Y_2O_3和CeO_2对镁砂烧结性能及显微结构的影响  

Effects of Y_2O_3 and CeO_2 on sintering and microstructure of magnesite

作　　者：刘磊[1] 王周福[1] 何俊鹏[1] 王晓玲[1] 

机构地区：[1]武汉科技大学耐火材料与高温陶瓷国家重点实验室培育基地,湖北武汉430081

出　　处：《耐火材料》2012年第5期340-343,共4页Refractories

基　　金："973计划"前期研究专项(2012CB722702)

摘　　要：以菱镁石于950℃制得的轻烧MgO粉(≤0.088 mm)为主要原料,分别加入质量分数为1%、2%、3%、4%的Y2O3和CeO2混匀,压制成型后于1 600℃煅烧3 h,冷却后测其体积密度和线收缩率,并利用XRD、SEM、EDS分析试样的物相组成及显微结构,以研究Y2O3和CeO2对镁砂烧结性能和显微结构的影响。结果表明:1)引入Y2O3和CeO2均有利于镁砂的烧结致密化,镁砂试样的体积密度和烧后线收缩率随其加入量的增加而增大;在加入量相同的情况下,加入Y2O3对镁砂的促烧结作用比加入CeO2的更明显。2)引入的Y2O3和CeO2都有部分固溶于方镁石晶体内,使MgO晶格发生畸变,有利于MgO晶粒发育良好,晶粒长大,晶界明显;Y2O3能与镁砂中的CaO、SiO2形成钇硅酸盐相分布在晶粒之间,而部分CeO2以游离形式存在于晶粒之间。3)与引入CeO2的试样相比,引入Y2O3的试样中气孔更加集中,晶界更加清晰,MgO晶粒尺寸较大,这是由于Y2O3和CeO2的性质差异造成稀土离子参与固溶体粒子取代程度不同的缘故。The specimens were prepared using ≤0.088 mm light burnt magnesite powder from magnesite calcined at 950℃ as main starting material,adding 1 mass% ,2 mass%,3 mass% and 4 mass% Y2O3 and CeO2,respectively,mixing,molding,and firing at 1600 ℃ for 3 h. The effects of rare earth oxides （Y2O3 and CeO2） on the sintering and microstructure of magnesite were studied by determining bulk density and shrinkage rate in dimensions,and analyzing the phase composition and microstructure by means of XRD, SEM and EDS. Results indicate that= （1）Y2O3 and CeO2 are in favor of the densification of magnesite,and the bulk density and shrinkage rate in dimensions on heating increase with the additions of Y2O3 and CeO2 increasing;for the same addition,Y2O3 accelerates the sintering of magnesite more obviously than CEO2;（2） parts of Y2O3 and CeO2 solid-solve in periclase crystals and cause the deformation of MgO crystal lattice,which results in well-developed MgO crystals with large size and clear crystal boundary;Y2O3 can react with CaO and SiO2 forming yttrium silicate phases which distribute among crystal grains,and part of CeO2 exists among crystal grains in free form;（3）compared with the specimens with CeO2 ,the specimens with Y2O3 have more centralized pores,clearer crystal boundary,and bigger MgO crystal grains because the characteristics difference between Y2O3 and CeO2 results in the different degrees of rare earth ions replacing solid solution grains.

关 键 词：镁砂 稀土氧化物 氧化钇 氧化铈 烧结致密化 晶格畸变 

分 类 号：TQ175.4[化学工程—硅酸盐工业]