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Effect of sintering temperature and siliconcarbide fraction on density, mechanical properties and fracture mode of alumina-silicon carbide micro/nanocomposites

Rahimnejad Yazdi, A ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.matdes.2011.12.038
  3. Publisher: 2012
  4. Abstract:
  5. In this study Al2O3-SiC micro/nanocomposites have been fabricated by mixing alumina nanopowders and silicon carbide micro/nanopowders, followed by hot pressing at 1550, 1600, 1650 and 1700°C. The density, mechanical properties and fracture mode of Al2O3-SiC composites containing different volume fractions (2.5%, 5%, 7.5%, 10% and 15%) of micro/nanoscale SiC particles were investigated and compared with those of alumina. The relative density of composites could reach values very close to theoretical density, especially after sintering at 1700°C. However, relative density declined by increasing the SiC fraction at the same sintering temperature. The flexural strength of composites was best for sintering temperature of 1700°C and showed a maximum of 545MPa for Alumina-10%SiC sintered at 1700°C. Hardness showed a remarkable increase by adding SiC and reached a pick of 22.6GPa for Alumina-15%SiC. Fracture toughness and fracture mode of alumina and composites with 5%, 10% and 15% SiC sintered at 1700°C were also investigated. Composites were tougher than alumina and the scanning electron microscopy observations showed that fracture mode changes from intergranular for alumina to transgranular for composites. Finally X-ray diffraction analysis could not detect any chemical reactions between Al2O3 and SiC particles
  6. Keywords:
  7. Fracture mode ; Intergranular ; Nano powders ; Relative density ; SiC particles ; Sintering temperatures ; Theoretical density ; Transgranular ; Aluminum ; Density (specific gravity) ; Fracture ; Hot pressing ; Scanning electron microscopy ; Silicon carbide ; Sintering ; Textures ; X ray diffraction analysis ; Sintered alumina
  8. Source: Materials and Design ; Volume 37 , May , 2012 , Pages 251-255 ; 02641275 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0261306911008673