Calculation Model for Surface Tension of Slag Melt

Based on the coexistence theory of slag melt structure and Butler’s equation,a new calculation model has been proposed for the calculation of surface tension of slag melt.This model establishes a specific correlation between surface tension and mass action concentrations(activities) in the melt and on its surface on the basis of inner and surficial structures of slag melt.Calculated surface tensions of CaO-SiOand MnO-SiOslag melts are consistent with those measured.Furthermore,iso-surface tension lines of CaO-MnO-SiOslag melt have also been calculated.

Effects of MgO content and CaO/Al_2O_3 ratio on surface tension of calcium aluminate refining slag

Surface tension of calcium aluminate refining slag was measured by the Slide method at 1823 K.Based on different levels of the MgO content and the mass ratio of CaO to Al_2O_3,the effects of MgO content and the mass ratio of CaO to Al_2O_3 on surface tension were investigated.The results indicate that surface tension decreased with increasing MgO content(from 0 to 4.86%),followed by an increase with further increasing MgO content up to 11.33%.The trend that surface tension changed with the mass ratio of CaO to Al_2O_3 was the same as the trend that surface tension changed with the MgO content.The surface tension was varied from 0.617 N/m to 0.710 N/m,for the mass ratio of CaO to Al_2O_3 varying between 0.60 and 1.28.An attempt was made to estimate surface tension of CaO-Al_2O_3-MgO slag and its sub-system,and the application showed that the model worked well.

Effect of MgO and SiO_2 on surface tension of fluoride containing slag

Surface tensions of slag addition Mg O and Si O2 based on conventional 70%CaF 2-30%Al2O3 and 60%Ca F2-20%Ca O-20%Al2O3(mass fraction) at 1300 °C, 1400 °C and 1500 °C were investigated. Influence mechanism of Mg O and Si O2 on slag surface tension was also analyzed. Results indicate that surface tension decreases with the increase of Mg O content in the case of the Mg O content(mass fraction) less than 8%, however, when Mg O content(mass fraction) is from 8% to 30%, surface tension increases with the increase of Mg O content. When Si O2 content(mass fraction) is from 2% to 8%, surface tension decreases with the increase of Si O2 content. Additionally, the relationship between surface tension and optical basicity is a monotonically increasing linear function. Research findings can provide important reference for slag design and the study of slag-metal interfacial tension.

Effect of CaO/Al_(2)O_(3)on structure,viscosity,and surface tension of electroslag remelting-type CeO_(2)-bearing slag

The structure of electroslag remelting-type CaF_(2)–CaO–Al_(2)O_(3)–CeO_(2)slag with various CaO/Al_(2)O_(3)mass ratios and its correlation with viscosity and surface tension were investigated.The Raman analysis of the slag shows that with increasing CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag,the polymerization degree of the slag decreased,which was because more complex[AlO_(4)]-tetrahedral units of Q_(Al)^(3) and Q_(Al)^(4)were depolymerized to form relatively simpler structural units Q_(Al)^(0),Q_(Al)^(1),and Q_(Al)^(2),and the excess oxygen ions introduced by CaO promoted the transformation of[AlO_(4)]-tetrahedral units to[AlO_(6)]-octahedral units.Increasing CaO/Al_(2)O_(3)mass ratio has an obvious effect on reducing the viscosity and activation energy for viscous flow of the slag,resulting from the depolymerization of the slag.Owing to the decrease in the polymerization degree and the increase in the total Ca^(2+)content of the slag,the surface tension of the slag increases with the increase in CaO/Al_(2)O_(3)mass ratio.The surface tension of the slag changes slightly with the temperature,irrespective of CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag.

