Influence of Al3+ on Hydrothermally Synthesized Xonotlite Whiskers in CaO-SiO2-H2O System

Influences of Al3+ concentration on hydrothermally synthesized xonotlite whiskers were researched in this paper. The crystal phase composition and morphology of the products were analyzed and characterized using XRD and SEM techniques. The results indicate that Al3+ concentration have great impact on the crystal phase composition and morphology of the xonotlite whiskers in CaO-SiO2-H2O system under the condition of initial CaO/SiO2 mol ratio of 1.0, reactant concentration of 0.05 mol·L-1 , at 225 ℃ for 15 h. The main crystal phase of hydrothermally synthesized products had a phase transition from xonotlite to tobermorite, and the morphology changed from fibrous to tabular with increasing the concentration of Al3+ ion. At last, in order to prepare the pure xonotlite whiskers via hydrothermal synthesis in CaO-SiO2-H2O system, the Al2O3 contents in raw materials should be less than 1%.