scholarly journals Efeito da soldagem nas propriedades mecânicas e metalúrgicas do aço API 5L X65

2021 ◽  
Vol 22 (38) ◽  
pp. 215-222
Author(s):  
Rodrigo Fadrique ◽  
Jorge Luis Braz Medeiros ◽  
Luciano Volcanoglo Biehl ◽  
José de Souza ◽  
Carlos Otávio Damas Martins
Keyword(s):  
Metal Base

Este estudo avaliou as propriedades mecânicas e metalúrgicas de uma junta de topo soldada em tubulação de aço API 5L X65, aço microligado, amplamente utilizado na indústria offshore. O procedimento inicia com o revestimento (cladding) da região a ser soldada e vizinhança com metal de adição, através do processo de soldagem TIG que também é utilizado nos diferentes passes de raiz. O revestimento da junta soldada foi realizado pelo processo SMAW. Esses procedimentos de soldagem foram avaliados com a utilização de corpos de prova, submetidos a ensaios mecânicos e metalúrgicos requeridos por normas aplicáveis à indústria offshore. Adicionalmente, foram realizados ensaios complementares, relacionados ao tamanho de grão austenítico na Zona Termicamente Afetada (ZTA) e Zona de Fusão (ZF). Concluiu-se que o procedimento de soldagem utilizado pode ser largamente aplicado na indústria, sem comprometimento significativo do metal base, ZTA e ZF, minimizando a necessidade de tratamentos térmicos posteriores. Palavras-chave: Soldagem. Cladeamento. Microligado.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

Novel Electronics Enabled by Rare Earth Arsenides Buried in III-V Semiconductors

1993 ◽  
Vol 301 ◽  
Author(s):  
S. James Allen ◽  
Dan Brehmer ◽  
C.J. PalmstrØm
Keyword(s):  
Rare Earth ◽  
Epitaxial Layers ◽  
Hot Electron ◽  
Surface Geometry ◽  
Electron Effective Mass ◽  
Metal Base ◽  
Lattice Match ◽  
Linear Material ◽  
Shubnikov De Haas Oscillations ◽  
Electron Transistors

ABSTRACTHeterostructures consisting of III-V semiconductors and epitaxial layers of the rare earth monoarsenides can be grown by molecular beam epitaxy. By alloying ErAs with ScAs, lattice match can be achieved with (Al,Ga)As. Using magneto-transport measurements, we show that these layers are semi-metallic with equal electron and hole concentrations, 3.0 ×1020 cm−3. Shubnikov-de Haas oscillations are used to confirm the predicted Fermi surface geometry and measure the electron effective mass and the coupling to the 4f spin on the Er3+ ion. Remarkably, the material shows no transition from semimetal to semiconductor as the film thickness is reduced to three monolayers. Below three monolayers the films are not uniform and are believed to consist of islands three monolayers high.This system provides a unique opportunity to explore novel electronics based on controlled transport through semimetal/semiconductor heterostructures. Lateral transport through semimetal islands immersed in a δ-doped layer may provide a fast non-linear material for THz electronics. Vertical transport through thin epitaxial layers may enable resonant tunneling hot electron transistors with a semi-metal base. Preliminary experiments on transistor like test structures measure some transfer through a 10 monolayer thick semimetal base. They also identify overgrowth of the III-V semiconductor on the semimetal layer as the key materials issue.

scholarly journals An innovative metal base denture design for a 55-year-old menopausal woman

2013 ◽  
Vol 4 (2) ◽  
pp. 468 ◽  
Author(s):  
Vishwas Bhatia ◽  
Garima Bhatia ◽  
Nitul Jain ◽  
AshwaniKumar Jadon
Keyword(s):  
Menopausal Woman ◽  
Metal Base

Lannion downstream bridge over the Léguer River

2021 ◽  
Author(s):  
Ambra Chioccariello ◽  
Mohamed Chaabouni ◽  
Thomas Lavigne
Keyword(s):  
Reinforced Concrete ◽  
Architectural Design ◽  
River Flow ◽  
Bottom Plate ◽  
Box Girder ◽  
Metal Base ◽  
Total Length

<p><br clear="none"/></p><p>With a total length of about 210 m, the new Lannion downstream bridge will cross the river with an “S” shape path. Deck will be made up of a steel and concrete composite box girder. To reduce impacts on the river flow, only a pier will be placed in the riverbed. It consists of a steel tetrapod formed by four legs, embedded on the bottom plate of the box and designed as extensions of box’s webs. Crutches meet on a metal base resting on a reinforced concrete pier. The architectural design consists of a light structure characterized by natural and maritime shapes: an homage to the site’s history and landscape.</p><p><br clear="none"/></p>

Adhesives for the Installation of Cast Basalt Elements on Metal and Comparison of Properties when Using Different Types of Fillers