Viscosity and surface tension of CaF_(2)-CaO-Al_(2)O_(3)-based slag with varying SiO_(2) and B_(2)O_(3) contents for ESR of rotor steel

The effect of SiO_(2) and B_(2)O_(3) on viscosity and surface tension of CaF_(2)-CaO-Al_(2)O_(3)-MgO-SiO_(2)-B_(2)O_(3) slag designed for electroslag remelting of rotor steel was investigated.The viscosity of the slag melts increases with increasing the SiO_(2) content from 0.37 to 8.03 mass%,and the viscous activation energy increases from 54.21 to 58.49 kJ/mol.Increasing B_(2)O_(3) content of the slag from 0 to 3.62 mass%exhibits a similar effect on the viscosity,and the activation energy increases from 47.30 to 55.71 kJ/mol.The increase in the viscosity and activation energy for viscous flow of slag is attributed to the enhanced polymerization degree of slag melts network with increasing either SiO_(2) or B_(2)O_(3) content.The surface tension of slag melts decreases with increasing temperature.The surface tension of slag melts decreases with increasing either SiO_(2) or B_(2)O_(3) content,which is originated from the increase in the polymerization degree and the decrease in the CaO content of the slag.

High-temperature wetting behavior between slag and refractory

Slag corrosion is one of the main factors of the damage of refractory,and its primary manifestations involve the melting of refractory in slag and the slag penetration into refractory,both of which are highly related to the wetting behavior between slag and refractory.The high-temperature wettability could be characterized by parameters including the surface tension,adhesion work,and spreading coefficient of the slag on refractory surface,and it could be suppressed by altering the slag/refractory interface,thus resulting in an improved anti-corrosion performance.From this,the key knowledges of the slag corrosion,theory of wetting behavior and test of high-temperature contact angle were firstly summarized.Then,the major factors influencing the high-temperature slag wetting behavior were discussed based on the aspects of slag composition,refractory composition,and surface microstructure.Finally,the future research direction was proposed in this field.

低碳铝镇静钢精炼渣理化性能研究及动态调控

为提升低碳铝镇静钢水的可浇性,基于低碳铝镇静钢精炼渣的热力学计算,研究典型组分CaO/Al2O3(C/A)、SiO_(2)、FeO对精炼渣液相线温度、1650℃黏度和表面张力的影响规律,结合精炼渣理化性能(熔点和黏度-温度曲线)测试结果,建立吹氩直上精炼渣动态调控模型,并投入生产实践应用。结果表明:随着C/A增加,精炼渣熔点在渣中SiO_(2)质量分数为5%时单调升高,在渣中SiO_(2)质量分数为10%时先降后升,另随C/A的增加精炼渣黏度及黏度-温度曲线的转折温度升高;精炼渣组分范围为C/A 0.75~1.50、SiO_(2)质量分数0~10%、FeO质量分数2%~6%时,可获得较低的液相线温度、较高的黏度和表面张力。生产实践中应用建立的模型可实现造渣物料的动态加入,精炼渣理化性能的稳定性得到显著提升,精炼渣的C/A和全铁(TFe)质量分数标准差明显降低;液相线温度、1650℃时的黏度和表面张力平均值分别降低6.9℃、增加0.0206 Pa·s和0.0109 N/m;全氧(TO)质量分数均值由2.78×10(-3)%下降为2.25×10(-3)%,改进了19.1%,钢水的可浇性得到显著改善。

MgO含量对CaO-Al_(2)O_(3)-TiO_(2)基连铸保护渣界面性质的影响

高钛钢连铸生产过程中结晶器内的钢渣界面反应较为严重,易造成连浇困难、铸坯品质下降等问题。利用热丝法对3%、8%、10%三种不同MgO质量分数的保护渣接触角进行了测定,并基于此计算出表面张力和渣钢界面张力,此外结合拉曼光谱和Scigress软件模拟,从微观结构的角度分析了MgO含量与渣钢界面张力的变化规律。研究结果表明,1723 K温度下,保护渣中MgO质量分数为3%、8%、10%时,接触角为35°、36.7°、39.8°;保护渣的表面张力为516.3、523.1、525.6 mN/m;渣钢界面张力为1421、1425、1440 mN/m。MgO质量分数在8%~10%时,渣钢界面张力上升速率明显加快,导致钢渣间的界面反应减弱,使得钢渣更容易分离。

