铅富氧侧吹氧化-还原过程动力学模拟

基于有效平衡反应区概念开发了一个过程模型,用于研究铅富氧侧吹氧化-还原过程动力学。该方法充分考虑了气-渣-金多相反应、传质动力学以及能量守恒。采用简化的流动方程连接各个反应区,假定反应区内达到局部热力学平衡,将热力学计算链接到动力学模拟。硫化铅精矿脱硫反应和富铅渣碳热还原反应采用FactSage计算,炉渣和金属的传质系数由数值模拟获得。对实际工业过程中不同时刻的样品进行元素分析和相分析,验证了该模型。当前开发的过程模型,可预测铅富氧侧吹熔炼过程中物相及其成分随时间的变化,有望用于过程控制和智能工厂的建设。     

腐蚀电极阳极过程稳定性的非线性非平衡热力学分析

本文将非线性非平衡态热力学的基本原理运用在腐蚀金属电极体系中,对电极的阳极过程稳定性进行初步分析,从热力学的角度证明了强极化条件下的活性阳极溶解和钝化分别是电极系统在远离平衡条件的两个稳定状态.     

用Wilson方程预测三元液态合金的热力学性质SCIEI

本文试图将Wilson方程应用于液态合金.研究结果表明该式只用二元系双分子相互作用参数就能简便地算出三元液态合金各组元的活度,其结果与实验数据基本一致,并且由经典热力学判别式验证是可靠的。因此,Wilson方程适用于预测液态合金的热力学性质。     

用WiSon方程预测三元液态合金的热力学性质SCIEI

本文试图将Wilson方程应用于液态合金.研究结果表明该式只用二元系双分子相互作用参数就能简便地算出三元液态合金各组元的活度,其结果与实验数据基本一致,并且由经典热力学判别式验证是可靠的。因此,Wilson方程适用于预测液态合金的热力学性质。     

腐蚀电极阳极过程稳定性的非线性非平衡热力学分析

本文将非线性非平衡态热力学的基本原理运用在腐蚀金属电极体系中，对电极的阳极过程稳定性进行初步分析，从热力学的角度证明了强极化条件下的活性阳极溶解和钝化分别是电极系统在远离平衡条件的两个稳定状态．     

红土镍矿真空碳热还原脱镁的热力学研究

高镁低品位红土镍矿开发利用的关键在于提取镍的同时,重视金属镁等金属的综合回收利用。本文从热力学角度针对真空碳热还原红土镍矿脱除金属镁的过程进行了分析及能耗估算,探索处理红土镍矿的新工艺的热力学可行性。热力学计算表明,真空碳热还原红土镍矿脱除金属镁是可行的。当体系压强100Pa左右的条件下,MgO被还原的温度大于1478K,Ni、Fe以及部分硅将优先被还原为金属;过程能耗理论估算表明:当红土镍矿∶煤炭(质量比)=100∶42,1600K~1800K条件下还原处理1吨红土镍矿,需消耗1.12吨~1.17吨标准煤。     

联合法生产海绵钛还原-蒸馏过程的能量分析

为了研究联合法生产海绵钛还原-蒸馏过程的能源利用效率,以热平衡测试为基础,依据热力学第一定律和热力学第二定律,对还原-蒸馏过程进行了能分析和分析。能分析结果表明利用副产品MgCl2的高温物理热是节能主攻方;向分析结果表明减少内部传热和不可逆反应的损失,是还原-蒸馏过程节能降耗的关键。     

葡萄糖在氧化锰矿浸出过程中的分解动力学

研究在硫酸水溶液体系葡萄糖还原浸出氧化锰矿过程中的分解动力学,通过测定溶液中COD含量的变化,考察葡萄糖用量、硫酸浓度、氧化锰矿用量和反应温度对葡萄糖氧化分解速率的影响。结果表明:提高硫酸浓度、氧化锰矿用量和反应温度可以加快浸出反应过程葡萄糖的氧化分解速率。葡萄糖的氧化分解过程可以用指数经验模型来描述,属于扩散-化学反应混合控制。通过拟合动力学数据,获得葡萄糖氧化分解反应的活化能为41.80 k J/mol,COD、硫酸和氧化锰矿的表观反应级数分别为2.0,0.927和0.976。     

