Optimization of Stir Casting Process Parameters to Improve the Hardness Property of Al/RHA Matrix Composites

The development of inexpensive materials reinforced metal matrix composites has become an important area of research interest in Material Science and its growing rapidly in various engineering fields. Therefore, the need for optimization becomes necessary in developing a composite material when different process parameters are to be used simultaneously. This is an efficient method to design a metal matrix composite with reliable and predictable mechanical properties which will be highly beneficial to the manufacturing industry. The application of trial and error method for the design of process parameters is found to be highly costly, time consuming and difficult to achieve desired products with optimum properties. In this study, composites of aluminium alloy reinforced with locally available inexpensive rice husk ash (RHA) was developed by stir casting method. In the manufacturing of the composites of Al/RHA, a three factor historical data (HD) model was used to design the experiment. The factors considered are weight fraction (5%, 10% and 15%), particle size (150 µm, 300 µm and 600 µm) and stirring time (10 mins, 20 mins and 30 mins) at stirring speed of 140 rpm, while hardness is the major response. Response surface methodology was used in this study to investigate the effect of the casting parameters for the performance of the Al/RHA composites. The Vickers hardness test was performed on the composite specimens. The hardness test revealed that the particle size, weight fraction and stirring time have their effect on the hardness of the composite. Highest hardness was obtained at 150 µm particle size, 15% weight fraction and stirring time of 30 mins. This study attempts to establish the trend between processing parameters with hardness of composite.