A mica/nepheline glass-ceramic prepared by melting and powder metallurgy at low temperatures

Mica glass-ceramics usually have high melting temperatures. In this work, mica glass-ceramics were prepared by the combination of melting and powder metallurgy at low temperatures. Firstly, a SiO2-CaO-B2O3-MgO-Na2O-ZnO glass powder with a melting temperature as low as 1000 °C was prepared. Subsequently, the glass powder mixed with different contents of fluorphlogopite was remelted at 1300 °C to synthesize the ultimate glass frit. After disintegration, the mica glass-ceramic powder can be sintered at low temperatures of 800–950 °C, and a relative density as high as 90% can be obtained. The phase constitutions and microstructures of the bulk glass-ceramics were characterized by X-ray diffraction and scanning electron microscopy. The results illustrated that the glass-ceramics were mainly made up of flake-like fluormica and columnar nepheline, accompanied by augite, forsterite and some other minor phases. The transverse rupture strength and the hardness of mica glass-ceramics were both low at 800 °C for the high porosity, and decreased with the increase of mica phase at 850 °C. Nevertheless, the highest strength of the glass-ceramic with 30% mica reached 97.42 ± 10.2 MPa, which can be potentially applied for engineering applications.