碳纤维/聚苯硫醚热塑性复合材料电阻焊接工艺

本文针对航空器结构用碳纤维/聚苯硫醚(CF/PPS)复合材料为研究对象，开展电阻焊接工艺研究；利用CF/PPS复合材料混编织物作为电阻元件，成功制备了CF/PPS复合材料层板电阻焊接接头；重点利用Taguchi方法和方差分析获取CF/PPS复合材料层板电阻焊接最佳工艺参数(电流为12 A，压力为1.5 MPa，时间为30 min)及各参数对焊接接头剪切强度的贡献(电流为83.37%，压力为9.55%，时间为6.02%)。最佳焊接工艺参数焊接的接头单搭接剪切强度约为17.88 MPa；同时，对最佳参数焊接试样(H-LSS)和较低剪切强度试样(L-LSS)的焊接接头截面和剪切失效断口形貌进行了观察和分析。结果表明:H-LSS试样的焊缝区域树脂填充和浸润良好，且主要剪切失效形式为层间剪切失效，即为纤维与树脂基体脱黏及CF/PPS织物复合材料断裂混合失效；L-LSS试样的焊缝区域树脂填充和浸润较差，存在较多空隙，且剪切失效形式为焊缝界面脱黏失效。      

老化环境对碳纤维增强聚醚酰亚胺树脂基复合材料超声焊接头性能的影响

超声焊接技术因其高效、环保被认为是复合材料连接的有效方式之一。复合材料超声焊接头在不同使用环境中可能会存在一定的老化效应。文中以碳纤维增强聚醚酰亚胺复合材料(CF/PEI)超声焊接头作为研究对象，采用单搭接剪切强度(LSS)和接头破坏形貌的扫描电子显微镜观察的方法对CF/PEI复合材料超声焊接头在高温、水煮和湿热环境中的老化性能进行了评估。研究结果表明，复合材料超声焊接头单搭接剪切强度在较高温度时（110～170℃）存放5 h、吸水率在1%以上及湿热环境中（30℃，湿度50%）存放不同时间（5～15 d）后均出现明显下降。     

化学镀锡层对镁铝异种金属超声波焊接的影响

为提高镁铝异种金属超声波焊接接头强度,预先在铝合金表面镀锡后进行镁铝异种金属超声波点焊,并对接头的微观组织和力学性能进行分析.研究表明:无镀锡层的镁铝超声波焊接接头界面出现了大量的Mg_3Al_2和Mg_(12)Al_(17)相,其接头的最大拉伸剪切强度为27.5 MPa;含镀锡层的铝镁超声波焊接结合区由镁锡反应扩散层、残余锡层和铝锡反应扩散层组成,其中,铝锡反应层是固溶体层,镁锡反应层主要是过饱和的固溶体基体及弥散析出的中间相Mg_2Sn,其接头的最大拉伸剪切强度为32.9 MPa.镀锡层的加入有效阻止了镁铝的相互扩散,抑制了硬脆的Mg-Al系金属间化合物的生成,提高了镁铝超声波焊接接头强度,与镁铝超声波焊接相比最大拉伸剪切强度提高了19.6%.     

SiC颗粒增强铝基复合材料的纯铜中间层液相扩散焊

采用Cu箔中间层在Ar气氛保护、550℃条件下过渡液相扩散焊(TLP)焊接SiC颗粒(SiC_P)增强Al基复合材料SiC_P/ZL101和SiC_P/Al (SiC_P 10vol%),对母材与焊接接头的微观组织、剪切强度、焊接接头剪切断面与断裂路径等进行分析。结果表明:在铸Al(ZL101)与纯Al(Al)基体中,分别通过共晶温度较低的Al-Si-Cu(524℃)三元共晶反应与Al-Cu(548℃)二元共晶反应实现中间层金属/基体金属(M/M)界面润湿。其中铸Al基体焊接接头中虽有颗粒偏聚,但由于Al-Si-Cu三元共晶反应的Cu含量(26.7wt%)低于Al-Cu二元共晶反应的Cu含量(33wt%),SiC_P/ZL101焊接接头焊缝中CuAl₂相少于SiC_P/Al焊接接头焊缝中的CuAl₂相,且未出现CuAl₂相的聚集,故其强度较高。Cu中间层形成的金属间化合物CuAl₂相是影响焊接接头力学性能的重要因素,两种复合材料焊接接头的剪切强度分别为85.4 MPa和73 MPa。      

