magnesium alloy, Ni-SiC nanocomposite coating was applied by pulse electrodeposition. The effect of current density, in the range of 20-90 mA/cm , on corrosion behavior of AZ91 was investigated. The morphology and phase analysis of the coatings were studied using Scanning Electron Microscopy (SEM) and X-Ray Difraction (XRD) analysis, respectively. The corrosion behavior of the coated AZ91 alloy was investigated by potentiodynamic polarization. Microhardness measurement of the coatingsshowed a 347% enhancement. The results also revealed a significant improvement in corrosion resistance, that is, the corrosion current density decreased from 2.69 mA/cm for uncoated specimen to 0.003 mA/cm the sample coated at current density of 90 mA/cm and the corrosion potential increased from -2.069 V for uncoated specimen to -0.07 V for the sample coated at current density of 90 mA/cm.

Keywords:

Ni-SiC , nano-composite coating , pulse electrodeposition , corrosion current density , corrosionpotential