Mn evaporation and denitrification behaviors of molten Mn steel in the vacuum refining with slag process

Considering the precise composition control on the vacuum refining of high-Mn steel, the behaviors of both Mn evaporation and nitrogen removal from molten Mn steel were investigated via vacuum slag refining in a vacuum induction furnace. It was found that the reaction interfaces of denitrification and Mn evaporation tend to migrate from the surface of slag layer to the surface of molten steel with the gradual exposure of molten steel during the vacuum slag refining process. Significantly, compared with the experimental group without slag addition, the addition of slag into steel can result in a lower Mn evaporation rate constant of 0.0192 cm·min~(-1) at 370 Pa, while the denitrification rate is almost not affected. Besides, the slag has a stronger inhibitory effect on Mn evaporation than the reduced vacuum pressure. Moreover, the inhibitory effect of the slag layer on Mn evaporation can be weakened with the increase of the initial Mn content in molten steel. The slag layer can work as an inhibitory layer to reduce the Mn evaporation from molten steel, the evaporation reaction of Mn mainly proceeds on the surface of the molten steel. This may be attributed to the Mn mass transfer coefficient for one of reaction at steel/slag interface, mass transfer in molten slag, and evaporation reaction at slag/gas interface is lower than that of evaporation reaction at steel/gas interface. The introduction of slag is proposed for both denitrification and manganese control during the vacuum refining process of Mn steels.

PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 Pa, respectively.

In-situ growth of a CdS window layer by vacuum thermal evaporation for CIGS thin film solar cell applications

Highly crystalline and transparent CdS films are grown by utilizing the vacuum thermal evaporation （VTE） method. The structural, surface morphological, and optical properties of the films are studied and compared with those prepared by chemical bath deposition （CBD）. It is found that the films deposited at a high substrate temperature （200 ℃） have a preferential orientation along （002） which is consistent with CBD-grown films. Absorption spectra reveal that the films are highly transparent and the optical band gap values are found to be in a range of 2.44 eV-2.56 eV. Culnl_xGaxSe2 （CIGS） solar cells with in-situ VTE-grown CdS films exhibit higher values of Voc together with smaller values of Jsc than those from CBD. Eventually the conversion efficiency and fill factor become slightly better than those from the CBD method. Our work suggests that the in-situ thermal evaporation method can be a competitive alternative to the CBD method, particularly in the physical- and vacuum-based CIGS technology.

High-Resolution Sensors for the Operation and Control of a Novel Vacuum Evaporation Technology

Industrial liquid waste streams could be significantly reduced by evaporation. Using evaporation technologies, not only the amounts are reduced, but the opportunities of potential economic reuse of the solutes are also promoted. In the process developed by authors’ company, fast and efficient vaporization was achieved due to the high evaporation area and vacuum conditions. To investigate the details of the process, an experimental pilot equipment was constructed. The fine resolution monitoring of pressure and temperature conditions is essential in the system, which was implemented by a number of low response-time sensors. In this section of the research work, the developing and testing of the monitoring system customized for this aim was performed. Since the number of the sensors and the data rate is high, the control system was simplified (as possible), and instead of D/A converters author created a digital data management system. This system was capable of managing the 255 sensor’s signals simultaneously in one channel, which seemed to be sufficient for this task. The error statistics of authors’ system was excellent, even in industrial conditions.

Modeling and Simulation of Lithium Vacuum Evaporation Process Using COMSOL Multiphysics

Based on the COMSOL Multiphysics simulation software,this study carried out modeling and numerical simulation for the evaporation process of liquid metal lithium in the vacuum free molecular flow state.The motion of lithium atoms in the evaporation process was analyzed through a succession of studies.Based on the available experimental values of the saturated vapor pressure of liquid metal lithium,the relationship between saturated vapor pressure and temperature of liquid lithium in the range of 600 K-900 K was obtained.A two-dimensional symmetric model(3.5 mm×20 mm) was established to simulate the transient evaporation process of liquid lithium at wall temperatures of 750 K,780 K,800 K,810 K,825 K,and 850 K,respectively.The effects of temperature,the evaporation coefficient,back pressure,and length-to-diameter ratio on the evaporation process were studied;the variation trends and reasons of the molecular flux and the pressure during the evaporation process were analyzed.At the same time,the evaporation process under variable wall temperature conditions was simulated.This research made the evaporation process of liquid lithium in vacuum molecular flow clearer,and provided theoretical support for the space reactor and nuclear fusion related fields.

