植酸在镁合金表面处理中的应用研究

采用稀土铈盐在镁合金表面生成了化学转化膜,通过扫描电镜、能谱分析等手段研究了采用植酸对镁合金表面及其表面化学转化膜进行后处理的改性作用,讨论了植酸浸泡溶液与工艺参数对吸附膜增重的影响.研究表明,镁合金表面植酸浸泡吸附膜以及化学转化膜植酸浸泡处理后膜层的增重随植酸浓度的增加、温度的升高及时间的延长而增大,所得化学转化膜经植酸浸泡处理可改善膜层表面龟裂,提高镁合金及其表面转化膜的耐蚀性,代替对环境污染严重的铬酸盐处理技术;并对镁合金表面膜的微观形貌与元素组成进行了表征.     

镁合金热处理的研究现状及发展趋势

热处理对镁合金的影响已受到广泛关注.综述了当今国内外现有的镁合金热处理的方法(如退火、固溶、时效、形变热处理、氢化处理、表面热处理等)以及特点,阐述了热处理工艺对镁合金显微组织、力学性能、腐蚀性能的影响,最后展望了镁合金热处理的发展方向.     

摩托车轮毂镁合金微弧氧化工艺

微弧氧化技术试验研究多,但大型生产应用较少.为此,以大面积镁合金轮毂为例,探讨了镁合金微弧氧化的实际应用,并对镁合金轮毂微弧氧化的工艺参数进行了优化,对膜层的质量进行检测.结果证明:微孤氧化用于镁合金轮毂表面处理效果较好,对大面积镁合金表面处理有着重要的参考价值.     

表面处理镁合金疲劳性能的研究现状

随着镁合金应用的日益广泛,其疲劳性能也越来越受到人们的重视.对近年来有关表面处理镁合金疲劳性能的研究进行了总结,归纳了喷丸处理、滚压强化、阳极氧化、激光熔融等表面处理方法对镁合金疲劳性能的影响及机理.最后对改善镁合金疲劳性能未来应重点发展的表面处理技术进行了展望.     

从重庆长安公司看中国镁的应用技术

以JM5-74C变速器壳体为例介绍了汽车传动部件用镁产品的设计思路,并就镁合金的压铸工艺、生产用模具、熔融镁合金的防氧化方案、机械加工工艺、表面处理策略等问题进行了探讨.通过讨论展示了我国目前镁合金在汽车部件上的应用技术现状.     

镁合金非铬酸盐表面处理

讨论了ZM5镁合金非铬酸盐表面处理工艺.分析了前处理、化学转化膜等因素对涂膜质量的影响.利用显微硬度计、扫描电镜和杠杆式万能强度试验机分析测定了涂层的表面形貌、硬度和附着力.结果表明,在优化的工艺条件下,所得的涂层均匀且与基体的结合能力良好,对镁合金基体有较好的保护作用,提高了ZM5镁合金的耐湿热性、硬度等性能.     

镁合金表面光亮酸蚀工艺研究

镁及其合金表面极易氧化而失去金属光泽,而用常规方法处理后表面往往呈黑灰或灰白等,影响其美观性.为此,通过正交试验对镁合金表面无Cr、F光亮酸蚀工艺进行了优选,确定其最佳工艺参数为:含PO34-的溶液50%(体积比,下同),具有缓蚀及整平作用的辅助溶液(含氮杂环类物质)50%,温度20～40 ℃,时间1～10 min.此工艺处理镁合金反应速度适中,不易发生过腐蚀,处理后合金表面光亮度高.     

镁合金表面磷化膜组织结构与性能的研究

镁合金表面处理已成为镁合金领域的一个研究热点,而磷化又是镁合金表面处理的一个重要方向.采用一种典型磷化液和磷化工艺在镁合金表面成功制备出磷化膜,重点对其组织结构和耐蚀性能进行了研究.发现磷化膜不同微区的组织结构存在一定差异,磷化膜的耐蚀性能与磷化膜的微区化学组成有关.     

AZ91D镁合金前处理工艺对化学镀镍的影响

为了获得适合在AZ91D镁合金上进行化学镀镍的前处理工艺,借助扫描电子显微镜、金相显微镜等设备研究分析了不同前处理工艺对AZ91D镁合金化学镀镍层形貌及性能的影响,并确定了更适合在镁合金上进行化学镀镍的酸洗和活化工艺.结果表明,经此工艺处理后的镁合金表面均匀平整,施镀后可获得表观平整光亮、胞状结构均匀致密、与基体结合力及耐蚀性良好的非晶态Ni-P合金镀层.与常用的处理方法相比,这种新工艺处理温和,更适合在镁合金上使用.     

镁合金化学转化处理

综述了镁合金表面化学转化处理特别是无铬转化处理的现状、主要工艺以及在不同处理工艺下得到的转化膜的特性,重点介绍了铬酸盐转化膜,磷酸盐转化膜、重金属含氧酸化合物转化膜,稀土转化膜和有机化合物等工艺的具体研究状况,展望了镁合金化学转化膜的发展趋势,指出随着镁合金应用领域的拓宽和环保要求的提高,镁合金无铬化学转化处理的研究将越来越得到重视.     

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.……     

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.……     

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...     

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.     

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.     

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 ...