Synthesis and Sintering of Cordierite from Ultrafine Particles of Magnesium Hydroxide and Kaolinite

Thermal reactions of magnesium compounds and kaolinite were investigated to obtain dense cordierite ceramics without additives. Magnesium hydroxide was precipitated from aqueous solution in the form of ultrafine hexagonal tabular particles of about 0.1 µm, and heating this mixture with kaolinite in a mole ratio of MgOAl 2 O 3 2SiO 2 resulted in formation of an amorphous state at about 900°C following thermal decomposition. µ‐Cordierite was then crystallized from the amorphous phase at about 950°C, and gradually transformed into alpha‐cordierite. Firing the pressed specimens yielded a dense alpha‐cordierite ceramic with a relative density of 97.7% at 1350°C.