Intercritical Heat Treatment Assessment on the Mechanical, Thermal, Tribological and Corrosion Behaviour of MWCNT/Snail Shell Ash Reinforced A6061 Aluminium Alloy Nanocomposites

There has been increased interest in aluminium matrix nanocomposites due to their excellent strength-to-weight ratios, outstanding wear resistance and high levels of thermal stability compared with traditional alloys. This research examines how mechanical, thermal, tribological and corrosion properties of hybrid aluminium matrix composites containing multi-walled carbon nanotubes (MWCNTs) and snail shell ash (SNSA) were impacted by variable Intercritical heat treatment methods. Hybrid composites were fabricated via stir casting at 2 wt% MWCNTs and 2 wt% SNSA in an A6061 aluminium matrix. The composite samples underwent heat treatment through a sequence of solution sing at 540°C, followed by quenching in one of three media (distilled water; oil; or ice), and then through artificial aging at 160°C for eight hours. The mechanical characterisation of the composites was assessed using hardness, tensile, compressive and impact tests, while techniques to measure wear behaviour included a pin-on-disc tribometer. Thermogravimetric analysis (TGA) was used to assess thermal stability, whereas a gravimetric study in H₂SO₄ and NaCl environments was performed to evaluate direct corrosion behaviour. Overall, heat treatment was shown to have a significant effect on the performance of the composite samples. The highest hardness was observed in the ice-quenched samples (987.25 MPa); the highest compressive and impact strength was seen in the water-quenched samples (580 MPa and 20.0 MPa, respectively); while the oil-quenched samples had the greatest thermal conductivity (296.76 W/mK). The microstructural analysis following heat treatment revealed that all samples yielded grains of refined size, and the dispersion of the reinforcements was improved. The corrosion results indicate that the corrosion resistance was also improved; however, it was dependent on the conditions surrounding quenching as well as the corrosive environment. Overall, hybrid nanocomposites developed in this study have demonstrated significant potential for use in high-performance applications including automotive components and thermal management systems.