Time‐Temperature‐Transformation Curves for Kaolinite‐α‐Alumina

The C‐shaped time‐temperature‐transformation curves (T‐T‐T curves) of cristobalite formation and the L‐shaped T‐T‐T curves of α‐alumina reaction were established for a high‐purity kaolinite‐α‐alumina mixture during heating. The results revealed that cristobalite formation in kaolinite was retarded by the presence of α‐alumina between 1250° and 1350°C and was totally prohibited above 1380°C due to the reaction of kaolinite with α‐alumina to form secondary mullite. The reaction of α‐alumina with kaolinite was initiated at about 1250°C. It became quite extensive above 1380°C and was extremely fast at 1600°C and above, indicating the strong effect of the eutectic liquid formation at ∼1587°C in silica‐alumina. The effectiveness of the established T‐T‐T curves was demonstrated and discussed.