Crystallization behavior and mechanical properties of mica-diopside based glass-ceramics from granite wastes with different SiO2/MgO ratio

Abstract

Mica-Diopside based glass-ceramics were generated by melting method from granite wastes. The effects of SiO2/MgO (S/M) molar ratios on crystallization behavior, microstructure and mechanical characteristics of glass-ceramics were investigated. The analysis indicated that with the increase of S/M, the glass transition temperature (Tg) increased. The higher heat treatment temperature facilitated the formation of Forsterite than Nepheline. With S/M ratio rising, diopside turned into the main crystal phase instead of Forsterite along with Tainiolite as the minor phase at 850 °C and 900 °C respectively. At 900 °C, the crystallinity of glass-ceramics dropped with S/M ratio increasing. Meanwhile, there were some columnar crystals interleaving with granular crystals, and the average size of crystals obviously decreased. After heated at 900 °C, their Vickers-hardness fell dramatically with S/M rising, while the fracture toughness increased initially followed by a decrease, reaching the largest value of 1.97 MPa·m1/2 with the S/M ratio of 2.82.