2021 ◽  
Vol 898 ◽  
pp. 35-41
Author(s):  
Jakub Hodul ◽  
Tomáš Žlebek ◽  
Lenka Mészárosová ◽  
Aleš Jakubík ◽  
Rostislav Drochytka
Keyword(s):  
Construction Industry ◽  
Raw Materials ◽  
Physical And Mechanical Properties ◽  
Mineral Admixtures ◽  
Maximum Efficiency ◽  
Organic Additives ◽  
Metal Base ◽  
Secondary Raw Materials ◽  
Ecological Benefit ◽  
Different Types

The polymeric adhesives for the installation of basalt elements on a metal base are designed primarily for environments with increased chemical and mechanical stress. They are composed of polymer resins (epoxy, polyurethane) as binders, as well as organic additives and mineral admixtures that mainly fulfill the function of filler. In all sectors of today's construction industry, maximum efficiency in the production of materials is required for sustainability purposes, which, however, must never be at the expense of the quality or the required performance. Due to these requirements, great emphasis is placed on the maximum use of secondary raw materials. Talc is used as the primary filler for polymer adhesives. Sawdust, tire rubber, and fly ash are used as secondary raw materials. The use of these in building supplies can positively affect some physical and mechanical properties of polymeric adhesives. Also, the use of secondary raw materials has the above-mentioned ecological benefit. Basic properties, such as bulk density and adhesion to both metallic and basalt elements, were monitored. The details of the cohesion of the adhesive with the bonded material, as well as the distribution of secondary raw materials in the polymer matrix, were assessed microscopically.

scholarly journals Metodologia Não Destrutiva de Determinação da Indentação no Processo de Soldagem a Ponto por Resistência Elétrica em Chapas de Aços Galvanizados

2017 ◽  
Vol 22 (2) ◽  
pp. 139-146
Author(s):  
Adriano Cássio Baldim ◽  
Sebastião Carlos da Costa ◽  
Carlos Andrés Arango Hincapié ◽  
Roney Fonseca ◽  
Thairone Conti Serafini Aguiar
Keyword(s):  
Metal Base

Resumo A soldagem das chapas de aço galvanizado, em sua grande maioria é realizada através do processo de soldagem a ponto por resistência elétrica, principalmente no setor automotivo. Apesar de suas vantagens, no momento em que ocorre a fusão a pressão exercida pelo eletrodo vence a resistência do material culminando em uma leve penetração do eletrodo no metal base. Este fenômeno é denominado de indentação. Neste contexto, este trabalho estudou a indentação do ponto soldado, com o objetivo de determinar a penetração do eletrodo por meio de um método não destrutivo. Para isto, foram avaliados os sinais gerados por um sensor que registra o deslocamento do eletrodo durante as fases do processo de soldagem a ponto, utilizando como base, a leitura da expansão térmica da chapa de aço galvanizado. A profundidade da indentação foi revelada graficamente pelo sensor de deslocamento do eletrodo em comparação a medição realizada com o relógio apalpador por métodos estatísticos. Evidências mostraram que o sinal de deslocamento do eletrodo, mostrou ser um eficiente método na determinação da indentação no processo de soldagem a ponto por resistência elétrica em chapas de aços galvanizados.

GaInP Selective Area Epitaxy for Heterojunction Bipolar Transistor Applications

1996 ◽  
Vol 448 ◽  
Author(s):  
S. H. PARK ◽  
S.-L. FU ◽  
P. K. L. YU ◽  
P. M. ASBECK
Keyword(s):  
Light Field ◽  
Defect Density ◽  
Forward Bias ◽  
Dark Field ◽  
Bipolar Transistor ◽  
Heterojunction Bipolar Transistor ◽  
Current Gain ◽  
Selective Area Epitaxy ◽  
Metal Base ◽  
Selective Area

AbstractA study of selective area epitaxy (SAE) of GalnP lattice matched to GaAs is presented. The selectively regrown GaInP is used as the emitter of a novel heterojunction bipolar transistor (HBT) device structure. Successful SAE of GalnP on both dark field (mostly covered) and light field (mostly open) SiO2 masks is compared. To characterize the critical regrown heterojunction, diodes and HBTs were fabricated and measured. It is found that a pre-growth pause of either TEGa or PH3 results in forward bias characteristics with low leakage and an ideality factor of ~1.25, indicating low interfacial defect density. Non-self aligned regrown emitter HBTs grown with a dark field mask scheme have been fabricated. Devices with an emitter area of 3x12 μm exhibit small signal current gain up to 80 with an fT and fMAX of 22 GHz and 18 GHz, respectively. To further improve the performance of these devices, a structure with a self-aligned refractory metal base contact and light field regrowth is proposed.

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