摘要
研究了分别添加0,1%,1.5%,3%的氮化硼 的Al2O3-MgO浇注料分别在空气和埋炭气氛下于 1600℃保温3h烧成后的物理性能和抗渣性能,借助 X射线衍射仪、扫描电子显微镜对材料的物相变化和 显微结构进行了分析和观察。研究结果表明:(1)在空 气中1600℃烧成时,BN氧化生成B2O3并放出N2,B2 O3与Al2O3反应生成一定量的过渡液相,促进了浇注料 烧结,使浇注料线收缩增大,体积密度升高,显气孔率 下降,抗折强度明显提高;而当BN加入量超过1%时, 其氧化后形成大量的气孔,阻碍了浇注料的致密化过 程,影响了浇注料的上述物理性能。(2)在埋炭条件下 烧成时,浇注料中BN不易被氧化,它的存在使浇注料 难于烧结,同时,浇注料中引入的镁砂和铝酸钙水泥与 氧化铝反应伴随着一定体积膨胀,使浇注料体积密度 下降,显气孔率增加,抗折强度下降。(3)在空气和埋 炭条件下的抗渣试验发现,当在浇注料中加入1%BN 时,其抗转炉终渣侵蚀性能均有较大的提高。但两种 试验条件下浇注料抗渣作用机理不同:在空气中,BN 氧化后形成的过渡液相吸收了生成镁铝尖晶石等反应 所伴随的体积膨胀,促进了浇注料烧结,抑制了渣的渗 透和侵蚀;而埋炭条件下,浇注料基质中的氮化硼难以 被氧化物熔渣润湿,阻碍了渣的渗透和侵蚀,因而使浇 注料具有优良的抗渣侵蚀性和渗?
The physical property and slag resistance of Al 2O 3-MgO castables containing boron nitride 0,1%,1.5% and 3% respectively after firing at 1600 ℃ for 3 h in air and in coke bed were studied.The phase changes and microstructures of the castables were analyzed and observed by XRD and SEM.The results indicate: (1)when the castable is fired in air, BN will be oxidized forming B 2O 3 and releasing N 2,and then B 2O 3 reacts with Al 2O 3 producing a little transit liquid phase.It is responsible for linear shrinkage and favorable for the increase of bulk density,decrease of the apparent porosity and remarkable increase of CMOR when BN addition is 1 wt%.However,when BN addition is higher than 1 wt%,the formation of much porosity results from oxidation of BN hindering the densification process and affecting physical properties of the castable.(2) BN is not easily oxidized when it is fired in coke bed.The existence of BN in the matrix is unfavorable for sintering of castable.Meanwhile,the volume expansion occurs in sintering process due to in-situ formation of magnesia alumina spinel.All the above reasons deteriorate the physical properties (bulk density,apparent porosity,CMOR,etc).(3)The slag-resistance experiments in air and in coke bed show that the slag-resistance of the castable will be much promoted when 1 wt% BN is added compared with the castable without adding BN.Such slag-resistance mechanism is supposed the formation of appropriate transitional liquid phase is favorable for sintering of castable containing BN in air,which prevents from slag penetration and corrosion.In coke bed,BN exists in the matrix of the castable that hinders slag penetration and increases the slag resistance.
出处
《耐火材料》
CAS
北大核心
2004年第6期402-406,共5页
Refractories
