蓝晶石对硅溶胶结合Al_2O_3-SiC-C浇注料性能的影响

Effects of cyanite additions on properties of silica sol bonded Al_2O_3- SiC- C castables

为了提高Al2O3-Si C-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Al2O3-Si C-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1 400℃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1 400℃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1 400℃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,1 400℃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 Al2O3- Si C- C castables at high temperatures,cyanite was used to replace part of white corundum. Effects of cyanite additions（ 0,1%,2%,3%,4%,5%,and6%,by mass） on physical properties of the castables after dried and fired at 1 400 ℃ for 3 h were researched. 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 cyanite 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 opposite 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 porosity,cold crushing strength and cold modulus of rupture of the specimens fired at 1 400 ℃ for 3 h are better 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.