A Study on the Corrosion and Mechanical Properties of an Al6063 Reinforced With Egg Shell Ash and Rice Husk Ash

Aluminium based metal matrix composites (MMCs) have received considerable attention in the last decade for its potential industrial applications. One of the challenges encountered using Aluminium based MMCs is understanding the influence of the reinforcement particles on the corrosion resistance and mechanical properties. In this study the corrosion behaviour and mechanical properties of Al6063 reinforced with egg shell ash and rice husk ash were investigated. Waste Egg Shell Ash (ESA) and Rice Husk Ash (RHA) 212 μm in size were used to produce the composites with 10 wt% of reinforcements via stir casting technique. The RHA and ESA were added in the ratios of 10:0, 7.5:2.5, 5:5, 2.5:7.5, 0:10. Unreinforced Al6063 was used as baseline material. Immersion tests, potentiodynamic polarization techniques, tensile tests, optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the composites. The results showed that reinforcing with 7.5 wt% RHA + 2.5 wt% ESA provided the highest resistance to corrosion. Generally, a reduction in the corrosion rates were observed for the reinforced composites as the wt% of RHA increased. Porosity levels of the composites reduced with an increase in the percentage of ESA in the matrix. Microstructural characterization using SEM and OM revealed a distribution of pits on the composite surfaces which was more severe with increasing RHA percentage. The UTS (ultimate tensile stress) results revealed that the composite containing 10 wt% RHA had the maximum value of 161 MPa. The results demonstrate that rice husk ash and eggshell ash can be useful in producing low cost Aluminium composites with improved corrosion resistance and tensile properties.