铀表面纳米铌镀层的结构及其抗腐蚀性能

铌镀层硬度高,化学稳定性好,抗大气腐蚀性能优良,与铀的热膨胀系数接近,可作为铀的防腐蚀镀层,过去对该镀层结构研究不够.为此,采用磁控溅射离子镀技术在贫铀表面以不同偏压制备了铌镀层,利用X射线衍射仪和扫描电镜对镀层的组织结构进行了表征,利用电化学测试技术对铀表面铌镀层在含50 μg Cl~-的KCl水溶液中的抗腐蚀性能进行了研究.结果表明:铌镀层平整致密,但存在靶材飞溅颗粒形成的镀层缺陷,铌镀层为bcc结构,存在择优取向与晶粒细化等特性,为纳米层;在含50μg/g Cl~-的KCl溶液中,金属铌的腐蚀电位-138.5mV高于贫铀的腐蚀电位-641.2 mV,铌镀层对贫铀是一种阴极性镀层,对贫铀的保护基于其对腐蚀介质的物理屏障作用;镀铌贫铀样品的极化电阻和电化学阻抗幅值远大于贫铀,腐蚀电流远小于贫铀,铌镀层对贫铀基体具有良好的腐蚀防护作用.     

镀镍冲孔钢带的耐蚀性能和电化学机理研究

通过浸泡法测量了镀镍冲孔钢带在Ni(NO3)2溶液中的腐蚀速率,采用动电位极化曲线、电化学阻抗谱(EIS)和XPS分析进行了镍沉积层在5%NaCl溶液中的电化学腐蚀行为和机理研究,结果表明,冲孔钢带基体沉积镍层显著改善了抗腐蚀性能,镍沉积层的固有性质和钝化膜的形成是提高镀镍冲孔钢带防腐性能的主要因素,相比于Watts镀液,从柠檬酸钠溶液中制备的镀镍冲孔钢带极化电阻高、腐蚀电流小、电极转移电阻大和腐蚀速率小。     

电化学方法研究腐蚀介质对热浸镀Al-Zn-Si-RE合金镀层腐蚀行为的影响

为研究腐蚀介质对热浸镀Al-Zn-Si-RE合金镀层腐蚀行为的影响,利用电位-时间曲线、Tafel曲线和电化学阻抗谱技术研究了合金镀层在不同盐度、温度和pH值的NaCl溶液中的电化学腐蚀行为,利用扫描电子显微镜(SEM)观察不同腐蚀介质下极化测试后合金镀层的腐蚀形貌.结果表明:随着NaCl溶液温度或浓度的提高,热浸镀Al-Zn-Si-RE合金镀层均出现腐蚀电位负移、镀层腐蚀倾向增大、腐蚀速率增加、腐蚀抗力降低的现象;此外,酸性和碱性条件均会加快镀层在NaCl溶液中的腐蚀速率,其中镀层在pH值为11.0的碱性条件下,腐蚀电流最大,阻抗谱容抗弧幅值最小,说明镀层腐蚀速率最快,耐蚀性最差.     

化学镀镍技术在凝汽器铜管上的应用

采用电化学方法测量了HSn70 1A黄铜管、316L不锈钢管和表面镀镍的HSn70 1A黄铜管在下花园电厂循环水介质中的电偶腐蚀电流、阳极极化曲线、极化电阻和电化学阻抗,综合评价和比较了上述几种材料在循环水介质中的耐腐蚀性。结果表明在给定的循环水介质中,相对于黄铜管基材,化学镀镍层是阳极性镀层;镀镍铜管的耐腐蚀性远远好于黄铜管,接近于不锈钢。本文的实验结果为镀镍管在下花园电厂的工业应用提供了可靠的理论依据,目前该厂已在1号机凝汽器上安装使用了若干根镀镍铜管,这也是镀镍铜管在凝汽器上的首次应用。     

化学镀镍磷层孔隙率的电化学评价

钢铁基体上的化学镀镍磷层属于阴极保护镀层,其孔隙率测定非常重要.为此,对化学镀镍磷层孔隙率电化学测定方法进行了探索.通过研究钢铁和化学镀镍磷层在不同介质中电化学行为的区别,选择了5%H2SO4作为测试介质,并研究了该介质中不同孔隙率镀镍磷层的电化学行为.结果表明:随镀层孔隙率的减少,镀层的自腐蚀电位逐渐从铁的自腐蚀电位向纯镍磷镀层的自腐蚀电位变化.而应用常规的孔隙率检测方法只能检测较大的孔隙.电化学方法与贴滤纸法孔隙率测试结果是一致的,说明该方法可行.     

