DEVELOPMENT OF COMPOSITE USING ALUMINIUM, CERAMIC AND INDUSTRIAL WASTE

Abstract

Aluminium matrix composites (AMCs) have been the subject of a lot of scholarly interest as a lightweight structural material for aerospace and advanced engineering applications, mainly because of their high strength-to-weight ratio, wear resistance and high thermal stability. Among aluminium alloys, AA2024 is generally used in aerospace structures due to its outstanding specific strength and fatigue strength. In spite of this, its relatively low level of hardness and tribological performance restricts its range of applications to highly abrasive environments. Accordingly, the present study attempts to develop and characterize a hybrid aluminium matrix composite based on AA2024 reinforced with titanium diboride (TiB2), waste glass powder (WGP) and nano-copper oxide (Nano-CuO) particles. The main aim of this study is to developed AA2024-based hybrid composites using stir casting method and systematically understand the mechanical, tribological, microstructural and thermal characteristics of the composites using both experimental and computational methods. Composite samples were generated in 8 different formulations by varying amounts of TiB2 substitution of waste glass powder and keeping the nano-CuO as the reinforcement same at 0.25 wt.%. Mechanical characterization revealed a considerable improvement in strength and hardness with the addition of hybrid reinforcements. The optimum composition consisting of 5 wt.% TiB₂, 2.5 wt.% WGP, and 0.25 wt.% nano-CuO exhibited the highest ultimate tensile strength of 580.37 MPa and yield strength of 431.39 MPa compared with 495 MPa and 375 MPa for the base alloy. Similarly, flexural strength increased from 640 MPa to vi 803.37 MPa, while hardness improved from 137 HV to approximately 170 HV. However, a gradual reduction in ductility from 14% to 6% and a slight decrease in impact energy from 2.09 J to 1.91 J were observed, indicating a typical strength–toughness trade-off associated with ceramic particle reinforcement. Microstructural analysis using scanning electron microscopy and energy dispersive spectroscopy confirmed fairly particle distribution, grain refinement, and good interfacial bonding between the matrix and reinforcements. Fractographic studies found a mixed ductile-brittle type failure. Subsequent true stress-strain examinations supported the fact that the hybrid composites possess enhanced strain-hardening behaviour. Finite-element simulations based on the constitutive model of Hollomon showed good agreement with experimental data with the predictive discrepancy limited to 4%-5% thus verifying the reliability of the computational model. The tribological performance of the composites was investigated by assessing the influence of reinforcement content and process parameters, such as normal load, sliding velocity and sliding distance on the wear phenomenon. An optimization study using the Taguchi L16 orthogonal array showed high improvements in wear resistance and hardness due to the synergy of TiB2, WGP and nano-CuO addition. The minimum coefficient of friction obtained was 0.262 while the optimised wear rate, as checked by confirmatory tests, was 4.133 x10-3 g/m. Thermal expansion measurements also showed an increase in dimensional stability with the coefficient of thermal expansion reduced from 23.4 x 10-6 K-1 for the unreinforced alloy to around 21.8 to 22.4 x 10-6 K-1 in the reinforced composites. Overall, the fabricated hybrid AA2024 composites displayed enhanced mechanical strength, superior wear resistance and increased thermal stability which reveals their promising applicability to the advanced aerospace and high-performance engineering environment.