CaF_2对MgO-CaO材料缺陷形成及烧结性能的影响  

Effect of CaF_2 on the Defects Formation and Sintering Properties of MgO-CaO Materials

作　　者：张寒[1] 丁雄风 赵惠忠[1] 余俊[1] 聂建华[1] 

机构地区：[1]武汉科技大学,武汉430081

出　　处：《人工晶体学报》2014年第1期198-202,共5页Journal of Synthetic Crystals

基　　金：国家级大学生创新创业训练计划项目(201210488086);国家自然科学基金(50774057)

摘　　要：以分析纯Mg(OH)2和Ca(OH)2为原料,CaF2为添加剂,通过行星球磨机混合后机压成型,经1650℃×3 h烧成,制备了MgO-CaO材料。采用XRD和SEM对试样进行了分析表征。结果表明:随着CaF2加入量的增大,试样的体积密度逐渐增大,显气孔率减小,试样的致密化程度增强,而CaF2加入量超过2wt%后,试样的致密化程度降低。CaF2促进MgO-CaO材料致密的实质在于,CaF2晶体结构中存在大量的八面体空隙,由于自身的热缺陷,F-进入间隙位而形成填隙离子,留下带正电的F-空位,在迁移过程中易与O2-发生静电吸引,增大了O2-的扩散速度,增强了MgO的扩散,进而促进方镁石晶粒的长大。MgO-CaO materials were generated using analytically pure Ca （OH）2 and Mg （OH）2 as raw materials and CaF2 as dopant, mixing and pressing by planetary ball mill, then sintered at 1650 ℃ for 3 h. The characterization of samples were analyzed by scanning electron microscope （SEM） and X-ray diffraction （XRD）. The results show that with increasing the addition of CaF：, the bulk density of the samples increased, while the apparent porosity decreased and the densification of MgO-CaO materials promoted. When the amount of CaF2 exceeded 2wt% nature of CaF2 promoting densifieation of MgO-CaO , the densification degree of samples decreased. The materials could be concluded as follows： due to its thermal defects, F- entered into the octahedral voids that existed in CaF2 crystal structures and produced F- vacancies with positive charge, then combined with O^2- vacancies by electrostatic attraction during the migration process, which increased the diffusion speed of O^2- and enhanced the diffusion of MgO, then promoted the growth of periclase grains.

关 键 词：CAF2 MG(OH)2 CA(OH)2 离子空位 扩散 

分 类 号：TB332[一般工业技术—材料科学与工程]