Effects of seeding on phase transformation and mechanical properties in complex-alkoxide-derived cordierite gel powder

Abstract

Cordierite gel powder prepared by the hydrolysis of an alkoxide complex was seeded with crystalline α-cordierite particles. The effects of seeding on the phase transformation and mechanical properties were studied. The unseeded cordierite gel powder crystallized into α-cordierite via μ-cordierite at 1050 °C. The μ-α cordierite transformation caused microcracks which led to poor flexural strengths of about 30 MPa, although the strength of μ-cordierite was 160 MPa. The seeding appeared to promote a direct formation of the α-cordierite from the amorphous state. The development of microcracks due to μ-α cordierite transformation could be prevented by the modified crystallization behavior, resulting in the improved flexural strength of α-cordierite of 190 MPa. The seeding also lowered the crystallization temperature of α-cordierite to 900 °C, which could be attributed to the epitaxial crystallization of the complex-alkoxide-derived cordierite gel powder.