Effects of Cr2O3 on physical and mechanical properties of in-situ spinel containing castable

Increasing demands for cement, iron and steel industries for refractories with suitable workability in severe conditions (without any environmental risks), make the refractories’ researches to be an active area. Refractories containing Spinel has been developed with addition of chromia as a substitute in refractories using Magnesite - chromite. In this research, different amounts of Cr2O3 were applied in situ spinel containing castable and its effects on the physical and mechanical properties of the system were investigated. After mixing the raw materials, they were poured into the mold, using casting and vibrating methods. After drying samples at 110 °C, sintering process was conducted at 1400 and 1600 °C. Physical and mechanical properties were measured (including balk density, apparent porosity and cold crushing strength (CCS)). X-ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM) were used to study the formed phases and microstructure. The results indicate that increasing the amount of Cr2O3, strength, bulk density and apparent porosity were decreased. Change in the apparent porosity was due to filling properties of Cr2O3 at low temperature and it seems to be related to the liquid phase sintering at high temperature. The data indicated that the CCS was increased by increasing Cr2O3 content and temperature. The XRD pattern showed that MgAl2O4, Mg(Al,Cr)2O4 and (Al1- xCrx)2O3 were the main detected phases in the system.