Mechanical properties of 2.0-3.5 mol% Y2O3-stabilized zirconia polycrystals fabricated by the solid phase mixing and sintering method

Hiroshi Ohnishi, Hironori Naka, Tohru Sekino, Yuichi Ikuhara, Koichi Niihara

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

The crystal phase and mechanical properties of 2.0 to 3.5 mol% Y 2O3-stabilized zirconia polycrystals sintered from agitator milled powders (solid phase mixing, SPM) were investigated. Powders containing 2.5 and 2.8 mol% Y2O3 showed higher sinterability than those containing 2.0 and 3.5 mol% Y2O3. The thermal expansion curve of the 2.5 and 2.8 mol% Y2O3 samples exhibited a monoclinic to tetragonal phase transformation during the heating stage, with a linear relationship observed during cooling. However, a hysteresis was not observed during the heating and cooling stages when the Y2O3 content and sintering temperature were increased. The 2.0 mol% Y2O3 sample exhibited the transformation and hysteresis, even though the sintering temperature was increased. The relationship between the flexural strength and grain size for the sample with 2.0 mol% Y2O3 was not linear, but exhibited a peak. The flexural strength of the 2.5 and 2.8 mol% Y2O3 samples increased as the grain size increased, and then over a certain grain size the flexural strength remained constant and independent of the grain size. The flexural strength and fracture toughness of the 2.0 mol% Y2O 3 sample might be dominated by microcrack-toughening. On the other hand, those for the 2.5 and 2.8 mol% Y2O3 samples were dependent not only on the stress-induced transformation, but also on the compressive residual stress and microcrack-toughening caused by the transformation. The relationship between the fracture toughness and V f √h, where Vf is the tetragonal phase fraction and h is the transformation depth, for the 2.0, 2.5 and 3.5 mol% Y2O 3 samples was non-linear and exhibited a peak; however, that for the 2.8 mol% Y2O3 sample was linear.

Original languageEnglish
Pages (from-to)1270-1277
Number of pages8
JournalJournal of the Ceramic Society of Japan
Volume116
Issue number1360
DOIs
Publication statusPublished - 2008 Dec

Keywords

  • Compressive residual stress
  • Flexural strength
  • Fracture toughness
  • Microcrack-toughening
  • Solid phase method
  • Stress-induced transformation
  • Transformed depth

ASJC Scopus subject areas

  • Ceramics and Composites
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry

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