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Influence of Carbon Deficiency and Hafnium Oxide Doping on Reactive Spark Plasma Sintering of the Ta2O5–C System

Authors
  • Simonenko, E. P.1
  • Simonenko, N. P.1
  • Nagornov, I. A.1, 2
  • Shichalin, O. O.3, 4
  • Belov, A. A.3, 4
  • Shlyk, D. H.3
  • Papynov, E. K.3, 4
  • Mokrushin, A. S.1
  • Sevastyanov, V. G.1
  • Kuznetsov, N. T.1
  • 1 Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, 119991, Russia , Moscow (Russia)
  • 2 Mendeleev University of Chemical Technology of Russia, Moscow, 125047, Russia , Moscow (Russia)
  • 3 Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690022, Russia , Vladivostok (Russia)
  • 4 Far Eastern Federal University, Vladivostok, 690091, Russia , Vladivostok (Russia)
Type
Published Article
Journal
Russian Journal of Inorganic Chemistry
Publisher
Pleiades Publishing
Publication Date
Dec 14, 2021
Volume
66
Issue
12
Pages
1887–1894
Identifiers
DOI: 10.1134/S0036023621120172
Source
Springer Nature
Keywords
Disciplines
  • Inorganic Materials and Nanomaterials
License
Yellow

Abstract

Abstract―Features of the application of the method of spark plasma sintering, as one of the most effective and promising for the manufacture of super-refractory oxygen-free ceramics, have been studied for the reactive consolidation of highly dispersed powder Ta2O5–HfO2–C with a carbon deficiency in comparison with that necessary for the synthesis of metal monocarbides. The initial powder has been obtained by the sol-gel method with a calculated ratio n(Ta) : n(Hf) = 9 : 1, confirmed experimentally using the EDX method. Spark plasma sintering experiments of the resulting system have been carried out in a dynamic vacuum at a pressure of 25 MPa and temperatures of 1600 and 1700°C (higher temperatures led to the outflow of molten oxides from the molds before the beginning of carbothermal synthesis of TaC–HfC). The presence of tantalum subcarbide Ta2C in the obtained ceramic is more advantageous than the oxide impurities and the formation of which under the selected conditions has been predicted by thermodynamic calculations. Its absence can be explained by the fact that equilibrium is not achieved when heating, holding, and cooling the sample.

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