Continuous-fiber reinforced composites: A new generation

The mechanical and physical properties of aluminum-matrix composites reinforced with high-performance continuous alumina fibers are reviewed and compared with those of other structural materials. Continuous-fiber reinforced aluminum-matrix compositesoffer outstanding improvements in specific strength and specific stiffness over conventional alloys and particulate composites. Thelongitudinal tensile strength of an aluminum matrix reinforced with 55–65 vol.% alumina fibers is in the range ofl.4-1.9 GPa, the longitudinal Young's modulus is 220–240 GPa, and the density is 3.2-3.4 g/cm3. The mechanisms of strengthening and fracture under longitudinal, transverse, and shear loading are reviewed. Examples of applications are presented that are representative of the range of product forms being developed.     

A new high strength and high tolerance-resistance A1-Li alloy

In order to develop a new high strength and high tolerance-resistance Al-Li alloy which can be used in aerospace industry, the effects ofmicroalloying elements such as Mg, Ag, Mn and Zn on the mechanical properties of Al-Cu-Li alloys were studied. The results show that the strengthening effects of Mg＋Ag and Mg＋Zn additions are higher than those of the individual Mg, Ag or Zn addition. The element Mn can also bring some extent strengthening effects on the alloys, but it has nothing to do with the other microalloying elements present or not. Finally, a new Al-Li alloy with Mg＋Zn＋Mn additions was developed, which possesses high strength and high tolerance-resistance promising properties for aerospace applications.     

A new electrical contact alloy with high reliability based on gold

A new gold alloy (NSCGA) was designed and prepared for light duty precision contacts. The microstructure, mechanical, electrical and applied properties of the NSCGA alloy were studied. The NSCGA alloy contains copper, palladium, platinum, nickel and rhodium as well as gold. The unique structure comprised of two phases, a gold-rich solid solution as the matrix and a platinum-rich solid solution as a strengthening phase. The matrix presents short-range ordering in the temperature range 200-900°C, which leads to the specific resistance of the alloy decreasing, and a modulated structure at low temperatures, which is responsible for age strengthening. The NSCGA alloy has low specific resistance, high tensile strength and high Vickers hardness. Various TO-5 type relays (TO-5 relay is a sealed mini relay with magnetic preservation) with NSCGA alloy as contacts were prepared and tested in a special relay factory under industrial conditions. NSCGA alloy contacts showed stable and low contact resistance, long loading life and high reliability, superior to that of an available conventional sixcomponent palladium alloy. The NSCGA alloy and the composites with NSCGA alloy as a covering layer and copper alloys as a base have been evaluated in various TO-5 type mini relays and other electric products.     

高速动车组列车模型车车体制造工艺设计

针对新一代高速列车模型车车体非正常制造工艺的特点,制定了“最快速、最节约、最美观”的工艺设计原则.从车体材料选用、装配工艺和焊接工艺三个方面,对模型车车体的制造工艺分别进行了适应性设计.通过工艺实施验证,顺利完成了模型车车体的制造任务,为今后设计制造轨道车辆新产品样车积累了宝贵经验.     

Thermoelectric properties of tin-filled skutterudites prepared by mechanical alloying process

Sn-filled (Fe, Co)Sb₃ skutterudites of the form of Sn_yFe₃Co₅Sb₂₄ (0≤y≤1.5) were synthesized by the mechanical alloying of elemental powders followed by vacuum hot pressing. The phase transformations that occur during both mechanical alloying and vacuum hot pressing were examined by X-ray diffraction. Single-phase Sn-filled skutterudite was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. The thermoelectric properties of the hot-pressed specimens were evaluated as a function of temperature and tin content. The void filling of tin (up to y=1.0) in Fe₃Co₅Sb₂₄ appeared to increase the thermoelectric figure of merit.     

新一代焊接机器人的技术发展

最新一代焊接机器人MOTOMAN-VA、VS系列由传统的6轴机器人变成7轴机器人,这使得新型机器人在动作的灵活性上有了质的飞跃,提高了避免干涉的能力,可以保持同一姿态进行避障焊接作业能力,现场布置非常紧凑.同时,新一代焊接机器人的焊接功能也得到增强.     

Photovoltaic devices fabricated with a p-type conjugated multi-branched molecules

New multi-branched crystalline molecules were synthesized through Horner(Emmons reactions using hexyl-substituted thiophene-based carbaldehydes as dendrons and [1,2,4,5-tetra-(diethoxy-phosphorylmethyl)-benzyl]-phosphonic acid diethyl ester as the core unit. 1,2,4,5-Tetrakis((E)-2-(5′-hexyl-2,2′-bithiophen-5-yl)vinyl)benzene (HPBT) and 1,2,4,5-tetrakis((E)-2-(5′-dodecyl-2,2′-bithiophen-5-yl)vinyl)benzene (DPBT) have different alkylene peripheral moities such as the hexyl and dodecyl group. The molecules were employed to fabricate organic photovoltaic (OPV) cells with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). As a result, HPBT-based bulk heterojunction with PCBM exhibited higher short-circuit current density and open circuit voltage, resulting in a higher power conversion efficiency of around 0.944%.     

