Valorization of Coal Ash Waste in AA6061-graphene Nanocomposites Towards Environmental Sustainability
J. Environ. Nanotechnol., Volume 15, No 1 (March 2026) pp. 435-444
Abstract
AA6061-fly ash (FA)-graphene nanoplatelet (GNP) hybrid nanocomposites (HNCs) were stir cast using 2 wt.% GNP and 3-15 wt.% FA. Adding leftover FA as strengthening promotes sustainability and value. Density study showed that increasing FA reduced theoretical and experimental densities and increased porosity. The sample HNC4 (12 wt.% FA+2 wt.% GNP) had 13.372% (estimated) and 15.712% (experimental) density, lower than as-cast AA6061, but 71.193% higher porosity. Mechanical assessment demonstrated maximal strengthening for HNC4, with universal tensile strength (UTS), flexural strength, and micro-hardness improving 32.464%, 25.581%, and 32.609%, respectively. Ductility and impact strength reduced by 94.525% and 21.795%, demonstrating the strength-toughness balance. The insulating properties and contact phonon scattering of FA reduced thermal conductivity by 24.944%. Due to enhanced hardness and GNP-rich tribo-film development, moderate reinforcement levels lowered wear loss (WL) and coefficient of friction (CoF). The sample HNC5 (15 wt.% FA+2 wt.% GNP) showed marginal deterioration beyond the optimal composition (density decreased by 3.382%, porosity rose by 14.593%). For HNC5, UTS, flexural strength, and impact strength diminished by 2.837%, 1.713%, and 5.405%, while hardness elevated slightly (3.158%). There was 7.692% and 7.317% increase in WL and CoF, indicating reinforcement saturation, particle consolidation, and tribo-film destabilization. The sample HNC4 exhibited the best lightweight-mechanical performance ratio.
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Reference
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