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

摘要： 为了提高镁钙材料的抗水化性能,以白云石粉和轻烧镁粉为主要原料,添加纳米Fe₂O₃,结合剂采用无水树脂,于150 MPa下成型,在1 650 ℃煅烧3 h后制成镁钙材料。研究纳米Fe₂O₃的添加量(质量分数分别为0、2%、4%、6%和8%)对镁钙材料性能的影响。结果表明:在1 650 ℃条件下,纳米Fe₂O₃可以与试样中CaO生成低熔点相Ca₂Fe₂O₅,有助于促进镁钙材料中晶粒的重排长大,进而促进烧结,但若材料内存在过多低熔点相会影响材料高温强度。纳米Fe₂O₃的增加使得镁钙材料中Ca₂Fe₂O₅的含量增加,体积密度增大,显气孔率减小,抗水化性能提高。抗热震性呈先降后升的趋势。当纳米Fe₂O₃添加量为2%(w)时,试样的力学性能最好,同时抗水化性能显著提高。

关键词: 镁钙材料, 纳米Fe₂O₃, 抗水化性, 力学性能