Preparation of glass-ceramic by low-pressure hot-pressing sintering of CaO-MgO-Al2O3-SiO2(-CaCl2) glass powder.

CaCl 2 can dissolve in the silicate glasses, and thus, using the CaCl 2 -bearing glass for the preparation of glass-ceramic could be a potential method for treating CaCl 2 -bearing wastes. In this work, two kinds of glass powders, CaO-MgO-Al 2 O 3 -SiO 2 and CaO-MgO-Al 2 O 3 -SiO 2 -CaCl 2 , were sintered at 825–850 ℃ to prepare the glass-ceramic. Besides, a low-pressure (19.1kPa) hot-pressing sintering technology was applied to reduce the porosity and pore size of the glass-ceramic. The addition of CaCl 2 (5 wt%) reduced the polymerization degree, glass transition temperature, crystallization peak temperature, and crystallization activation energy of the glass. Augite was the main crystalline phase of the glass-ceramic, and the addition of CaCl 2 promoted the precipitation of anorthite. The glass-ceramic prepared from the Cl-containing glass always exhibited a higher bending strength than that obtained from the Cl-free glass. When sintered at 825 ℃ for 8 h, the glass-ceramic showed the highest bending strength of 171 MPa. [ABSTRACT FROM AUTHOR]