Effect of the particle size distribution of spinel on the mechanical properties and thermal shock performance of MgO-spinel composites

Aksel C., Riley F.

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, vol.23, no.16, pp.3079-3087, 2003 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 23 Issue: 16
  • Publication Date: 2003
  • Doi Number: 10.1016/s0955-2219(03)00102-x
  • Journal Name: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.3079-3087
  • Keywords: fracture surface energy, mechanical properties, MgAl2O4, MgO, particle size distribution, thermal shock resistance, work of fracture, FRACTURE, REFRACTORIES, TOUGHNESS, CERAMICS, BEHAVIOR
  • Anadolu University Affiliated: No

Abstract

The influence of varying the amounts of spinel with a similar median particle size, but with different distribution, on the mechanical properties and thermal shock performance of MgO-spinel composites was investigated. Mechanical properties of composites decreased significantly with increasing spinel content due to the thermal expansion mismatch. However, gamma(WOF) values of composites increased markedly, because of a significant change in the fracture mode from transgranular to intergranular fracture. A narrow distributed spinel A (Alcoa MR66) particles resulted in shorter initial crack propagation distances from the spinel particles, but spinel B (Britmag 67) particles with a significantly broader distribution were the origins of longer interlinked cracks. The improved resistance to thermal shock in MgO-spinel composites can therefore be attributed to the microcrack networks developed around the spinel particles, associated with the high values of gamma(WOF), and not to an increased K-1c. On the basis of theoretically calculated R''' values and experimentally found gamma(WOF)/gamma(i) ratios, resistance to thermal shock damage would be more strongly favoured with materials containing spinel B particles, rather than spinel A, for which a much larger volume% was required to achieve a similar improvement. (C) 2003 Elsevier Ltd. All rights reserved.