共查询到19条相似文献,搜索用时 171 毫秒
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连铸过程通常采用调节配炭量和配炭方式来调节保护渣的熔化速度和熔融层状结构。本文通过单向加热炉模拟保护渣在结晶器内的熔化过程,研究了六种炭质材料对保护渣熔化速度和熔融结构的影响。结果表明:含量相同时对保护渣熔化速度的控制作用最强的是500目超细石墨,而后依次是:半补强炭黑、390石墨、中超炭黑、土状石墨、增碳剂;配炭方式相同时,保护渣的熔化温度越高,其熔化速度越慢;采用炭黑加石墨的配炭方式时保护渣的烧结层厚度随炭含量增加而减薄,且若炭黑量小于2%时形成多层熔融结构,否则将形成不含半熔层的三层结构。 相似文献
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通过对不同炭质材料和炭含量下连铸保护渣熔化性能的研究 ,得出炭质材料对保护渣熔化速度和熔融模型的影响规律 ,并对保护渣的烧结机理进行了讨论。 相似文献
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在保护渣的研制中,通过使用热特性仪,能够有规律的反映炭质材料对保护渣的熔化速度的控制效应,故提出一种用热特性仪测试保护渣熔化速度的测定方法. 相似文献
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建立了分析圆坯连铸机上保护渣层中热过程的有限元模型,所采用的是低炭(C≤6%)保护渣,其结论已在实际测量中得到了验证。研究了连铸过程中熔融渣厚度对保护渣性能及工艺参数的影响。 相似文献
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为了开发高速板坯连铸用保护渣,本文探讨了熔融保护渣的粘度,熔化速度。研究结果如下:1)从阴,阳离子相互作用参数及网络结构的函数方程计算熔融保护渣的粘度。2)从每单位体积碳含量和碳酸含量的函数方法计算熔化速度。3)以5.0m/min的浇铸速度结晶器保护渣利用效果最好。 相似文献
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利用机械化学原理对连铸结晶器用保护渣进行超细复合处理,在保护渣微颗粒表面上生成微量碳化硅熔点材料,可有效地延缓保护渣熔化速度,大幅度减少保护渣中外加碳含量,避免超低碳钢铸坯增碳。 相似文献
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《Canadian Metallurgical Quarterly》2013,52(4):467-476
The melting behaviour of mould powder during continuous casting is an important consideration with respect to caster performance, production rate and steel quality. Two important factors, powder composition and carbon addition, are critical to control the properties and melting behaviour of the mould flux. In this study, the effect of different carbonaceous materials on the melting characteristics of mould powders was evaluated. Correlations were established between the structural factors and chemical reactivity of carbon and melting behaviour of mould flux. In addition, two examples are given of the effect of flux composition on casting performance for specific steels. A flux with reasonable basicity and additives was designed for the casting of heat-resistant steel (Incoloy 800) to reduce surface cracks. Another flux was designed for the casting of non-magnetic steel containing high aluminium by partially replacing SiO2 with Al2O3 to limit aluminium oxidation by SiO2. 相似文献
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Kezhuan Gu Wanlin Wang Juan Wei Hiroyuki Matsuura Fumitaka Tsukihashi Il Sohn Dong Joon Min 《Metallurgical and Materials Transactions B》2012,43(6):1393-1404
An investigation was carried out to study the heat-transfer phenomena across mold flux film by using infrared emitter technique (IET). With IET, it is possible to develop the mold fluxes with a liquid layer at the top and a solid layer in contact with copper mold with the degree of varying crystallization. The dynamic crystallization and melting process of the mold fluxes as well as their effects on the overall heat-transfer rate in the mold were successfully conducted. The single hot thermocouple technique (SHTT) was also employed in this investigation to study the melting and crystallization behaviors of mold fluxes for the interpretation of IET results. The results suggested that the interfacial thermal resistance between the solidified mold flux and copper mold would significantly influence the heat-transfer rate in continuous casting and the melting of the mold flux tends to enhance the overall heat-transfer rate. The technique established in this article by utilizing the IET can be well applied to the investigation of mold flux thermal properties, which in turn gives guidelines for the design of new mold flux for continuous casting. 相似文献
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Effect of Carbon Properties on Melting Behavior of Mold Fluxes for Continuous Casting of Steels 总被引:1,自引:0,他引:1
Mold fluxes are synthetic slags used to coverthe liquid steel meniscus during continuous castingof steel.The flux,whichis continuously fed on thesurface of liquid pool during casting,melts first andthenflowsintothe gap between mold wall and solid-ified steel shell.It is well known that the perform-ance of the flux can greatly affect both the castingoperation and product quality.Because of its i mpor-tance,intensiveinvestigations have been performed,and considerable progress has been made[1-6].… 相似文献
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在包晶钢连铸过程中,裂纹类缺陷频繁出现。生产实践表明,采用结晶性能较强的保护渣可以有效减少纵裂纹的发生,但会恶化保护渣的润滑功能。近年来,超高碱度保护渣由于兼具开始结晶温度低、结晶速率快的特点,可以成功协调包晶钢连铸过程中润滑与传热的矛盾。但在超高碱度条件下,有关组分对保护渣结晶性能的影响研究不多,且相应的熔渣结构特征也鲜有报道。Na2O作为保护渣中一种常见的组元,对调节保护渣性能具有重要作用。论文采用半球点熔化温度测试仪、旋转黏度计以及高温原位结晶性能测试仪分析了超高碱度下(综合碱度R=1.75)Na2O对连铸保护渣熔化流动特性以及凝固结晶性能的影响规律和作用机制。研究结果发现,随着Na2O含量增加,保护渣的黏度(1 300 ℃)、熔化温度、转折温度和结晶温度都呈下降趋势,结晶速率呈现先减小后增大的趋势,当Na2O质量分数为6%时结晶速率最低。此外,研究还发现超高碱度保护渣中主要析出相为枪晶石(Ca4Si2F2O7),随着Na2O含量进一步增加,渣中出现新的结晶相CaF2和Na2CaSiO4F。 相似文献
