AN INVESTIGATION ON THE INFLUENCE OF SIC VOLUME PERCENT AND HEAT-TREATMENT ON THE CORROSION BEHAVIOUR OF AL-6063/SICp COMPOSITES IN HCL – H2SO4 ENVIRONMENT

Abstract

The influence of SiC volume percent and temper conditions (namely, as-cast, solutionized, and artificial age hardening at 180⁰C and 195⁰C) on the corrosion behaviour of Al6063 alloy composites and its monolithic alloy in acidic environment (pH 1.37) has been investigated. The composites were produced using a two step stir casting approach having volume percents of 12 and 15. It was observed that preferential corrosion attack of the composites occurred along grain boundaries and by pitting within the grains at particulate/matrix interfaces. The composites exhibited a greater susceptibility to corrosion in comparison to the monolithic alloy for all temper conditions. Furthermore, solutionizing and water quenching treatment was observed to significantly improve corrosion resistance of the unreinforced Al-6063 alloy while ageing at both 180⁰C and 195⁰C significantly increased its corrosion susceptibility. However, for the 12 and 15 volume percent SiC reinforced Al-6063 composites, it was observed that both solutionizing and water quenching, and the age hardening treatments improved corrosion resistance in comparison to the as-cast temper condition. Unlike its unreinforced alloy, the effect of the type of heat-treatment was almost invariant on the corrosion resistance of the composites.