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Abstract
Structural evolution of palygorskites, calcinated from 300° to 1200°C, was studied and ceramic materials were fabricated by hot pressing three types of palygorskite (PG1, PG2 and PG3) at 1000°C. In the calcination process, palygorskite transformed into cordierite, cristobalite and enstatite at 1200°C. After hot pressing, the bending strength and Young's modulus of PG1 ceramics reached 187 MPa and 87 GPa, respectively showing 125% and 30% increase compared to that of PG2 ceramics. The highest mechanical properties of PG1 ceramics can be attributed to its distinct fracture mode, namely intragranular fracture. Moreover, graphite carbon was detected in PG1 ceramics. Carbon-reinforced palygorskite-based ceramics was obtained by hot pressing synthesized acetamide modified pure palygorskite (PG3). Acetamide was carbonized during hot pressing. The bending strength of the carbon-reinforced PG3-based ceramics was 100 MPa, which showed a 33% increase compared with that of the PG3 ceramics.