Cr_2O_3含量对凝胶粉结合铝镁不烧砖力学性能的影响

The Effects of Cr_2O_3 Addition on Mechanical Properties of Gel Powder Bonded Al_2O_3-MgO Unfired Bricks

以各种粒径的棕刚玉、白刚玉(<0.047mm)、镁砂细粉和α-Al_2O_3为主要原料,铝凝胶粉为结合剂,研究了了Cr_2O_3粉加入量对精炼钢包铝镁不烧砖线变化率、抗折强度、耐压强度、显气孔率、体积密度和高温抗折强度的影响,并借助XRD和SEM研究了不烧砖的物相组成和显微结构。结果表明:随着Cr_2O_3粉加入量的增加,材料烘干后的显气孔率降低,体积密度上升,而强度变化不明显;高温处理后,当Cr_2O_3加入量为超过1%后,材料的抗折耐压强度逐渐降低;高温抗折强度也是先增大、后降低。本实验条件下,Cr_2O_3粉加入量在1%时,不烧砖的性能较好。

The effects of additions of Cr2O3 fines on the properties of Al2O3- MgO unfired bricks for refining ladel were investigated using brown corundum,white corundum（0.047mm）,MgO fine andα-Al2O3 as the main raw material,and Al2O3-SiO2 gel powder as binder.The emphasis focused on the properties of linear change rate, Modulus of rupture（MOR）,compressive strength,apparent porosity,bulk density and hot modulus of rupture （HMOR）.The phase compositions and microstructure were also determined by means of X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results showed that apparent porosity of materials was went down and the bulk density was increased with the increase of addition of Cr2O3 fines at 1he normal temperature,but the strength of materials wasn＇t changed markedly;apparent porosity was increased and bulk density was reduced, when the amount of Cr2O3 fine was over 1%at the high temperature;Meanwhile,apparent porosity increased and compressive strength decreased due to dimensional expansion caused by the formation of solid solution oi （Al,Cr）2O3.HMOR of specimens were first increased and then decreased as the incease of Cr2O3 fines.The Al2O3-MgO unfired bricks possessed overall optimum properties when 1%Cr2O3 fines were added under the experimental conditions.