Comparative Analysis of Mechanical Properties in Aluminum Casts Using Synthetic and Natural Moulding Sands

This study was carried out to investigate the effect of synthetic and natural moulding sand on aluminum cast. In pursuit of the overall aim of this study, a sand characterization test which entails the determination of moisture content, permeability, porosity and sieve analysis of the sand were done on the synthetic and natural moulding sand. The results of the moisture content test show that moisture absorption is higher in natuaral sand (37.25%) when compared to synthetic sand (27.17%); the result of the permeability test reveals that the gas emission rate is higher for natural sand (7.63ml/min) when compared to synthetic sand (6.17ml/min); the result of the porosity reveals that the pore spaces for natural sand (44.4%) is higher when compared to synthetic sand (42.8%); the result of the sieve analysis reveals that the grain fineness number of synthetic sand was found to be (28.5) when compared to natural sand value of (39.18). This contributes to the surface quality of the aluminum alloy. In furtherance of the investigation, a number of mechanical tests were carried on the aluminium cast samples obtained from synthetic and natural sand moulding respectively. The hardness test result reveal that aluminium cast from natural sand (77.35HRC) show a better hardness quality when compared to synthetic sand (73.35HRC); the compression test result show that the aluminium cast from synthetic sand fracture at a value 23.30mm, while that of natural sand cast sample fracture at a value 0.61mm under the same apply load; tensile test results reveals that aluminium cast from natural sand had a higher tensile strength at maximum load of (27.8KN) at breaking point, when compare to the aluminium cast of synthetic sand having a maximum load of (18.7KN) at breaking point. Finally, a microstructural test was carried out and the results of the optical image obtained show that aluminium cast from synthetic sand had better surface layer when compared with that of natural sand aluminium cast on the basis of a closely packed structure with less dark pores. Arising from these study, it can be deduced that aluminium cast from natural sand is suitable for applications where hardness and tensile strength are important, while aluminium from synthetic sand is suitable for applications where compression properties are crucial.