Use Of Barrier Layer Research Articles

SYNTHESIS AND INVESTIGATION OF PROPERTIES OF MULLITE-CORUNDUM CERAMICS AS A COMPONENT OF CERAMIC COMPOSITE MATERIALS

The paper studies the conditions for synthesis of mullite-corundum ceramics obtained on the basis of Al2O3 and SiO2. The composition of mullite-corundum ceramics with an Al2O3 content < 80 wt.% has been determined, which ensures the best thermomechanical compatibility with molybdenum. The possibility of obtaining a composite material based on a mullite-corundum matrix and molybdenum, as well as its use as a barrier layer at the interface of Мo–Si-containing ceramics, has been confirmed. It is established that use of barrier layer significantly reduces the likelihood of thermal stresses in the interface of the two phases. It is shown that there is a need to refine the technological parameters of the preparation of the powder Al2O3–SiO2 mixture to increase the thermochemical compatibility of molybdenum with mullite-corundum ceramics.

Влияние шероховатости барьерного слоя на формирования наночастиц катализатора роста углеродных нанотрубок

This article compares TiN layers produced by electron beam evaporation (EBE) and atomic layer deposition (ALD) for the effect of barrier layer deposition technology on the formation of carbon nanotube (CNT) growth catalyst nanoparticles. The layers obtained by EBE have a roughness 1.5 times higher than the layers deposited by the ALD method (Ra = 1 nm and Ra = 0.6 nm). Nanoparticles formed on the surface of the EBE layer are characterized by a large average size (about 30 nm) and a 1.3 times greater dispersion of the distribution compared to nanoparticles formed on the ALD layer. TiN layers obtained by EBE are characterized by better surface wettability in comparison with ALD layers. The contact angle for catalyst nanoparticles on the surface of the EBE layer of TiN is about 30 degrees and approaches 90 degrees for ALD layers. Catalyst spreading is due to the Wenzel model. It is shown that the higher surface roughness of the EBE samples is associated with the crystallization of TiN, since the layer formation process proceeds at a higher temperature compared to the ALD process. For this reason, the use of barrier layers obtained by the ALD method is preferable for the formation of CNT growth catalyst nanoparticles on their surface.

Effect of Barrier Layer Roughness on the Formation of Nanoparticles of the Carbon Nanotube Growth Catalyst

This article compares TiN layers produced by electron beam evaporation (EBE) and atomic layer deposition (ALD) for the effect of barrier layer deposition technology on the formation of carbon nanotube (CNT) growth catalyst nanoparticles. The layers obtained by EBE have a roughness 1.5 times higher than the layers deposited by the ALD method (R a =1 nm and R a =0.6 nm). Nanoparticles formed on the surface of the EBE layer are characterized by a large average size (about 30 nm) and a 1.3 times greater dispersion of the distribution compared to nanoparticles formed on the ALD layer. TiN layers obtained by EBE are characterized by better surface wettability in comparison with ALD layers. The contact angle for catalyst nanoparticles on the surface of the EBE layer of TiN is about 30 degrees and approaches 90 degrees for ALD layers. Catalyst spreading is due to the Wenzel model. It is shown that the higher surface roughness of the EBE samples is associated with the crystallization of TiN, since the layer formation process proceeds at a higher temperature compared to the ALD process. For this reason, the use of barrier layers obtained by the ALD method is preferable for the formation of CNT growth catalyst nanoparticles on their surface. Keywords: electron beam evaporation, atomic layer deposition, roughness, wetting, catalyst nanoparticles.

Analyzing metallurgical interaction during arc surfacing of barrier layers on titanium to prevent the formation of intermetallics in titanium-steel compounds

