In-situ crystallization of ferrochrome slag and quartz for preparing cordierite materials

Abstract

Ferrochrome slag (FS) contains a large number of glass phase, which cannot be effectively transformed into crystalline phases during the reutilization for fabricating ceramic materials. In this study, cordierite with a low expansion coefficient was successfully prepared from FS and quartz. The composition and structural characteristics of FS were analyzed. The phase evolution, microstructure, coefficient of thermal expansion (CTE), and material properties were studied. With 34 wt% quartz and maximum cordierite crystal content of 75.1 wt%, the glass phase decreased from 78.7 to 12.7 wt%. The melted quartz generated silica-rich microdomains with high viscosity during heating. Subsequently, the nuclear dynamic conditions were improved to promote the formation of cordierite crystals. Appropriate sintering temperature and holding time can boost the crystallization rate of the glass phase. Further, the diffusion of silica-rich microdomains was beneficial for the formation of cordierite crystals. Finally, the optimal cordierite ceramic material was obtained at 1300 °C for 2 h with a flexural strength of 38.3 MPa and CTE of 3.01 × 10−6/°C. These studies provide an effective way of re-utilizing large volumes of FS, and suggest a new method for preparing ceramic materials using high-temperature silicate waste residues.