蓝晶石对硅溶胶结合 Al2O3－SiC－C 浇注料性能的影响

摘要

为了提高 Al2 O3－SiC－C 浇注料在高温使用过程中的体积稳定性，用蓝晶石粉部分替代 Al2 O3－SiC－C 浇注料中的白刚玉粉，研究了蓝晶石加入量（质量分数分别为0、1％、2％、3％、4％、5％和6％）对浇注料经烘干和1400℃保温3 h 热处理后物理性能的影响。结果表明：随着蓝晶石加入量的增加，试样经1400℃保温3 h 热处理后由微收缩逐渐变为微膨胀，体积稳定性以蓝晶石加入量为5％（w）时为最好。经110℃烘24 h 后试样的显气孔率、常温耐压强度和常温抗折强度变化都很小，体积密度基本上呈降低趋势；经1400℃保温3 h 热处理后试样的显气孔率基本上呈先升高后降低的变化趋势，体积密度则呈相反的变化趋势，并且均以蓝晶石加入量3％（w）为拐点；常温耐压强度和常温抗折强度略有降低，但降低幅度很小。同一配比的试样，1400℃保温3 h 热处理后的体积密度、显气孔率、常温耐压强度、常温抗折强度均比经110℃烘24 h 后的高。XRD、SEM和 EDS 分析表明，蓝晶石发生了一次莫来石化反应而产生体积膨胀，有效缓解了试样的烧结收缩，使试样具有较好的体积稳定性。%In order to improve the volume stability of Al2 O3 -SiC-C castables at high temperatures,cyanite was used to replace part of white corundum.Effects of cyanite additions (0,1%,2%,3%,4%,5%,and 6%,by mass)on physical properties of the castables after dried and fired at 1 400 ℃ for 3 h were re-searched.The results show that,with the increase of cyanite addition,(1)after fired at 1 400 ℃ for 3 h,the castables vary from mild shrinkage gradually into slight expansion,the volume stability is the best when cy-anite addition is 5%;(2)for castables fired at 110 ℃ for 24 h,the apparent porosity,cold crushing strength and cold bending strength only change a little,the bulk density gradually decreases;(3)for castables fired at 1 400 ℃ for 3 h,the apparent porosity increases at first and then decreases,the bulk density has the op-posite change tendency,3% cyanite addition is the inflection point;(4)the cold crushing strength and cold modulus of rupture of the castables reduce little.With the same ingredient,the bulk density,apparent po-rosity,cold crushing strength and cold modulus of rupture of the specimens fired at 1 400 ℃ for 3 h are bet-ter than those of the ones dried at 110 ℃ for 24 h.The combined analysis of XRD,SEM and EDS shows that,cyanite self generates mullite with volume expansion,reducing the sintering shrinkage,which is good for the volume stability.