纳米Al_2O_3对刚玉质耐火材料结构和性能的影响

Effects of nano-Al_2O_3 on microstructure and properties of corundum refractories

在以板状氧化铝、电熔白刚玉、烧结氧化铝微粉为主要原料的刚玉质耐火材料中通过机械混合法和前驱体(铝溶胶)法引入0、0.5%、1.0%、1.5%和2.0%(质量分数,下同)的纳米Al2O3,混练均匀后,以180MPa的压力压制成125mm×25mm×25mm的试样,于120℃干燥12h后,在硅钼棒电炉中于不同温度(1400℃、1500℃、1600℃和1650℃)下保温4h烧成,然后测定烧成后试样的体积密度、显气孔率、常温抗折强度和高温抗折强度,并采用SEM分析烧成后试样的显微结构。结果表明:以前驱体法引入纳米Al2O3对材料性能的优化效果明显好于机械混合法;在相同的工艺条件下,加入1.5%的纳米Al2O3对提高烧成试样的体积密度、常温抗折强度和高温抗折强度作用最明显;当纳米Al2O3加入量超过1.5%时,烧成试样的强度迅速降低。

Corundum refractories were prepared with tabular alumina, white fused alumina and calcined alumina micropowder as main starting materials. Different contents of nano-Al2O3 powder （0,0.5%, 1.0%, 1.5%, 2.0%） were added to the mixture by mechanical mixing and sol method respectively. The mixture was mixed for 5 min,and formed to 125 mm ×25 mm ×25 mm specimens under 180 MPa. The specimens were dried at 120 ℃ for 12 h and fired at 1400 ℃, 1500 ℃, 1600 ℃, 1650 ℃ for 4 h in electric furnace with Molybdenum Disilicide Heating Elements. The bulk density（ BD）, apparent porosity（AP）, cold modulus of rupture （CMOR） and hot modulus of rupture（HMOR） were measured and the microstructure was analyzed by SEM. The results show that： compared with mechanical mixing, adding nano-Al2O3 powder by sol -gel method leads to better optimization. Proper amount of nano powder （1. 5% ） could improve BD,CMOR and HMOR of the specimens obviously under the same firing condition ;If the addition of nano-Al2O3 in the composites was excessive （ 〉 1. 5 % ） ,the strength of the specimens decreases sharply.