CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系的粘性活化能

采用CaO-Si02-Na20-CaF2-Al2O3-MgO渣系，通过测定粘度和粘性活化能，建立二次回归正交设计模型，借此研究了粘性特征与碱度、Na20含量、CaF2含量、Al2O3含量及MgO含量之间的关系，为设计开发连铸保护渣提供了理论依据。研究结果表明，粘性活化能随着渣中碱度、Na2C03含量和CaF2含量的增加而减小；Al2O3和MgO对粘性活化能的影响与碱度密切相关。连铸保护渣的粘度和粘性活化能具有相似的变化规律。     

CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系的结晶温度

通过差热分析仪测定了CaO-SiO2—Na2O-CaF2—Al2O3—MgO系连铸结晶器保护渣的结晶温度。在本实验渣系条件下，连铸保护渣的结晶温度随着渣中CaO／SiO2值、Na2CO3含量、CaF2含量和MgO含量的增加而升高，随着渣中Al2O3含量的增加而降低。化学成分通过改变粘度，来影响晶核形成速度和晶体成长速度，从而决定了连铸保护渣的结晶性能。结晶温度随着保护渣粘度的降低而升高。     

助熔剂对CaO-Al2O3基保护渣理化性能的影响

针对高铝钢用钙铝基连铸保护渣在浇铸过程中存在的渣条严重、粘结漏钢报警频发等问题,通过调整助熔剂含量,考察了以B2O3替代CaF2对保护渣熔化温度、黏度及结晶性能的影响。结果表明,随着B_2O_3替代CaF2质量分数的增加,保护渣的熔化温度和转折点温度不断降低,高温下的黏度不断提高。而且,CaF_2质量分数较高时,保护渣的析晶性能较强,高温处析出Ca_(12)Al_(14)O_(32)F_2。随着B_2O_3取代CaF2质量分数的增加,保护渣的析晶性能受到明显抑制,析晶物相的变化规律为Ca_(12)Al_(14)O_(32)F_2→2CaO·Al2O3·SiO2→单一液相。B2O3取代CaF2质量分数为10%时,保护渣的析晶性能得到有效抑制,可有效降低粘结报警频率,满足高铝钢种的浇铸需求。     

碱度对CaO-SiO2-Al2O3系熔渣微观结构的影响

为了明确精炼渣冶金功能的微观本质,本文模拟精炼渣的化学组成,采用拉曼光谱测定并解析了CaO-SiO2-Al2 O3系实验渣的熔体结构.结果表明,熔渣中Si4+以[SiO4]-四面体结构形式存在,随着碱度的升高,Q1Si和Q2Si含量减少,Q0Si含量增加;Al3+以[AlO4]-四面体和[AlO6]-八面体结构形式存在...     

B2O3对高铝钢连铸保护渣理化性能的影响

高铝钢连铸过程中,为了避免或减轻钢液中Al与保护渣中SiO2发生反应,设计了低SiO2、高Al2O3含量的高铝钢连铸保护渣,通过添加适量的酸性氧化物B2O3协调熔渣酸碱性,利用实验分析了B2O3含量对高铝钢保护渣熔融特性、黏度特性及渣膜传热特性的影响.结果表明,B2O3含量在4%～10%时,随着B2O3含量增加,保护渣熔化温度、黏度、黏流活化能均降低,渣膜热流密度增加;保护渣的等温转变曲线(TTT曲线)向孕育时间增加的方向移动,晶体生长速率降低;实验条件下,增加B2O3含量可抑制保护渣中CaF2的析出.     

CaO-SiO2-Al2O3-Fe2O3渣系脱磷行为

利用Factsage软件计算了Al2O3含量对CaO-SiO2-Al2O3-Fe2O3四元渣系熔点和黏度的影响,并通过实验研究了在1 400℃时,CaO-SiO2-Al2O3-Fe2O3四元渣系对高磷铁水脱磷行为的影响.结果表明:渣中Al2O3的质量分数在3％～6％之间时,随着A12O3含量的增加,渣系的熔化温度迅速降低,进一步增加渣中的A12O3含量,渣系的熔化温度逐渐增加;Al2O3对CaO-SiO2-Al2O3-Fe2O3渣系的黏度影响不大;渣中Al2O3的质量分数在3％～6％之间变化时,渣系脱磷能力变化不是很大,脱磷率维持在91％左右,进一步增加渣系中A12O3的量,脱磷率逐渐下降;Al2O3对脱磷率产生影响可能是其改变了炉渣中液相所占比例,进而影响磷从铁水中向液相渣的传质过程.     