水分在粘接接头界面的扩散系数和动力学

为研究水分在粘接接头界面的扩散行为，采用X射线能谱（EDX）分析方法计算了水分在碳／碳复合材料粘接接头界面的扩散系数和扩散动力学，并比较了水分在不同表面处理方法处理的碳／碳复合材料粘接接头界面的扩散系数和扩散动力学．结果表明，经偶联剂处理的碳／碳复合材料耐久性能要好于化学氧化和砂纸打磨处理，这与剪切强度测试结果相一致．     

铝基复合材料(Al2O3p/6061Al)过渡液相扩散连接

研究了Al-Si合金中间层Al2O3p/6061Al复合材料过渡液相扩散连接接头的显微结构和连接工艺参数对接头剪切强度的影响。连接区主要由Al-Si合金组成，无Al2O3颗粒，接头裂纹起源于Al-Si合金与Al2O3颗粒界面处，并主要在连接区Al-Si合金中扩展，连接工艺参数对接头剪切强度影响程度依次为Al-Si合金中间层厚度、连接温度、保温时间。选择合适的连接工艺参数，接头剪切强度可达70－80MPa。     

扩散焊条件下Al2O3P/6061Al复合材料中氧化膜的行为

研究了Ａｌ２Ｏ３ｐ／６０６１Ａｌ铝基复合材料扩散焊接头区域氧化膜随焊接温度变化的规律,分析了氧化膜的变化机理,探讨了氧化膜对接头强度的影响。结果表明,在扩散焊时,随焊接规范的变化Ａｌ２Ｏ３ｐ／６０６１Ａｌ铝基复合材料接头区域的氧化膜含量及形态有明显的改变,这与Ｍｇ＋４／３Ａｌ２Ｏ３→Ａｌ２ＭｇＯ４＋２／３Ａｌ反应有关,氧化膜的变化直接影响着焊缝的接头强度。     

Fe3Al/18-8异种材料真空扩散焊工艺研究

研究了Fe3A1/18-8异种材料扩散焊中工艺参数对界面结合、接头变形状况和剪切强度的影响.采用金相显微镜和扫描电镜(SEM)分析了不同焊接工艺条件下Fe3Al/18-8异种材料扩散焊接头的显微组织特征.结果表明合适的扩散焊工艺参数为:加热温度1 020～1040℃,保温时间45～60 min,焊接压力12～15 MPa.     

碳纤维感应元件厚度对碳纤维增强热塑性复合材料感应焊接接头力学性能及断裂形式的影响

利用碳纤维织物与树脂薄膜制备了0.2 mm、0.3 mm与0.5 mm 3种不同厚度的碳纤维感应元件，并开展碳纤维增强热塑性复合材料(Carbon fiber reinforced thermoplastic composite,CFRTP)感应焊接建模仿真与工艺试验。观察CFRTP感应焊接接头成形形貌，开展接头拉伸剪切强度测试与断口形貌分析，着重探究感应元件厚度对接头力学性能与断裂形式的影响。研究结果表明：碳纤维感应元件能在不引入异质材料的前提下实现CFRTP的高质量感应焊接，但接头界面温度分布具有明显的不均匀性；随着感应元件厚度的增加，过量的树脂会降低接头的成形效果、连接质量与力学性能，同时界面的有效连接面积也随之减小；当感应元件厚度为0.2 mm时，焊接接头的拉伸剪切强度最高可达23.77 MPa；焊接接头的断裂形式包括感应元件内聚破坏、母材表层自破坏、界面破坏和混合破坏，造成接头失效的断裂机制根据感应元件厚度的改变而发生变化。     

TiAl多层膜焊接Cu-Al2O3异种材料接头性能研究

为探究热循环对陶瓷-铜接头性能的影响,采用Al-Ti纳米多层膜作为中间层材料焊接铜与陶瓷,并对接头进行分析。结果表明,接头力学性良好,整个焊接接头分为铜、扩散反应区、致密反应区以及陶瓷四个区域;经500次热循环试验后,连接区域面积缩小,扩散反应区出现空洞且整个接头扩散区变小,鱼骨状组织变粗大,剪切强度显著降低。     

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.……     

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.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

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.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.