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Thermodynamic Analysis of the CaO–Y2O3–ZrO2–Ti–Fe2O3 System as a Precursor for SHS-Produced Pyrochlore-Based Ceramics

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Abstract

The paper reports on the thermodynamic analysis of the CaO–Y2O3–ZrO2–Ti–Fe2O3 system as a precursor for SHS-produced pyrochlore-based ceramics. Adiabatic combustion temperature Tad and equilibrium concentration of pyrochlore were first calculated for the quasi-ternary system Y2O3–ZrO2–(Ti + Fe2O3) containing no CaO. It was found that, in the presence of CaO, a best yield of Zr-enriched pyrochlore ceramic can be reached within the following domain of green compositions (wt %): CaO 2.5–5.0, Y2O3 22.5–35.0, ZrO2 7.5–22.5, and (40% Ti + 60% Fe2O3) 45.0–60.0; within this domain, Tad = 2100–2400°K. Although in control experiments Tad was found to be within the range 1700–1970 K, nevertheless the combustion products always showed the presence of pyrochlore-based ceramic, as predicted by thermodynamic analysis.

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Correspondence to K. B. Podbolotov or T. V. Barinova or B. B. Khina.

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Translated by Yu. Scheck

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Podbolotov, K.B., Barinova, T.V., Khina, B.B. et al. Thermodynamic Analysis of the CaO–Y2O3–ZrO2–Ti–Fe2O3 System as a Precursor for SHS-Produced Pyrochlore-Based Ceramics. Int. J Self-Propag. High-Temp. Synth. 28, 239–244 (2019). https://doi.org/10.3103/S1061386219040113

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Keywords:

  • SHS
  • combustion synthesis
  • CaO–Y2O3–ZrO2–Ti–Fe2O3 system
  • pyrochlore Y2Ti2O7
  • zirconolite CaZrTi2O7
  • thermodynamic analysis