Science of Sintering 2015 Volume 47, Issue 3, Pages: 237-248
https://doi.org/10.2298/SOS1503237D
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Nickel-graphite composites of variable architecture by graphitization-accompanied spark plasma sintering and hot pressing and their response to phase separation
Dudina D.V. (Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia + Novosibirsk State University, Novosibirsk, Russia)
Ukhina A.V. (Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia)
Bokhonov B.B. (Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia + Novosibirsk State University, Novosibirsk, Russia)
Mali V.I. (Lavrentiev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia)
Anisimov A.G. (Lavrentiev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia)
Bulina N.V. (Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia)
Skovorodin I.N. (Institute of Automation and Electrometry SB RAS, Novosibirsk, Russia)
We report the formation and phase separation response of nickel-graphite
composites with variable-architecture phases by graphitization-accompanied
consolidation via Spark Plasma Sintering and hot pressing. It was shown that
the application of pressure during consolidation is crucial for the
occurrence of graphitization and formation of 3D graphite structures. We
evaluated the suitability of the synthesized composites as precursors for
making porous structures. Nickel behaved as a space holder with the particle
size and spatial distribution changing during consolidation with the
temperature and determining the structure of porous graphite formed by phase
separation by dissolution in HCl. The response of the consolidated Ni-Cgr to
separation of carbon by its burnout in air was studied. The result of the
carbon removal was either the formation of a dense and continuous NiO film on
the surface of the compacts or oxidation through the compact thickness. The
choice between these two options depended on the density of the compacts and
on the presence of carbon dissolved in nickel. It was found that during the
burnout of graphite from Ni-Cgr composites, sintering, rather than formation
of pores, dominated.
Keywords: spark plasma sintering, hot pressing, nickel, graphitization, phase separation, microstructure, electron microscopy