The Effect of K2CO3 on the SiC Formation by Carbothermal Reduction of Chamotte

Abstract

The enhancement of mechanical or physicochemical properties in kaolinitic ceramics has often been achieved through the nature and volumetric fraction of their constituent phases. Free silica in these ceramics contributes to a decrease in creep resistance. Therefore, improving their properties is contingent upon controlling free silica. The objective of this study is to enhance the mechanical properties of kaolinitic ceramics through the transformation of silica to form silicon carbide. This transformation is based on the carbothermal reaction. The work methodology involves the addition of active carbon and potassium carbonate to chamotte to ensure optimal reactivity between carbon and silica at high temperatures. Various techniques were used, including mechanical tests, physical measurements, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Researchers have highlighted the carbothermal reaction at temperatures ranging from 1300 to 1500 °C. Through SEM observations and XRD analysis, we have demonstrated the formation of silicon carbide in fibre form, leading to an increase in mechanical strength. The addition of K₂CO₃ lowers the temperature of silicon carbide formation. These transformations significantly affect shrinkage but not apparent density or porosity due to the interplay of conflicting phenomena.