Optimization of fabrication process parameters of stir-cast Rice Husk Ash (RHA) and Alumina (Al2O3) reinforced Aluminium – Silicon hybrid composite

Abstract

Materials research and development have shifted from monolithic materials to composite materials owing to the
benefits of composites such as reduced weight, low cost, high performance, economic and environmental
sustainability especially in the automotive industry. Agricultural waste derivatives have shown great potential of
been utilized as complimentary reinforcements in the development of metal matrix composites. The present study
is aimed at optimizing the fabrication process parameters particle size (S) of RHA and weight percent(wt%) of
RHA as a complimentary reinforcement. Two sets of nine Aluminium-Silicon reinforced RHA/AL2O3 hybrid
composites were fabricated using two-step stir casting technique. Mean particle size and weight percent of the
reinforcement were varied according to Taguchi L9 Design of Experiment (DOE). One set of the cast composite
were then solution heat treated by heating to 530oC for 2hrs quenching in water at 60oC and age hardened at
175oCfor 4hrs. Mechanical properties were determined for both heat treated and non-heat-treated composites.
Regression models were developed for mechanical properties of the heat-treated composites. The fabrication
process parameters - mean particle size of RHA (s) and weight percent of RHA (wt.%) were then optimized using
Taguchi method using Minitab 18 Software for the multiple performance of mechanical properties of the heattreated composites. Multiple performance optimization showed the most dominant factor levels are level 3 for
ultimate tensile strength (UTS) and hardness (HRB), while for wear rate (WR) dominant factor level was level 1.
ANOVA results at 95% confidence level showed that mean particle size(s) of RHA had a highest contribution
(61.13% in UTS, 83.70% in HRB and 78.17% in WR). The results of this optimization have shown that particle
size of RHA and weight percent of RHA have significant effect on the ultimate tensile stress UTS, hardness HRB
and wear rate WR of the hybrid composite.