以废茶叶为还原剂在硫酸溶液中还原浸出氧化锰矿（英文）

采用废茶叶在硫酸溶液中还原浸出加蓬和湘西氧化锰矿石,探索废茶叶用量、硫酸浓度、固液比、浸出温度和反应时间对浸出过程的影响。对加蓬氧化锰矿,优化的浸出条件为:氧化锰矿与废茶叶的质量比10:4、硫酸浓度2.5 mol/L、固液比7.5:1、浸出温度368 K、浸出时间8 h;在此条件下,加蓬氧化锰矿的浸出率几乎达100%。对于湘西氧化锰矿,优化浸出条件为:氧化锰矿与废茶叶的质量比10:1、硫酸浓度1.7 mol/L、液固比7.5:1、温度368 K、浸出时间8 h;在此条件下,锰的浸出率达到99.8%。氧化锰矿的还原浸出过程符合内扩散控制模型,加蓬和湘西氧化锰矿石的还原浸出反应表观活化能分别为38.2 kJ/mol和20.4 kJ/mol。采用X-射线衍射(XRD)和扫描电子显微镜(SEM)对浸出前、后的锰渣进行表征。     

Mg-Pr二元体系热力学优化（3）

相图热力学优化是材料设计理论和方法最重要的组成部分，是新材料的开发和应用的重要依据之一。相图计算即CALPHAD技术，主要是依据化学热力学原理和基本关系，计算热力学体系的平衡性质。一个物质体系的热力学特征函数确定以后，这个物质体系的全部热力学性质都可以计算出来，其中包括相图。镁合金是最轻的一种金属结构材料，广泛应用于航空航天、汽车、电子工业等许多领域。镁-镨合金作为镁合金的一种，也具有非常广阔的应用前景。本工作采用瑞典皇家工学院开发的相平衡计算软件Thermo-Calc系统，利用CALPHAD技术，通过选择或建立合理的热力学模型，将相图和热力学数据联系起来，对镁-镨二元合金体系相图和热力学数据进行热力学优化和评估，获得自洽的Mg-Pr体系的热力学描述即体系中所有物相，包括溶体相和金属间化合物的Gibbs自由能，为相关材料的设计和工艺制定服务。     

CHANGES IN COMPOSITION DURING A. C. ESR——Ⅰ. Theoretical Development

本文以低碳低合金钢为例,考察了电渣重熔反应体系的总的化学行为,基于渗透理论和薄膜理论,提出了一个新的电渣重熔过程化学反应及传质模型。理论上说,该模型可适用于任何钢和合金的电渣重熔过程,可更精确地估算熔渣和金属两相内的成分变化。对该理论模型作了求解,讨论和确定了模型各参数。     

活性SiO2在焊接熔渣-金属界面化学反应的热动力学分析

针对焊接熔渣-金属冶金反应远离平衡的特性，从非平衡态热力学及液-液两相交互作用耦合的角度建立了液态熔渣组成中SiO2与熔敷金属间的化学反应热动力学模型。对建立的模型通过试验测试，并借助于Matlab工具软件进行了非线性数值求解。定量计算结果表明，焊接过程各区域的冶金反应方向及限度存在明显的不同，熔滴反应区正向氧化反应偏离平衡态的距离远大于熔池反应区逆向脱氧反应偏离平衡的距离。同时反应所处的温度及熔渣中SiO2含量都在一定程度上影响反应的方向及限度，从而对焊缝金属的增氧产生重要影响。     

