Enhancement of Tensile Strength of Coconut Shell Ash Reinforced Al-Si Alloys: A Novel Approach to Optimise Composition and Process Parameters Simultaneously

The research presents a novel approach to develop high-strength functionally graded composite materials (FGCMs) by using recycled coconut shell ash (CSA) particles as reinforcement for a hypereutectic Al-Si alloy matrix. Using a centrifugal casting technique, test specimens are prepared for the study under ASTM standards. The optimal combination of materials to maximise the materials’ overall tensile strength is obtained through the mixture methodology approach. The results show that CSA particles in the matrix material increase the tensile strength of the produced material. Process parameters, melting temperature and rotating speed were found to play a pivotal role in determining the tensile strength. A better tensile strength of the material is obtained when Al-Si = 90.5 wt%, CSA = 9.5 wt%, rotating speed = 800 RPM, and melting temperature = 800 °C; the proposed regression model developed has substantial predictability for tensile strength. This work presents a methodology for enhancing the tensile strength of FGCMs by optimising both the material composition and processing parameters. The achieved tensile strength of 197.4 MPa, at 800 RPM and 800 °C, for a concentration of 7.5 wt% CSA particles, makes these FGCMs suitable for use in multiple engineering sectors.