Effect of SiC particle size on corrosion behavior of pressure infiltrated Al matrix composites in a NaCl solution

Abstract

In this study, the effect of SiC particle size on corrosion behavior of Al-60 vol.% SiC particle composites has been investigated. Three different SiC particle composites, having mean diameters of 13, 23 and 37 μm, were produced by a pressure infiltration technique at 750 °C. The corrosion tests were carried out in 3.5 wt.% NaCl environment up to 28 days. Experimental results showed that the weight loss of the composites increased with increasing particle size and exposure time. However, weight loss of the composites having 13- and 23-μm particle sizes remained almost constant after 3–5 days of exposure time. Scanning electron microscopic (SEM) analysis and potentiodynamic polarization measurements revealed that composite having 13-μm SiC particles exhibited higher corrosion resistance than that of the composites having 23- and 37-μm SiC particles. Experimental results showed that intermetallics as a result of reaction between Al and SiC particle has a beneficial effect on corrosion resistance of the composites due to interruption of the continuity of the matrix channels within the pressure infiltrated composites.