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Investigation on Mechanical Properties of Alumina Spinel Zirconia Nanocomposites Fabricated Through Gelcasting Process

Khoshkalam, Mohamad | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43576 (07)
  4. University: Sharif University Of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Faghihi Sani, Mohammad Ali
  7. Abstract:
  8. Zirconia Toughened Alumina (ZTA) is a well-known ceramic matrix composite due to its high fracture toughness and good mechanical properties. Addition of spinel (MgAl2O4) to ZTA inhibits alumina grain growth and produces phase boundaries with low strength. This phenomenon leads to formation of a ceramic matrix composite with special mechanical properties such as high temperature super plastic deformation. However, the room temperature mechanical properties of alumina-spinel-zirconia (AMZ) composite such as fracture toughness were rarely investigated by researchers. In this research the AMZ nanocomposite powders were synthesized via solution combustion method. The dense AMZ composite samples were fabricated through gelcasting process. The effect of spinel and zirconia content on mechanical properties as well as microstructure of AMZ composite samples was investigated. The maximum Vickers hardness (18.83 GPa) and flexural strength (563.743 MPa) were achieved in the sample with 10 vol% spinel and 10 vol% zirconia. The sample with 10 vol% spinel and 20 vol% zirconia had the maximum fracture toughness (6.67 MPa√m). The main cause of improving fracture toughness via increasing spinel and zirconia content is the enhanced intergranular crack propagation
  9. Keywords:
  10. Alumina ; Spinel ; Zirconia ; Mechanical Properties ; Gelcasting

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