Calcium oxide is used as an alkali-resistant material and in the production of refractories despite its low hydration resistance. To increase the hydration resistance, densified structure is required and several studies have been made of the influence on the sintering and increase in the hydration resistance of ceramics based on CaO with various additives. In the present investigation, the effects of an oxide ceramic, Fe2O3, addition on the densification and slaking resistance of CaO were studied based on CaCO3 as a starting material. Iron nitrate was used as the source of Fe2O3 for the control of homogeneous mixing and for less impurities. In addition, the hydration behavior of fused CaO including Fe2O3 was also investigated. CaCO3, involving 0.5 wt% Fe2O3, sintered at 1700 οC for 1 h showed a dense microstructure and a 8% amount of hydration in comparison with a 25% amount of hydration of pure CaO. The fused amorphous CaO showed a weak structure for resistance to hydration. The CaO samples, which have calcium ferrite products (Ca3Fe15O25 or CaFe3O5) through the slaking testing, showed relatively high hydration resistance. In this study, the hydration behavior of densified CaO with Fe2O3 additive was examined on the basis of the phase and microstructural changes before and after slaking tests.

Keywords: Calcium oxide, Hydration resistance, Densification, Iron oxide.