Thermophysical Properties of High-Frequency Induction Heat Sintered Graphene Nanoplatelets/Alumina Ceramic Functional Na
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Thermophysical Properties of High-Frequency Induction Heat Sintered Graphene Nanoplatelets/Alumina Ceramic Functional Nanocomposites Iftikhar Ahmad, Tayyab Subhani, Nannan Wang, and Yanqiu Zhu (Submitted December 6, 2017; in revised form March 27, 2018) This paper concerns the thermophysical properties of high-frequency induction heat (HFIH) sintered alumina ceramic nanocomposites containing various graphene nanoplatelets (GNP) concentrations. The GNP/alumina nanocomposites demonstrated high densities, fine-grained microstructures, highest fracture toughness and hardness values of 5.7 MPa m1/2 and 18.4 GPa, which found 72 and 8%, superior to the benchmarked monolithic alumina, respectively. We determine the role of GNP in tuning the microstructure and inducing toughening mechanisms in the nanocomposites. The sintered monolithic alumina exhibited thermal conductivity value of 24.8 W/mK; however, steady drops of 2, 15 and 19% were recorded after adding respective GNP contents of 0.25, 0.5 and 1.0 wt.% in the nanocomposites. In addition, a dwindling trend in thermal conductions with increasing temperatures was recorded for all sintered samples. Simulation of experimental results with proven theoretical thermal models showed the dominant role of GNP dispersions, microstructural porosity, elastic modulus and grain size in controlling the thermal transport properties of the GNP/alumina nanocomposites. Thermogravimetric analysis showed that the nanocomposite with up to 0.5 mass% of GNP is thermally stable at the temperatures greater than 875 °C. The GNP/ alumina nanocomposites owning a distinctive combination of mechanical and thermal properties are promising contenders for the specific components of the aerospace engine and electronic devices having contact with elevated temperatures. Keywords
ceramics, interfaces, microstructure, nanocomposites, sintering, thermal analysis
1. Introduction Development of thermally stable functional ceramics with excellent thermal management is imperative for the specific components of numerous advanced devices, working at elevated temperatures, such as aeroengine components, insulation for rocket electronics assemblies and missile nozzle parts (Ref 1). It is unfortunate that the monolithic ceramics like alumina, silicon nitride and several others carry insufficient thermophysical properties, therefore unsuitable for aforesaid components (Ref 2). In recent years, carbon-based nanostructures in diverse morphologies are considered for tuning the thermal properties of monolithic alumina (Ref 3). Most of the CNT/alumina nanocomposite investigated for thermal conductivity recorded a liner drop as a function of CNT increments with the exception of Kumari et al. report, who claimed better thermal properties despite the issues of poor sinterability and high porosity in the CNT/alumina nanocomposites (Ref 4). 2D graphene nanoma-
Iftikhar Ahmad, Center of Excellence for Research in Engineering Materials, King Saud University, P.O. Box 800, Riyadh 11421, Kingdom o
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