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

Abstract

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 SiC_p and the formation of aluminium carbide (Al₄C₃) at the interface which degrades mechanical performances of the composites. To overcome these challenges, this study used magnesium for improved wettability, heat treatment of reinforcement particles (SiC_p) and application of metallic (SiO₂) coating on the SiC_p before addition to melt to improve Al-SiC_p wettability in the manufacture of Al-2.5%Mg/xSiC_p composites. The SiC_p coating reduce direct interaction and promote wetting between SiC_p and molten Al to developed Al-2.5%Mg/xSiC_p composites. The percentage weight of SiC_p varied from 5 wt% to 20 wt% (uncoated and coated) at 5 % intervals. The mechanical properties tests were conducted to examined the effects of coating and variation of volume percentage of SiC_p on the composites developed. The results obtained showed that the reinforced alloy with both uncoated and coated SiC_p performed favorably well compared to the control sample with 0% SiC_p. The improvement of interfacial strength was observed in the composites developed with coated SiC_p as the coating of SiC_p enhanced its diffusion with Al-2.5%Mg.