Al_2O_3-CaO熔渣性能的研究

采用旋转柱体法测量了Al2O3-CaO二元渣的黏度,采用重锤法测量了渣的密度,采用拉筒法测量了渣的表面张力,采用四探针法测量了渣的电导率.结果表明,共晶点处熔渣的高温流动性最好,1500℃时,该渣样的粘度只有0.57Pa·s;随着CaO/Al2O3质量比增加,熔渣密度减少,表面张力减小,电导率增加;渣温为1450~1500℃时,熔渣密度在2.775~2.713g/cm3之间变化,表面张力在0.6405~0.6107N/m之间变化,电导率在0.549~1.101(-·cm)-1之间变化.该二元渣作精炼渣时重熔电耗低,去夹杂能力强.但其熔点高、粘度大,所得合金表面质量差.

包钢高炉渣含氟和碱金属限量的实验研究

实验表明，包钢高炉渣中氟和碱金属含量严重影响炉渣的冶金性能，其中ＣａＦ２占主导地位。渣中ＣａＦ２和（Ｋ２Ｏ＋Ｎａ２Ｏ）分别降至３．５２％和０．１９％左右时，炉渣粘度和熔化性温度就可接近普通高炉渣的水平。将渣中ＣａＦ２降至２．５２％以下，对提高包钢高炉渣的表面张力才会有明显效果。

CaF_2-CaO-Al_2O_3-SiO_2-MgO五元渣的表面张力及其在镍基合金电渣重熔的应用

试验研究了五元渣(/%:50~65CaF_2,6~15CaO,18~30Al_2O_3,4~10Si0_2,1~7MgO)的组元含量、熔渣温度(1 330~1 463℃)对表面张力的影响。结果表明,随熔渣温度升高,其表面张力下降,1 463℃五元渣的表面张力为0.372~0.418 N/m。60CaF2-15CaO-6SiO_2-18Al_2O_3-5MgO具有较低的表面张力(0.375 N/m),较好的流动性和低粘度值。3 t电渣炉熔炼镍基合金Inconel 600和625的工业应用结果表明,电渣锭成分均匀,[O]≤20×10^(-6),[N]≤50×10^(-6),平均电耗从原ANF-6渣重熔的1 933 kWh/t降至1 326 kWh/t。

B_2O_3－MgO－SiO_2－Al_2O_3－CaO系渣组成对熔体物性的影响

用柱体旋转法测定了Ｂ_２Ｏ_３—ＭｇＯ—ＳｉＯ_２—Ａｌ２Ｏ_３—ＣａＯ系富硼镁渣的粘度及熔化性温度，用双柱联称法测定熔渣的密度及表面张力．实验结果表明：富硼镁渣的粘度及熔化性温度随渣中Ｂ_２Ｏ_３含量的增加而降低；当Ｂ_２Ｏ_３含量一定时，随渣中ＭｇＯ量及渣碱度的增加而增大．熔体的密度及表面张力随ＭｇＯ量增加或ＳｉＯ_２量减少而增大，分别为（２．５±０．５）ｔ·ｍ^（－３）和０．４－０．６Ｎ·ｍ^（－１）．

MgO对CaO-Al_2O_3-MgO熔渣性能影响的实验研究

为探讨Mg O在Ca O-Al2O3-Mg O熔渣中的作用机理,通过高温实验,研究Mg O对Ca O-Al2O3-Mg O渣系熔点、黏度以及表面张力的影响。结果表明：熔渣的软化温度、半球点温度和流动温度随Mg O含量的增加均呈现出先降低后升高的变化规律,当w（Mg O）为6%～12%时,渣系熔点较低而且熔渣软化区间相对较小;当w（Mg O）为8%时,渣样的黏度值相对较低,而黏度波动幅度和相对波动范围则在w（Mg O）分别为4%和8%时最小;随着Mg O含量的增加,熔渣的表面张力在不同温度下变化规律略有不同,当w（Mg O）为6%时,熔渣的表面张力均出现了最低值,随温度的升高,熔渣的表面张力呈减小的趋势。

