摘要:
为了研究以矾土做原料合成铁铝尖晶石时其SiO2成分对合成铁铝尖晶石的影响,以氧化铁粉、α-Al2O3粉和碳粉为原料,分别加入质量分数为0、2%、5%和8%的SiO2粉,在氮气气氛中分别于1 400、1 450、1 500、1 550°C保温4h合成铁铝尖晶石.通过对所合成铁铝尖晶石的烧结性能、物相组成及微观结构进行分析,研究了SiO2加入量对铁铝尖晶石合成及烧结性能的影响.结果表明:氮气气氛下,加入2%(w)SiO2能够促进铁铝尖晶石的合成及烧结;加入大于5%(w)SiO2时,试样的体积密度迅速下降,SiO2与氧化铁生成大量的低熔点液相,Al2O3则以刚玉相存在,反而阻碍铁铝尖晶石相的生成.采用特级矾土为原料合成铁铝尖晶石时,由于矾土中杂质SiO2和TiO2以及R2O的大量存在,导致矾土基铁铝尖晶石的体积密度更低,烧结性能更差,用其制备的方镁石-铁铝尖晶石制品的性能较差.可见,合成铁铝尖晶石以矾土为原料是不合适的.%Hercynite was synthesized by using Fe2O3,α-Al2O3 and carbon powders as starting materials,adding SiO2 powder (0,2%,5% and 8% in mass),and firing in N2 atmosphere at 1 400,1 450,1 500 and 1 550 °C for 4 h,respectively.Influence of SiO2 addition on synthesis and sintering properties of hercynite was researched by analyzing the sintering performance,phase composition and microstructure.The results show that 2% SiO2 can accelerate the synthesis and sintering of hercynite in N2 atmosphere;when SiO2 addition is more than 5%,bulk density of the specimen falls rapidly,for Fe2O3 reacts with SiO2 generating a large quantity of low melting phase,and Al2O3 exists in corundum,impeding the formation of hercynite phase.Many impurities such as SiO2,TiO2 and R2O in special grade bauxite decrease bulk density and sintering performance of the synthesized bauxite based hercynite.The properties of periclase-hercynite bricks prepared from the synthesized hercynite are poor.So,bauxite is inappropriate to synthesize hercynite.