Structure Evolution of Slag Films of Ultrahigh-Basicity Mold Flux During Solidification

Structure of Solidified Films of CaO-SiO₂-Na₂O Based Low-Fluorine Mold Flux<strong> </strong>

“…Several recent researches suggest a film with higher basicity and cuspidine ratio tend to has a higher conductivity [26,27] . The roughness of film surfaces contacted with the probe are with no causal relationship with crystallization [24,25] . Although, those approaches indicate crystals Thus, besides the larger thermal contact resistance provided by the larger surface roughness of solid slag film, which already proved in other works [24,25] , another explanation of mold fluxes with high-basicity and high-fluorine content can provide more stable performaces than the mold flux applied in this study is: cracks form in a fully crystallized film does not have the evolution process as shown in Figure 4b and 4c, besides, a thicker film with a smaller ratio of glassy layer also decreases the effect of internal cracks on the heat flux fluctuations.…”

“…The continual formation and fusion of cracks naturally contributes to the heat flux fluctuation (especially in the early stage of solidification, as shown in Figure 2). No similar cracks and large heat flux fluctuations were observed in solid films with high ratio of crystals [20,24,25] . Several recent researches suggest a film with higher basicity and cuspidine ratio tend to has a higher conductivity [26,27] .…”

“…The results of the thickness and heat flux density of films are shown in Figure 2. show similar fluctuation of heat flux through solidified fluorine-free films [20] , but for conventional and ultrahigh-basicity mold fluxes (with high F content), no apparent fluctuation was detected [24,25] . The fluctuation of heat flux densities is partially contributed by the formation and evolution of internal cracks of glassy films upon solidification, which will be discussed below.…”

“…Second, the probe is in a cubic shape with small width-thickness ratio, the obtained solid films are more likely affected by two-dimension cooling, which could affect the structure of films. To solve those problems, a water-cooled copper probe with a much smaller volume and large width-thickness ratio was developed to obtain consistent film thicknesses, structures, and reliable heat flux densities [20,24,25] .…”

Effect of Shear Stress on Isothermal Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Slags

“…Presently, the main method involves regulating the crystallization behavior of mold fluxes, such as increasing the basicity of mold fluxes to produce many crystals that control the horizontal heat transfer over the meniscus region. However, lubrication of the shell can be deteriorated by the high-alkalinity mold fluxes, and it can even enhance the possibility of breakout by sticking [4,5,6]. Therefore, the low-basicity and high-crystallization mold fluxes become the ideal slags for the casting of peritectic steels.…”