单斜氧化锆加入量对方镁石-尖晶石材料性能的影响

Effect of monoclinic ZrO_2 addition on properties of periclase-spinel refractories

为了进一步提高方镁石-尖晶石质耐火材料的性能,在以电熔镁砂颗粒(粒度为3~1和≤1 mm)、电熔镁砂细粉(粒度≤0.088 mm)和烧结尖晶石颗粒(粒度≤1 mm)为主要原料的方镁石-尖晶石质耐火材料中,分别添加质量分数为0、2%、4%和6%的单斜氧化锆细粉(≤0.088 mm),经混练、成型、干燥后,分别在1 600和1 700℃保温3 h烧成,检测烧后试样的显气孔率、体积密度、常温抗折强度、常温耐压强度、抗热震性和加热永久线变化,并分析部分试样的物相组成和显微结构。研究表明:1)添加单斜氧化锆细粉会提高烧后试样的烧后收缩和致密度,降低试样的常温强度和弹性模量;当单斜氧化锆加入量为2%(w)时,试样的抗热震性最佳。2)随着烧成温度的提高,试样的烧后收缩和致密度均增大,常温强度变化不大。1 700℃烧成后,Zr O2除了以mZr O2形式存在外,还有少量t-Zr O2和Al0.1Zr0.9O1.95存在,增加了材料的直接结合程度。3)当单斜氧化锆细粉加入量为2%(w),烧成温度为1 700℃时,烧后试样的综合性能较优。

In order to improve the properties of periclase-spinel refractories,the specimens were prepared using fused magnesia（3-1 mm,≤ 1 mm,≤0. 088 mm） and sintered spinel（≤1 mm） as raw materials,adding monoclinic zirconia（≤0. 088 mm） to the specimens with mass fraction of 0,2%,4% and 6%,respectively,milling,shaping and drying,and then firing at 1 600 ℃ and 1 700 ℃ for 3 h,respectively. The permanent linear change rate,apparent porosity,bulk density,cold modulus of rupture,cold crushing strength and thermal shock resistance were tested,the phase composition and microstructure of some specimens were analyzed. The research reveals that：（1） the addition of monoclinic zirconia fines can increase the shrinkage and density,reduce the cold strength and elastic modulus of the specimens; when the monoclinic zirconia addition is 2%,the thermal shock resistance is the best;（2） increasing the firing temperature can enhance the shrinkage and densification,and change the cold strength slightly; after fired at 1 700 ℃,besides m-ZrO2,ZrO2 also exists in forms of a little t-Zr O2 and Al0.1 Zr0.9 O1.95,which enhance the direct bonding of the material;（3） better comprehensive properties of the periclase-spinel refractories can be reached at 1 700 ℃ with 2% monoclinic zirconia.