电沉积工艺参数对块体纳米晶镍硬度的影响

采用直流电沉积方法,通过改变特殊添加剂C7H4NO3SNa·2H2O浓度、电流密度、沉积液温度,制备出不同硬度的块体纳米晶镍覆层材料,利用高分辨透射电子显微镜(HRTEM)对沉积覆层材料的组织形貌进行分析,利用显微硬度计测量沉积层材料的显微硬度,对块体纳米晶镍硬度的变化规律进行分析.结果表明:通过改变工艺参数,可获得结构致密,组织均匀的块体纳米晶覆层材料.块体纳米晶镍的硬度随着添加剂C7H4NO3SNa·2H2O浓度的增加而增加;随电流密度的增加,呈现增加趋势,在700A·m-2至1100A·m-2范围内,基本保持不变;随着温度的增加而下降.     

烧结温度对TiAl合金块体材料组织和性能的影响

采用机械合金化和等离子烧结工艺成功制备细晶TiAl合金,研究不同烧结温度(750~1050℃)对所得块体材料的显微组织和力学性能的影响。XRD研究发现:完全固结的块体材料主要由γ-TiAl和α2-Ti3Al相组成。采用SEM和TEM观察块体材料的显微组织。当烧结温度为950℃时,所得的块体材料致密度高,接近完全致密化,其压缩屈服强度为2106 MPa。当烧结温度大于950℃时,致密度未发生明显变化,块体材料的屈服强度有所下降。     

激光烧结快速制备自由形状纳米块体材料的试验研究

基于选区激光烧结快速成形技术，以纳米Al2O3粉体材料为研究对象，进行了自由形状纳米块体材料制备的研究。研究结果表明，在适当的工艺参数下，可制备出任意形状的Al2O3块体材料，材料内部组织结构致密，晶粒尺寸保持在40nm以内。与其他烧结方法相比，激光烧结制备的纳米材料晶粒尺寸更为细小，组织结构更为致密。     

金属铝纳米晶块体材料的制备与性能表征

在惰性气体保护的全封闭系统内,采用直流氢电弧蒸发-冷凝与放电等离子烧结相结合的技术制备出高致密度、晶粒尺寸细小且分布均匀的纯铝纳米晶块体材料.对制备材料的结构分析表明,铝纳米晶块体具有很高的纯度,纳米晶界面洁净无杂相.对制备的铝纳米晶块体的力学性能测试表明,其显微硬度为2.12GPa,比铝粗晶材料提高了约6倍;而弹性模量与粗晶块体相比变化不大.     

纳米复合Al-Ni-Y系铝合金的制备技术

部分晶化非晶铝合金因其优异力学性能备受关注,对块体非晶铝合金制备技术的研究意义重大.本工作通过紧耦合惰性气体雾化技术制备了Al82Ni10Y8非晶及纳米晶粉末,随后利用超高压固结成形技术对雾化粉末进行致密化.制备所得的块体材料获得了非晶及纳米晶的复合结构.利用差示扫描量热分析,X射线衍射,扫描电镜和透射电镜等测试手段对合金的热稳定性,物相组成,微观组织和形貌进行了分析,并探讨了合金的可能致密化机理.     

用粉末烧结法制备Fe3Al金属间化合物块体材料

采用粉末烧结技术对人工研磨得到的纯Fe3Al元素粉末按一定的比例混合后进行烧结,并对烧结体进行不同条件的热处理,制备出Fe3Al金属间化合物块体材料.利用光学金相显微镜、X射线衍射分析了所制备的块体材料的物相组成和显微组织.结果表明,烧结试样经1 100℃保温12 h随炉冷至600℃保温1 h空冷处理,可以得到较均匀、致密的Fe3Al金属间化合物块体材料.     

微结构对Bi_2Sr_2Co_2O_y化合物电性能的影响

通过溶胶-凝胶法制备单相Bi2Sr2Co2Oy化合物,通过添加PEG20000和超声分散对化合物粉体微结构进行调控,采用SPS烧结得到了致密的块体.探索了微结构对Bi2Sr2Co2Oy化合物电性能的影响规律.结果表明,添加PEG20000和超声分散可以明显降低Bi2Sr2Co2Oy化合物粉体的晶粒尺寸,使烧结块体的晶粒尺寸大幅度减小,从而显著提高材料的电性能.温度为873K时,添加PEG20000并超声处理所制备样品烧结块体获得了最高ZT值0.041.     

高频脉冲电铸Ni-Co纳米复合块体微观结构分析

采用高频脉冲电铸工艺制备出了镍钴纳米复合块体材料，利用场发射扫描电镜、能谱和X射线衍射的方法，重点研究了复合块体沉积层的表面形貌、相结构和结晶取向。结果表明．高频率和润湿剂的添加对沉积层的细化有重要影响，高频脉冲电铸能够获得微观组织致密、均匀的复合块体材料。     

超声化学结合放电等离子烧结制备In4Se3化合物的热电性能研究

采用超声化学和后续还原热处理工艺合成了单相In4Se3化合物粉体,并结合放电等离子烧结技术(SPS)制备了致密的块体材料.对所得的块体材料的微结构和热电传输性能进行了系统研究.结果表明,块体样品的晶粒细小、排列紧密并存在显著的择优取向,同时样品中存在大量精细的层状结构,这使得块体样品的电热传输性能也表现出明显的各向异性.由于具有较高的Seebeck系数和较低的热导率,沿着SPS压力方向上样品表现出较好的热电性能,其最大ZT值在700 K可达到0.56,这与其它物理技术制备的In4Se3多晶材料的性能相当.     

熔体旋甩法制备Zn4Sb3热电材料微结构的研究

采用真空熔融-熔体旋甩-退火-放电等离子烧结（SPS）工艺制备了单相β-Zn4Sb3块体热电材料。对退火前后的薄带和SPS烧结后块体材料的相组成和微结构进行了分析和表征。结果表明：熔体旋甩后分相的薄带在退火后转变成主相为Zn4Sb3的薄带，退火薄带SPS烧结后得到了致密的β-Zn4Sb3块体材料；冷却速率和退火工艺对薄带自由面和与Cu辊接触面的物相和形貌变化影响较大；该工艺制备的β-Zn4Sb3块体热电材料致密，晶粒尺寸细小，约为50-80nm。     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.