Novel ceramics prepared from inferior clay rich in CaO and Fe 2 O 3 : Properties, crystalline phases evolution and densification process

Abstract Inferior clay rich in CaO and Fe 2 O 3 is a typical clay with huge reserves in southwest of China, which cannot be used in traditional aluminosilicate system ceramics. To efficiently utilize the inferior clay, a method of preparing novel ceramics containing CaO and Fe 2 O 3 was put forward. In this study, effects of inferior clay proportion on properties, CaO on evolution of crystalline phases and Fe 2 O 3 on densification process were analyzed by XRF, XRD, TG-DTA and SEM-EDS combined with physical properties tests. The results showed that addition of inferior clay (from 20 to 70 wt%) significantly affected sintering temperature (from 1190 to 1130 °C). High activity CaO decomposed by carbonate transformed into anorthite and diopside at low temperature. Fe 2 O 3 promoted generation of low-temperature liquid phase, which facilitated densification process. The fired ceramics (60 wt% inferior clay) sintered at 1130 °C exhibited excellent properties with water absorption of 0.05%, linear shrinkage of 6.8% and flexural strength of 70 MPa. This batch was applied into an industrial experiment and 1160 m 2 qualified ceramics (ISO 10545-4:2004) were fabricated.