Electrochemical reaction mechanism of aqueous polysulfide solution

1　ＩＮＴＲＯＤＵＣＴＩＯＮＷｈｅｎａｌｋａｌｉｎｅｈｙｄｒｏｇｅｎｓｕｌｆｉｄｅｓｏｌｕｔｉｏｎ ,ｒｅｐｒｅ ｓｅｎｔｅｄｂｙＮａ2 Ｓ ,ｉｓｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｌｙｏｘｉｄｉｚｅｄ ,ｐｏｌｙ ｓｕｌｆｉｄｅｉｏｎｓａｒｅｆｉｒｓｔｌｙｆｏｒｍｅｄａｎｄｔｈｅｐｏｌｙｓｕｌｆｉｄｅｉｏｎｓａｒｅｆｉｎａｌｌｙｔｒａｎｓｉｔｅｄｉｎｔｏｅｌｅｍｅｎｔａｌｓｕｌｆｕｒ .Ｔｈｉｓｐｒｏ ｃｅｓｓｉｓａｎｅｗｍｅｔｈｏｄｕｓｅｄｔｏｔｒｅａｔＨ2 Ｓｗａｓｔｅｇａｓａｎｄｉｔｈａｓｓｏｍｅｅｃｏｎｏ…     

Self-organized criticality of liquefaction in saturated granules

1　ＩＮＴＲＯＤＵＣＴＩＯＮＳｅｌｆ ｏｒｇａｎｉｚｅｄｃｒｉｔｉｃａｌｉｔｙｉｓａｐｒｏｃｅｓｓｉｎｗｈｉｃｈｉｎｖａｒｉ ａｂｌｅｅｎｅｒｇｙｉｓｃｏｎｔｉｎｕａｌｌｙｇｉｖｅｎｔｏａｓｙｓｔｅｍｆｒｏｍｔｈｅｏｕｔ ｓｉｄｅａｎｄｉｓｆｉｎａｌｌｙｄｉｓｓｉｐａｔｅｄｉｎｔｈｅｆｏｒｍｏｆｔｈｅ“ａｖａｌａｎｃｈｅ” .Ｓｅｌｆ ｏｒｇａｎｉｚｅｄｃｒｉｔｉｃａｌｉｔｙｉｓａｆｒａｃｔａｌｃｏｎｃｅｐｔｆｉｒｓｔｂｒｏｕｇｈｔｆｏｒｗａｒｄｂｙＢａｒｋｅｔａｌ[1] ,ｗｈｉｃｈｈａｓｔｈｅ“ａｖａｌ…     

Properties of cadmium sulfide thin films deposited by chemical bath deposition with ultrasonication

Ultrasonic agitation was applied during the chemical bath deposition of CdS thin films. Ultrasonication resulted in a dramatic change in the surface morphology, growth rate, and optical properties of CdS films. There were virtually no colloidal particles adsorbed on the surface. The surface roughness measured by atomic force microscopy was reduced by a factor of two. Band gap energy increased to 2.39 eV from 2.37 eV. X-ray patterns showed that the preferred orientation changed from hexagonal (002)/cubic (111) to hexagonal (101). Optical transmission improved in the wavelength range larger than 520nm. The chemical reaction for CdS formation started at a lower temperature under ultrasonication, and dense films were obtained even when the chemical composition of the aqueous solution deviated far from optimum conditions.     

Magnetohydrodynamic modeling for an OVD reactor setup

A three-dimensional magnetohydrodynamic model of an inductively coupled plasma depositor has been developed and applied to describe the process of outside vapor deposition during manufacturing of preforms for optical fibers. The steady state continuity, momentum, enthalpy and diffusion equations are solved consistently with the energy coupling accomplished through the electromagnetic field of an induction coil and the radiation losses from the plasma. Local thermodynamic equilibrium, steady and laminar flow, and optically thin plasma are assumed. A chemical surface reaction serving as a boundary condition for species mass fractions in the fluid is set to describe the deposition process. The model supplies information about the flow and temperature distribution of the fluid, the electromagnetic field, and the deposition rate on the target surfaces for complex real geometries.     

Generalized chemical potential diagram and its applications to chemical reactions at interfaces between dissimilar materials

The characteristic features of the generalized chemical potential diagram are discussed and compared with those of chemical equilibrium calculations and of phase diagram calculations. An emphasis is placed on their applications to interfaces between materials having different chemical bonds such as alloys, ceramics, and salts. To provide a reasonable basis for analyzing complicated concentration profiles resulting from interface reactions between high-temperature materials, a simple thermodynamic model based on a local equilibrium approximation is proposed to represent reactive diffusion paths in generalized chemical potential diagrams. Experimentally observed reaction profiles are examined by taking into account kinetic factors such as diffusion, surface reaction rate, and nucleation at a heterogeneous interface.     

