Properties of mullite-zirconia composites prepared through reaction sintering kaolin, α-Al2O3, and ZrO2

F. Sahnoune*, N. Saheb, P. Goeuriot

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

4 Scopus citations

Abstract

Mullite-zirconia composites were synthesized through reaction sintering Algerian kaolin, α-Al2O3, and ZrO2. Phases present and their transformations were characterized using x-ray diffraction. Quantitative phase analysis was performed following the Rietveld method. Hardness and fracture toughness were measured by Vickers indentation. The flexural strength was measured using a Universal Testing Machine. It was found that the microstructure of samples sintered for 2 hours at 1600?C was composed of mullite grains which have whiskers' shape and ZrO2 particles. In the composite containing 16 wt. % ZrO2, the ratio of tetragonal zirconia transformed to monoclinic zirconia was relatively small and did not exceed 18%. However, in the composite containing 32 wt. % ZrO 2 around 75% of the tetragonal structure changed to monoclinic structure. Also, it was found that the increase of ZrO2 content from 0 to 32 wt. % decreased the microhardness of the composites from 14 to 10. 8 GPa. However, the increase of ZrO2 content from 0 to 24wt. % increased the flexural strength of the composites from 142 to 390 MPa then decreased it with further increase of ZrO2 content. The fracture toughness increased from 1. 8 to 2. 9 MPa. m1/2 with the increase of ZrO2 content from 0 to 32 wt. %; and the rate of the increase decreased at higher fractions of ZrO2content. The average linear coefficient of thermal expansion (within the range 50 to 1450°C) for samples containing 0 and 16 wt. % ZrO2 sintered at 1600°C for 2 hours was 4. 7 x10 -6 K-1 and 5. 2 x10-6 K-1 respectively.

Original languageEnglish
Title of host publicationMaterials Science and Engineering Applications
Pages1772-1778
Number of pages7
DOIs
StatePublished - 2011

Publication series

NameAdvanced Materials Research
Volume160-162
ISSN (Print)1022-6680

Keywords

  • Ceramic matrix composites
  • Mullite
  • Reaction sintering
  • Zirconia

ASJC Scopus subject areas

  • General Engineering

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