This paper considers a possibility to obtain high-quality butt junctions of bimetallic sheets from steel clad with a layer of titanium, with the use of barrier layers. The task that was tackled related to preventing the formation of Ti-Fe intermetallic phases (IMPs) between the steel and titanium layer. The barrier layers (height ~0.5 mm) of vanadium and copper alloys were surfaced by arc techniques while minimizing the level of thermal influence on the base metal. To this end, plasma surfacing with a current-driving wire and pulsed MAG surfacing were used. The obtained samples were examined by methods of metallography, X-ray spectral microanalysis, durometric analysis. It has been established that when a layer of vanadium is plated on the surface of titanium, a defect-free structure of variable composition (53.87–65.67) wt % Ti with (33.93–45.54) wt % V is formed without IMPs. The subsequent surfacing of steel on a layer of vanadium leads to the formation of eutectics (hardness up to 5,523 MPa) in the fusion zone, as well as to the evolution of cracks. To prevent the formation of IMPs, a layer of bronze CuBe2 was deposited on the surface of vanadium. The formed layer contributed to the formation of a grid of hot cracks. In the titanium-vanadium-copper transition zones (0.1–0.2 mm wide), a fragile phase was observed. To eliminate this drawback, the bronze CuBe2 was replaced with bronze CuSi3Mn1; a defect-free junction was obtained. When using a barrier layer with CuSi3Mn1, a defect-free junction was obtained (10–30 % Ti; 18–50 % Fe; 5–25 % Cu). The study reported here makes it possible to recommend CuSi3Mn1 as a barrier layer for welding bimetallic sheets "steel-titanium". One of the applications of the research results could be welding of longitudinally welded pipes of main oil and gas pipelines formed from bimetallic sheets of steel clad with titanium.

MP65-16 CREATION OF A STANDARDIZED HYPOSPADIAS TEMPLATE IN THE ELECTRONIC MEDICAL RECORD

You have accessJournal of UrologyPediatrics: Hypospadias and Penile Surgery (MP65)1 Apr 2020MP65-16 CREATION OF A STANDARDIZED HYPOSPADIAS TEMPLATE IN THE ELECTRONIC MEDICAL RECORD Christopher Long*, Luis Braga, John Wiener, Mark Zaontz, and Melise Keays Christopher Long*Christopher Long* More articles by this author , Luis BragaLuis Braga More articles by this author , John WienerJohn Wiener More articles by this author , Mark ZaontzMark Zaontz More articles by this author , and Melise KeaysMelise Keays More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000940.15AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The lack of standardized reporting in hypospadias limits quality improvement and comparative effectiveness research. Variability in surgical decision making and reported complication rates in hypospadias surgery warrants further study to improve care delivery outcomes. Barriers to collaboration include small patient number, single institution efforts, and variability in patient assessment and reporting. Our goal was to create a document that could be shared across institutions, standardizing the documentation process. METHODS: A review of currently existing hypospadias scoring systems, data collection forms from existing registries (INSPIRE, HOLD) and expert opinion identified various datapoints for documentation. Expert feedback was obtained to determine necessary elements for surgical billing, a complete operative note and data elements for hypospadias reporting. Collaboration with an electronic health record (EHR) vendor established reportable data elements. A standardized clinical documentation form was created for preoperative measurements, intra-operative details and post-operative follow-up was created. RESULTS: An EHR standardized document was created for both documentation and research purposes (Figure 1). The operative note includes the type of repair, the planned intervention, type of anesthesia. The initial operative assessment includes the location of the urethral meatus, associated scrotal anomalies, the presence and degree of penile curvature, and the quality of the urethral plate. Specifics for orthoplasty, glansplasty, and urethroplasty are captured. Further granular details such as suture utilization, use of barrier layers, and duration of stent placement amongst others are also included, if the user elects to utilize them. The follow up note includes both functional and cosmetic assessment, reporting complications in a standardized fashion. CONCLUSIONS: This template standardizes the documentation of both intraoperative and follow up patients with hypospadias; it serves the dual purpose of clinical documentation and quality reporting. Furthermore, this will facilitate collaboration across institutions to improve the quality of the urologic literature. We present this work to foster broad utilization across centers. Source of Funding: none © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e979-e980 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Christopher Long* More articles by this author Luis Braga More articles by this author John Wiener More articles by this author Mark Zaontz More articles by this author Melise Keays More articles by this author Expand All Advertisement PDF downloadLoading ...

Ultranarrow-waveguide AlGaAs/GaAs/InGaAs lasers

We have designed, fabricated and studied ultranarrow-waveguide heterostructure lasers emitting in the spectral range 1000 – 1100 nm. The lasers have been characterised by current – voltage, light – current, far-field intensity distribution and internal optical loss measurements. The ultranarrow-waveguide lasers have been shown to have a threshold current density of ∼75 A cm−2, internal quantum efficiency near 100 % and internal optical loss near the lasing threshold under 1 cm−1, which corresponds to the level of standard heterostructures. We have demonstrated the possibility of obtaining up to 5 W of output power in continuous mode and up to 30 W in pulsed mode, with a beam convergence (FWHM) of 17.8°. The slope of the internal optical loss as a function of pump current for the ultranarrow-waveguide lasers can be markedly lower than that in lasers with a standard design, but internal quantum efficiency drops to 40 % with increasing pump current. The use of barrier layers in ultranarrow-waveguide lasers makes it possible to substantially reduce the drop in internal quantum efficiency.

