Thermal transformations in ultrafine plasmochemical zirconium dioxide powders

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Abstract

The methods of thermal analysis and X-ray diffraction are used to investigate polymorphic transformations taking place under heating and cooling in nonstabilized ultrafine ZrO2 powders (ZrO2 UFP) synthesized in a plasmochemical process. It is found out that ZrO2 UFP is characterized by an increased content (up to 55 mass%) of tetragonal-phase particles, which is associated with the size effect of its stabilization. Heating of UFP within T = (25-700) °C, which is followed by the release of H2O, CH2O, and CO2, does not result in a change in its structural-phase state, while annealing within the temperature interval T = (700-1,000) °C gives rise to an increased growth of the size of t-ZrO2 crystallites and results in an elevated tetragonality of the crystal lattice (c/a). A complete t-ZrO2 → m-ZrO2 transition occurs as a result of heating the powder up to T = 1,300 °C. The effect of the dimensional factor on temperature characteristics of polymorphic m → t transitions and the value of their temperature hysteresis is established. It is shown that the powder particle size exerts the most pronounced influence on the temperature-dependent position of the point of martensitic transformation M s. As this influence is increased, M s is shifted toward the region of higher temperatures. This is followed by a decreased temperature hysteresis of the m → t martensitic transformations.

Original languageEnglish
Pages (from-to)1603-1609
Number of pages7
JournalJournal of Thermal Analysis and Calorimetry
Volume119
Issue number3
DOIs
Publication statusPublished - 2015

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Keywords

  • Methods of thermal analysis
  • Polymorphic transformations
  • Size factor
  • Temperature hysteresis
  • Ultrafine powders
  • Zirconium dioxide

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics

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