高炉炉缸用后炭砖中脆化层的研究

Research of the brittle layer in carbon brick of blast furnace hearth after use

采用钻孔取芯的方法,在用后高炉炉缸的不同部位取得了完整的用后炭砖样品。对这些样品中的脆化层进行基础性研究,包括宏观物貌、微观结构、物性参数和化学组成等,同时比较了单向正压力作用下炭砖的破坏形态和微观结构形态。认为脆化层出现在炉役的早期,发展在中期,稳定在后期。以微裂纹形态出现的早期脆化层是应力作用的结果,后期因穿过裂纹的煤气流中所含碱金属等物质的沉积和腐蚀,加剧了脆化层的质变和范围的扩大,进而改变了砖衬结构的传热体系,直至建立新的热平衡。提出改善炭砖的基质和孔径并提高导热性和抗疲劳损伤能力是弱化脆化层的形成、提高炭砖使用效果的有效途径。

The carbon samples were obtained by boring in different parts of the hearth wall of the blast furnace after use. By doing research of the brittle layers of these samples, including the macroscopic appearance, the microcosmic structure, physical properties and chemical compositions, and comparing with the failure mode and the micro-structure of new carbon brick after pushing in the positive direction, it is concluded that the brittle layer began to appear at the early stage, developed in the middle stage, and stabilized in the later stage in the campaign. The reason of brittle layer formation in micro-crack in the early stage is the stress. And in the later stage, the deposition and the corrosion of the alkali metal in the gas through these micro-crack make the brittle layer to metamorphose and expand. The teat transfer system of lining structure is destroyed until the new heat balance is established. It is put forward that improving the stroma and aperture of the carbon brick, and increasing the thermal conductivity and the anti fatigue ability are the effective ways to weaken the formation of the brittle layers and to enhance the use effect of the carbon brick.