MgCO_(3)微粉对刚玉质弥散型透气砖性能的影响

Effect of MgCO_(3) micropowder on properties of corundum based dispersive purging plugs

为提高刚玉质弥散型透气砖的性能,以电熔白刚玉颗粒及细粉、α-Al_(2)O_(3)微粉、Cr_(2)O_(3)微粉等为原料,固定骨料与基质的质量比为85∶15,分别用质量分数为0、1%、2%、3%的MgCO_(3)等量替代电熔白刚玉细粉制备了刚玉质弥散型透气砖,研究了MgCO_(3)微粉加入量对其性能的影响。结果表明:加入1%(w)MgCO_(3)微粉时,试样常温耐压强度、常温抗折强度和高温抗折强度增加;继续增加加入量,试样的常温和高温强度下降,体积密度减小,显气孔率升高,且透气度变化不大。加入的MgCO_(3)高温下分解生成的MgO与基质中的Al_(2)O_(3)反应生成尖晶石起增强作用,当加入量过多时,试样膨胀率和高温强度下降,这与体系生成了低熔点相有关。

To improve the properties of corundum based dispersive purging plugs,fused white corundum particles and fine powder,α-Al_(2)O_(3)micropowder and Cr_(2)O_(3)micropowder were used as raw materials,the mass ratio of aggregates to matrix was 85∶15,and the fused white corundum fine powder was substituted with MgCO_(3)by different amounts(0,1%,2%and 3%,by mass).The effect of the MgCO_(3)micropowder addition on the properties of the purging plugs was studied.The results show that with 1%MgCO_(3)powder,the cold crushing strength,the cold modulus of rupture,and the hot modulus of rupture of the samples increase,while as the addition keeps increasing,the cold and hot strengths decrease,the bulk density decreases,the apparent porosity increases,and the air permeability slightly changes.MgO from the decomposition of MgCO_(3)at high temperatures reacts with Al_(2)O_(3)in the matrix to form spinel creating strengthening effect.With excessive MgCO_(3),the expansion rate and hot strength of the samples decrease,which is related to the formation of low melting point phases in the system.