Cordierite/ZrO2 composites with 5 to 25 wt% ZrO2 were fabricated by pressureless sintering, and their densification behavior, fracture strength, fracture toughness, microstructure and thermal expansion behavior were studied. The ZrO2 addition into cordierite matrix affects the densification behavior and mechanical properties of the composites. By dispersing 25 wt% ZrO2, densified cordierite/ZrO2 composite with a relative density of 98.5% was obtained at optimum sintering condition of 1440°C/ 2H. Both fracture strength and toughness were enhanced with increasing ZrO2 content. The fracture strength and toughness were increased from 140 to 290 MPa and from 1.6 to 3.5 MPa·m1/2, respectively, by dispersing 25 wt% ZrO2 into the cordierite matrix. ZrO2 particles were homogenously dispersed into cordierite matrix, which intragranular particles were fine (< 100 nm) and intergranular particles were coarse. The toughening mechanisms in the present composites were mainly attributed to martensitic transformation toughening. Then, the addition of ZrO2 is likely to have little deleterious effect upon thermal expansion coefficient of cordierite.

Keywords: Cordierite, ZrO2, Composite, Toughening, Pressureless Sintering