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The melting behaviour of mould powder during continuous casting is an important consideration with respect to caster performance, production rate and steel quality. In this experimental study the effect of different carbonaceous materials on the melting characteristics of mould powders was evaluated. Using X‐ray diffraction, different types of carbon were quantitatively characterized in terms of their internal structure and reactivity experiments were conducted to investigate potential relationships between the structural morphology of carbons and their reactivity. High temperature microscopy and drip test experiments were then used to investigate the melting behaviour of mould powders containing different carbonaceous materials. From the results obtained, correlations were established between the structural factors, chemical reactivity and melting behaviour. 相似文献
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分别测定研究了在空气和氩气条件下,不同碳质材料(石墨和活性炭)及不同碳酸盐(MnCO3和Li2CO3)对同一种低碳(w(C)=3.0%)连铸保护渣熔速的影响。结果表明:在氩气保护下的熔速远比在空气中慢;使用石墨的熔速比使用活性炭的慢;MnCO3和Li2CO3的加入量分别存在最大值w(MnCO3)=12%和w(Li=CO3)=9%;在低于最大值的范围内,加入MnCO3或Li2CO3可显著降低熔速。 相似文献
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Carbon dissolution from graphite and coals was investigated by using a carburizer cover technique in an induction furnace.
The intent of the study was to investigate the influence of factors governing the rate of carbon dissolution from carbonaceous
materials, especially coals, into Fe-C-S melts. The factors studied were the initial melt carbon and sulfur concentrations
and the wettability between carbonaceous materials and the melt.
It was found that graphite dissolves markedly faster than coal. The rate of carbon dissolution from graphite could be decreased
by increasing the sulfur in the melt. Also, poor wetting could retard the rate of carbon dissolution by reducing the surface
area for mass transfer. Carbon dissolution from graphite is controlled by mass transfer in the liquid boundary layer adjacent
to the solid/liquid interface. The rate of carbon dissolution from coal is more sensitive to the molten iron composition.
A higher initial melt carbon and sulfur content retards the rate of carbon dissolution from coal more significantly than from
graphite. However, the rate constant of coal char dissolution does not show a strong dependence on the wettability. Carbon
dissolution from coals is most likely governed by a mixed-control mechanism that includes liquid-side mass transfer. The mechanisms
underlying the influence of bath sulfur on carbon dissolution from graphite and coals are discussed. 相似文献
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The interfacial phenomena between carbonaceous materials such as graphite, coke, coal, and char and Fe-C-S melts are important
due to the extensive use of these materials in iron processing furnaces. However, the understanding of the interfacial phenomena
between these kinds of carbonaceous materials and molten iron alloys is far from complete. In this study, graphite was selected
as the solid carbonaceous material because its atomic structure has been well established. The sessile drop method was adopted
in this investigation to measure the contact angle between solid graphite and molten iron and to study the interfacial phenomena.
The influence of carbon and sulfur content in Fe-C-S melts on the wettability of solid graphite has been investigated at 1600
°C. The melt carbon content was in the range of 0.13 to 2.24 wt pct, and the melt sulfur content was in the range of 0.05
to 0.37 wt pct. X-ray energy-dispersive spectrometer (EDS) analysis was conducted on an HITACHI S-4500 scanning electron microscope
to detect composition distribution at the interfacial region. It was found that contact of solid graphite with Fe-C-S melts
will result in a nonequilibrium reactive wetting. It involved carbon transfer from the solid to the liquid and iron transfer
from the liquid to the solid. The Fe-C-S melts exhibited relatively poor wetting when the reactions were absent. The mass
transfer between solid graphite and Fe-C-S melts was observed to strongly enhance the wetting phenomena. It is proposed that
the decrease of system free energy corresponding to the mass transfer reactions strongly influences the formation of the interface
region and results in the progressive spreading of the wetting line. The composition and thickness of the graphite/iron interfacial
layer was dependent on the intensity of mass transfer across the interface. The resulting change in the interfacial energy
γ
ls is a strong function of mass transfer, and it varies in accordance with time of contact. The influence of carbon content
on the wetting phenomena could only be seen at in the initial stages, whereas the influence of sulfur on the wettability was
found when the system approached equilibrium. Therefore, the interfacial tension in its equilibrium condition at the graphite/Fe-C-S
melt interface was determined only by the extent of sulfur adsorption at this interface. 相似文献