SiC加入量及烧成气氛对MgO-MgAl_2O_4质耐火材料性能的影响
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摘要
为改善炭素焙烧炉火道墙的导热性能,以高纯镁砂(5~2、≤2和≤0.088 mm)和预合成镁铝尖晶石(≤1 mm)为原料,SiC粉(≤0.088 mm)为添加剂,热固性酚醛树脂为结合剂,经配料、成型、烘干、1 500℃热处理3 h后,制备了MgO-MgAl_2O_4质耐火材料试样,并分别研究了SiC粉的加入量(质量分数分别为0、1%、2%、3%和4%)和烧成气氛(空气气氛或埋炭气氛)对MgO-MgAl_2O_4质耐火材料性能和显微结构的影响。结果表明:当SiC加入量为3%(w)时,经空气气氛烧后试样综合性能最好;当SiC加入量为4%(w)时,经空气气氛烧后试样的中心部位SiC氧化成SiO气体,形成边缘致密而中心疏松的蓄热体结构,热导率急剧下降;加入SiC后经埋炭烧后试样,由于SiC被氧化成SiO气体,导致试样孔隙率增加,试样的强度及热导率有所下降。
In order to improve the thermal conductivity of the flue wall of carbon baking furnaces,high purity magnesia(5-2 mm,≤2 mm,< 0. 088 mm) and pre-synthesized magnesium aluminate spinel(≤1 mm)were used as starting materials,SiC(< 0. 088 mm) as an additive,and thermosetting phenolic resin as a binder to prepare MgO-MgAl_2O_4 refractories. The starting materials were batched,shaped,dried,and fired at 1 500 ℃ for 3 h to obtain the final specimens. The effects of SiC addition(0,1%,2%,3%,and 4%,by mass) and firing atmosphere(in air or carbon embedded atmosphere) on the properties and microstructure of MgO-MgAl_2O_4 refractories were investigated. The results show that the specimen fired in air with3% SiC shows the optimum comprehensive properties; for the specimen with 4% SiC fired in air,SiC in its central part is oxidized into SiO gas,forming a regenerator structure dense in the edges but loose inside,which results in a sharp decrease of the thermal conductivity; for the specimens fired with carbon embedded,SiC is oxidized into SiO gas,which increases the porosity and declines the strength and thermal conductivity.
In order to improve the thermal conductivity of the flue wall of carbon baking furnaces,high purity magnesia(5-2 mm,≤2 mm,< 0. 088 mm) and pre-synthesized magnesium aluminate spinel(≤1 mm)were used as starting materials,SiC(< 0. 088 mm) as an additive,and thermosetting phenolic resin as a binder to prepare MgO-MgAl_2O_4 refractories. The starting materials were batched,shaped,dried,and fired at 1 500 ℃ for 3 h to obtain the final specimens. The effects of SiC addition(0,1%,2%,3%,and 4%,by mass) and firing atmosphere(in air or carbon embedded atmosphere) on the properties and microstructure of MgO-MgAl_2O_4 refractories were investigated. The results show that the specimen fired in air with3% SiC shows the optimum comprehensive properties; for the specimen with 4% SiC fired in air,SiC in its central part is oxidized into SiO gas,forming a regenerator structure dense in the edges but loose inside,which results in a sharp decrease of the thermal conductivity; for the specimens fired with carbon embedded,SiC is oxidized into SiO gas,which increases the porosity and declines the strength and thermal conductivity.
引文
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[2]张恒海,吕博,杨笠,等.新型HY-MAC快速导热火道墙砖研发和应用[J].轻金属,2013,34(2):69-78.
[3]张恒海.炭素焙烧炉面温度偏高的原因与危害及处理措施[C]//第二届国际铝用炭素技术会议论文集,青岛,2010:151-152.
[4]AKSEL C,AKSOY T.Improvements on the thermal shock behaviour of Mg O-spinel composite refractories by incorporation of zircon-3mol%Y2O3[J].Ceram Int,2012,38(5):3673-3681.
[5]EMMEL M,ANEZIRIS C G,SPONZA F.In situ spinel formation in Al2O3-Mg O-C filter materials for steel melt filtration[J].Ceram Int,2014,40(8):13507-13513.
[6]曹振兴,张伟,石干.二次尖晶石化反应对MA-Al2O3材料烧结的影响[J].耐火材料,2011,45(6):417-419.
[7]陈娜,赵惠忠,周芬,等.复合添加Ti O2和Zr O2对Mg O-MA材料性能的影响[J].耐火材料,2013,47(4):259-262.
[8]ZHU T B,LI Y W,SANG S B.Formation of hollow Mg O-rich spinel whiskers in low carbon Mg O-C refractories with Al additives[J].J Eur Ceram Soc,2014,34(6):4425-4432.
[9]GHOSH A,SARKAR R,MUKHERJEE B.Effect of spinel content on the properties of magnesia-spinel composite refractory[J].J Eur Ceram Soc,2004,24(9):2079-2085.
[10]张寒,余俊,赵惠忠.镁铝尖晶石粉加入量对Mg O-MA质材料性能的影响[J].耐火材料,2015,49(2):131-133.
[11]李楠,顾华志,赵惠忠.耐火材料学[M].北京:冶金工业出版社,2012:392-396.