Step-Directed Deposition of Au Nanostructures By Electron Beam Evaporation

Au atoms were vaporized by electron beam evaporation, and their subsequent growths on Si (111 ) and highly ordered pyrolytic graphite (HOPG) substrates were studied using atomic force microscopy. Results show that Au nanoparticles tend to nucleate and grow regularly along the step edges of HOPG, however, nanoparticles are distributed homogeneously over the whole Si substrate. The possibility of controlled growth of Au in ultrahigh vacuum with peculiar surface structures was preseuted.

Recovery of cadmium by high-temperature vaccum evaporation from Ni-Cd batteries

High temperature vaccum evaporation is a recycling technology that includes a selective material recovering process. The fundamental research on a process of disassembling and recovering selected materials from Ni Cd batteries was conducted using self designed experimental apparatus. An effective recycling technology based on the evaporation phenomenon of batteries and the elements of cadmium under the laboratory condition was studied. The results show that: (1)Ni/Cd can be effectively recovered by vacuum distillation at appropriate temperature, pressure and time, and high purity cadmium (>99%) can be obtained through the process; (2)the effective distillatory temperature should be at the range of 5731 173 K; (3)the higher the evaporation temperature, the lower the purity of cadmium in condensate

钢液真空处理过程中Mn挥发动力学研究

Mn作为提高钢材强度的主要元素之一,在钢液真空处理过程中的挥发会对钢材成分及质量控制产生不利影响,因此,明确钢液中Mn的挥发机理,并据此精确调控钢液中Mn含量,对于保证钢材质量显得尤为重要。本研究针对X80管线钢的真空精炼处理过程,分析了气相压强和熔炼温度对钢液中Mn挥发行为的影响。结果表明:随着熔炼温度的升高和气相压强的降低,钢液中Mn挥发速率明显加快;在熔炼温度1903 K、气相压强19 Pa、处理时间40 min条件下,Mn挥发率高达92.26%。在熔炼温度1823~1973 K、气相压强19~670 Pa条件下,Mn挥发遵循一级反应规律,其表观挥发速率常数在(0.41~26.56)×10^(-5)m/s范围内;在气相压强19~670 Pa、熔炼温度1903 K的条件下,Mn挥发主要受气相传质的限制;在气相压强226 Pa、熔炼温度1823~1973 K的条件下,Mn挥发的表观活化能达到120.20 kJ/mol,限制性环节为气-液界面反应;本研究条件下,液相传质对Mn挥发速率的影响较小。

金属镥定向凝固过程中杂质分布的理论研究

高纯镥作为稀土金属,有着重要研究价值。文章通过理论计算分析了真空电子束熔炼和定向凝固下镥锭中杂质Fe和Al的分布,研究了蒸发和分凝效应耦合作用下金属镥的提纯效果以及影响机制。结果表明,电子束定向凝固金属镥过程中,虽然杂质Al的饱和蒸气压大于Fe杂质的饱和蒸气压,但Fe杂质蒸发传质系数大于杂质Al。金属镥中杂质Fe和Al分布不仅受固液界面分凝的控制,还受气液界面蒸发的控制,金属镥锭高度60%以下区域的Fe含量由4.836×10^(−3)降低到了6.2×10^(−5),Al含量由7.75×10^(−4)降低到了3.3×10^(−8),有着较好的提纯效果。熔炼温度和凝固速率是影响电子束定向凝固镥金属过程中杂质分布的两个重要参数。一个纯度较高且分布均匀的镥金属锭可以通过合理控制熔体温度和凝固速率来获得。

