Development and fabrication of functionally graded aluminium metal matrix composite for automobile component applications.
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Date
2021
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Abstract
In recent times, interest in aluminium matrix composites (AMCs) have garnered traction over conventional aluminium alloys as the material of choice in the manufacturing of components for various engineering applications. Engineering components developed from single-element material are increasingly less favored over materials engineered from two or more elements. The rise in the demand for a multifunctional engineering material to exhibit opposing yet complementary engineering properties at different spatial positions within the material due to functionality requirements, has birthed several innovative fabrication processes.
This study focuses on the development and fabrication of functionally graded aluminiummetal matrix composite (FGAMMC) through the liquid metallurgy route for proposed automobile component production. Industrially produced A356 aluminium alloy and silicon carbide powders (Al-SiC) was adopted as the base matrix and reinforcement materials for the fabrication of the metal matrix composites. Centrifugal casting technique was used to fabricate seven samples of Al-SiC functionally graded aluminium metal matrix composites with varied reinforcements particle size and weight percent addition. Samples A, B, and C contained 1 wt.%, 3 wt.%, and 5 wt.% of SiC of size 7 μm reinforcement, respectively, while samples E, F, and G had 1 wt.%, 3 wt.%, and 5 wt.% of SiC of size 15 μm reinforcement respectively. Sample D with no reinforcement additions served as the control sample for the experiment.
Microstructural characterization showing the elemental composition and reinforcement distribution of silicon carbide particles within the matrix of the cast composite was carried out using optical microscopy (OM), optical emission spectroscopy (OES), energy dispersion xray (EDX), and scanning electron microscopy (SEM). The influence of SiCp on the mechanical, wear behavior and thermal properties of the cast aluminium composites were determined by subjecting the cast samples to mechanical, tribological, and thermal tests. Sample C with 5 wt.% and 7 μm of SiC particle reinforcement recorded improved hardness,compressive strength, Young's modulus, shear strength, and shear modulus of 112.7 HV0 1, 3107 MPa, 6.39 GPa, 14.4 GPa, and 9.29 GPa, respectively. Tribological analysis show an increase in the cast composites' wear resistance and frictional coefficient proportional to the frequency of contact between the counterface ball of the tribometer and the dispersed SiC reinforcements in the composites' matrices. Thermogravimetric analysis showed the weight loss and heat flow rates exhibited by the cast samples as the temperature was increased from 25 °C to 1000 °C in an Argon environment. Although negligible weight loss was recorded for all the cast composites within the experimental temperature boundary, sample C with 7 𝜇m
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Doctoral Degree. University of KwaZulu-Natal, Durban.