A new method for welding aluminum alloy LY12CZ sheet with high strength

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高速冲槽机上一种新型可调工作台装置

高速冲槽机冲制硅钢片过程中,操作者需经常调整模具下模高度。为减轻劳动强度,提高劳动生产率,设计出一种可调工作台装置,可方便调节工作台高度,并且实现了无极调节。     

A new surgical grinding wheel for suppressing grinding heat generation in bone resection

Existing surgical technologies are unable to prevent thermal injury to adjacent tissues such as nerves that result from grinding heat generated during bone resection. To address this problem, bone grinding experiments were conducted under irrigation using commercial surgical diamond wheels to clarify the grinding characteristics. On the basis of the findings, new diamond wheels coated with submicron-sized titanium dioxide particles were developed to enhance the hydrophilicity of the wheel surfaces. The developed grinding wheels significantly suppressed bone temperature elevation during grinding compared to the commercial wheels.     

新一代SiC功率器件及其在逆变焊机中的应用

目前逆变焊机普遍采用的Si基功率器件的性能已接近由其材料特性决定的理论极限,依靠Si基功率器件继续完善和提高逆变焊机性能的潜力已十分有限。SiC是一种革命性的宽禁带半导体材料,是下一代功率半导体材料的重点发展方向。介绍了新型SiC材料的特性及其功率器件的类型、原理和特点;对比分析SiC和普通Si基功率器件的性能;在此基础上探讨将SiC功率器件应用于逆变焊机的优势;分析和展望SiC功率器件在新一代逆变焊机中的应用前景。     

A new numerical simulation model for high pressure squeezing moulding

High pressure squeeze is the most popular moulding process applied in modern moulding machines.Because of the unique characters of moulding sand and nonlinearity of squeezing process,the mechanical model is of key importance for computer simulation.Drucker-Prager/Cap is a typical soil mechanical theory model and it was used to simulate the squeezing process in this study,while ABAQUS software is used to simulate dynamic stress/strain evolution during the process.The simulation agrees well with the experimen...     

Bendability of advanced high strength steels—A new evaluation procedure

The significant lightweight engineering potential of advanced high strength steels (AHSS) is limited by its moderate formability and altered failure behavior compared to mild steel grades. Especially bendability is crucial in automotive applications. The failure phenomena and underlying damage mechanisms in small curvature bending of AHSS are revealed in this work. A new characterization approach based on optical strain measurement is presented to comprehensively identify the failure stages, critical strains and bending angles in a user-independent manner. The novel approach is generalized and broadly applicable. Thus it gives a prerequisite for improved and material specific industrial process design in future.     

Synthesis and characterization of new photorefractive polymers with high glass-transition temperatures

This paper reports detailed synthesis and characterization of some new high-T_g photorefractive polymers, polyphosphazene P3–P8. They were obtained via a post-azo coupling reaction. The resulting materials have been characterized by means of ¹H NMR, ³¹P NMR, FT-IR, UV–vis, GPC and DSC. Chromophore contents up to 14 mol% have been realized. The polymers had high glass-transition temperatures and good optical transparency. Measurements reveal that they possess relatively large magnitude of photoinduced birefringence.     

Supernitrides: A novel generation of PVD hardcoatings to meet the requirements of high demanding cutting applications

Based on a unique sputtering technology using highly ionized plasmas a novel grade of high performance hard coatings, the Supernitrides with macro free morphology were developed. Within the scope of the investigations described, a characteristic (Ti, AI)N based Supernitride variant, with an AIN content doss to the conductivity limit of 65-67mol-% AIN was deposited on cemented carbide inserts. the films mechanical properties were extracted by means of nanoindentations and impact tests and compared to the corresponding ones of an effective state of the art (Ti₄₆AI₅₄)N coating. Milling investigations, conducted with both previous mentioned coatings, demonstrated the enhanced cutting performance of the applied Supernitride coating, especially at elevated cutting temperatures.     

A new high shear degassing technology and mechanism for 7032 alloy

Degassing is very important for aluminum alloys especially for 7xxx series alloys.In the present study,a high shear technology was used to degas 7032 aluminum alloy in order to study its degassing efficiency.The experimental results showed that the high shear technology can significantly degas 7032 aluminum alloy.By applying intensive melt shearing and an Ar injection of 60 seconds,the density index,D_i,was reduced from13.25%to 0.28%and the hydrogen concentration was significantly reduced from 0.31 to 0.10 mL/100 g Al.Compared with the conventional rotary degassing,high shear technology showed a much higher degassing efficiency,achieving a lower concentration of hydrogen in a shorter time.The water simulation experiment was used to study the mechanism of the high degassing efficiency.The small bubble size and the uniform distribution of Ar bubbles with the application of high shear technology are believed to be the main cause for the high degassing efficiency.     

下一代现场总线新标准--高速实时以太网PROFINET

工业以太网是当今工业通信发展最为迅速的技术,PROFINET是真正的实时工业以太网,可以实现在各种不同场合的应用,完成各种不同需求的控制任务。从传输协议角度上,PROFINET将数据分为:NRT、RT、和IRT三种不同的类型;从应用角度上,PROFINET分为:CBA和I/O,以此来实现工业控制的一网到底的革命。