Abstract: In order to effectively reduce the heat loss of lining materials and maintain a stable molten steel temperature,MgO-MgAl₂O₄-C refractories were prepared using high purity fused magnesia,self-made magnesium-aluminate spinel hollow aggregates,α-Al₂O₃ micropowder,magnesium-aluminate spinel powder,Si powder,Al powder and graphite as main raw materials,and thermosetting phenolic resin as the binder,heat-treating at 1 200 or 1 400 ℃ in the carbon embedded condition.The effect of the self-made magnesium-aluminate spinel hollow aggregates addition (0,3%,6%,and 9%,by mass) on the mechanical properties of lightweight MgO-MgAl₂O₄-C refractories was investigated.The results show that SiC and AlN are formed in the sample heat-treated at 1 200 ℃.Up to 1 400℃,plate-like MgAlON is found.With the increase of the magnesium-aluminate spinel hollow aggregates addition,the apparent porosity of the sample increases and the bulk density decreases.When the heat-treating temperature is 1 400 ℃,the sample with 6% magnesium-aluminate spinel hollow aggregates has the highest cold modulus of rupture and the cold crushing strength of 14.8 MPa and 121 MPa,respectively,and the modulus or rupture retention radio reaches 80%.The introduction of hollow aggregates changes the stress distribution direction and forms different dissipative mechanisms to strengthen and toughen the materials.

Key words: MgO-MgAl₂O₄-C refractories, hollow aggregate, MgAl₂O₄, mechanical properties

摘要： 为了有效降低内衬材料的热量损失,保持钢液温度稳定,以高纯电熔镁砂、自制镁铝尖晶石中空骨料、α-Al₂O₃微粉、镁铝尖晶石粉、Si粉、Al粉和鳞片石墨为主要原料,以热固性酚醛树脂为结合剂,经1 200 ℃和 1 400 ℃埋碳热处理制备了MgO-MgAl₂O₄-C耐火材料。探究了自制镁铝尖晶石中空骨料加入量(加入质量分数分别为0、3%、6%、9%)对轻质MgO-MgAl₂O₄-C耐火材料力学性能的影响。结果表明:经1 200 ℃热处理后试样中有SiC和AlN产生,升温至1 400 ℃时生成了片状MgAlON。随着镁铝尖晶石中空骨料加入量的增加,试样的显气孔率上升,体积密度下降。当热处理温度为1 400 ℃时,加入6%(w)镁铝尖晶石中空骨料试样的常温抗折强度和耐压强度均达到最大值,分别为14.8 MPa和121 MPa,抗折强度保持率高达80%。中空骨料的引入改变了应力分布方向,形成了不同的耗散机制,实现了对材料的增强增韧。

关键词: MgO-MgAl₂O₄-C耐火材料, 中空骨料, MgAl₂O₄, 力学性能