Crystallization of CaO–MgO–Al2O3–SiO2 glass ceramic derived from blast furnace slag via one-step method

Abstract

CaO–MgO–Al2O3–SiO2 glass ceramic was successfully prepared from blast furnace slag (BFS), which was the raw material, by the one-step thermal treatment. The comprehensive crystallization characteristic, phase transition, kinetic parameters of crystallization, microstructural evolution, and orientation relations between diopside and spinel were investigated using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction. Experimental results revealed that the beginning of crystallization and the end of nucleation overlapped. A thermal nucleation treatment applied in the special temperature region (791–840 °C) confirmed the coexistence of spinel and diopside by modern analytical methods, providing direct evidence of achieving bulk crystallization via the one-step method. Traditional spinel, which typically includes Fe, induces the formation of diopside. However, the spinel phase in this study did not contain sufficient Fe because the Fe content in the BFS was small. This suggests that the Mn-containing spinel phase served as the nucleation agent. The epitaxial growth mechanism was confirmed to be diopside {200}//spinel {111}, diopside [001]//spinel [112]. Moreover, glass ceramic crystallized at 980 °C has better corrosion resistance and has an acid and alkaline resistance of 96.64% and 99.41%, respectively. The one-step preparation of glass ceramic has profound significance in terms of energy saving and waste utilization. Furthermore, the results of this study have a guiding significance for the industrialization of the glass ceramic prepared by the one-step method.