铝液氢的界面反应过程动力学研究

建立了铝液中氢的界面反应过程的数学物理模型，对界面反应过程进行了动力学推导和计算。利用铝液直接测氢装置对氢的界面反应动力学过程进行了测试。计算结果与测试结果基本吻合。     

由弱极化曲线拟合估算腐蚀过程的电化学动力学参数

在腐蚀过程的阴极反应是由电化学反应过程和传质过程混合控制的情况下,腐蚀金属电极的弱极化曲线方程式包含4个电化学动力学参数。迄今还没有一个方法可以同时测定这些动力学参数。本文证明,利用高斯—牛顿曲线拟合法直接对腐蚀金属电极的弱极化曲线拟合,可以解决这一问题。编制了一个BASIC语言的计算程序,并讨论了编制程序时应加以考虑的问题。     

P2O5对熔渣界面氧迁移反应的影响及机理

利用同位素交换法测定了熔渣表面CO2与氧化铁熔渣之间氧迁移反应的速度常数,并基于电化学反应机制,分析了添加P2O5对该过程的影响,建立了一个新的反应动力学模型．该模型认为P2O5作为易挥发组分参与对电子的竞争,抑制氧迁移(CO2 2e=CO O^2-)主反应的进行．对实验数据的分析和拟合表明了模型的可用性,也辅证了反应的电化学机制．     

基于粘弹性理论异种材料的共烧结致密化

基于加压烧结粘弹性流动理论,引入烧结速率不匹配造成的界面应力,并考虑界面应力分布情况,建立两种材料共烧结致密化模型,描述共烧结界面应力对共烧结致密化的影响.通过两种材料自由烧结数据,进行材料参数拟合;通过拟合得到的材料参数进行共烧结致密化模型模拟.结果表明共烧结会使得试样中存在密度梯度,并且可能加大或者缩小界面处密度差异,对共烧结后界面结合强度造成影响.采用不同孔隙率的铜粉共烧结进行验证,实验测得共烧结试样密度梯度分布以及界面处密度差异变化和模型预测结果一致.     

金精矿碘化浸出过程动力学

采用碘-碘化物体系对金精矿进行浸出,通过实际矿石的浸出试验考察搅拌速度、浸出温度、碘浓度及碘离子浓度对金精矿碘化浸出反应动力学的影响。结果表明:提高搅拌速度对金的浸出有不利影响;通过对影响该体系动力学参数的考察,发现其符合核收缩模型,反应过程总体由界面化学反应控制,其表观活化能为31.674kJ/mol,碘浓度和碘离子浓度的反应级数分别为1和0.5,建立了金精矿碘化浸出过程的反应速率方程。     

上流式厌氧反应器改性污泥处理含铬废水的动力学模型

为揭示上流式厌氧反应器(UASB)改性污泥处理含铬废水过程中硫酸根还原与化学需氧量(COD)的去除、微生物增长之间的定量关系,在合理的假设及分析下,通过理论推导建立了COD降解与硫酸根还原的动力学模型,并通过实验测得了动力学参数.用不同硫酸根浓度下UASB改性污泥体系处理含铬废水过程中的数据对所建动力学模型进行了验证,S2-的实测值和理论值拟合很好(R=0.986 7),表明所建动力学模型可以描述UASB改性污泥处理含铬废水过程.     

界面反应对铝熔体与Si3N4多孔陶瓷界面的润湿作用

应用界面润湿理论从热力学角度计算了铝熔体和Si3N4陶瓷存在界面反应时的润湿角;通过测量不同浸渗时间下浸渗厚度,结合浸渗动力学模型,获得实际浸渗过程中铝合金熔体与Si3N4多孔预制体之间润湿角,并将该试验结果与上述理论计算结果相比较.研究表明:Al/Si3N4界面反应过程对熔体与预制体的润湿起到重要作用;应用界面润湿理论计算得到T=1223 K(950℃)时,Al/Si3N4界面实际接触角θ值为60.2°,界面反应对界面接触角的贡献达到47.6°,计算结果与浸渗动力学试验吻合.     

液铝和铜-硅合金的石墨反应润湿动力学（英文）

为了揭示反应润湿扩散过程的物理本质,提出一种解释其驱动力和润湿机理的能量模型。在真空条件下采用通管滴落法,研究熔融的Al及Cu-Si合金在石墨基板上的反应润湿铺展过程,由轴对称形状分析软件(ADSA)测量摄入图像的接触角。研究典型反应润湿的热力学和动力学过程,推导能量关系的热力学方程,计算石墨表面能和三相线处固-液界面能相对于时间的变化值,并建立关于界面能的动力学模型。借助实验验证该模型的合理性,表明在反应过程中固液界面能随时间呈指数关系下降。从能量角度可为反应润湿过程提供一种新的解释方法。     

固氟氯化铵焙烧法从包头稀土矿中回收稀土的动力学

研究了固氟氯化铵焙烧法分解包头混合型稀土精矿回收稀土的动力学.结果表明:固氟焙砂的氯化反应过程符合Bagdasarym提出的区域反应速率模型,氯化反应过程经过了两个串联反应步骤,且反应生成物的核按一个方向长大;反应速率方程遵从Erofeev方程的串联反应步骤模型,反应表观活化能Ea为36.831 KJ·mol-1,过程控制步骤是内扩散控制.     

