1,015 research outputs found
Peace and War in Hawi al-Hawa
No full textCopyright © 2020 The Author(s). Forty years have passed since the original research, during which Syria has witnessed decades of change and been plunged into civil war. This chapter gives a brief update on the participants and their families. It also describes developments within the village of Hawi Al-Hawa, which was severely impacted by the ISIS caliphate in Raqqa (2013–2018). With careful locating of old and new cultural forms, this book reveals important insights into the study of social relations in peace and war. With an emphasis on dialectical change and transformations, we can better situate what has happened in this part of Syria, and how this has affected social life. Transformative change and conflict have been part of the peace-time history of Syria, and war did not erase certain continuities. The chapter can help refine the study of social life in war and in peace, by paying attention to the lives lived, the struggles fought, and the ‘messy’ complexity of human social life. Despite the disruption and dislocation caused by conflict, using social media the families continue to be socially engaged with each other and the village. The village and the family are still important categories of belonging for the people of Hawi al-Hawa.https://www.taylorfrancis.com/chapters/mono/10.4324/9781003050551-18/peace-war-hawi-al-hawa-sulayman-khalaf?context=ubx&refId=78635be9-c1a7-46c6-a9cd-6df2123b996
Study of Effect of Al Addition into Sn-Ag Solder on Microstructure and Bondability
Get PDFWe researched the effect of Al addition into Sn-Ag solder alloys. Addition of small amount of Al into Sn-Ag alloys made sub-grains in the β-Sn phase finer. And many Ag2Al particles were dispersed. Both primary phase and eutectic phase in Sn-Ag-Al alloys were almost evenly deformed against tensile stress. Ag2Al particles obstructed the propagation of crack during thermal cycle, so propagation rate was delayed. Sn-2Ag-0.05Al and Sn-2Ag-0.1Al showed better mechanical property and thermal cycle property than Sn-3Ag-0.5Cu
Interfacial Dissolution Reaction and Thermal Fatigue Cycle Property for Sn-Ag-Al Solder Alloy/Cu
Get PDFWe investigated interfacial dissolution reaction and thermal fatigue cycle properties for Sn-Ag-Al solder alloy/Cu. Sn-Ag-Al solder alloys showed better tensile and thermal fatigue property than Sn-3Ag-0.5Cu. The dissolution speed Cu into Sn-2Ag-0.1Al is higher than that into Sn-3Ag-0.5Cu. We guessed the difference of the morphology and the speed of crack propagation between Sn-2Ag-0.1Al and Sn-3Ag-0.5Cu was generated by changing microstructure of solder near reaction layer.「Mate 2004 エレクトロニクスにおけるマイクロ接合・
実装技術シンポジウム - ブロードバンドインターネット時代に向けた生産技術革新とサイエンス」論文集収録
Composition and structure of Al-Sn alloys formed by constant potential electrolysis in an AlCl3-NaCl-KCl-SnCl2 molten salt
Get PDFTo form Al-Sn alloys for bearing materials, molten salt electrolysis was performed in an AlCl3-NaCl-KCl molten salt containing SnCl2 at 423 K. The voltammogram showed that the cathodic reduction of the Sn ions started at a potential of 0.5 V vs. Al/Al(III) in the molten salt showing that deposition of pure Sn was possible at 0.5 V. Co-deposition of Al and Sn occurred at potentials more negative than 0.1 V. The co-deposit was composed a solid solution of Al and Sn. The ratio of the Sn in the electrodeposits decreased with the potential from 100 at.% at 0.2 V to 19 at.% at -0.3 V. In the structural observations, electrodeposits with an alternate stacked structure of Al and Sn is obtained at -0.075 V. (c) 2012 Elsevier Ltd. All rights reserved
Synergy of Sn micro-alloying and thermomechanical processing on formability and precipitation behavior of Al-Mg-Si-Cu-Zn alloys
