Fabrication of spectrally selective solar power absorber material via powder metallurgy process / Mohd Zakuan Zabri

Mohd Zakuan , Zabri (2019) Fabrication of spectrally selective solar power absorber material via powder metallurgy process / Mohd Zakuan Zabri. Masters thesis, University Malaya.

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Abstract

In recent years, studies on the effects of nanofiller materials addition in metal matrix composites have been progressing in order to develop new materials for various applications. In this research work, aluminum-based composites reinforced with carbon nanofillers, i.e., multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) that are distributed in the matrix of aluminum (Al) nanocomposites have been investigated to determine the optical properties, i.e., spectral selectivity behavior of Al nanocomposite materials. Over the years, most of the researchers have been investigating the effects of nanofillers on thermal, electrical, and mechanical properties of metal-based composites. However, none of the studies concentrated on the optical properties of Al nanocomposites, especially with MWCNTs and GNPs. Thus, the focus of this research is more toward the effects of both MWCNT and GNP nanofillers on the optical properties of Al nanocomposites. Al matrix composites were filled with different compositions of nanofillers, i.e., functionalized and pristine carbon nanofillers (5 to 15 wt. %) and fabricated using powder metallurgy (PM) process. Samples morphology, optical, and microhardness properties were measured for different compositions of Al-MWCNT-GNP nanocomposites. Dispersion of carbon nanofillers and spectral selectivity behavior of Al nanocomposites were enhanced with the addition of functionalized nanofillers (MWCNTCOOH-GNPCOOH). X-ray diffraction (XRD) analysis confirmed the existence of functionalized and pristine MWCNT-GNP nanofillers without the presence of aluminum carbide (Al4C3). Micro-Vickers hardness values of Al nanocomposites added with MWCNTCOOH-GNPCOOH were higher compared to the samples added with MWCNT-GNP/MWCNT/GNP. Light absorption was enhanced in the ultraviolet-visible-near-infrared (UV-Vis-NIR) region (from 200 to 2,500 nm) whereas reflectance was improved in the near-infrared-far-infrared (NIR-FIR) region (from 3,000 to 14,000 nm) with the addition of MWCNTCOOH-GNPCOOH nanofillers. The highest selectivity ratio obtained was 14.60 for Al nanocomposites with the addition of 2.5 wt. % MWCNTCOOH and 2.5 wt. % GNPCOOH.

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