Abstract: In order to improve the properties of magnesia-zirconia refractories,the pre-synthesized CaZrO₃ (≤ 0.074 mm) with different CeO₂ extra-additions (0,1% and 2%,by mass) was firstly prepared using calcium carbonate,desilicated zirconia and CeO₂ as raw materials.Then,the pre-synthesized CaZrO₃ was mixed with fused magnesia (3-1,1-0.074 and ≤0.074 mm),and pressed into cylindrical and strip specimens under 250 MPa.The magnesia-zirconia refractories were prepared by heat treatment at 1 600 ℃ for 3 h.The effects of the pre-synthesized CaZrO₃ powder addition (10%,15% and 20%,by mass) on the properties of the materials were studied.The results show that:(1)a certain amount of CeO₂ forms a solid solution with ZrO₂,which makes ZrO₂ exist in the form of t-ZrO₂ at room temperature,stabilizes the crystal form of ZrO₂,and promotes the formation of CaZrO₃;(2)CeO₂ promotes sintering and is conducive to densification;the microcrack toughening caused by the difference on the thermal expansion coefficient between CaZrO₃,ZrO₂ and periclase improves the thermal shock resistance;the composite spinel and CaZrO₃ formed by the specimens and RH slag block pores and improve the slag resistance;(3)when adding 20% of the pre-synthesized CaZrO₃ with 1% CeO₂,the specimen has the optimal performance.

Key words: pre-synthesized CaZrO₃, magnesia-zirconia refractories, CeO₂, sintering properties, slag resistance, thermal shock resistance

摘要： 为提高镁锆材料的性能,首先以碳酸钙、脱硅锆和CeO₂为原料,制备不同CeO₂外加量(加入质量分数分别为0、1%和2%)的≤0.074 mm的预合成CaZrO₃粉,然后分别将其与3~1、1~0.074和≤0.074 mm的电熔镁砂混匀,在250 MPa压力下压制为圆柱试样和长条试样,于1 600 ℃保温3 h热处理制备了镁锆质耐火材料。研究了预合成CaZrO₃粉加入量(质量分数分别为10%、15%和20%)对材料性能的影响。结果表明:1)一定量的CeO₂与ZrO₂形成固溶体,使ZrO₂在室温下以t-ZrO₂形式存在,稳定了ZrO₂的晶型,促进了CaZrO₃的生成。2)CeO₂促进烧结,有利于致密化;CaZrO₃、ZrO₂与方镁石之间的热膨胀系数差产生的微裂纹增韧提高了抗热震性;材料与RH炉渣生成的复合尖晶石和CaZrO₃,堵塞气孔,提高了抗渣性。3)当外加1%(w)CeO₂预合成CaZrO₃,且预合成CaZrO₃加入量为20%(w)时,试样性能最佳。

关键词: 预合成CaZrO₃, 镁锆质耐火材料, CeO₂, 烧结性能, 抗渣性, 抗热震性