Proton-Conducting Ceramics for Metal-Supported Solid Oxide Fuel Cells and Electrolysis Cells

Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600 °C. The porous metal substrate provides the advantages of MS-SOCs such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness. The cell structure for fuel cell and electrolysis operation is shown in Figure 1. To incorporate proton-conductors into metal-supported cell configuration through co-sintering fabrication, a key factor is that the proton conductors must be compatible with reducing atmosphere sintering, as the porous metal substrate can not be fired in oxidizing atmosphere. In this work, viability of co-sintering fabrication of metal-supported proton conducting solid oxide cells is investigated. Candidate proton-conducting ceramics including perovskite-type oxides BaZr0.7Ce0.2Y0.1O3-δ (BZCY), SrZr0.5Ce0.4Y0.1O3-δ (SZCY), and Ba3Ca1.18Nb1.82O9-δ (BCN), pyrochlore-type oxides La1.95Ca0.05Zr2O7-δ (LCZ) and La2Ce2O7 (LCO), and acceptor doped rare-earth ortho-niobates La0.99Ca0.01NbO4 (LCN) were synthesized via solid state reactive synthesis or sol-gel synthesis. These ceramics are sintered at 1450°C in reducing environment alone and supported on Fe-Cr alloy metal support, and their key characteristics such as phase formation, sintering property, and chemical compatibility with metal support are determined. Most electrolyte candidates suffer from one or more challenges identified for this fabrication approach, including: phase decomposition in reducing atmosphere, evaporation of electrolyte constituents, contamination of the electrolyte with Si and Cr from the metal support, and incomplete electrolyte sintering. BZCY is particularly interesting because of its high proton conductivity, but it is found to suffer from reaction with Si and Cr present in the metal support, and loss of Ba via evaporation during sintering. Various approaches to overcome these limitations are proposed, and preliminary assessment indicates that the use of barrier layers, low-Si-content stainless steel, and sintering aids warrant further development. In contrast, La0.99Ca0.01NbO4 is found to be highly compatible with the metal support and co-sintering processing in reducing atmosphere, allowing dense electrolyte and porous electrode made of LCN to be co-sintered on porous stainless steel, Figure 2. A metal-supported cell is fabricated with La0.99Ca0.01NbO4 electrolyte, ferritic stainless steel support, Pt air electrode and nanoparticulate ceria-Ni hydrogen electrocatalyst. The total resistance is 50 Ω∙cm2 at 600 °C. This work clearly demonstrates the challenges, opportunities, and breakthrough of metal-supported proton-conducting solid oxide cells by co-sintering fabrication. Figure 1

Approaches for co-sintering metal-supported proton-conducting solid oxide cells with Ba(Zr,Ce,Y,Yb)O3-δ electrolyte

Abstract Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600 °C. The porous metal substrate provides the advantages of MS-SOCs such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness. In this work, the viability of co-sintering fabrication of metal-supported proton conducting solid oxide cells using BaZr1-x-yCexYyO3-δ (BZCY) is investigated. BZCY ceramics are sintered at 1450 °C in reducing environment alone and supported on Fe Cr alloy metal support, and key characteristics such as Ba loss, sintering behavior, and chemical compatibility with metal support are determined. Critical challenges are identified for this fabrication approach, including: Contamination of the electrolyte with Si and Cr from the metal support, incomplete electrolyte sintering, and evaporation of electrolyte constituents. Various approaches to overcome these limitations are proposed, and preliminary assessment indicates that the use of barrier layers, low-Si-content stainless steel, and sintering aids warrant further development.

