Abstract: In this paper， a steel plant with high pulling speed thin thickness slab continuous casting process as the object is studied， the specific process parameters of the pulling speed of 5.5 m/min， pouring temperature of 1 544 ℃， crystallizer water pressure of 15.6 Pa， the cooling water temperature of 39.1 ℃， and the inverted taper of the crystallizer 7.5 mm and so on.In the process of on-site continuous casting， it was found that the risk of slag rolling increased and the casting bond alarm occurred frequently， the conventional slags and non-Newtonian fluid mold flux with only shear-thinning properties could not effectively in solving these problems .With the mold flux of medium carbon steel on-site as the original mold flux ， combined with additives such as MgO and SiC ， a new type of protective slag with strong shear-thinning properties and high surface tension is prepared. The shear thinning properties， surface properties and microstructure of mold flux were detected and studied by rotating cylinder method and other methods. The results show that with the increase of SiC content， the shear thinning property， contact angle， surface tension and interface tension of the mold flux all show the trend of increasing first and then decreasing， the content of C-O bond and C-Si bond increases， and the degree of molecular polymerization increases . When the SiC content is 0.98%， the shear thinning property is the strongest， and the contact angle， surface tension and interfacial tension are the largest. This enables the mold flux to meet the viscosity requirements at different shear rates， thus effectively suppressing the crystallizer slag rolling behavior and reducing the risk of bond leakage.

Key words: Mold Flux, Shear Thinning, Sessile Drop Method, Surface Tension, Microstructure

摘要： 以某钢厂高拉速薄板坯连铸工艺为研究对象，工艺参数拉速为5.5 m/min、浇注温度1 544 ℃、结晶器水压15.6 Pa、冷却水温度39.1 ℃以及结晶器倒锥度7.5 mm等。现场连铸生产过程中发现，拉速提高后卷渣风险加剧和铸坯黏结报警频发，传统保护渣和仅具有剪切变稀性质的非牛顿流体保护渣均不能有效解决这些问题。以现场用中碳钢保护渣为原始保护渣，加入氧化镁和碳化硅等添加剂，制备出一种既具有较强剪切变稀特性又具有较高表面张力的新型保护渣。采用旋转圆筒法等方法对保护渣的剪切变稀性质、表面性质和微观结构进行检测和研究。结果表明，随着碳化硅含量的增加，保护渣的剪切变稀性质、接触角、表面张力和界面张力均呈现先增大后减小的趋势，碳氧键和碳硅键的含量升高，分子聚合度增大。当碳化硅含量为0.98%时，剪切变稀性质最强，接触角、表面张力和界面张力最大。这可以满足在不同剪切速率下对保护渣黏度的要求，从而有效降低卷渣风险，同时抑制黏结漏钢事故的发生。

关键词: 保护渣, 剪切变稀, 座滴法, 表面张力, 微观结构