硅线石含量对轻质莫来石-刚玉耐火材料的显微结构与性能的影响

Effect of Sillimanite Content on Microstructure and Properties of Lightweight Mullite-Corundum Refractories

以多孔球形莫来石为骨料,板状刚玉细粉、硅线石和粘土为基质,经1400℃、1500℃和1600℃保温3 h烧成,制备了四组轻质莫来石-刚玉耐火材料。采用X-射线衍射仪(XRD)和扫描电子显微镜(SEM)对试样的物相组成和显微结构进行表征,研究了烧成温度及硅线石含量(4%、6%、8%和10%)对试样常温物理性能和显微结构的影响。结果表明:(1)当硅线石含量不变时,随着烧成温度的升高,试样的显气孔率逐渐减小,体积密度逐渐增大,线收缩率逐渐增加,常温耐压强度先降低后升高;(2)当硅线石的含量从4%增加到8%时,经1400℃烧后,试样的显气孔率和体积密度变化不大,当硅线石含量超过8%时耐压强度显著下降;经1600℃烧后,随硅线石含量的增加,试样的体积密度减小,强度降低,线收缩率也由2.5%减小到1.5%;(3)当硅线石含量为6%、烧成温度为1400℃时,试样的线收缩率为0.86%,耐压强度为36.1 MPa,热导率为0.249 W/(m·K)(300℃),试样基质中气孔的d_(50)为46.7μm。

Using porous spherical mullite as aggregate, tabular c o r u n d u m as p o w d e r, sillimanite and clay as marix, four groups of lightweight mullite c o r u n d u m specimens were prepared and sintered at 1400℃ , 1500 and 1600 for 3 h. T h e phase composition and microstructure were investigated through X-ray diffractometry （XRD ） and scanning electron microscopy （ SEM ）. Effect of sintering temperature and sillimanite content on physical properties and microstructure of lightweight mullite-corundum refractories were studied. T h e results showed that： （1） W h e n the sintering temperature increased from 1400℃ to 1600℃ , the apparent porosity of specimens decreased, the bulk density increased, the linear shrinkageincreased, the cold compressive strength first decreased and then increased. （2） W h e n the sillimanite content increased from 4% to 8 % , the apparent porosity and bulk density of the specimens remained constant which was sintered 1400 . W h e n the sillimanite content was more than 8 % , the coldcompressive strength decreased significantly; after sintered 1600 , the bulk density of the specimendecreased, the cold compressive strength decreased, and the linear shrinkage decreased from 2. 5 % to 1. 5% with the increase of sillimanite content. （3） T h e specimen with 6% sillimanite content which wassintered at 1400 Tl has low linear shrinkage（0. 86% ） , high cold compressive strength（36. 1 M P a ） ,low thermal conductivity （0. 249 W / （ m · K ） , 300 ） and smaller average pore size in the matrix ofspecimen（ d50 = 46. 7 μm）.