CORROSION BEHAVIOUR OF ADVANCED COMPOSITES CONTAINING SURFACE MODIFIED SIC AS REINFORCEMENT

Abstract

The interface structure, micro-voids, pits, delamination, intermetallic compounds and internal stresses are the utmost critical factors influencing the corrosion performance of composite materials making them unsuitable for use in structural applications. One useful technique to control such adverse effect in composites is surface modification of the reinforcement. The present investigation involved the implementation of chemical techniques, particularly electroless plating (EP), to modify the surface of silicon carbide (SiC) particles by depositing a layer of nickel phosphorous (Ni-P) onto them. These plated SiC particles were subsequently employed in the production of Al/Ni-pSiC composites using the powder metallurgy (PM) method, with different weight percentages of plated SiC content ranging from 5% to 15%. The corrosion behaviour was assessed by potentio-dynamic polarization tests in 3.5% NaCl solution at room temperature. Results confirmed that AlNi-pSiC composites exhibit a greater resistance to pitting, in contrast to pure aluminium and Al/SiC composites without plating. The enhanced corrosion resistance in Al/Ni-pSiC composites can be attributed to strong interfacial bond, grain refinement, CTE difference, formation of Ni3Al, and reduced potential difference.