Mechanical and degradation behaviour of multilayer barrier films

The use of innovative flexible multilayer barrier films in the food packaging and the agricultural sectors is growing rapidly. A series of experimental PE-based multilayer films with barrier EVOH and PA layers, which simulate specific features of films used in the agrifood sector, was produced with different percentages of stabilisation. An experimental methodology was developed for the analysis of the mechanical behaviour of these specially designed multilayer films. The photodegradation behaviour of the multilayer films was investigated, by exposing them to controlled accelerated ageing. It was shown that the presence of a low ductility barrier layer, adversely affects both, the mechanical and the ageing behaviour of multi-layer films without stabilisation. Likewise, the stabilised multilayer films with barrier experience a shorter lifespan, than the multilayer stabilised PE films without barrier layers. The results suggest that the possible use of barrier layers in agricultural or food packaging mulitilayer film structures, should take into consideration the detrimental effect of these layers in their mechanical behaviour and durability.

Modeling electrochemical partial oxidation of methane for cogeneration of electricity and syngas in solid-oxide fuel cells

This paper uses computational models to evaluate strategies for scaling electrochemical partial oxidation (EPOX) processes from the laboratory scale to practical application. In addition to producing electrical energy alone, solid-oxide fuel cells (SOFC) can be operated with hydrocarbon fuel streams to produce synthesis gas (H 2 and CO) as well. SOFC systems are usually operated to consume most of the fuel and produce electricity. However, by operating with a hydrocarbon fuel at relatively high flow rates, the exhaust-gas composition can be predominantly syngas. In this case the steam (and CO 2), produced from electrochemical and thermal reactions, reacts to reform the hydrocarbon fuel within the catalytic anode support structure. A practical limitation of electrochemical partial oxidation operation is the fact that carbon tends to deposit on Ni-based anode catalysts. The present paper explores the use of barrier layers to prevent carbon deposits. The results show that a tubular cell can be designed to deliver syngas and electricity using methane as the primary fuel.

Electrical and physical characteristics of ultrathin hafnium silicate films with polycrystalline silicon and TaN gates

Metal-oxide-semiconductor transistors of ultrathin hafnium silicate films (equivalent oxide thickness (EOT) of 12.5–14 Å) with polycrystalline silicon and metal (TaN) gates have been demonstrated. Well-behaved transistor characteristics and EOT stability of Hf silicate with n+ polysilicon indicates good compatibility with polysilicon gate process without use of barrier layer. Transmission electron microscopy analysis indicates that the films have no top interfacial layer with both TaN and polysilicon gates. The films also remain amorphous and show no indication of phase separation even after a 950 °C dopant activation anneal. Hf silicate films also show excellent transistor characteristics with TaN gate. NH3 pretreatment results in degraded transistor characteristics for TaN and poly gate samples. Good capacitance–voltage characteristics and negligible hysteresis (<10 mV) was observed in the capacitors after a 1000 °C activation indicating good electrical stability at high temperatures and minimal charge trapping.

Epoxy Resin as Inhibitor for Nitramine Containing Composite Modified Double Base (CMDB) Propellants

Abstract Epoxy resin was investigated as inhibitor for nitramine containing Composite modified double base (CMDB) propellants. Inhibited CMDB propellants were statically (rocket firing under static condition) evaluated at ambient, hot (+60°C) and cold (-30°C) temperatures. Incompatibility problem between epoxy resin and CMDB propellants were overcome by use of barrier layers of fast-setting isophthalic acid based polyester resin (Acrolite-471). Storage ageing trials at ambient and hot (+60°C) temperatures were also studied for propellant-inhibitor bond failure at above mentioned temperatures.

Chemical vapour deposition of diamond onto iron based substrates—The use of barrier layers

When Fe is exposed to the plasma environment suitable for the chemical vapour deposition of diamond, the surface is rapidly covered with a thick layer of graphitic soot and C swiftly diffuses into the Fe substrate. Once the soot reaches a critical thickness, diamond films nucleate and grow on top of it. However, adhesion of the film to the substrate is poor owing to the lack of structural integrity of the soot layer. A thin coating of TiN on the Fe can act to prevent diffusion and soot formation. Diamond readily grows upon the TiN via an a-C interface layer, but the a-C-TiN interface is weak and delamination occurs at this interface. In order to try and improve the adhesion, the use of a high dose Ti implant was investigated to replace the TiN coating.