No full textThe effect of Sn micro-alloying on microstructure evolution, formability and precipitation behaviour of Al-Mg-Si-Cu-Zn alloys were systematically studied by experimental techniques and theoretical calculations. Results show that Sn addition can accelerate both the precipitation and re-dissolution of the Fe-rich phase during casting and homogenising treatments, which thereby determined the final microstructure. A significant retarding effect to natural ageing precipitation was observed with increasing Sn content in quenching samples, but this effect was weakened in pre-aged samples, as explained by DSC and simulations. The different number densities of the strengthening phase β″at the same artificial aging state are mainly attributed to the changed activation energy of the β″ phase affected by the formed Sn-containing Mg-Zn clusters and Mg-Si clusters. Trace Sn participating in the formation of GP zones, Sn-containing MgZn2 phase and new precipitating sequences during ageing were proposed for the first time.</p
Corrosion of Al-Sn-Bi alloys in alcohol at high temperatures. Part I: Effects of the metallurgical structure of the alloys and the metal salt additions to alcohol
Get PDFCorrosion of free machining Al alloys that contain Sn and Bi was investigated at 391-415K in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) with/without SnCl2, Sn(OC2H5)4, FeCl3, and CuCl2. The Al-Sn-Bi alloy displayed severe pitting corrosion in MEEE as did the Al-Sn alloy in BEEE at 415K, and Sn and Sn/Bi were enriched on the surface of pits. Immersion tests of pure Al in MEEE containing Sn/Cu-salts at 415K also showed severe corrosion and the deposition of metallic Sn and Cu on the surface. The corrosion mechanisms are discussed in terms of the electro-catalytic activity of the Sn enriched on the surface
Microstructure and thermal fatigue property assessment for lead free Sn-low In-Al system solder alloy
Get PDF従来より使用されてきたSn-Pb共晶はんだは、鉛の人体への有害性を問題化し、2006年には欧州での使用が禁止される。現在、世界的に鉛フリーはんだの開発が進められ、Sn-3Ag-0.5Cuが日本において有力な代替はんだとして用いられているが、過酷な環境下での熱疲労性や衝撃特性に劣るなどの問題が指摘されている。
大型のパワーモジュール接合は、放熱性を第一に材料が選定される為に、熱膨張係数の大きく異なる材料が接合される場合があり、温度サイクルが負荷されると基板が反り、はんだ接合部に多大な熱応力が発生する(1)。当研究室では、これまで温度サイクルに対して信頼性の高いはんだ合金の開発を目指しており、Sn-Ag-Al系合金を有力なはんだ材料として提案している(2)。しかしながら、Sn-Ag-Al系は金属間化合物を形成する系であることから、新たな材料として単相組織を形成するSn-低In系合金に着目した。
本研究では、Sn-低In系の実装凝固時の組織観察、及び微量Al添加した時の組織形成の検討を行った。また、基板からのCu溶解の抑制として、はんだ中へのNi添加の効果について検討した(3)。作成したSn-In-Al系合金をパワーモジュール接合に適用し、温度サイクル試験を実施し、クラックの進展距離から熱疲労特性の評価を行った。A Heat-cycle test has been carried out and cycle periods and crack propagations have been studied to evaluate the reliability of Sn-In-Al alloy on a power module solder joint in the case where Cu is used as a base plate. The heat cycle test was carried out at the temperature 233K-398K.and each cycle was 120 min. The clack length was measured by cutting the joint surface along its diagonal and the cross section was observed. Measured crack lengths in each cycle and the crack propagation velocity of Sn-In-Al alloy is greatly lower than that of Sn-3Ag-0.5Cu and fatigue characteristics are satisfactory
Corrosion of Al–Sn–Bi alloys in alcohols at high temperatures. Part II: Effect of anodizing on corrosion
Get PDFNine kinds of Al alloys were anodized to form porous anodic oxide films, and then anodized specimens were immersed in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) at 415 K. Al-1.0%Sn-1.0%Bi alloy was corroded severely in both BEEE and MEEE, whereas other 8 alloys showed no corrosion. The corrosion proceeded under the anodic oxide films through cracks formed in the film. Cathodic polarization in Cu electroplating solution after corrosion suggested that the crack formation during immersion in hot MEEE is due to thermal expansion of the substrate and Sn and Bi containing particles included in the anodic oxide film
Ordering of organic molecules on templated surfaces
Get PDFThis thesis describes the controlled growth of molecular nanostructures using modified metallic and semiconductor surfaces. The Ag/Si(lll)-(root3 x root3),the Sn/Cu(100) surface alloy system and the Bi/Si(100) nanolines and (2xn) surfaces were all investigated as suitable substrates for the controlled growth of pentacene, (C22H14) or trimesic acid, (C6H3(COOH)3) organic molecules. The following techniques were used in this study; Scanning Tunnelling Microscopy (STM), Low Energy Electron Diffraction (LEED), Normal Incident X-Ray Standing Waves (NIXSW) and Temperature Programmed Desorption (TPD).
