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在连铸过程中,结晶器保护渣在通过控制润滑来实现较好的可浇性和铸坯质量方面起到重要作用。在缺乏结晶器保护渣不同热物性的情况下,黏度是判断结晶器保护渣润滑性能的必要参数。许多研究人员(包括笔者)证实了熔融的结晶器保护渣的流变性能。实际操作中,在剪切速度约为10~40 s-1的结晶器上表面,为减少卷渣,需要高黏度保护渣;但是在剪切速度为100~1 000 s-1的结晶器壁,为了保证最大的润滑性能,保护渣黏度应该低。因此,这个特定的属性可能有利于实际连铸过程。目前的研究试图通过用旋转黏度计测量Ca O-Ca F2-Si O2、Ca OCa F2-B2O3-Si O2和Ca O-Ca F2-Si O2-Si3N4基保护渣体系的黏度来表征该体系的黏弹性(名为流变性能)。旋转黏度计配备一个1 623 K温度下受控氧逸度的熔炉。而且,通过拉曼光谱和XPS分析来了解结晶器保护渣黏弹性和结构之间的关系。根据结果,所有经检测的结晶器保护渣都具有流变性能,当剪切速率增大时,黏度降低。应用Oswald-De Waele指数模型来定量每个结晶器保护渣的剪切变稀度,得出每个结晶器保护渣的聚合度与剪切变稀行为的强度大体上成比正。
In the continuous casting process, the mold fluxes play an important role in achieving better castability and slab quality by controlled lubrication. In the absence of different thermophysical properties of mold flux, viscosity is an essential parameter for judging the lubricity of mold flux. Many researchers (including the author) have confirmed the rheological properties of molten mold fluxes. In practice, a high-viscosity mold flux is needed to reduce entrainment at a mold upper surface with a shear rate of about 10-40 s-1; however, at a mold wall with a shear rate of 100-1000 s-1, , In order to ensure maximum lubrication performance, mold flux viscosity should be low. Therefore, this particular property may be beneficial to the actual casting process. The present study attempts to characterize the viscosity of this system by measuring the viscosities of CaO-Ca F2-Si O2, Ca OCa F2-B2O3-Si O2 and CaO-Ca F2-Si O2-Si3N4 based mold fluxes using a rotational viscometer Flexible (named rheological properties). The rotary viscometer is equipped with a furnace with a controlled oxygen fugacity of 1 623 K. Also, understanding the relationship between mold viscoelasticity and structure by Raman spectroscopy and XPS analysis. Based on the results, all the tested mold fluxes had rheological properties and decreased in viscosity as the shear rate increased. The Oswald-De Waele index model was used to quantify the shear thinning of each mold powder and to conclude that the degree of polymerization of each mold powder is generally positive proportional to the shear thinning behavior.