Dynamic Hydrothermal Synthesis of Super-Low Density Xonotlite Thermal Insulation Materials from Industrial Quartz Powder

Xonotlite was synthesized by dynamic hydrothermal methode with industrial quartz powder as the siliceous materials and calcium hydroxide derived from hydration of calcined calcium carbonate as calcareous material.This paper focused on the influence of particle size of the industrial quartz powder, the mass ratio of water and solid reactants (W/S) and additives on the product composition, apparent density and crystal morphology. The products were characterized by X-ray powder diffraction (XRD), scanning eletron microscope (SEM) and other analysis methodes. Results indicated that in a certain range to decrease particle sizes of quartz powder could improve the content of xonotlite under the help of potassium hydroxide and zirconium oxychloride, the content of xonotlite could reach 99.5% when the particle size of quartz powder decrease to 4.65um no need to the common level of below 1 um in some literature. The product had a very high xonotlite content and perfect particle morphology when the ratio of W/S was controled over 30%; under the help of strontium ions and zirconium ions xonotlite fiber became significantly slimmer with a greater ratio of length to diameter,which was easier to obtain super-low density xonotlite thermal insulation materials.