Thermodynamics of the hydrothermal synthesis of xonotlite

Abstract Xonotlite, as a multifunctional inorganic material, has been widely used in the fields of building insulation, friction braking, and bionic composite materials. However, main method producing xonotlite, dynamic hydrothermal method, is regarded black box process. Optimization synthesis conditions can only be achieved through trial-and-error experimentations, there are inconsistencies experimental results reported literature. In this work, we established thermodynamic model Ca(OH) 2 -SiO -H O system under conditions, investigated influencing factors xonotlite synthesis. The show that, predicted lowest temperature approximately 170 °C. Furthermore, an optimum condition to with purity 99% proposed follows: reaction temperature, 200 °C; Ca/Si ratio, 0.9–1.0; water-solid no more than 20; pH, 7–8. This new process confirmed by experiments.