Corrosion behaviour of SiC and Al2O3 reinforced Al 7075 hybrid aluminium matrix composites by weight loss and electrochemical methods

Abstract

The corrosion study of Al 7075 hybrid metal matrix composites reinforced with equal weight percents (2.5, 5, 7.5, and 10) of silicon carbide and aluminium oxide is investigated in the present work by weight loss and electrochemical methods. In this study, composite specimens prepared by the squeeze casting technique were analyzed at room temperature to estimate the rate of corrosion in a 3.5% NaCl solution for various intervals using the weight loss method. As a consequence, a hybrid Al7075 composite reinforced with 10% SiC and 10% Al2O3 had a lower corrosion rate of 0.9997 mmpy than pure Al7075, which had a maximum corrosion rate of 3.4481 mmpy. The corrosion rate of hybrid composites is determined by the tafel polarization method and the electrochemical impedance spectroscopic method. These experiments showed that the corrosion rate of the hybrid metal matrix composite Al7075 + 10% SiC +10% Al2O3 was 0.630 mmpy less than that of the monolithic 7075 alloy. The corrosion morphology behaviour of the Al 7075 and their hybrid composite samples is observed by SEM. The SEM micrographs implied that SiC and Al2O3 reinforcements with the matrix alloy produced good interfacial and intermetallic bonding and hence decreased the corrosion rate.