Effectiveness of use of barrier layers for increasing the operating life of lanthanum hexaboride base thin-film cathodes

Effectiveness of use of barrier layers for increasing the operating life of lanthanum hexaboride base thin-film cathodes

Observations on the Growth and Impact of Intermetallic Compounds on Tin‐Coated Substrates

Tin and solder coatings interact with substrates commonly used in the electronics industry to produce layers of intermetallic compounds at temperatures above and below the melting point of the coatings. Observations on the rates of compound growth at room temperature for durations of up to 12 years are reported and related to the published results for shorter times at higher temperatures. Recent results concerning the effect of intermatallic compound growth on the solderability of coatings and on the strength of soldered joints are presented. In both cases it is apparent that retarding the rate of compound growth could be useful and the use of barrier layers for this purpose is considered.

Metallization for very-large-scale integrated circuits

Progress in patterning technologies and computer-aided circuit designs have brought us to the threshold of very-large-scale integrated (VLSI) circuits with 100 000 or more devices to be integrated on a silicon chip. In this paper we review thin film applications in the fabrication of contacts and interconnects for VLSI circuits. Device structures suitable for both bipolar and metal/oxide/semiconductor (MOS) VLSI circuit applications tend to have shallow junction depths and contact areas (silicon-metal interfaces) in the 0.2–0.5 μm and 1–2 μm 2 ranges respectively; also some of the circuits require Schottky barrier diodes. Consumption of silicon in the contact windows needs to be minimized with the use of silicide layers for silicon-metal contacts. The formation and use of platinum silicide layers for bipolar applications are reviewed. Our observations indicate that the carbon and oxygen present in Czochralski-grown silicon crystals interfere in platinum silicide formation and affect the electrical characteristics of the contacts. The use of barrier layers in VLSI metallization is illustrated. The interdependence of film microstructure, electromigration-induced failures and VLSI interconnection reliability is examined. The integration of a large number of components on a VLSI chip with a single level of interconnections consumes more chip area. Long interconnection paths adversely affect circuit performance. Multilevel interconnections (conductor/insulator/ conductor) offer an attractive solution to increase the packing density and circuit performance. The application of PtSi/(Ti:W)/(AlCu)/SiO 2/(Ti:W)/Al film layers in the fabrication of a bipolar VLSI circuit with a minimum feature size of 1.25 μm is illustrated. As the complexity of VLSI circuits continues to grow with micron size device structures, three or more levels of interconnections compatible with shallow junctions on the substrates and complex packaging technologies are required. Areas of concern and desirable features in VLSI metallization are summarized.

Metallization for Very-Large-Scale Integrated Circuits

Progress in patterning technologies and computer-aided circuit designs have brought us to the threshold of very-large-scale integrated (VLSI) circuits with 100 000 or more devices to be integrated on a silicon chip. In this paper we review thin film applications in the fabrication of contacts and interconnects for VLSI circuits. Device structures suitable for both bipolar and metal/oxide/semiconductor (MOS) VLSI circuit applications tend to have shallow junction depths and contact areas (silicon-metal interfaces) in the 0.2–0.5 μm and 1–2μm2 ranges respectively; also some of the circuits require Schottky barrier diodes. Consumption of silicon in the contact windows needs to be minimized with the use of silicide layers for siliconmetal contacts. The formation and use of platinum silicide layers for bipolar applications are reviewed. Our observations indicate that the carbon and oxygen present in Czochralski-grown silicon crystals interfere in platinum silicide formationand affect the electrical characteristics of the contacts. The use of barrier layers in VLSI metallization is illustrated. The interdependence of film microstructure, electromigration-induced failures and VLSI interconnection reliability is examined. The integration of a large number of components on a VLSI chip with a single level of interconnections consumes more chip area. Long interconnection paths adversely affect circuit performance. Multilevel interconnections (conductor/insulator/conductor) offer an attractive solution to increase the packing density and circuit performance. The application of PtSi/(Ti: W)/(Al-Cu)/SiO2 /(Ti: W)/A1 film layers in the fabrication of a bipolar VLSI circuit with a minimum feature size of 1.25 μm is illustrated. As the complexity of VLSI circuits continues to grow with micron size device structures, three or more levels of interconnections compatible with shallow junctions on the substrates and complex packaging technologies are required. Areas of concern and desirable features in VLSI metallization are summarized.

Use of barrier layers as a means of increasing the high-temperature stability of tungsten in contact with boron nitride

Use of barrier layers as a means of increasing the high-temperature stability of tungsten in contact with boron nitride