Development of cordierite/mullite composites using industrial wastes

Ceramics containing cordierite and mullite as their principal phases are promising for many applications, due to properties such as a low coefficient of thermal expansion, high durability, low dielectric constant, resistance to thermal shock, and refractoriness. The objective of this study was to produce ceramic composites suitable for use as refractory materials. The raw materials were subjected to chemical characterization and the formulations to physical, chemical, and mineralogical characterization. The specimens were formed by pressing, dried at 110°C, and sintered from 1150°C to 1300°C for 2 hours. The following properties were then determined: linear shrinkage, water absorption, apparent porosity, and flexural modulus of rupture. The phases formed, crystal morphology, and coefficient of thermal expansion were evaluated. The cordierite and mullite phases were observed in all formulations at 1250°C and 1300°C. The results obtained from the formulations with a higher content of fine kaolin residue suggest that these formulations have the potential to be used for the manufacture of refractory materials such as furnace rollers and supports.