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The Effects of Composition on Hardness and Toughness of ZrO2-Based Ceramics

Farooghi, Mohammad | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46704 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Nemati, Ali
  7. Abstract:
  8. The purpose of this thesis is the construction of hard and tough Zirconia bodies from economical raw materials using minimum sintering time and temperature.
    Stabilizers cause tetragonal particles to be remained in cubic phase. Most additives are Ca, Ce, Mg and Y ions the whole of which are rare earth elements and make solid solutions with Zirconia.
    In this project different percents of CaO, MgO, CeO2, and Y2O3 were mixed with ZrO2 and they were sintered after granulation, cold pressing and Cold Isostatic Pressing. Using jar milling and fast milling, the particle size of purchased ZrO2 was reduced to 0.7 um. The whole needed additives were purchased with particle size below 300 nm. The green bodies were sintered in 1400 or 1500 oC for 1 or 2h. Parameters including hardness, toughness and density were measured. Best results were achieved in bodied made up of Zirconia and Y2O3, CeO2 or MgO when sintered in 1400oC for 2h. In ZrO2-3mol%Y2O3 the parameters hardness, density, toughness and the amount of tetragonal phase were 1258HV, 96.23%, 4.1MPa.m0.5 and 5.6% respectively. For ZrO2-4 mol%Y2O3-0.5mol%MgO the mentioned parameters were 1233HV, 97.32%, 5.6MPa.m0.5 and 6.2% respectively. In addition, the mentioned parameters for ZrO2-4mol%Y2O3 were 1210HV, 96.16%, 4.6MPa.m0.5 and 58% respectively and for ZrO2-3mol%Y2O3-0.5mol%MgO, they were 1293HV, 97.82%, 5.8MPa.m0.5 and 68% respectively. The best results were belonged to ZrO2-12mol% CeO2 where hardness, density, toughness and the percent of tetragonal phase were 1272 HV, 7.3MPa.m0.5, 98.64% and 82% respectively
  9. Keywords:
  10. Toughness ; Zirconia ; Hardness ; Calcium Oxide ; Yttrium ; Cerium ; Magnesium Oxide

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