镁合金环保型阳极氧化成膜工艺

利用正交试验对AZ9D压铸镁合金环保型阳极氧化成膜工艺进行了研究，结果表明，环保型阳极氧化成膜工艺能在镁合金上形成银灰色的氧化膜层，其耐腐蚀性与结合力接近于传统含铬工艺DOW17所形成的膜层，阳极氧化膜主要由MgAl2O4组成，为不规则多孔结构，其孔径比铝合金阳极氧化膜孔径大得多，在成膜过程中，阳极氧化电压和成膜剂是影响氧化膜性能的主要因素。     

镁合金浸锌及膜层彩化工艺

用化学法和阳极氧化法研究了AZ91镁合金浸锌和浸锌膜层表面彩化新工艺，结果表明：AZ91镁合金表面可以得到均匀，致密的锌膜层，而且可以用阳极氧化法使浸锌膜层表面变成彩色，并且在热力学上证明浸锌反应是可行的。     

镁合金摩托车轮毂微弧氧化的成膜机理及膜层的耐蚀性能

为了获得较高质量的微弧氧化膜层,采用脉冲微弧氧化技术在碱性硅酸盐溶液体系中对AM60B镁合金摩托车轮毂进行微弧氧化,利用SEM、XRD、金相显微镜和盐水喷雾等方法研究了氧化成膜的过程和所得陶瓷层的耐蚀性能,分析了陶瓷层的厚度、致密层和疏松层等之间的关系以及膜层的成膜机理,获得最优微弧氧化电解液成分及工艺参数：9g／L硅...     

铝合金在大脉冲电流下的快速成膜工艺及微观组织分析

采用阳极氧化表面处理的方法对铝活塞顶面进行处理,开发了一种在大脉冲电流下在活塞表面上快速生成一层厚阳极氧化膜的工艺方法,讨论了各种主要氧化条件如H2SO4浓度、添加剂、电流密度、电解液温度、电压及时间等对此快速成膜的影响,并用扫描电镜SEM对其微观组织进行了分析.     

镁合金高压阳极氧化工艺研究

为开发耐蚀性能优良的镁合金阳极氧化工艺,用正交试验对AZ91D镁合金高压阳极氧化成膜工艺进行了研究,并利用扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、全浸腐蚀试验和极化曲线等分别研究了镁合金阳极氧化膜层的表面形貌、相成分、元素成分、价态和膜层的耐蚀性等.获得了AZ91D镁合金高压阳极氧化的最佳成膜工艺参数为:10 g/L KOH,5 g/L NaF,5 g/L Na2SiO3,0.5 g/L Na2B4O7, 100 mL/L乙二醇, 75 mL/L丙三醇, 50 mL/L组分G;电流密度 8.9 mA/cm2,氧化时间 30 min.在最佳工艺下所得阳极氧化膜层呈多孔结构,孔洞分布比较均匀,孔径尺寸约为1～2 μm;氧化膜层主要由Al2SiO5、MgF2和MgAl2O4相组成;氧化膜层的耐蚀性明显优于传统含铬DOW17工艺所得氧化膜层的耐蚀性.     

难溶粉体对硫酸溶液中铝阳极氧化膜性能的影响

论述了铝在硫酸阳极氧化溶液中添加Ａｌ２Ｏ３、ＳｉＣ、ＴｉＯ２和ＣＢ（炭粉）等难溶性粉体后对铝阳极氧化过程和氧化膜的影响。实验表明，氧化的槽电压、膜层硬度、耐磨性及耐蚀性随粉体不同而不同。     

染色和封孔对铝阳极氧化膜结构和耐蚀性的影响

目前,染色和封孔对铝阳极氧化膜的结构和耐蚀性的影响尚不清楚,且有机染色工艺还不够好。采用200 g/L H2SO4电解液在高纯铝表面制备了综合性能良好的阳极氧化膜,通过含芳香烃的有机偶氮染色剂DLM2203和DLM2707对铝阳极氧化膜进行染色处理,用沸水对染色膜进行封孔处理。采用扫描电镜(SEM)、X射线衍射仪(XRD)、红外光谱仪等分析铝阳极氧化膜及染色膜的表面形貌和相组成,并采用动电位极化曲线、电化学阻抗谱等分析铝阳极氧化膜和染色膜的耐蚀性能。结果表明:铝阳极氧化膜染色均匀,表面平整;染色膜经过沸水封闭处理后,其外观颜色变浅;铝阳极氧化膜经染色处理后,厚度和显微硬度都略有增大;沸水封闭导致染色膜厚度略有增大,而显微硬度减小;铝阳极氧化膜的部分孔洞可被DLM2203染色剂充分吸附而成功染色;DLM2707有机染色剂对铝阳极氧化膜有一定的腐蚀作用;铝阳极氧化膜和2种染色膜的相组成相同;偶氮染料分子可以吸附在铝阳极氧化膜的多孔结构内与表面上;染色膜的腐蚀电流密度相对于高纯铝降低了4个数量级,耐蚀性能较好;铝阳极氧化膜与染色膜的阻抗值均处在同一数量级上,耐腐蚀性能基本相近。     

乙二胺四乙酸对镁合金阳极氧化膜性能的影响

阳极氧化电解液的组成和浓度会影响镁合金表面氧化膜的表面质量及防护性能。在以Na OH+Na₂Si O₃+Na₅P₃O₁₀为主要成分的基础电解液中添加不同含量的乙二胺四乙酸对Mg₉₇Y₂Zn₁-1.5Al镁合金进行阳极氧化,研究不同含量的乙二胺四乙酸对镁合金阳极氧化膜的质量和耐蚀性的影响。结果表明:乙二胺四乙酸能够提高镁合金阳极氧化过程中的成膜电压,乙二胺四乙酸的加入量直接影响氧化膜的表面质量及耐蚀性能。试验中最佳乙二胺四乙酸的浓度为0.03 mol/L,此时阳极氧化膜光滑致密,自腐蚀电流密度低,腐蚀失重量小,耐腐蚀性能高,可以较长时间有效地保护镁合金。     

钝化液温度对铝阳极氧化膜性能的影响

对铝及其合金进行钝化处理是提高其耐蚀性的有效手段.研究了工业纯铝普通阳极氧化膜在不同温度钝化液(Alsur408)条件下处理的表面形貌、组织结构、厚度和耐腐蚀性规律.结果表明,阳极氧化的工业纯铝氧化膜表面有均匀的纳米级孔洞,经不同条件钝化后,在氧化膜表面生成钝化膜,厚度约为1μm;随着钝化温度增加,钝化膜逐渐增厚,表面形貌致密平整;当钝化液温度高于50℃时,表面裂纹明显,耐腐蚀性表现为先增强后减弱;当钝化液温度为40℃时,钝化膜表面平整致密,无微裂纹,自腐蚀电位为0.1V,耐腐蚀性最高.     

AZ31镁合金无铬阳极氧化新工艺

为了提高镁合金的耐腐蚀性能,采用直流阳极氧化工艺研究了一种新型无Cr环保型镁合金阳极氧化配方及工艺.溶液主要成分包含NaOH、Na3PO4、KF、铝盐和适量添加剂.结果表明,氧化膜主要由MgO和MgAl2O4组成;该环保型阳极氧化新工艺所获得的膜层的耐腐蚀性能等级为9级,优于传统的HAE工艺(8级),对AZ31镁合金能提供更有效的保护.     

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 ...