EFFECT OF SiO2 SURFACE OXIDATION COATING OF SILICON CARBIDE PARTICLES REINFORCEMENT ON THE MECHANICAL PROPERTIES OF Al-2.5%Mg/xSiCp DEVELOPED BY STIR CASTING METHOD

The literature revealed that composites developed through stir casting process suffer some limitations such as low wettability and insufficient bonding between the molten Al and SiCp and the formation of aluminium carbide (Al4C3) at the interface which degrades the mechanical performances of the composites. To overcome these challenges, this study used magnesium for improved wettability, heat treatment of reinforcement particles (SiCp) and application of metallic (SiO2) coating on the SiCp before adding to melt for improving Al-SiCp wettability in the manufacture of Al-2.5%Mg/xSiCp composites. The SiCp coating reduces direct interaction and promotes wetting between SiCp and molten Al to develop Al-2.5%Mg/xSiCp composites. The percentage weight of SiCp varied from 5 wt% to 20 wt% (uncoated and coated) at 5 % intervals. The mechanical properties tests were conducted to examine the effects of coating and variation of volume percentage of SiCp on the composites developed. The results obtained showed that the reinforced alloy with both uncoated and coated SiCp performed favorably well compared to the control sample with 0% SiCp. The improvement of interfacial strength was observed in the composites developed with coated SiCp as the coating of SiCp enhanced its diffusion with Al-2.5%Mg.