The room temperature growth and ordering of trimesic acid on the AgfSi(ll1)-(root3 x root3) surface was investigated. An oblique unit cell was determined and a model proposed for the highly ordered close-packed domains.
The discovery of a new submonolayer phase on Sn/Cu(100) and the re-examined known phase are discussed. New models for these reconstructions are proposed. Adsorption of trimesic acid at room temperature on the clean substrate the lowest Sn coverage phase were studied. Two new Sn coverage dependent structures were discovered and bonding schemes in upright and flat orientations are discussed.
BifSi(100)-(2xn) surface was exploited as a template for the ordered growth of pentacene, which exhibited orientation specific adsorption. The Bi/Si(100)-(2xn) single domain surface created on vicinal silicon was used to test the suitable of Daresbury 4.2 beamline for NIXSW Imaging experiments and the quality of the results are discussed
Evaluation of Thermal Fatigue Cycle Property for Solder Joints in C-BGA with Sn-Ag-Al Solder Alloy
Get PDF携帯電話を代表とした電子機器は近年小型化が急速に進むに伴い、BGA(Ball Grid Allay)及びCSP(Chip Size Package)等の高密度実装が用いられてきている。加えて、バンプの微細化が進行しており、はんだ接続部の信頼性に対する要求はますます厳しくなっている。
電子機器の使用時において、BGA接合部はチップの発熱及び放熱によって、熱サイクル環境下に曝される。特に自動車向け搭載機器では、より厳しい熱サイクル環境下に置かれることになる。従って、耐熱疲労特性の向上は、はんだ接続部の信頼性向上を目指す上で必要不可欠な課題であると考えられる。
現在、熱サイクルに対して信頼性の高い鉛フリーはんだとして、Sn-Ag-Cu系はんだが用いられつつあるが接合基板の種類やバンプ形態によっては、必ずしも高信頼性を得られない。本研究室では、過酷な熱サイクル条件下に置かれる実装機器への使用を想定した鉛フリーはんだ合金の研究を進めている。著者らは以前に、絶縁基板としてセラミックスを、ベース基板としてCuを用いたパワーモジュール接合について熱サイクル試験を実施し、Sn-Ag-Al系合金がSn-Ag-Cu系はんだと比較して優れた熱疲労特性を示すことを報告している(1)。
本研究では、熱膨張係数の違いが大きい基板同士の接合により、はんだ接合部に負荷される熱応力が多大となるC-BGA接合にSn-Ag-Al系合金はんだを用いて熱サイクル試験を実施した。その結果を、Sn-Ag-Cu系はんだを用いた場合の結果と比較・検討することにより、Sn-Ag-Al系合金はんだの熱疲労特性を評価した。We investigated thermal fatigue cycle property for solder joints in C-BGA with Sn-Ag-Al solder alloys. Sn-2Ag-0.1Al showed better property than Sn-3Ag-0.5Cu against thermal fatigue. Sn-2Ag-0.1Al solder bump were deformed during thermal cycle, and it was thought that this deformation inhibited large stress concentration at the interface
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