resumo
The paper describes the fabrication by liquid-phase spark plasma sintering (SPS) of composites of dense silicon carbide (SiC) with up to 20 vol.% graphene nanoplatelets (GNPs), and discusses the relationships between composition, microstructure and electrical conductivity. The structural integrity of the GNPs is preserved during the whole process, as observed by Raman spectroscopy. The effects of the applied pressure (50 MPa) during SPS result in the preferential orientation of the GNPs perpendicular to the pressing axis and anisotropic electrical behaviour. The electrical conductivity measured in the direction perpendicular to the SPS pressing axis is 4 to 6 times higher than the parallel counterpart. The conductivity increases up to three orders of magnitude with increasing GNPs fraction, reaching values of 4380 S m(-1) at room temperature for materials with 20 vol.% GNPs. The conduction mechanism of the composite is analysed as a function of the GNPs content. (C) 2015 Elsevier Ltd. All rights reserved.
palavras-chave
IMPEDANCE SPECTROSCOPY; RAMAN-SPECTROSCOPY; THERMAL-EXPANSION; BAND-STRUCTURE; SIC POLYTYPES; RESISTIVITY; COMPOSITES; PHASE; GRAPHITE; NANOCOMPOSITES
categoria
Materials Science
autores
Roman-Manso, B; Domingues, E; Figueiredo, FM; Belmonte, M; Miranzo, P
nossos autores
Eddy Michael Pedro Domingues
Bolseiro de pós-Doutoramento
Filipe Miguel H Lebre R Figueiredo
Investigador Principalagradecimentos
This work was supported by the Spanish Government under the project MAT2012-32944, and by the Portuguese Foundation for Science and Technology (FCT) through projects CICECO-FCOMP-01-0124-FEDER-037271 (Ref. FCT PEst-C/CTM/LA0011/2013) and Investigador FCT 2013 contract number IF/01174/2013. B. Roman-Manso wants to acknowledge the financial support given by the JECS Trust of the European Ceramic Society through grant N.201353 to perform the electrical measurements at the Univ. of Aveiro, Portugal.