X100钢表面Ni-WS2镀层在油田采出水中的耐蚀性能研究

为了提高X100管线钢在油田采出水中的耐蚀性,在X100钢表面上采用电镀技术制备了Ni-WS2镀层,考察了其在60℃、流速0.6 m/s的腐蚀液中浸泡24.0 h后的电化学性能;使用扫描电子显微镜(SEM)观察镀层腐蚀前后的微观组织结构及厚度,通过X射线衍射仪(XRD)分析镀层腐蚀前后的相组成;采用动电位极化曲线(PDP)和电化学阻抗谱(EIS)测试对镀层的耐腐蚀性能进行评价.结果 表明:Ni-WS2镀层的腐蚀产物由Fe3C和FeOOH组成,相较于X100钢基体具有更正的腐蚀电位、较高的阻抗值,且腐蚀电流密度较低,腐蚀形貌显示镀层腐蚀程度较轻且仍致密均匀.由此可见,在X100管线钢表面电镀Ni-WS2镀层可以大幅提高X100管线钢的耐腐蚀性.     

304不锈钢在钻井废弃液中的腐蚀行为

目前针对钻井废弃液中材料的腐蚀研究尚属空白。采用浸泡腐蚀试验、电化学阻抗谱(EIS)、动态极化曲线、扫描电镜(SEM)研究了304不锈钢在钻井废弃液介质中浸泡不同时间后的腐蚀情况。结果表明:浸泡腐蚀初期(5~10 d),试样的腐蚀电流密度显著增加,对应的自腐蚀电位和极化电阻减小,耐腐蚀性能变差;而随着浸泡时间的延长(10~30 d),腐蚀电流密度减小,极化电阻增大,腐蚀减缓;浸泡30~90 d期间,极化电阻、自腐蚀电位显著增加;整个浸泡腐蚀期间试样表面的保护膜层处于生成-破坏-自修复的动态变化中,这使得304不锈钢的耐腐蚀性能较好,浸泡腐蚀90 d后的试样表面生成了较为均匀的保护膜。     

A7N01S-T5铝合金在84消毒液中的电化学行为

为了研究消毒液对高铁车厢铝合金腐蚀的影响,采用动电位极化和电化学阻抗2种电化学测量技术,研究了高铁车体A7N01S-T5铝合金在不同浓度(100,200,400,800,1 000 mg/L) 84消毒液中的电化学行为,取自来水作为对照试验,使用VHX-2000C超景深三维体式显微镜观察试验后铝合金电极的微观形貌。结果表明:电化学阻抗谱中的Nyquist谱电极过程受活化和扩散控制,随着消毒液浓度升高电荷转移电阻和低频阻抗值减小并趋于一致;极化曲线的阴极过程和阳极过程分别以析氢反应和氧化还原反应为主,随着消毒液浓度升高,自腐蚀电位在不断负移后趋于一致,点蚀电位不断负移,腐蚀电流密度逐渐增大后趋于一致;随着消毒液浓度升高合金表面腐蚀由点蚀发展为全面腐蚀,腐蚀区域扩展缓慢,腐蚀速度减缓。     

N80钢CO2腐蚀过程的EIS研究

应用电化学阻抗谱研究了N80钢在饱和CO2的模拟地层水中CO2腐蚀过程的电化学行为.结果表明:在饱和CO2的模拟地层水中阻抗谱出现三个时间常数,分别对应高频的容抗弧,中低频的感抗弧和低频的容抗弧.阳极极化条件下的阻抗谱与自腐蚀电位下的阻抗谱形状相同,表明腐蚀机理未发生改变.但极化条件下反应电阻下降,反应速率加快.阴极极化条件下,阻抗谱未出现感抗弧,表明阴极过程不存在吸附中间产物.     

SAF2507在高温高浓度磷酸中的电化学性能

采用动电位极化、电化学阻抗谱技术对超级双相不锈钢SAF2507在高温高浓度磷酸中的腐蚀行为进行研究。结果表明,SAF2507在64%~72%的85℃磷酸中发生自钝化,且随着浓度增加到80%~88%时,腐蚀电流密度增大,其值仍较小。SAF2507在25~70℃的76%浓度磷酸中,有二次活化现象。随温度升高,SAF2507的反应过程由电化学步骤控制转变为电化学和扩散反应共同控制,且容抗弧半径逐渐减小,极化电阻逐渐减小,耐蚀性能下降。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...