Ba^(2+)离子掺杂对C_2S结构稳定性的影响  

Effect of Ba^(2+) doping on stability of C_2S structure

作　　者：邹千 马妍[1] 王玺堂[1] 王周福[1] 刘浩[1] 刘奇[1] 

机构地区：[1]武汉科技大学省部共建耐火材料与冶金国家重点实验室,湖北武汉430081

出　　处：《耐火材料》2016年第4期265-268,共4页Refractories

基　　金：973计划前期研究专项(2014CB660802)

摘　　要：为了避免镁钙质耐火材料表面的C_2S保护层发生晶型转变导致的剥落,从而延长镁钙材料的使用寿命,以分析纯Ca(OH)_2、Si O_2、Ba CO_3为原料,在按n(Ca O):n(Si O_2)=2 1配料的纯C_2S试样中掺入不同量的Ba CO_3(其掺入量以Ba O质量分数分别为1%、2%、3%、4%、5%和6%计算),于1 450℃保温3 h烧结制备了掺杂不同量Ba^(2+)离子的C_2S试样。通过观察烧后试样的粉化程度,并利用XRD和TEM分析物相组成和晶体结构,研究了引入Ba^(2+)离子对C_2S晶体结构稳定性的影响,同时探讨了Ba^(2+)离子稳定C_2S晶体结构的机制。结果表明:未掺杂Ba^(2+)离子的试样已完全粉化,只有γ-C_2S纯相;而掺杂Ba^(2+)离子的试样烧后粉化情况均有所减轻,其中引入4%(w)Ba O的试样没有出现粉化及明显的裂纹,仍保持β-C_2S的晶体结构。其稳定机制是:在C_2S中引入适量Ba^(2+)离子后,Ba^(2+)离子取代部分Ca^(2+)离子,降低了缺陷自由能,从而稳定了β-C_2S。In order to avoid the C2S layer spalling caused by phase transition on the surface of MgO-CaO refrac-tories,and prolong the service life,C2S specimens with different Ba2＋ doping amounts were prepared using ana-lytically pure Ca（0H）2,Si02 and BaC03 as starting materials,keeping n（CaO） ： n（Si02） = 2：1 and introducing different amounts of BaC03（the corresponding mass ratio of doped BaO is 1%,2%,3%,4%,5%,and 6%,re-spectively） ,firing at 1 450 ℃ for 3 h. The pulverization degree of the specimens was observed. The phase com-positions and crystal structure was characterized via XRD and TEM,respectively. Effect of Ba2＋ doping on the crystal structure stability of C2S was investigated and the stabilization mechanism was also discussed. The re-suits show that the specimen without Ba2＋ doping is completely pulverized,only y-C2S phase is detected. Whereas,the pulverization phenomenon of the specimens containing Ba2＋ is improved. For the specimen with 4% BaO doping,the pulverization and obvious cracks disappear,and the structure of β-C2S is maintained. The stabilization mechanism is that when a moderate amount of BaO is introduced into C2S,partial Ca2＋ ions are re-placed by the Ba2＋ ions,reducing the defect free energy,and stabilizing β-C2S phase.

关 键 词：镁钙质耐火材料 反应烧结 掺杂 硅酸二钙 钡离子 稳定机制 

分 类 号：TQ175[化学工程—硅酸盐工业]