• Preparation of tetragonal zirconia powders by a solid state reaction: Kinetics, phases and morphology

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    • Keywords

       

      Tetragonal zirconia; powder preparation; solid state reaction

    • Abstract

       

      Powders of tetragonal (t)ZrO2 have been prepared by a solid state reaction between sodium metazirconate and sodium metaphosphate. The reaction temperatures and times have been varied between 450 and 550°C and 5 and 75 h, respectively. Zirconia powder, mostly in thet andt′ phases, is obtained. The yield of ZrO2 powder increases monotonically with time at all reaction temperatures according to a phase boundary controlled kinetics. The fraction oft phase also increases with time at 450°C and 500°C but goes through a maximum at 550°C, the highest temperature employed. A maximum of 55% of the precursor monoclinic zirconia (used to prepare sodium meta zirconate) is converted tot phase at 500°C/75 h. The ZrO2 powder consists of crystallites of size 9–25 nm agglomerated into particles having average size between 2 and 4µm. The agglomerates have a breaking strength of 100 MPa. A hydrothermal treatment is found to break the agglomerates into smaller sizes. Grinding the powder in a mortar and pestle converts only 12% of thet phase into monoclinic, indicating that substantial fraction of the tetragonal phase is the non transformable varietyt′. Heating experiments also confirm this.

    • Author Affiliations

       

      V V Mishra1 A K Garg1 D C Agrawal1

      1. Materials Science Programme, Indian Institute of Technology, Kanpur - 208 016, India
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  • Bulletin of Materials Science | News

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