An investigation of microgalvanic corrosion using a model magnesium-silicon carbide metal matrix composite

Abstract

In order to investigate the role of silicon carbide in microgalvanic corrosion of magnesium-based metal matrix composites (MMCs), a high-purity MMC was specially prepared by magnetron sputtering magnesium on to a substrate surface impregnated with silicon carbide particles. The corrosion of the model MMC was then studied by microscopic examination following immersion for up to 36 h in 3.5 wt% NaCl solution at the corrosion potential and by potentiodynamic polarization. The MMC revealed a comparatively low corrosion current density, about 10μA cm −2, and corrosion proceeded in a relatively uniform manner across the macroscopic surface of the specimen. Of most relevance to the purpose of the work, there was no evidence of microgalvanic corrosion around silicon carbide particles, indicating that the particles had virtually no influence on corrosion of the MMC.