干熄炉斜道区莫来石-红柱石砖的损毁研究

测试并比较了使用4年后干熄炉斜道区莫来石-红柱石过梁砖不同部位(炉腔侧、风道侧和芯部)砖体的体积密度、显气孔率、耐压强度、化学组成,利用XRD和SEM分别分析了其物相组成和显微结构变化,并对其损毁机制进行了探讨。结果表明:1)莫来石-红柱石砖原始强度较低,易遭受炉体结构应力和热应力破坏;2)与砖体芯部相比,炉腔侧和风道侧受环境气氛影响更大,结构更为疏松,强度下降更明显;3)高温下红柱石莫来石化导致的体积膨胀、低熔点相侵入形成的新物相以及弱还原气氛下SiO2的分解破坏了材料的结合体系,造成了材料致密度的降低和强度大幅下降,是除了炉体结构应力、热应力等因素外,导致干熄炉斜道区莫来石-红柱石砖破坏的不可忽略的因素。

Degradation mechanism of mullite-andalusite bricks for inclined channel area of CDQ ovens

Different positions(chamber-side,air-flue side and the core)of a mullite-andalusite lintel brick,which has served at the inclined channel area of a CDQ oven for 4 years,were investigated and compared in terms of the bulk density,apparent porosity,cold crushing strength and chemical composition;the phase composition and the microstructure were analyzed by means of XRD and SEM;and the degradation mechanism was discussed.The results show that:(1)the original mullite-andalusite brick presents low strength,which is vulnerable to the impact of structural stress and thermal stress in the oven;(2)compared with the core of the brick,the chamber-side and the air-flue-side of the brick are influenced much more severely by the atmosphere in the oven,showing a looser structure and much more strength loss;(3)the volume expansion caused by the mullitization of andalusite and the formation of new phases by the intrusion of low-melting point phases as well as the decomposition of SiO2 in weak reducing atmosphere destroy the bonding system of materials leading to the significant declination of the density and strength,which,in addition to the structural stress and thermal stress etc.,are non-ignorable factors for the degradation of mullite-andalusite bricks in the inclined channel area of CDQ ovens.