镁合金层状复合材料的爆炸焊接研究

为获得兼具镁合金与其他金属优点的层状复合材料,按照Stivers,Wittman模型,计算动态参数,选取下限工艺,进行AZ31B镁合金与1060铝合金、5083铝合金、T2铜合金、TA2钛合金、S31603不锈钢、Q345R钢的爆炸焊接实验。结果表明:AZ31B镁合金作为基板与1060铝合金复合率超过90%,与其他材料复合率低于50%(不含Q345R钢);与5083铝合金复合的界面结合强度最低。AZ31B镁合金作为复板与1060铝合金、T2铜合金、TA2钛合金、S31603不锈钢、Q345R钢复合率均超过90%,与5083铝合金的复合率只有15%,且复层均脆性断裂严重。这是由于AZ31B镁合金与5083铝合金都含有Mg、Zn等低熔点元素,在爆炸焊接界面易气化、熔化易生成金属间化合物,导致复合率与结合强度偏低。AZ31B镁合金具有密排六方结构,塑性变形能力差的特性。随着应变速率增加,强度增加,塑性降低,导致严重脆性断裂。     

镁合金层状复合材料的爆炸焊接研究

为获得兼具镁合金与其他金属优点的层状复合材料,按照Stivers,Wittman模型,计算动态参数,选取下限工艺,进行AZ31B镁合金与1060铝合金、5083铝合金、T2铜合金、TA2钛合金、S31603不锈钢、Q345R钢的爆炸焊接实验。结果表明:AZ31B镁合金作为基板与1060铝合金复合率超过90%,与其他材料复合率低于50%(不含Q345R钢);与5083铝合金复合的界面结合强度最低。AZ31B镁合金作为复板与1060铝合金、T2铜合金、TA2钛合金、S31603不锈钢、Q345R钢复合率均超过90%,与5083铝合金的复合率只有15%,且复层均脆性断裂严重。这是由于AZ31B镁合金与5083铝合金都含有Mg、Zn等低熔点元素,在爆炸焊接界面易气化、熔化易生成金属间化合物,导致复合率与结合强度偏低。AZ31B镁合金具有密排六方结构,塑性变形能力差的特性。随着应变速率增加,强度增加,塑性降低,导致严重脆性断裂。     

45钢表面超音速电弧喷涂Ti-Al涂层的组织与性能研究

采用自行开发研制的超音速电弧喷设备，在45钢表面制成了钛铝合金复合涂层。并利用金相显微镜、X射线衍射仪、扫描电镜、电子探针，对涂层的成分、相结构、显微组织及其结合强度、显微硬度进行了研究。结果表明，利用超音速电弧喷涂设备，可以在45钢表面形成 度高、孔隙率低，结合强度较好和硬度高的Ti-Al合金涂层。     

“三软”煤层沿空掘巷复合支护技术研究与应用

通过对“三软”煤层综放工作面掘进巷道应力分析,合理布置沿空掘巷,并科学有效地提出36U型钢＋36U型钢合抱焊接点柱＋喷浆复合支护工艺,保证“三软”煤层大型断面复合支护的稳定。     

无机粉体表面改性技术现状与发展趋势

1 表面改性工艺 表面改性工艺依表面改性的方法、设备和粉体制备方法而异。目前工业上应用的表面改性工艺主要有干法工艺、湿法工艺、复合工艺3大类。干法工艺根据作业方式的不同又可以分为间歇式表面改性工艺和连续＋表面改性工艺；湿法工艺又可分有机包覆改性工艺和无机沉淀包膜改性工艺；复合工艺又可分为机械化学与表面化学包覆改性复合工艺及沉淀反应与表面化学包覆改性复合工艺两种。     

6061铝合金加工技术在国内的研究进展

综述了6061铝合金加工技术研究的进展,主要包括6061铝合金的合金化、复合技术、表面处理、塑性加工、焊接工艺等方面,分析了6061铝合金加工技术研究存在的问题,并指出了6061铝合金加工技术研究的重点.     

铝合金-钢爆炸焊接装药量与界面性能的关系(英文)

通过设计不同的爆炸焊接工艺参数爆炸复合了铝合金-钢爆炸复合板,并对复合板的界面性能进行了显微分析和力学性能测试,探讨了爆炸焊接装药量对复合板界面性能的影响。结果表明:在铝合金-钢复合板的的结合界面产生了一层金属间化合物并且在化合物中产生了许多微裂纹。随着装药量的增加,界面化合物的厚度略有增加,其上微裂纹的的数量也有所增加。复合界面的剪切强度随着装药量的增加而有所降低。界面化合物对复合板强度产生不利影响,铝合金-钢爆炸焊接时应尽量采用小药量。     

客车钢板合金化镀层对防腐性能的影响

研究了不同锌铁合金化工艺对ST14钢的镀层及镀层对腐蚀的影响，用光学显微镜观察了合金化层的组织形貌，用X射线衍射方法分析了合金化层表面的相组成，用电位差仪测量了电位，并进行了盐雾腐蚀实验。结果表明：不同工艺的合金化层分别为Г＋δ1相和Г＋δ1＋ξ相；表面化学成分分别为FeZn7和FeZn7＋FeZn11；合金化层的电位分别为-920和-900mV左右，比ST14钢板的电位-620mV小，可作为阳极性涂层对钢铁基体起保护作用。锌铁合金化后的ST14防腐蚀性能远远超过ST14，且单相（61）较之双相（δ1＋ξ）有更好的防腐能力。     

缸套渗碳淬火工艺的改进

渗碳钢20crMnTi执行一次淬火工艺后,硬度值偏低,在48—50HRC之间,金相组织为粗针状马氏体＋35残余奥氏体＋未溶碳化物,因为粗针马氏体与残余奥氏体的存在,使得渗碳件的强度及表面硬度降低。执行二次淬火工艺后表面硬度达到了60HRCP以上,组织为隐晶马氏体＋弥散的颗粒状碳化物,该工艺有效的减少了残余奥氏体量,提升了渗碳件的硬度及耐磨性。     

工艺参数对Ni-SiC纳米镀层SiC粒子复合量的影响

采用超声波辅助电沉积方式,在45钢表面制备了Ni-SiC纳米复合镀层。根据阴极电流密度、PH值和搅拌速度对Ni-SiC纳米复合镀层SiC粒子复合量的影响,获取Ni-SiC纳米复合镀层最佳条件的工艺参数;并利用扫描电镜(SEM)、高分辨率透射电镜(HRTEM)研究工艺参数对Ni-SiC纳米复合镀层表面形貌和微观组织结构的影响。结果表明,获取Ni-SiC纳米复合镀层最佳工艺参数为阴极电流密度6A/dm~2,pH值=4,搅拌速度300r/min。由最佳工艺参数制得的Ni-SiC纳米复合镀层表面呈胞状,SiC粒子粒径尺寸较小,其平均粒径为21.5nm。     

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.