Abstract: In order to improve the comprehensive performance of high density zirconia metering nozzles for continuous casting of steel billets,dense zirconia materials were prepared using 60 mass% monoclinic zirconia powder and 40 mass% fused magnesia stabilized zirconia powder as raw materials,extra-adding 1.1 mass% magnesia micropowder and a certain amount of yttria micropowder as the stabilizers.The materials were formed into 125 mm×10 mm×10 mm specimens and standard nozzle cores,and fired at 1 730 ℃ for 8 h.The effects of yttria extra additions (0,0.325%,0.65%,0.975%,and 1.3%,by mass) on the properties,microstructure,and phase composition of zirconia materials were studied.The results show that with the increase of the yttria extra-addition,the netlike microcrack can be bridged,and the cold modulus of rupture and erosion resistance to molten steel of the material can be improved.However,the reduction in the proportion of monoclinic zirconia and the bridging of netlike microcrack are detrimental to the thermal shock resistance of the material.By controlling the yttria extra-addition,the thermal shock resistance and erosion resistance to molten steel of the material can meet different working conditions.

Key words: magnesia-stabilized zirconia, metering nozzle, monoclinic zirconia, thermal shock resistance, liquid steel erosion resistance

摘要： 为了提高钢铁小方坯连铸用高密度氧化锆定径水口的综合性能,以60%(w)的单斜氧化锆粉、40%(w)的电熔氧化镁稳定氧化锆粉为主要原料,外加1.1%(w)的稳定剂氧化镁微粉和一定量的氧化钇微粉,成型为125 mm×10 mm×10 mm的试样和标准水口芯,经1 730 ℃保温8 h制备了高密度氧化锆材料。研究了稳定剂氧化钇外加量(外加质量分数分别为0、0.325%、0.65%、0.975%和1.3%)对氧化锆性能、显微结构、物相组成的影响。结果表明:增加氧化钇的外加量,可以弥合网状微裂纹,提高材料的常温抗折强度与耐钢液冲刷性,但单斜氧化锆相占比减少与网状微裂纹的弥合对材料抗热震性不利。通过控制氧化钇外加量,可以调整材料的抗热震性与耐钢液冲刷性,以满足不同的工况要求。

关键词: 镁稳定氧化锆, 定径水口, 单斜氧化锆, 抗热震性, 耐钢液冲刷性