关键词: 镁钙材料, 纳米Fe₂O₃, 抗水化性, 力学性能

Abstract: In order to investigate the effects of nano-Fe₂O₃ on the hydration resistance and other properties of magnesia-calcia materials,dolomite powder and light-burned magnesia were used as the main raw materials.Nano-Fe₂O₃ powder was added,an anhydrous resin served as the binder,the mixtures were pressed at 150 MPa,and then sintered at 1,650 ℃ for 3 h to prepare magnesia-calcia (MgO-CaO) clinker specimens with a CaO content of 30 wt%.The effects of nano-Fe₂O₃ addition (0,2,4,6,and 8 wt%) on the properties of the clinkers were examined.The results show that at 1,650 ℃,nano-Fe₂O₃ can react with CaO in the magnesia-calcia clinker to form the low-melting phase Ca?Fe₂O₃,which facilitates grain rearrangement and growth and thus promotes sintering; however,an excess of this low-melting phase impairs high-temperature strength.With increasing nano-Fe₂O₃ content,the amount of Ca₂Fe₂O₃ increases,the bulk density rises,the apparent porosity decreases,and hydration resistance improves.The thermal-shock resistance first decreases and then increases:when the Fe₂O₃ addition is less than 2 wt%,enhanced densification makes thermal stresses harder to relieve,leading to a decrease in strength retention; when the addition exceeds 2 wt%,the generated low-melting phase together with micropores helps to alleviate thermal stresses,resulting in higher strength retention.When the nano-Fe₂O₃ addition is 2 wt%,the magnesia-calcia clinker exhibits the best mechanical properties while its hydration resistance is significantly improved.

Key words: magnesia-calcia clinker (MgO-CaO clinker), nano-Fe₂O₃, hydration resistance, mechanical properties