从冶金级硅中加压去除杂质铝的动力学

研究加压浸出过程中盐酸溶液提纯冶金级硅过程的动力学特征以及去除杂质Al时颗粒粒度、反应温度、总压强、盐酸初始浓度等因素对动力学的影响。结果表明:反应过程符合核收缩模型的固态产物层扩散方程;反应过程中,表观反应活化能为34.067 kJ/mol,表观反应级数为0.346。硅粉粒度、温度、压强和盐酸浓度共同对Al去除率的影响的动力学数学模型经过不同条件下实验结果与计算结果进行对比验证,使用该模型计算所得结果与实验结果吻合较好。     

The kinetics of silicon dioxide chemical vapour deposition III: Experimental verification of the model

In this paper a general analysis of chemical vapour deposition of silicon dioxide by oxidizing silane with oxygen is presented. In Part II a mathematical model of the process was presented. The proposed model is based on the scheme of surface reactions described in Part I. The non-linear equation describing the process obtained contains unknown coefficients. In this paper these coefficients are computed by fitting the model to the experimental data. With regard to the non-linearity of the model, the Marquardt method of non-linear regression is applied for this purpose. The verification of the model comprises verification of the physical and statistical significance of computed coefficients and comparison of the experimental and computed deposition rates.It is found that very good consistence is achieved. The influences of reagent concentrations and temperature on the process kinetics are analyzed. It is established that the key parameter determining the type of control of the process kinetics is the oxygen to silane ratio.     

Electrochemistry of oxygen ion transport in slag

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CELLULAR AUTOMATA MODELLING OF GRAIN COARSENING DURING REHEATING AND VALIDATION WITH THE EXPERIMENTAL RESULTS

1. IntroductionG rain coarsening isthe processby w hich the m ean grain size ofan aggregate ofcrystalsincreases.A n understanding ofgrain coarsening isoffundam entalim portance forpredicting the average grain sizeand grain size distribution,w hich are dir…     

Identification of the transfer function of dynamic cutting processes — A comparative assessment

A knowledge of the transfer characteristics of the cutting process is one of the crucial factors needed for the assessment of the dynamic stability of the machining system. Yet, it is still not possible to obtain a reliable analytical model, neither based on theoretical considerations nor on experimental data.The objective of this paper is to introduce a method for the determination of the cutting process transfer function in the form of analytical models based on experimental data. The Dynamic Data System (DDS) approach has made it possible to adequately characterize the dynamic cutting process from observations of random force and vibration components.The theoretical concepts and modelling procedure have been demonstrated using actual experimental data. Subsequently, a comparative assessment of the obtained results is given with respect to two typical existing methods, the shear plane method and the double modulation method, representing the static and dynamic methods respectively.     

The kinetics of hydrogen evolution and oxygen reduction on Alloy 22

The kinetics of hydrogen evolution and oxygen reduction on Alloy 22 in 5 M NaCl + xHCl + yNaOH solutions as a function of pH at temperatures ranging from 20 to 95 °C have been investigated. The hydrogen evolution reaction proceeds via two basic mechanisms; the reduction of H⁺ at pH < 4 and the reduction of H₂O at higher pH values. Analytical expressions for the exchange current density for the hydrogen evolution reaction on Alloy 22 are also developed for the two mechanisms, in a form that they can be used in corrosion models for assessing the performance of this alloy in high level nuclear waste (HLNW) repositories. The kinetics of oxygen reduction have also been explored over wide ranges of pH and temperature. However, this reaction is complicated by the formation of H₂O₂ as an intermediate in a two-electron transfer reaction. Nevertheless, kinetic parameters have been obtained for this reaction and an expression has been developed that allows calculation of the exchange current density over a wide range of conditions. Finally, the kinetic data are used to identify probable mechanisms for hydrogen evolution and the reduction of oxygen on Alloy 22.     

The effect of heat transfer on local solidification kinetics of eutectic Al-Si cast alloy

Recently, Fourier thermal analysis (FTA) has been proposed as a suitable technique to obtain information about local solidification kinetics in casting alloys. In this work, FTA was applied to a near-eutectic aluminum-silicon cast alloy in order to seek experimental evidence supporting the solidification kinetics obtained from this method. Also, a heat-transfer/solidification-kinetics model was used to compare predictions with experimental results. The metallographic findings, focused on interlamellar eutectic spacings in different locations within a cylindrical casting, support the solidification kinetics obtained from FTA. The model and experimental outcome including FTA results and metallographic observations suggest that local solidification kinetics depend strongly on local heat transfer, and the analysis of this dependence may be used to explain the observed changes in microstructural characteristics at different locations within castings.     

Mathematical model of pyritic smelting process for copper-nickel mineral in oxygen top-blown furnace

1　INTRODUCTIONTheideaofrefiningcopperandnickelwithpyriticsmeltingprocessinoxygentop blownfurnacehascomeintobeingforitsachievementinoxygen converterofsteelmaking processfrom 196 0s.Thefirstpyriticsmeltingfurnacewithoxygentop blownsmeltingnickelhadbeenputintoproductionatNorthNickelCo .ofRussianin 1986 .Nowadays ,thistech nologyhasbeenimportedandemployedinJinchuanNonferrousMetalCo .ofChina .Inthepastdecades ,theutilizationofflashsmeltingfurnaceinnonferrous makinghasgotextensivedevelopmen…     

罩退炉温度场模拟与高碳钢8CrV球化退火工艺研究

边界对流换热系数和钢卷径向等效导热系数是影响燃气罩式退火炉内传热的两个最主?问１疚耐ü⒏志硭蔡却加邢拊抡婺Ｐ停哉质酵嘶鸸讨械奈露瘸》植冀辛四Ｄ饧扑恪ＤＰ透菔导释嘶鸸ひ涨呃词┘颖呓缣跫哂幸欢ǖ募扑憔取＝岷戏抡婺Ｐ偷募扑憬峁贫烁咛季馄?CrV的球化退火工艺,获得了良好的球化退火组织,该钢的屈服强度、抗拉强度和布氏硬度等力学性能参数均得到明显改善。