Effects of Cr۲O۳ 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 Cr۲O۳ 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 ۱۱۰ °C, sintering process was conducted at ۱۴۰۰ and ۱۶۰۰ °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 Cr۲O۳, strength, bulk density and apparent porosity were decreased. Change in the apparent porosity was due to filling properties of Cr۲O۳ 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 Cr۲O۳ content and temperature. The XRD pattern showed that MgAl۲O۴, Mg(Al,Cr)۲O۴ and (Al۱- xCrx)۲O۳ were the main detected phases in the system.

Keywords:

Chromium oxide , Spinel , Castable , XRD , SEM