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Volume 6 Research & Reviews: Journal of Material Sciences
ISSN: 2321-6212 Advanced Materials 2018
September 04-06, 2018
September 04-06, 2018 | Zürich, Switzerland
21st International Conference on
Advanced Materials & Nanotechnology
Boron carbide-based ceramics for thermostructural application: Sintering by SPS and mechanical
performances
Alexandre Maître, G Antou, N Pradeilles and R Belon
University of Limoges, France
Boron carbide is a promising ceramic in the armor field and in nuclear reactors due to its low weight, its high hardness
and its high capacity to absorb neutrons. These excellent properties result from unusual characteristics of B-B and B-C
chemical bond. In the literature, there is a general agreement about the existence of solid solubility of carbon with the stable
phase BxC and a large range extending from 8 to 20 at.% C. So, the mechanical properties of boron carbide monoliths
depend on their chemical composition (i.e. carbide stoichiometry, presence of secondary phases such as free carbon) and
on microstructural characteristics (i.e. porosity level, grain size). In the present work, fully-dense boron carbide monoliths
exhibiting fine microstructure (i.e. submicrometric grain size) are shaped and sintered by spark plasma sintering. Two
different commercial powder batches, exhibiting different stoichiometries and various amounts of secondary phases are used.
Their chemical composition is well-defined by coupling different methods (TEM, XRD, IGA) and are correlated with their
mechanical properties, characterized frommeso- to macro-scopic scales by nano-indentation and ultrasonic pulse echography.
The presence of secondary phases (graphite and boric acid) is noticed in various proportions in each powder batch. Their effect
on the mechanical features of the corresponding boron carbide-based ceramics has been investigated. So, if the boric acid
disappears during the sintering step, the graphite remains. However, for the considered amounts of graphite (lower than 1
wt.%), the low variation in graphite content have no significant effect on hardness and elasticity. At the opposite, the presence
of oxygen in solid solution, leading to a boron oxycarbide phase, induces a decrease of both hardness and elasticity.
Figure 1: TEM observation of a particle of boron carbide (batch HD) exhibiting free carbon under the graphite form (indicated by the white arrows)
and an amorphous layer (black arrows).
Recent Publications:
1. Aselage TL, Tissot RG. Lattice Constants of Boron Carbides. J. Am. Ceram. Soc. 1992;75:2207–2212.
2. Niihara K, Nakahira A, Hirai T. The Effect of Stoichiometry on Mechanical Properties of Boron Carbide. J. Am.
Ceram. Soc. 1984;67;C-13.
3. Belon R, Antou G, Pradeilles N, Maître A . Mechanical behaviour at high temperature of spark plasma sintered boron
carbide ceramics. Ceram. Int. 2017:43:6631–6635 (2017).
4. Moshtaghioun BM, Gómez-García D ,Domínguez-Rodríguez A et al. Enhancing the spark-plasma sinterability of
B4C nanopowders via room-temperature methylation induced purification. J. Eur. Ceram. Soc. 2016;36:2843–2848.
5. SairamK, Sonber JK, Murthy TS et al. Influence of spark plasma sintering parameters on densification and mechanical
properties of boron carbide. Int. J. Refract. Met. Hard Mater. 2014;42:185–192.
Alexandre Maître et al., Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C3-020