InSb-In共晶体磁阻薄膜的制备及特性分析

利用纯度为99.99%的铟和锑单质为原料,采用真空蒸发法,制备了InSb-In共晶体磁阻薄膜,对薄膜进行热处理。通过实验对锑化铟薄膜的物相构成、表面形貌进行分析,探讨成膜条件、退火条件等因素对薄膜结构及性能的影响。结果表明,InSb薄膜是InSb和In的共晶体。

面向药材贮藏的热泵干燥系统实验研究

目的针对药材贮藏前传统干燥处理方法效率低,药材易变质,处理能耗高,不利于药材高品质贮藏等问题,优化药材干燥处理方法至关重要。方法采用真空低温干燥技术,设计一套以真空干燥箱为传质系统进行低温干燥的热泵干燥处理系统。系统包含基于热泵压缩机驱动的真空低温干燥系统、真空泵、变频风机等设备,通过对其进行干燥性能实验研究,分析获得热泵冷凝温度、空气入口风速以及空气入口温度对该系统干燥性能的影响。结果在环境真空压力−40~0 kPa实验条件下,热泵真空低温干燥系统的干燥量、干燥效率、传质系数及传热系数最大值分别为3.96 kg/h、44.19%、3.75 g/(m^(2)·s)、3.25 W/(m^(2)·℃),析湿过程传质系数及传热系数最大值分别为44.51 g/(m^(2)·s)及36.03 W/(m^(2)·℃),热泵系统最大能效为6.08。对实验数据进行回归分析,得到热泵真空低温干燥系统干燥效率模型,模型计算值与实验值的最大偏差在±21%以内,平均偏差为9.18%,预测效果较好。结论相较于常压下热泵低温干燥技术,基于真空低温干燥技术的热泵干燥系统能够有效提高药材干燥效率,降低药材干燥处理过程中的能源消耗,为药材高品质贮藏提供保障。

连续镀膜在真空蒸镀中的应用

蒸发镀膜是现有薄膜沉积中最为泛用的镀膜技术。针对现有蒸发镀膜设备在进行大批量薄膜制备时效率低下这一问题,基于规模生产需求设计了一种连续式蒸发镀膜设备,该设备通过设置多个仓室,仓与仓之间通过隔断阀连接,用以保持薄膜沉积仓内的真空度,真空室内设有工件盘自动装卡装置,可以节约大批量薄膜制备时重复真空抽气的时间及人工装卡时间。通过理论验算、真空抽气时间计算、受力仿真验证了结构的可行性和薄膜沉积效率的提升。

膜式烧碱蒸发工艺中Ⅰ效真空度低的原因及处理

分析了粒(片)碱生产中Ⅰ效蒸发器真空度低的原因,并提出处理方法。

中试减压蒸馏装置切割俄罗斯原油试验研究

俄罗斯原油性质上为轻质原油,API值为34.5,属于中间基原油,其中馏分段大于520℃的组分为20.84%。首次采用中试单级减压蒸馏装置,通过对刮膜蒸发器和残渣系统等技术改造,获取的减压渣油馏分中≥525℃的组分含量高于75%,达到预期目标,可以为延长石油集团碳氢技术研究中心悬浮床加氢裂化装置提供合格原料。

制盐多效蒸发真空节能技术探讨与应用

多效蒸发制盐工艺中末效的真空度直接影响各效蒸发压力和温度,进而影响传热效率、二次蒸汽的冷凝和不凝气的排除,对产量和能耗造成影响。因此,提高末效真空系统效率对多效真空制盐的节能提效至关重要。本文通过对多效蒸发制盐过程的工作能力及真空度进行研究,得到实现末效真空及整个制盐过程节能降耗的指导思路,据此研究探讨一种多管喷射真空节能技术,供有相似情况的生产单位交流探讨。

