Optimization of Stir Casting Process Parameters for Fabrication of A6082-SNSA/MWCNT Hybrid Composites: Taguchi Approach

This research investigates the influence of four stir different casting parameters— weight percentage Shea nut shell ash (SNSA), weight percentage Multi-walled carbon nanotubes (MWCNT), stirring speed (SS), and stirring time (ST) on the density (D), hardness (H), compressive strength (C.S), coefficient of friction (CoF), and specific wear rate (SWR) of developed A6082-SNSA/MWCNT hybrid composites. Taguchi L9 orthogonal array design and grey relational analysis (GRA) were employed for multi-objective optimization, with the aim to minimize D and SWR while maximizing H, C.S, and CoF. X-ray fluorescence (XRF) analysis confirmed that SNSA is rich in reinforcing oxides such as SiO₂, Al₂O₃, and Fe₂O₃, while X-ray diffraction (XRD) analysis revealed strong crystalline peaks of SiO₂ and supporting phases, validates the suitability of SNSA as a reinforcement material. Optimal processing parameters of 4 wt% SNSA, 3 wt% MWCNT, 450 rpm stirring speed, and 4.5 minutes stirring time were determined. ANOVA results revealed that MWCNT content and stirring time as the most statistically significant factors affecting composite properties (p < 0.05). Scanning Electron Microscopy (SEM) of the optimized composite showed uniform distribution of reinforcement particles with some process-induced defects such as cracks, voids, and agglomerations. XRD analysis also suggested the formation of interfacial Niobocarbide (NbCO) phases, while the detection of MWCNTs was limited, potentially due to their low concentration or XRD machine limitations. These findings demonstrate the viability of using SNSA and MWCNTs in the optimization of A6082-based hybrid composites for enhanced mechanical and tribological performance.