反应烧结法合成镁铝尖晶石耐火材料

Synthesis of magnesia alumina spinel refractories by reaction sintering

以合成镁铝尖晶石(分为<350μm、<177μm和<74μm三种粒级)、镁砂(粒度<88μm)和刚玉粉(粒度<44μm)为原料,配制成尖晶石粒度不同,n尖晶石:n镁砂:n刚玉粉分别为80:10:10、60:20:20、40:30:30、30:35:35、20:40:40和10:45:45的试料,分别以100MPa、150MPa和200MPa的压力压制成50mm×20mm的柱状试样,在120℃干燥24h后于1600℃2h烧成,通过反应烧结法合成镁铝尖晶石耐火材料。测量烧后试样的线变化率、显气孔率和体积密度,并利用XRD和SEM分析烧后试样的相组成和显微结构。试验结果表明:随着镁砂和刚玉粉含量的增加以及尖晶石原料粒度的增大,烧后试样的线收缩率和体积密度减小,显气孔率增大;随着成型压力的增大,试样的线收缩率和显气孔率减小,体积密度增大;采用粒度<177μm的尖晶石原料,按n尖晶石:n镁砂:n刚玉粉=20:40:40的比例配料,在200MPa压力下成型,经1600℃2h烧成,可获得显气孔率为16.3%,烧成线收缩率为0.42%的镁铝尖晶石耐火材料。

Magnesia-alumina spinel （ 〈350μm, 〈177μm and 〈74μm）,magnesia （ 〈88μm） and corundum powder （ 〈44μm） were used as the starting materials. The magnesia-alumina spinel specimens with n（spinel）： n （ magnesia ）： n（ corundum powder ） of 80 ： 10 ： 10,60 ： 20 ： 20,40 ： 30 ： 30,30 ： 35 ： 35,20 ： 40 ： 40 and 10 ： 45 ： 45 were prepared by pressing at 100 MPa,150 MPa and 200 MPa,then dried at 120 ℃ for 24 h and sintered at 1600℃ for 2 h by reaction sintering. The linear change rate,apparent porosity and bulk density of the specimens were determined,the phase composition and microstructure of the specimens were analyzed by XRD and SEM. The results showed that the apparent porosity of the specimens increased with the increasing of magnesia and corundum powder content as well as the spinel size,on the contrary,the bulk density and linear shrinkage rate decreased The bulk density ot the specimen increased with the increasing of molding pressure.however,the apparent porosity and linear shrinkage rate decreased. With the spinel size less than 177 μm,the composition of n（ spinel ）： n（ magnesia）： n（ corundum powder） being 20：40：40,the molding pressure of 200 MPa and the sintering condition of 1600 ℃ for 2 h,the spinel refractories with the apparent porosity of 16.3% and the linear shrinkage rate of 0.42% were obtained.