普通烧结镁砂骨料中杂质相对镁碳耐火材料抗热震性和高温断裂行为的影响  

Influence of Impurities in Ordinary Sintered Magnesia Aggregates on Thermal Shock Resistance and High Temperature Fracture Behavior of MgO–C Refractory

作　　者：汪超 李亚伟[1] 徐小峰[1] 陈启龙 王官正 WANG Chao;LI Yawei;XU Xiaofeng;CHEN Qilong;WANG Guanzheng(Wuhan University of Science and Technology,The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,National-provincial Joint Engineering Research Center of High Temperature Materials and Lining Technology,Wuhan 430081,China)

机构地区：[1]武汉科技大学,省部共建耐火材料与冶金国家重点实验室,高温材料与炉衬技术国家地方联合工程研究中心,武汉430081

出　　处：《硅酸盐学报》2024年第6期2094-2106,共13页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金联合基金重点项目(U1908227);青海省科技成果转化专项(2023–GX–102)。

摘　　要：镁碳砖是炼钢过程中重要的耐火材料之一。为进一步提高其抗热震性,本文利用普通烧结镁砂存在少量低熔点相特性,在镁碳材料制备过程中部分替代电熔镁砂骨料,使之在服役条件下(1 000~1 700℃)材料基体内产生局部液相,缓解材料中应力集中的问题。结果表明:经1 000℃热处理后镁碳材料内普通镁砂骨料保持完整;温度升至1 400℃,部分普通镁砂骨料中的杂质溶出并向周围基质中扩散,骨料瓦解呈多孔结构。此外,基质内因单质硅的引入,除形成大量的晶须状和颗粒状Mg_(2)SiO_(4)相外,还出现了Si C晶须;1 600℃热处理时,杂质溶出扩散加剧,基质中存在颗粒状Mg2SiO4相和Si C晶须。上述材料在高温下的结构变化,提高了材料的强度,甚至高温抗折强度,改善了材料的抗热震性能。高温劈裂实验表明,烧结镁砂的孔隙结构缓解了应力集中,而1 400℃条件下液相的形成促进了烧结和基质中晶须的形成,增加裂纹沿骨料–基质界面扩展的比例,最终导致材料的断裂能和抗热震因子增加。Introduction MgO–C refractories are extensively utilized as lining materials for smelting equipment(i.e.,converters,ladles,and electric arc furnaces)due to their excellent resistance to slag erosion and thermal shock.Nevertheless,under high scrap ratio smelting conditions,MgO–C refractories are subjected to mechanical stress due to the introduction of scrap steel and thermal stress caused by frequent fluctuations in service temperatures,resulting in a substantial reduction in their operational lifespan.It is thus crucial to further enhance the mechanical properties and thermal shock resistance of MgO–C refractories.In recent years,effective approaches on the composition and structural design of materials are explored,which include the construction of nanostructure matrices,light-weighting and strengthening of magnesia-based aggregates,the introduction of novel additives,and the optimization of secondary carbon in binders.Among them,calcium magnesium aluminate(CMA)aggregates as a novel porous aggregate have attracted much attention.At elevated temperatures,it induces a partial liquid phase within the material matrix,effectively mitigating internal thermal stresses,repairing micro-cracks resulting from thermal shock,and facilitating the formation and growth of spinel whiskers.Consequently,a substantial enhancement in both toughness and thermal shock resistance of the material is achieved.In fact,ordinary sintered magnesia aggregates contain certain impurity phases,such as merwinite(with a melting point of 1550℃)and andradite(with a melting point of 1170℃).When conventional fused magnesia aggregates partially are substituted with ordinary sintered magnesia aggregates in the preparation of MgO–C refractories,localized liquid phases can be generated within the matrix at high temperatures,which may serve a similar function to CMA aggregates.Compared to CMA aggregates,ordinary sintered magnesia aggregates are more affordable,resulting in a substantial reduction in production expenses and facilitating the eff

关 键 词：镁碳耐火材料 普通烧结镁砂 显微结构演变 抗热震性 断裂行为 

分 类 号：TQ175[化学工程—硅酸盐工业]