刚玉-莫来石材料高温断裂性能

为了研究刚玉-莫来石材料的高温断裂和变形性能,采用三点弯曲法研究了红柱石、板状刚玉、电熔莫来石3种不同骨料刚玉-莫来石材料的高温抗折强度和应力-应变曲线,并从材料的显微结构得到解释.以红柱石为骨料的材料形成薄膜状莫来石-刚玉结构,未发现玻璃相存在;其强度最高温度点在1000 ℃,高低温强度相差不大;800～1400 ℃应力-应变曲线分别显示出弹性、塑性特点.以板状刚玉为骨料的材料,基质由粒状刚玉、少量柱状薄膜状莫来石和微量玻璃相组成;其强度最高温度点在800 ℃,高低温强度相差很大;800～1400 ℃应力-应变曲线分别显示出弹性、塑性和粘滞流动3个阶段.以电熔莫来石为骨料的材料,性能与红柱石骨料接近,只是强度最高温度点在800 ℃,断裂前的变形量稍大.莫来石充当了莫来石晶种的作用,形成刚玉莫来石网状结构.

Hot Rupture and Deformation of Corundum-Mullite Refractories

Hot rupture and deformation of corundum-mullite refractories was studied by three-point bending method. Our study included hot modulus of rupture and strain-stress curves up to 1400 ℃ with different aggregates of andalusite, tabular alumina and fused mullite. The results was interpreted by microstructure. When andalusite is used as fundamental aggregates as fired at 1450 ℃, the microstructure of corundum bonded by amorphous mullite without glass phase is formed; samples have high HMOR close to their CMOR and get highest hot strength at 1000 ℃; stress-strain curves show elasticity and plasticity regions during 800 ～1400 ℃. When tabular alumina is used as fundamental aggregates as fired at 1450 ℃, the microstructure of matrix is constituted by granular corundum, a small amount of columnar or amorphous mullite and trace quantity of glass phase; the HMOR gets highest at 800 ℃ and declines sharply above 800 ℃ with a big amount of deformation before rupture; stress-strain curves show three regions: elasticity, plasticity and viscous flow during 800 ～1400 ℃. When fused mullite is used as fundamental aggregates, the HMOR and strain deformation before rupture are similar to that using andulusite aggregates. But the temperature of top HMOR is 800 ℃ and it has a slightly bigger strain deformation. The corundum and mullite crystals constitute network owing to mullite as seed crystal.