CaO-SiO2 -A2O3系保护渣加Li2O对高铝钢20Mn23AlV连铸板坯表面纵裂纹的影响

研究了 1.5%～2.5% Al的20Mn23AlV钢200 mm × 1260 mm铸坯表面纵裂纹产生机理。结果表明:20Mn23AlV表面纵裂纹与结晶器保护渣变性有关。保护渣渣中加入5.49%的Li₂O大幅提高了该钢种浇注过程保护渣理化指标的稳定性,且有利于将该钢种连铸坯表面纵裂发生几率由23.8%降至0.3%以下。     

Li2O对CaO-Al2O3基保护渣结晶性能的影响

摘要：高铝钢用新型CaO-Al2O3基连铸结晶器保护渣结晶性能较强,在连续浇铸过程中易出现润滑与传热功能协调不均的问题。基于此,针对新型CaO-Al2O3基保护渣,考察了典型助熔剂Li2O对保护渣析晶温度、析晶物相等性能的影响,并进行了相关结晶动力学分析。结果表明,提高Li2O含量可使保护渣的临界冷却速率和初始结晶温度呈现先降低后升高的趋势,当Li2O质量分数为4%时,保护渣结晶倾向最弱。随Li2O质量分数从0增至6%,保护渣的结晶孕育时间先延长后缩短。析晶物相由CaAl4O7+CaF2转变为CaAl4O7+CaF2+LiAlO2,Li2O的加入及其含量的提高促进了LiAlO2的析出。此外,随Li2O质量分数从0增至6%,保护渣结晶活化能先增大后减小,析晶过程受到的阻力先增强后减弱,与结晶性能的变化规律相吻合。     

CaO-SiO2-Al2O3-CaF2系精炼渣对钢绞线用 SWRH82B钢中D类夹杂物的控制研究

通过钢渣平衡实验研究,分析了精炼渣成分对82B钢液T.O和点状不变形夹杂物成分的影响;通过Fact-Sage热力学计算,得出硅锰脱氧82B钢中MgO·Al₂O₃尖晶石夹杂的生成条件.结果表明:降低精炼渣碱度、提高Al₂O₃含量均利于钢水全氧含量的降低;随着Al₂O₃含量的提高,复合氧化物夹杂的熔点升高.当熔渣碱度为0.93、Al₂O₃含量为5.1%时,夹杂物熔点最低;熔渣碱度为1.14、Al₂O₃含量为25.6%时,高Al₂O₃活度的熔渣导致MgO·Al₂O₃尖晶石夹杂生成;熔渣碱度为1.97、Al₂O₃含量为25.9%时,由于碱度升高,钢中无MgO·Al₂O₃尖晶石类夹杂物生成;熔渣碱度为0.93、Al₂O₃含量为5.1%时,由于Al₂O₃含量降低,钢中无MgO·Al₂O₃尖晶石类夹杂物生成,且夹杂物熔点较低.      

CaO-SiO_2-Na_2O-CaF_2-Al_2O_3-MgO保护渣系的Al_2O_3吸收速率和粘度

采用CaO -SiO2 -Na2 O -CaF2 -Al2 O3-MgO渣系 ,通过测定熔渣的粘度和Al2 O3吸收速率 ,研究连铸保护渣的Al2 O3吸收速率与粘度及化学成分之间的关系。在一定条件下 ,当CaO SiO2 为1 .2左右时 ,粘度达到最小值 ,Al2 O3吸收速率达到最大值 ,分别为 0 .1 0Pa·s、8.4 0 3× 1 0 - 4 kg·m- 2 ·s- 1 。随着渣中Na2 CO3含量、CaF2 含量和MgO含量的增加 ,粘度减小 ,Al2 O3吸收速率增大。随着渣中Al2 O3含量的增加 ,粘度增大 ,Al2 O3吸收速率减小。粘度为Al2 O3吸收速率的主要控制因素。随着熔渣粘度的增加 ,连铸保护渣的Al2 O3吸收速率逐渐减小。     

Structural behavior of F~- in mould flux melt of CaO-SiO_2-Al_2O_3-Na_2O-CaF_2 system

The influence of fluorine on the structure of CaO-SiO2-Al2O3-Na2O-CaF2 continuous-casting-type slag was measured by Raman spectroscopy, and the degree of polymerization of mould flux and the structural behavior of F- in the melt were investigated by classifying and quantifying the structural species of F- ions. The results exhibit that the main structural units of Si-O tetrahedra are Q0, Q1 and Q2, and the actual measured number of non-bridging oxygen ions in the ［SiO4］-tetrahedra (denoted by NBO/T) increases from 2.73 to 3.44 with increasing the molar ratio of F to (F+O) (denoted by XF/X(F+O)) from 0.06 to 0.19. It means that the degree of polymerization of melt structure decreases with an increase in XF/X(F+O). In addition, most of F- ions were distributed in Si-O tetrahedra and Al-O tetrahedra. With increasing XF/X(F+O), the complex structural units Al-O tetrahedra are gradually replaced by discrete structural units AlF4- because of the breakage of Al-O bonds in Al-O tetrahedra by F- ions, and the Si-O (bridging oxygen) bonds of Si-O tetrahedra are broken to form ［SiOnF4-n］-tetrahedra by F- ions coordinating with Si4+.     

