Mechanical, and corrosive properties of AA7075 aluminium reinforced with rice husk ash particulates

Abstract

The mechanical and corrosive properties of AA7075 alloy reinforced with rice husk ash (RHA) particles were studied. AA7075 matrix composite reinforced with varying percentage weight compositions of rice husk ash particles (5%, 10%, 15% and 20% wt) were prepared using stir casting technique. The mechanical, and corrosive properties of the new material were compared with that of the matrix alloy. The mechanical properties were also improved due to the automated stirring action employed during the casting process. AA7075-RHA composites had improved mechanical properties compared to the base matrix (AA7075). In terms of tensile strength there was an increase in this mechanical property with an increase in weight fraction of RHA particle (51% at 10% RHA), hardness (25.67% at 20% RHA), while for impact resistance, the reverse was the case as there was a 10.98% decrease in the resistance of the composite as the reinforcement fraction increased from 0%–20% RHA. The progressive decreases in the impact strength of the reinforced composite were probably due to agglomeration and non-homogeneity at higher reinforcements values. Corrosion experiments carried out showed improved properties in the reinforced composite compared to the unreinforced alloy, the corrosive properties improved with an increase in weight fraction of RHA in terms of weight loss (20.63% at 10% RHA), potentio-dynamic polarization (30.7% at 10% RHA) and open circuit potential (1.60% at 20%RH). The developed composite may be suitably applied in high-speed rotating shafts and automotive engineered brake parts.

Keywords

• aluminium
• rice husk ash
• composite
• reinforcement
• metal matrix