氧化铝微粉加入量对低碳镁碳砖性能的影响

Influence of alumina micropowder on properties of low carbon MgO-C brick

以电熔镁砂、石墨、金属Al和氧化铝微粉为主要原料,热塑性酚醛树脂为结合剂,制备了w(C)<5%的低碳镁碳砖试样,研究了氧化铝微粉加入量(其质量分数分别为0、3%、5%、7%、9%)对低碳镁碳砖的常温物理性能、抗热震性和抗氧化性的影响。结果表明:(1)随着氧化铝微粉加入量的增加,低碳镁碳砖试样的体积密度、常温强度和高温强度均先升高后降低,显气孔率则先降低后升高;抗热震性和抗氧化性随微粉加入量的增加呈先改善后变差的趋势;其中,微粉加入量为5%的低碳镁碳试样综合性能最好。(2)低碳镁碳砖试样性能的改善主要是由于加入的氧化铝微粉和MgO在高温下原位反应生成连续分布的尖晶石,增强了基质的陶瓷结合;但氧化铝微粉加入量过大时,由于大量原位反应引起材料产生过大的体积膨胀,会导致基质结构疏松,从而恶化镁碳砖的性能。

Low carbon MgO-C brick with 5% C was prepared using fused magnesia,graphite,Al micropowder,and alumina micropowder as main starting materials,and thermosetting phenolic resin as binder.Influence of alumina micropowder additions（0,3%,5%,7%,and 9%）on cold physical properties,thermal shock resistance,and oxidation resistance of low carbon MgO-C brick was investigated.The results show that：（1）with alumina micropowder addition increasing,bulk density,cold and hot strength,thermal shock resistance and oxidation resistance of the low carbon MgO-C brick are first enhanced and then declined,apparent porosity first decreases and then increases.The optimum addition of micropowder is 5%;（2）the improvement of properties is attributed to formed continuous spinel by in-situ reaction of alumina micropowder and MgO at high temperature,which strengthens ceramic bonding of matrix.Excessive alumina micropowder is detrimental to the properties for the formation of in-situ spinel leads to the excessive volume expansion and loose matrix of low carbon MgO-C specimens.