Spark plasma sintering of textured GNPs reinforced advanced ceramic matrices

Reference	Presenter	Authors (Institution)	Abstract
14-054	Jacques RENNOTTE	RENNOTTE, J.(Belgian Ceramic Research Center); BISTER, G.(Belgian Ceramic Research Center); ERAUW, J.(Belgian Ceramic Research Center); DUPONT, V.(Belgian Ceramic Research Center); LARDOT, V.(Belgian Ceramic Research Center); CAMBIER, F.J.(Belgian Ceramic Research Center);	Over the last couple of years, graphene nano-platelets (GNPs) have been considered as an attractive reinforcement for advanced ceramics. Indeed, compared to carbon nanotubes, GNPs present advantages in terms of processability while enabling comparable improvement of the material mechanical behaviour, as well as, depending the case, of selected functional transport properties (e.g. electrical or thermal conductivity). The present study reports on the processing and performances of GNPs reinforced alumina based and ZrB2 based ceramic matrices. In both systems, the effect of the GNPs content, varied in the range 0.1 - 2.0 wt% on both the densification behaviour and microstructural development has been determined. The influence on the resulting properties of the extent of the preferential orientation of the GNPs within the matrix has been assessed as well. This degree of orientation was tailored by the specific conditioning approach of the GNPs/powder mixture and shaping method used to pre-form the compact prior its densification. Concurrently, care was taken to achieve optimum dispersion of the nano-fillers within the matrices. The densification has been performed by Spark Plasma Sintering, the high heating rates, lower maximum temperature and reduced holding times being favourable to guarantee the integrity of the carbon-based nano-fillers. For each composition studied, the experimental conditions leading to the achievement of near full density compacts have been assessed. The evolution of mechanical properties like the hardness, elastic modulus and fracture toughness in function of the GNPs content and their dependence on the orientation extent of the reinforcing phase will be discussed. The evaluation of the electrical conductivity and of its anisotropy by impedance spectroscopy and four-point probe method will be reported.
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