低碳连铸保护渣对水口耐材的侵蚀行为

 为达成“双碳”目标,目前国内钢铁企业致力于研发高性能的低碳、超低碳结晶器保护渣。低碳或超低碳结晶器保护渣具备适宜的物化性能,是高效、稳定连铸生产的基础保障,然而有关低碳保护渣对浸入式水口材料的润湿和侵蚀行为的研究甚少。通过高温润湿试验研究了中碳结晶器保护渣、低碳结晶器保护渣与ZrO₂-C水口耐火材料的润湿和侵蚀行为,结合微观结构分析阐明了低碳结晶器保护渣对浸入式水口渣线材料的侵蚀机理。研究结果表明,低碳结晶器保护渣与ZrO₂-C水口耐火材料的润湿性更好,且与传统型中碳结晶器保护渣相比较,在相同温度区间段内低碳结晶器保护渣与水口渣线ZrO₂-C材料的接触角小,熔渣在水口表面铺展更快;由微观结构分析可知,低碳结晶器保护渣对水口渣线ZrO₂-C材料的侵蚀程度较严重,且侵蚀深度更大。由于碳元素含量的影响,使得低碳结晶器保护渣与水口渣线ZrO₂-C材料润湿性更好,为低碳结晶器保护渣向水口内部溶解和渗透提供动力学条件。另外,相较于中碳结晶器保护渣,低碳结晶器保护渣与水口材料的碳浓度差更大,致使碳原子的扩散驱动力更强,进而影响两相界面的润湿、溶解以及化学反应。另外,通过工业试验结果表明,在连铸生产过程中,使用低碳结晶器保护渣时浸入式水口渣线部位颈缩更为严重,本研究结果可为连铸生产提供一定的指导和借鉴。

Erosion behavior of low carbon mold flux on submerged nozzle refractory

In order to achieve the goal of "double carbon", domestic iron and steel enterprises are currently committed to developing high-performance low-carbon and ultra-low carbon mold powder. Low carbon or ultra-low carbon mold flux has appropriate physical and chemical properties,which is the basic condition to ensure efficient and stable continuous casting production. However,there is little research on the wetting and erosion behavior of low carbon mold flux on submerged nozzle materials. In this paper,the wetting and erosion behavior between medium and low carbon mold flux and ZrO₂-C nozzle refractory were studied through high temperature wetting experiment. Combined with microstructure analysis,the erosion mechanism of low carbon mold flux on nozzle slag line material was clarified. The results show that the wettability of low-carbon mold flux and ZrO₂-C nozzle refractory is better,and compared with the traditional medium carbon mold flux,the contact angle between low-carbon mold flux and ZrO₂-C material is smaller and the mold flux spreads faster on the nozzle surface at the same temperature range. According to the microstructure analysis,the erosion degree of low-carbon protective slag on ZrO₂-C material of nozzle slag line is serious, and the erosion depth is large. Due to the influence of carbon content,the wettability between low-carbon mold flux and ZrO₂-C material of nozzle slag line is better,which provides favorable kinetic conditions for the dissolution and penetration of low-carbon mold flux into the nozzle. In addition,compared with medium carbon slag,the carbon concentration difference between low-carbon mold flux and nozzle material is larger,resulting in greater diffusion driving force of carbon atoms,which affects the wetting,dissolution and chemical reaction of the interface between the two phases. In addition, the industrial test results show that the necking of the slag line of the immersed nozzle is more serious when the low-carbon mold powder is used during the continuous casting production process. The results of this study can provide certain guidance and reference for the continuous casting production.