Fabrication and characterization of porous cordierite ceramics prepared from ferrochromium slag

Porous cordierite ceramics were successfully fabricated using ferrochromium slag, commercial alumina and silica powder as raw materials, without any additional pore forming agents, by sintering at temperatures ranging from 1100 to 1350 °C. The phase evolution, porosity, microstructure, mechanical properties, thermal expansion property and chromium leachability were systematically investigated. The results showed that the internal oxidation of forsterite in the slag contributed to the massive glassy phases formed in the prepared porous ceramics as well as the low-temperature sintering synthesis of cordierite, which started to form at 1100 °C and at 1350 °C, comprising up to ∼87.1 wt% of the ceramic. Furthermore, the iron oxides in the ferrochromium slag acted as pore forming agents at high temperatures, thereby resulting in significant volume expansion of the sample. The SEM images showed that the prepared cordierite ceramics had a porous microstructure composed of massive glassy phases embedded in polyhedral spinel and prismatic cordierite. In addition, the ceramic had a flexural strength of 47.26±1.01 MPa, coefficient of thermal expansion of 3.5×10-6/°C, and chromium leachability that was only half as large as that of the green sample.