Heat-Insulating, High-Temperature Materials on Cenosphere Base

Abstract

Cenospheres (microspheres) are silica-alumina fly ash lightweight fractions obtained from burning pulverized coal. These fractions are characterized by spherical particle shapes of 40 to 400 μm diameter (apparent bulk density 400 kg/m3). The thermal-insulation properties of microspheres are useful. A binder that ensures good strength and improves thermalinsulation properties of bonded materials is hydrated sodium silicate. These microsphere materials are characterized by: (a) apparent bulk density in the compressed state from 400 to 500 kg/m3, (b) compressive strength up to 6 MPa, (c) average mean heat capacity of 500 kJ/m3K at temperatures from 298 to 993 K, and (d) thermal conductivity in the range 0.13 to 0.38 W/mK at temperatures from 298 to 1273 K. The investigation made it possible to optimize the material composition for particular applications. Microsphere materials with silicate binders can be used in the building industry, in heating equipment, and in metallurgical and foundry work.

Hydrophobic Lightweight Cement with Thermal Shock Resistance and Thermal Insulating Properties for Energy-Storage Geothermal Well Systems

“…The diameter of spherical FCS is in the range between 5 and 500 µm, and the shell thickness is between 2 and 30 µm [14][15][16]. The TC of FCS is in the range of 0.13 to 0.38 W/mK, and the bulk density of the material is 0.3-0.5 g/cm 3 [17,18].…”