镁锆砖和镁铬砖的抗RH炉渣侵蚀性对比

为取代RH炉用镁铬材料,以电熔镁砂为主原料,分别加入单斜锆、脱硅锆、单斜锆与脱硅锆的混合粉、锆英石制备了ZrO2质量分数分别为15%和20%的镁锆砖,并利用静态坩埚法对比研究了镁锆砖和镁铬砖的抗RH炉渣侵蚀性。结果表明:对于Al2O3含量高且碱度(CaO/SiO2比)大的RH炉渣,镁锆砖抗侵蚀性能优于镁铬砖的;镁锆砖的侵蚀机理是砖中的ZrO2与渣中的CaO迅速反应,形成高熔点物相CaZrO3,能堵塞砖中的孔隙而形成致密保护层,从而阻止钢渣对镁锆砖的进一步侵蚀;而镁铬砖的侵蚀机理是渣中的Al2O3、Fe2O3等R3 和镁铬尖晶石中Cr3 交换,渣与砖反应生成的镁铝尖晶石和镁铁尖晶石使得材料变性,同时由于体积效应使镁铬材料鼓胀开裂,从而导致镁铬砖的严重侵蚀。

Comparison of corrosion resistance of magnesia-zirconia brick and magnesia-chrome brick to RH furnace slag

The magnesia-zirconia bricks containing 15% and 20% zirconia respectively were prepared with fused magnesite as starting materials,adding monoclinic zirconia,desilicon-zirconia,the mixed powder of monoclinic zirconia and desilicon-zirconia,zircon respectively to replace magnesia-chrome materials for RH furnace.The corrosion resistances of magnesia-zirconia brick and magnesia-chrome brick to RH slag was researched comparatively by static crucible method.The results show that:(1)The magnesia-zirconia brick has better corrosion resistance to RH slag with high alumina content and basicity(CaOSiO2)than that of magnesia-chrome brick;(2)The corrosion mechanism of MgO-ZrO2 brick is that ZrO2 in brick and CaO in slag react rapidly forming high melting point phase CaZrO3,which can fill the pores of brick forming dense layer and prevent the further penetration of steel slag to magnesia-zirconia brick;(3)The corrosion mechanism of MgO-Cr2O3 brick is that R3 in Al2O3 and Fe2O3 exchanges with Cr3 in magnesia-chrome spinel forming magnesia-alumina spinel and pleonaste,which results in denaturation of materials,and expansion and crack of magnesia-chrome brick because of volume effect as well,so the bricks are badly corroded.