New developments for vacuum coating of steel strips

Vapor deposited coatings onto strip steel are a promising alternative as functional layers for corrosion protection or high abrasion resistance.Conventional coating systems have some limits regarding environmental compatibility,the range of coating materials and application properties. Physical vapor deposition(PVD) is an environment-friendly technology and enables nearly unlimited material and process variety.Electron beam high-rate evaporation with deposition rates up to some micrometers per second is the most productive PVD technology for low cost coating.The combination of evaporation with powerful plasma is an efficient way to improve the layer properties.The developed plasma sources can be used for special plasma enhanced chemical vapor deposition(PECVD) processes too. The paper gives an overview about the latest developments in these technologies.Furthermore,the paper explains some examples of new layer stacks onto steel strips.While enhanced corrosion protection can be obtained by magnesium,aluminium or copper containing coatings other functional surface properties come more and more in the focus of interest.For instance,decorative gold colored layers,transparent scratch resistant layers,hard coatings and photo catalytic layers were deposited on running steel strips.Functional layers and layer systems for energy saving and sun energy absorption by solar thermal effects and photo voltaics are under development.The coatings are prepared under the conditions of very high deposition rates using our in-line vacuum coater for metallic strips and sheets with the name MAXI.The influence of the process and plasma parameters on the layer properties were investigated and will be demonstrated for some applications.

THEORETIC ENERGY CONSUMPTION OF NONFERROUS METALS BY VACUUM DISTILLATION

The expressions of heat of evaporation for metals at different temperatures were deduced from Clausius-Clapeyron equation and the total change of enthalpy.Those of Pb,Cd and Zn were calculated.Results showed that theoretic energy consumption decreased a little with the decrease of e-vaporation temperature,which can be used to determine the energy demand while these metals are distilled at different process temperatures and pressures.

Different Interaction Mechanisms of Evaporated Porphyrin Films Exposed to NO₂

In this work, metal free and zinc tetraphenylporphyrin films were employed as nitrogen dioxide (NO2) gas sensors. The films were vacuum evaporated and the sensor response was evaluated as changes in the optical absorption spectra, hydrophobic properties and conductivity at different gas concentrations. From UV-Vis results, important changes in the absorption peaks were observed after gas exposure. The morphology of the films before and after gas interaction was obtained by using scanning electron and atomic force microscopy. The films morphology showed a degradation after gas adsorption for the metal free system but gas entrapment for the zinc porphyrin film. In order to elucidate the gas adsorption phenomena, density functional theory calculations were also performed. Here, it was observed that the porphyrin chemical structure not only affects the gas coordination sites which affect the porphyrin electronic distribution and packing arrangement, but also, determines the gas detection mechanism for sensing applications.

X-shape oligo(thiophene)s as donor materials for vacuum-deposited organic photovoltaic cells

The films of two x-shape oligo（thiophene）s, 3, 4-dibithienyl-2, 5-dithienylthiophene （7T） and 2, 5-dibithienyl-3, 4- ditrithienylthiophene （11T）, which are prepared by vacuum evaporation, have been investigated as novel electron donor layers in two-layer photovoltaic cells. UV-Vis absorptions show red-shifted and broadened absorptions of the vacuumevaporated films as compared with those of the corresponding solutions and spin-coating films, which is beneficial for photovoltaic properties. X-ray diffraction （XRD） and differential scanning calorimetry （DSC） measurements show that the vacuum-evaporated films are almost amorphous. Two-layer photovoltaic cells have been realized by the thermal evaporation of 7T and llT as donors and N, N′-bis（1-ethylpropyl）-3, 4：9,10-perylene bis（tetracarboxyl diimide） （EP- PTC） as an acceptor. An energy conversion efficiency （ECE） of 0.18% of the cell based on 7T with an irradiation of white light at 100 mw/cm^2 has been demonstrated by the measurements of current （I）- voltage （V） curves of the cells to be higher than the ECE of the reference system based on donor dihexylterthienyl （H3T） that is linear and without α, β linkage.

红外探测器制备中不同镀金层的对比分析

针对红外探测器制备过程中的多种镀金工艺展开了研究,通过对不同工艺制备的镀金层进行扫描电镜观察,发现不同的镀金工艺制备的样品存在较大的差异。电镀金层的晶粒直径为2~3μm,真空蒸发镀金的晶粒直径为100~600nm,离子束溅射镀金的晶粒直径在30~70nm之间。对不同的方法制备的金层与铟焊料的扩散速度进行了试验及分析,发现晶粒尺寸越小铟的扩散速度越快。