富硼渣熔体物理性质测定

用化学试剂氧化物配制合成富硼渣，利用ＺＣ－１６００型高温综合测试仪、内柱体旋转法测定其粘度及熔化性温度；双柱联称法同时测定熔渣的密度及表面张力。探讨了富硼渣组成与熔体物理性质的关系，为优化硼铁矿高炉铁硼分离工艺提供依据。

B_2O_3－MgO－SiO_2－Al_2O_3－CaO熔渣的密度及表面张力

为综合利用开发硼铁矿资源，模拟硼铁矿高温选择性还原－熔融分离铁硼工艺的渣组成，用化学试剂合成配制Ｂ２Ｏ３－ＭｇＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＣａＯ渣样，在ＺＣ－１６００型高温综合测试仪上，用双柱联称法同时测定熔渣的密度及表面张力。结果表明：在１４６０～１５００℃密度为２．５±０．５ｇ·ｃｍ－３表面张力为０．４～０．６Ｎ·ｍ－１。其密度及表面张力均随渣中ＭｇＯ含量的增加，或随ＳｉＯ２量的减少而增大，随温度的提高而变小。

电渣重熔过程中熔滴滴落的影响因素

采用VOF方法来追踪钢渣两相界面,磁流体力学模块(MHD)来加载电流、电压对电渣重熔过程中熔滴滴落行为进行数值模拟.结果表明:电渣重熔过程中自耗电极端部熔滴的数目随着充填比的增加而增多;熔滴的尺寸随着自耗电极端部形状和界面张力的增加而增大.然而,熔滴的尺寸和数量随着输入电流的增大而减小.而且一些尺寸较大的熔滴在滴落的过程中受到了电磁力、重力以及浮力等力作用被分裂成几个尺寸较小的熔滴.从自耗电极端部滴落的熔滴不具有对称性,从而导致了渣池的流场不对称性.

Mgo-B_2O_3-SiO_2-CaO-Al_2O_3体系富硼渣表面张力的计算

基于熔渣结构的离子与分子共存理论和Butler方程建立了MgO-B_2O_3-SiO_2-CaO-Al_2O_3体系表面张力计算模型,计算了该体系及其子体系表面张力值,考察了熔渣表面张力随熔渣组分的变化规律,以期为富硼渣调控和综合利用提供参考。结果表明:本模型计算的熔渣表面张力值与实验值吻合较好,模型平均相对误差为9.03%。含B_2O_3的二元体系中,B_2O_3组元显著降低熔渣表面张力,纯氧化物表面张力值与形成氧化物阳离子的静电势及氧化物中离子键的分数有关。含B_2O_3的多元体系中,熔渣表面张力随着B_2O_3含量的增加而显著降低,但随着MgO和SiO_2质量比、CaO含量和Al_2O_3含量的增加而逐渐增大,且CaO和Al_2O_3含量对含B_2O_3渣表面张力的影响基本相当。

炼铜炉渣的物理化学性质

本文研究了工业闪速炉渣和贫化电炉渣的物理化学性质。采用目测变温法测定了二者的熔点;采用气泡最大压力法(BMP法)联合测定了二者的密度和表面张力;采用内圆柱体转动法测定了贫化电炉渣的粘度系数,并计算出了其在低温及高温区间的粘滞活化能。 基于有关理论和文献,本文对炼铜炉渣的化学组成与其物理化学性质之间的关系作出了合理解释,获得了有工业应用价值的结论。

大体积混凝土最大温升与里表温差的控制分析

以《大体积混凝土施工规范》GB50496-2009的计算方法为依据,对其进行了必要的改进,分别计算了不同厚度大体积混凝土的绝热温升和里表温差的温度场。为满足规范建议的50℃和25℃要求,需要采取相应的设计与施工措施,得到在不同混凝土强度等级下粉煤灰和矿渣粉掺量的下限值,以及在仅依靠掺加剂无法满足的情况下必须辅以的施工措施,以供设计和施工参考。