Physical and Structural Properties of Pulsed-DC Sputtered Al2O3, MgO and ZrO2 Coating for Mg Corrosion Control

Abstract

Magnesium has attracted a lot of attention over the last few decades, due to its light weight and potential use as biomaterial. However, the poor corrosion resistance of magnesium restricts its practical use for application where exposure to aggressive aqueous media is unavoidable. This paper describes the growth, characterization and corrosion analyses of Al2O3, MgO and ZrO2 coatings for slowing down the degradation of Mg. Different thicknesses of Al2O3, MgO and ZrO2 were deposited on pure magnesium (99.95%) substrates using pulsed-DC magnetron sputtering process. The phase composition and microstructure analyses were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The corrosion protection behavior of the Al2O3, MgO and ZrO2 coated samples were evaluated using electrochemical measurements as such open-circuit potential, potentiodynamics and EIS. The corrosion test were performed in 0.9 wt% saline solution. The results showed that the Al2O3-coated Mg alloy exhibit a much superior stability and lower corrosion rate. The surface analyses of the corroded samples showed that the coating improved the corrosion resistance, whereas the bare Mg suffered severe localized corrosion. Adhesion assay was performed on the Al2O3, MgO and ZrO2 coatings to determine their biocompatibility. The results showed significant cell attachment to the coating compare to the control (bare glass).