Browsing by Author "Kar, Subrat"

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    Graphene-incorporated aluminum with enhanced thermal and mechanical properties for solar heat collectors
    (American Institute of Physics, 2020) Pradhan, Sunil Kumar; Sahoo, Mihir Ranjan; Ratha, Satyajit; Polai, Balaram; Mitra, Arijit; Sathpathy, Bijoy; Sahu, Arun; Kar, Subrat; Satyam, Parlapalli V.; Ajayan, Pulickel M.; Nayak, Saroj Kumar
    A simple yet innovative approach has been made through a powder metallurgy route for the synthesis of aluminum–graphene (Al–Gr) composite materials for commercially viable solar thermal collectors. The Al–Gr composite (with 1 wt. % of graphene filler content) recorded an enhanced thermal conductivity of ∼280 W/mK, which is higher than that of pristine Al (∼124 W/mK), at room temperature. It has also been found that the prepared composite has a lower coefficient of thermal expansion. The structures and morphologies of the composites have been investigated in detail with the help of X-ray diffraction technique, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, etc. Furthermore, the density measurements showed that the composites retain ∼97.5% of the density of pristine aluminum even after the sintering treatment. X-ray micro-computed tomography revealed the structural integrity and non-porous nature of the samples, free from any defects and deformations. The thermal fusing of Al-based composite materials at 630 °C is found to be satisfactory with the required strength, and the composites showed at least ∼125% increase in the thermal conductivity than that of pristine Al. These results suggest that the Al–Gr composites can be deployed as solar thermal collectors and heat sink materials for thermal dissipation.
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    Large enhancement of thermal conductivity of aluminum-reduced graphene oxide composites prepared by a single-step method
    (Oxford University Press, 2023) Mitra, Arijit; Sahoo, Mihir Ranjan; Samal, Aiswarya; Pradhan, Sunil Kumar; Polai, Balaram; Sahoo, Krishna Rani; Kar, Subrat; Satpathy, Bijoy Kumar; Narayanan, Tharangattu N; Ajayan, Pulickel M; Satyam, Parlapalli V; Nayak, Saroj K
    Metal matrix composites have attracted extensive attention from both the research and industrial perspective. In this study, we prepared aluminum-reduced graphene oxide (Al–rGO) composites with enhanced thermal conductivity in an easy single-step process. Pristine Al shows a thermal conductivity of 175 Wm−1K−1 (standard deviation <5%), which increases to 293 Wm−1K−1 for an Al–rGO composite with 1% rGO. Analysis of theoretical models shows that a higher percentage of rGO inside the Al matrix creates a continuous network resulting in more available phase space through which heat carrier phonons travel with less scattering, and hence thermal conductivity of the composite increases. Furthermore, Al–rGO composites show an ∼5% increase in microhardness compared with pristine Al. The electrical resistivity of the composite is comparable to that of pristine Al for a narrow weight percentage of rGO, whereas a 70% enhancement in the thermal conductivity of the composite is observed for the same weight percentage range, suggesting possibilities for exploiting both high electrical and thermal conductivities for various applications.