高铝钢连铸保护渣性能的控制

 高铝钢连铸过程中,钢渣反应将导致连铸保护渣成分和性能发生较大的变化。论文从热力学方面分析了高铝钢钢渣反应特性,计算结果表明为了减少渣中SiO2的还原,应控制渣中的SiO2含量,此外,在连铸保护渣中配加MnO能抑制渣中SiO2的大量还原;同时采用高碱性高玻璃化连铸保护渣理论保证熔渣在钢渣反应和吸收Al2O3夹杂后性能的稳定性。在此基础上,进行了工业性试验,结果表明：高铝钢连铸保护渣吸收夹杂物后熔点和粘度变化不大,铸坯表面和皮下质量良好,完全满足高铝钢浇铸要求。     

Nb-Ti微合金钢的静态再结晶行为

 通过双道次压缩试验研究了Nb-Ti微合金钢的静态再结晶行为,确定了应变诱导沉淀析出前Nb-Ti微合金钢的静态再结晶激活能,并建立了静态再结晶动力学模型。采用面积法及积分-能量法计算的软化率,很好地反映了微合金钢的静态再结晶行为及应变诱导沉淀析出行为。应变诱导沉淀析出的鼻尖温度在900～925℃之间,静态再结晶的临界温度（SRCT）高于950℃。     

Properties of High Basicity Mold Fluxes for Peritectic Steel Slab Casting

 In high speed continuous casting of peritectic steel slabs, mold fluxes with high basicity are required for less surface defect product. However, the basicity of remaining liquid slag film tends to decrease in casting process because of the crystallization of 3CaO·2SiO2·CaF2. Thus, a way is put forward to improve mold fluxes′ properties by raising the original basicity. In order to confirm the possibility of this method, the effect of rising original basicity on the properties of mold fluxes is discussed. Properties of high fluorine based mold fluxes with different basicities and contents of CaF2, Na2O, and MgO were measured, respectively. Then, properties of higher basicity mold fluxes were discussed and compared with traditional ones. The results show that increasing the basicity index can improve the melting and flow property of mold fluxes. With the increasing basicity, crystallization rate of mold fluxes increases obviously and crystallization temperature tends to decrease when the basicity exceeds 1.35. The method presented before is proved as a potential way to resolve the contradiction between horizontal heat transfer controlling and solidified shell lubricating for peritectic steel slab casting. But further study on improving the flow property of liquid slag is needed. This work can be used to guide mold fluxes design for high speed continuous casting of peritectic steel slabs.     

Crystallization Behavior in Fluoride-Free Mold Fluxes Containing TiO2/ZrO2

  The time temperature transformation (TTT) diagrams of fluoride free mold fluxes containing TiO2/ZrO2 were constructed through the confocal scanning laser microscope (CSLM) technique. It was found that the crystallization temperature of F free mold fluxes containing TiO2 or ZrO2 increases, while incubation time decreases with increasing basicity. The crystallization tendency increases with the zirconia addition in slag melt, as it may be thought that the addition solubility is limited in molten slag and the solid particles act as heterogeneous nucleation sites. Three types of crystal morphologies were observed, corresponding to different crystallization mechanisms. CaSiO3 and Ca3Si2O7 precipitate in the slag with low basicity, and Ca2SiO4 was formed with increasing basicity. The addition of TiO2 promotes the precipitation of CaTiO3. The logarithm of crystal growth rate increased with increasing isothermal temperature, suggesting that the crystal/melt interface reaction is the controlling step in the present experiment.     

高铝钢连铸保护渣结晶矿相的研究

 针对高铝钢浇铸过程中保护渣Al2O3含量大幅增加而导致保护渣玻璃形态恶化的问题,采用SEM和XRD分析方法对高铝钢浇铸前后保护渣的显微组织和结晶矿相进行分析,研究了不同组分对保护渣结晶性能的影响。结果表明：高铝钢连铸保护渣初始SiO2含量较高,保护渣玻璃形态较好。浇铸过程中随着保护渣Al2O3含量的增加和SiO2含量的减少,保护渣的结晶率增加,玻璃性能变差;渣中Li2O容易与F-生成LiF晶相;渣中CaF2含量较高时,容易析出CaF2晶体。     

CaO－SiO_2－Al_2O_3－MgO渣系的作用浓度模型及其应用

应用炉渣的共存理论建立了ＣａＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＭｇＯ四元系的作用浓度模型，将大冶钢厂和上钢五厂以及日本山阳钢厂、的轴承钢精炼渣系代入模型进行计算。选取了对钢水的纯净度有直接影响的结构单元的作用浓度对三者的脱氧、脱硫能力以及钢中点状夹杂物形成趋势进行了分析。计算结果说明，大冶的精炼渣系点状夹杂物形成趋势小，而山阳的精炼渣系具有较强的脱硫和脱氧能力。分析结果与检验结果一致。     

高拉速用连铸保护渣的研究现状

概述了高拉速连铸的特点及对保护渣的要求，总结了国内外近年来在高拉速用连铸保护渣方面的研究、生产和应用现状。重点介绍了国内外近年来有关高拉速板坯连铸保护渣中各成分对粘度、熔化温度、熔化速度的影响以及保护渣生产制造工艺的研究成果和应用实例。