降低SiCp／Al气孔率的研究EI

分析了ＳｉＣｐ／Ａｌ复合材料中气体的来源。通过理论模型和实验分析，发现颗粒带入熔体中的气体是复合铸造法制备的ＳｉＣｐ／Ａｌ复合材料中气孔的主要来源。颗粒带入的气体可分为ＧⅠ和ＧⅡ两种类型。降低ＳｉＣｐ／Ａｌ的气孔率应从根本上杜绝气体的来源着手，特别应对颗粒带入的气体引起重视。稀释中间复合材料法正是根据这一思路设计的制备ＳｉＣｐ／Ａｌ的新的工艺方法。实验结果表明，利用该工艺制备的ＳｉＣｐ／Ａｌ复合材料的气孔率明显降低。     

碳化硅晶须和颗粒增强铝基复合材料的时效行为EI

综述了近年来碳化硅晶须（ＳｉＣｗ）和碳化硅颗粒（ＳｉＣｐ）增强铝基复合材料（ＳｉＣｗ（ｐ）／Ａｌ）时效行为的研究发展状况。主要包括碳化硅晶须与颗粒对基体时效硬化动力学、基体沉淀脱溶过程的影响规律和作用机制，以及影响ＳｉＣｗ（ｐ）／Ａｌ复合材料时效特性的因素。     

SiCp／Al复合材料的微观结构与界面

对用压力铸造法制造的碳化硅颗粒增强铝合金（ＳｉＣｐ／Ａｌ）复合材料的微观结构和界面进行了研究。结果表明：碳化硅颗粒在复合材料中均匀分布，复合材料的基体中有较高的位错密度，碳化硅颗粒中有少量的层错。研究还发现ＳｉＣｐ／Ａｌ复合材料中界面结合良好，没有反应物生成，并且在界面处没有发现孔隙存在。在复合材料拉伸断口上没有发现裸露的碳化硅颗粒，说明在复合材料拉伸破坏时ＳｉＣｐ－Ａｌ界面没有开裂，反映了压铸ＳｉＣｐ／Ａｌ复合材料中良好的界面结合。     

配对材料对Al—10SiCp复合材料滑动磨擦性能的影响

通过对Ａｌ－１０Ｓｉ／ＳｉＣｐ－４０Ｃｒ、Ａｌ－１０Ｓｉ／ＳｉＣｐ－Ｈ６２、Ａｌ－１０Ｓｉ／ＳｉＣｐ－Ａｌ－１０Ｓｉ／ＳｉＣｐ三对摩擦副的研究，发现配对材料对复合材料的抗磨损性能影响很大。结果表明，在试验条件下４０Ｃｒ钢适合与该铝基复合材料配对使用，而黄铜和该材料配对使用，则会大大降低复合材料耐磨损性能。另外，在较低载荷条件下，Ａｌ－１０Ｓｉ／ＳｉＣｐ自配对磨损率很低，亦能自配对使用。     

配对材料对Al-10Si/SiC_p复合材料滑动磨擦性能的影响

通过对Ａｌ－１０Ｓｉ／ＳｉＣｐ－４０Ｃｒ、Ａｌ－１０Ｓｉ／ＳｉＣｐ－Ｈ６２、Ａｌ－１０Ｓｉ／ＳｉＣｐ—Ａｌ－１０Ｓｉ／ＳｉＣｐ三对摩擦副的研究，发现配对材料对复合材料的抗磨损性能影响很大。结果表明，在试验条件下４０Ｃｒ钢适合与该铝基复合材料配对使用，而黄铜和该材料配对使用，则会大大降低复合材料耐磨损性能。另外，在较低载荷条件下，Ａｌ－１０Ｓｉ／ＳｉＣｐ自配对磨损率很低，亦能自配对使用。     

SiCp／Al—Li复合材料的微观结构性能,及断裂特征

本文对粉末冶金法制备的ＳｉＣｐ／Ａｌ－Ｌｉ复合材料进行了不同温度的拉伸试验和透射电镜分析。结果表明，该复合材料具有高的室温度和低的延伸率。在复合材料基体晶界和ＳｉＣ颗粒界面处理均存在一定宽度的无沉淀带。微裂纹常在基体晶界和ＳｉＣ颗粒界面处形成。复合材料的断裂裂形貌为韧窝加沿晶断裂。     

原位形成Al3Ti颗粒对SiCp／2024Al复合材料性能及微观结构的影响

本文采用粉末冶金法制制备了含Ｔｉ的ＳｉＣｐ／２０２４Ａｌ复合材料。研究表明，在复合材料制备工艺条件下，部分Ｔｉ与Ａｌ反应形成了Ａｌ３Ｔｉ，粗大的Ａｌ３Ｔｉ／Ｔｉ复合颗粒的存在降低了复合材料的室温拉伸强度和塑性，但可以提高屈服强度和弹性模量。     

复合电沉积法制备SiC_p／Cu复合材料的工艺研究EI

研究了用复合电沉积法制备ＳｉＣ_ｐ／Ｃｕ复合材料的工艺。结果表明，用复合电沉积法制备颗粒增强金属基复合材料是一种切实可行的方法。当镀液中ＳｉＣ颗粒含量为１５ｇ／１，电流密度为４Ａ／ｄｍ￣２，电镀温度１５～２０℃，板泵搅拌时，可获得含有２０ｖｏｌ％ＳｉＣ_ｐ的ＳｉＣ_ｐ／Ｃｕ复合材料。     

颗粒增强TiAl基复合材料及其Si的韧化作用研究EI

运用ＸＤ工艺制备了颗粒增强ＴｉＡｌ基复合材料。增强颗粒均匀分布于ＴｉＡｌ基体中并细化ＴｉＡｌ合金。通过在ＴｉＢ_２／ＴｉＡｌ、ＴｉＣ／ＴｉＡｌ复合材料中加入适量的Ｓｉ，颗粒增强ＴｉＡｌ基复合材料的室温延性得到了改善。     

热挤压对SiCW/Al复合材料塑性的影响

对ＳｉＣｗ／Ａｌ复合材料进行了热挤压，并用ＳＥＭ对拉利断口进行了观察和分析。研究结果表明，抗挤压能够明显地提高ＳｉＣｗ／Ａｌ复合材料的塑性。热挤压导致复合材料塑性提高的原因是由于热挤压变形造成基体塑性的提高，以及晶须的折断和沿挤压方向定向排列的结果。     

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.     

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...     

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.……     

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 ...