SOFTENING RESISTANCE AND CORROSION BEHAVIOUR OF ALUMINIUM MATRIX COMPOSITE REINFORCED WITH SILICON CARBIDE AND RICE HUSK ASH

Abstract

The softening resistance and corrosion behaviour of aluminium matrix composite developed with the use of rice husk ash (RHA) and silicon carbide (SiC) particulates as reinforcements were investigated in this research. RHA and SiC mixed in weight ratios 0:1, 1:2, 1:1, 1:2 and 1:0, were utilized to prepare 10 wt. % of the reinforcing phase with Al 6063 as matrix using double stir casting process. Open circuit potential (OCP) and potentiodynamic polarization measurements were used to study the corrosion behaviour with the aid of AUTOLAB PGSTAT 204N instrument while a Vickers hardness tester was use to study the hardness of the composites. The result shows that the hardness of the hybrid composites were relatively stable and preserve their microstructural integrity when exposed to repeated heating and cooling cycles and as such has a relatively good softening resistance. Furthermore, it was observed that Al 6063 reinforced with RHA and SiC exhibited varied levels of corrosion resistance in both 3.5 wt. % of NaCl and 0.3M of H2SO4 media as thermal cycle’s increases. It was noted that the hybrid reinforced composite had more resistance to corrosion than the unreinforced aluminium and single reinforced composite in 3.5 wt. % of NaCl solution. Also, the samples subjected to 18 cycles had the highest susceptibility to corrosion in the same 3.5wt % NaCl solution. However, in 0.3M H2SO4 solution, the composites displayed varied resistance to corrosion and it was noted that the composite with higher percentage of RHA content exhibited superior resistance to corrosion and samples subjected to 6 and 12 cycles exhibited a relatively low susceptibility to corrosion.