Refractory ceramics bonds from potassium-based inorganic polymer for advanced applications: Crystalline phase changes and descriptive microstructure

Understanding the structural and meso-scale properties of alkali activated matrices subjected to high temperature treatment, provides useful information on the stability of their self-life service or, fire resistance in extreme environments. The current project focuses on the transformation of phase and structural bonds within kyanite-reinforced refractory geopolymer. After being exposed to temperatures ranging from 1050 °C to 1250 °C, the micro-structural and macro-scale properties of the resulting matrices were evaluated using X-ray diffraction, chemical bond analysis, SEM-EDS, and resistance to flexural strengths. The fineness of the kyanite powder played an important role in the geopolymer composites' bonding system, as well as the crystallization of the cordierite phase during the sintering process. Further decomposition of kyanite minerals limited the thermal expansion to less than 0.8%, suggesting the formation of new and stronger bonds between the particles, which result in the formation of crystalline phases such as: cordierite, mullite, leucite and enstatite. These phases render the matrices compact and dense. Based on the findings, kyanite particles were discovered to be refractory components and fillers in the formation of refractory alkali-bonds ceramics, with environmental and eco-friendly benefits.