碳/碳复合飞机刹车材料低能摩擦性能研究

研究了碳/碳(简称C/C)复合飞机刹车材料在低能载条件下的摩擦磨损性能,分析了刹车力矩与刹车速度之间关系曲线,探讨了C/C复合材料因能载变化出现摩擦系数最大值的根本原因.结果表明:随着刹车比压增加,摩擦系数最大值下降;低能条件下C/C复合材料摩擦面较粗糙,磨损率约为正常能载下的两倍.     

化学气相沉积碳／碳复合材料性能研究

分析了化学气相沉积碳／碳（Ｃ／Ｃ）复合材料的刹车力矩和刹车速度的关系曲线及影响因素，结果表明，刹车力矩一刹车速度曲线上的初始力矩峰值随着摩擦界面温度的升高而增大，提高材料的石墨化度、改变刹车盘的结构、降低刹车比压的施加速度都可以降低初始力矩峰值，改善Ｃ／Ｃ材料的摩擦性能．Ｃ／Ｃ复合材料具有良好的自润滑性能，其磨损率仅为１．２×１０－３ｍｍ／次．它们具有较高的机械性能和热物理性能，完全可以满足飞机刹车的要求．     

高摩擦学性能碳／碳复合材料研制

探索了高摩热学性能碳／碳（Ｃ／Ｃ）复合材料的制备途径，设计出了高摩擦学性能Ｃ／Ｃ材料的组织模型，并按模型制备出了在碳纤维上分布着球状沉积碳组织的Ｃ／Ｃ材料，实验表明：这种Ｃ／Ｃ材料具有良好的摩擦磨损性能，刹车力矩和速度的关系曲线平稳，初始力矩峰值小，摩擦系数适中；磨损率小，摩擦面光滑；试样无分层、碎裂、掉块等失效情况。     

热解碳涂层碳纤维增强碳化硅复合材料热压工艺研究

采用经妥碳涂层的Ｍ４０ＪＢ碳纤维，以有机硅先驱体聚碳硅烷为粘结剂，絷压烧结制备了Ｃｔ／ＳｉＣ复合材料。测试了复合材料的性能并进行了对比，同时运用ＳＥＭ，ＴＥＭ等分析手段对复合材料的微观结构进行了表生。结果表明，所采用的碳纤维热解碳涂层对复合材料的性能有较大的影响，较好的热压温度为１８５０℃，压力为２５ＭＰａ。     

碳／碳复合材料的发展前景

论述了国内外碳／碳复合材料（Ｃ／Ｃ）的优越性、性能、工艺、应用及其前景。     

碳／碳材料快速CVD工艺结构性能及应用研究

首次提出了快速化学气相沉积碳／碳复合材料的工艺模型，设计出制备碳／碳复合材料的新工艺－－快速定向扩散法。这种方法能省去常规制备方法中需多次３人反复进行的中间机加工、高温热工处理工序，缩短制备周期约达１／４，制备的碳／碳复合材料的密度达到１．８５以上。弯曲强度、弯曲模量分别高达２４５ＭＰａ、４９ＧＰａ，氧化起始点将近提高３００℃。深入研究了快速化学气相沉积碳／碳复合材料的组织特征，揭示了工艺、性能和     

原位法表征碳／碳复合材料界面性能的研究

用单丝顶出和束顶出法分别测试了细编穿刺碳／碳（Ｃ／Ｃ）复合材料不同层次的界面粘结性能，研究了生产工艺对不同层次界面性能的影响，建立了顶出试验的力学模型，并用有限元方法分析了界面上应力的分布情况，对可能的界面破坏模式进行了预测，为最终优化Ｃ／Ｃ复合材料的生产工艺提供了依据。     

碳／碳复合材料在高能刹车副中的应用

碳／碳材料是碳基体用碳纤维增强的复合材料，它具有良好的韧性、导热性和导电性能，耐腐蚀、耐磨蚀性好，大量应用在飞机高能刹车副作热库材料，本文介绍了Ｃ／Ｃ复合材料用作高能刹车热库时，较钢、铍等金属材料有优势。还介绍了Ｃ／Ｃ材料的有关制造方法和抗氧化工艺等。     

碳／碳复合材料及其在航空上的应用前景

本文分四部分论述了碳／碳（以下称为Ｃ／Ｃ）复合材料及其发展形势：Ｃ／Ｃ复合材料的现状，工艺，性能及应用：Ｃ／Ｃ复合材料的制造工艺及其发展趋势：Ｃ／Ｃ复合材料的抗氧化保护涂层；Ｃ／Ｃ复合材料在航空上的应用前景。最后指出：Ｃ／Ｃ复合将逐渐由短期应用走向长期应用，制造工艺将由长时间走向短时间，抗氧化保护涂层将由单纯的表面涂覆走向立体多重涂覆，成本将大大降低，主要应用范围将逐渐由航天技术的结构功能材料发展     

Carbon′94西班牙国际碳会议论文题录

Ｃａｒｂｏｎ′９４西班牙国际碳会议论文题录大会报告１．碳，能源与环境ＬａｈａｙｅＪ２．碳与含氧分子的反应ＭｏｕｌｉｊｎＪＡ３．Ｃ／Ｃ复合材料中结构与性能的关系ＲｅｌｌｉｃｋＧＳ４．碳作为催化剂及催化剂载休Ｌｏｐｅｚ－ＧｏｎｚａｌｅｚＪＤ５．高密各向同...     

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 ...