Nanostructured materials: basic concepts and microstructure

Nanostructured Materials (NsM) are materials with a microstructure the characteristic length scale of which is on the order of a few (typically 1–10) nanometers. NsM may be in or far away from thermodynamic equilibrium. NsM synthesized by supramolecular chemistry are examples of NsM in thermodynamic equilibrium. NsM consisting of nanometer-sized crystallites (e.g. of Au or NaCl) with different crystallographic orientations and/or chemical compositions are far away from thermodynamic equilibrium. The properties of NsM deviate from those of single crystals (or coarse-grained polycrystals) and/or glasses with the same average chemical composition. This deviation results from the reduced size and/or dimensionality of the nanometer-sized crystallites as well as from the numerous interfaces between adjacent crystallites. An attempt is made to summarize the basic physical concepts and the microstructural features of equilibrium and non-equilibrium NsM.     

Generalized chemical potential diagram and its applications to chemical reactions at interfaces between dissimilar materials

The characteristic features of the generalized chemical potential diagram are discussed and compared with those of chemical equilibrium calculations and of phase diagram calculations. An emphasis is placed on their applications to interfaces between materials having different chemical bonds such as alloys, ceramics, and salts. To provide a reasonable basis for analyzing complicated concentration profiles resulting from interface reactions between high-temperature materials, a simple thermodynamic model based on a local equilibrium approximation is proposed to represent reactive diffusion paths in generalized chemical potential diagrams. Experimentally observed reaction profiles are examined by taking into account kinetic factors such as diffusion, surface reaction rate, and nucleation at a heterogeneous interface.     

Effects of product condensation on reaction-enhanced vaporization rates and on the transition from homogeneous to heterogeneous reaction in high-temperature metal oxidation

In order to predict the vaporization rate of fume-forming condensed phases into reactant-rich gases it is necessary to account for the strong augmentation of vapor transport rates caused by bulk flow into the reaction-condensation zone. For this purpose a simple film theory is developed based on the idealization of a thin reaction-condensation “front” supplied by convection-diffusion processes normal to the surface, but with condensate removal by convection processes parallel to the vaporizing surface. The steady-state position or “stand-off distance” of the front and, hence, its effect on the observed mass transfer rate, are determined by the demands of local reactant stoichiometry at the front and species conservation throughout the two-part film, subject to the imposed vapor and oxidizer boundary concentrations. As applied to the problem of metal vaporization into reactive atmospheres, it is shown that while we recover the results of Turkdogan, Grieveson, and Darken in highly dilute isothermal systems (i.e., metals far from their boiling points vaporizing into dilute oxygen-inert gas mixtures) appreciable additional effects due to the condensation process are predicted in the limit of oxidizer-rich ambient gases. Combining this extended theory with the notion that there is an upper limit to the attainable magnitude of the vaporization rate enhancement at which the reaction regime must change from homogeneous to heterogeneous, leads to predicted critical (transition) oxidizer pressures valid even approaching the practically important limit of pure gaseous ozidizer. On the assumption that this transition will occur when the metal vaporization rate approaches that expected in a vacuum (as has been experimentally observed by Turkdogan, Grieveson, and Darken), illustrative calculations are presented for the metals Na, Mg, Ca, Al, Be, Fe, and Zr vaporizing into oxygen-inert gas mixtures, and conclusions are drawn concerning the impossibility of the vapor phase reaction mode at surface temperatures too far below the metal boiling (or sublimation) point. It is also shown that the formalism can be extended to incorporate an alternative critical condition, perhaps more realistic under some experimental conditions, viz., oxygen penetration to the surface due to the finite thickness of the reaction zone. In either event, the model can be readily used to predict the homogeneous-heterogeneous transition locus and its dependence on the occurrence or nonoccurrence of product condensation, and physical, chemical, and aerodynamic parameters.