Mechanical and thermal behaviour of cordierite–zirconia composites

Abstract

Cordierite (Mg 2Al 4Si 5O 18) ceramics are susceptible of mechanical failure due to their low fracture toughness, which may hinder their application. Dispersion of ZrO 2 in cordierite to improve the mechanical properties has been extensively studied. However, little is known about the effect of such additions on both the sinterability and the mechanical properties of cordierite bodies fabricated from talc, kaolin and alumina mixes with additions of monoclinic ZrO 2, as most studies are concerned with additions of tetragonal ZrO 2 to cordierite powders. The present paper describes the in situ fabrication, the thermal and mechanical properties of sintered cordierite-based ceramic matrix composites containing dispersed particles of ZrO 2 obtained by mixing clay–talc–alumina mixtures with additions of monoclinic ZrO 2 up to 40 wt.%. The results obtained clearly demonstrate that the thermal expansion coefficient (CTE), elastic moduli ( E) and flexural strength ( σ r) were critically dependent on the mixing/milling conditions, the ZrO 2 content and the retained porosity.