Effect of ceramic matrix compositions on pore structure and properties of lightweight foamed ceramics

Abstract

Foamed ceramics were prepared with polishing slag and shale as raw materials. According to the phase diagram of CaO‐MgO‐Al2O3‐SiO2, a reasonable composition system was designed to obtain foamed ceramics with good property. The related properties of foamed ceramics were characterized by X‐ray fluorescence, X‐ray diffraction, thermogravimetric analysis/differential scanning calorimetry, field emission scanning electron microscopy, energy disperse spectroscopy, etc. The results indicate that, when the amount of polishing slag and shale are 30% and 60% respectively, foamed ceramic with bulk density of 0.225 g·cm−3 has good compressive strength and thermal conductivity, which are 1.95 MPa and 0.065 W/m·K, respectively. The element compositions of the matrix materials affect the melt viscosity, resulting in glass phase separation and the crystallization. The main phases of the foamed ceramics are anorthite CaSi2Al2O8, spinel MgAl2O4 and spinel Mg(Al, Fe)2O4. The internal relationship among melt, pores, and crystal precipitates was discussed.