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排序方式: 共有622条查询结果,搜索用时 640 毫秒
121.
The paper presents a new method of assessment of metal surface coverage with corrosion inhibitor and thus of inhibitor protective performance. It is based on the atomic force microscopy measurement performed in a contact mode. Apart from topography images the proposed approach allows acquisition of local DC maps and local electrical impedance spectra via application of DC bias voltage or AC perturbation signal between the conductive AFM tip and the substrate. Potentialities of this technique in inhibitor performance monitoring were illustrated on the example of copper/benzotriazole system exposed to elevated humidity environment. 相似文献
122.
T. Dudziak L. Boroń V. Deodeshmukh J. Sobczak N. Sobczak M. Witkowska W. Ratuszek K. Chruściel 《Journal of Materials Engineering and Performance》2017,26(3):1044-1056
This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes® 230®, alloy 263, alloy 617 and Haynes® 282®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes® 282®, alloy 263 and Haynes® 230®), MnCr2O4 (alloy 617, Haynes® 282® and Haynes® 230®), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes® 282®). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale. 相似文献
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Andrzej Ambroziak Andrzej Tobota Kazimierz Tokarz Pawel Kustron 《Welding International》2013,27(4):277-282
Selected methods of joining which can be used for manufacturing and repairing of car bodies by means of welding are presented in this article. Three kinds of 1 mm-thick steel sheets were used in the tests: deep drawing steel (DC04) and two-phase steels of increased high strength (DP600 and DP800). The comparative connections were carried out by means of resistance spot welding and with plug joints made by means of the MAG method and through braze welding. Comparative assessment of the strength and geometrical parameters of the test joints was then conducted. 相似文献
125.
Adam Szyszka Mateusz Wośko Bogdan Paszkiewicz Marek Tłaczała 《Materials Science-Poland》2013,31(4):543-547
Atomic force microscopy and Quantitative Mobility Spectrum Analysis (QMSA) were applied for characterization and evaluation of the quality of AlGaN/GaN heterostructures. The structural uniformity, growth mode and electrical properties of the heterostructures were determined. The obtained results indicated that the time of growth of the low temperature GaN nucleation layer influenced the morphology and electrical properties of the AlGaN/GaN heterostructure. 相似文献
126.
This paper deals with pool boiling of water–Al2O3 and water–Cu nanofluids on porous coated, horizontal tubes. Commercially available stainless-steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate a test heater. Aluminum porous coatings 0.15 mm thick with porosity of about 40% were produced by plasma spraying. A smooth tube served as a reference tube. The experiments were conducted under different absolute operating pressures of 200 kPa, 100 kPa, and 10 kPa. Nanoparticles were tested at concentrations of 0.01%, 0.1%, and 1% by weight. In all cases tested, enhancement heat transfer was always observed during boiling of water–Al2O3 and water–Cu nanofluids on smooth tubes compared to boiling of distilled water. Contrary to smooth tubes, addition of even a small amount of nanoparticles resulted in deterioration of heat transfer during pool boiling of water–Al2O3 and water–Cu nanofluids on porous coated tubes in comparison with boiling of distilled water. 相似文献
127.
The aim of this study was to investigate the effect of a constant magnetic field (CMF) on the electrodeposition of Co–Mo–W
alloys, and to observe changes in the topography of the alloy surface and its chemical composition. The investigation included
the use of Cyclic Voltammetry (CV), Coulometry (C), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis
(EDX). At higher electrolyte concentrations (so-called II), the CV method revealed an increase in cathode current density
in a CMF environment. During crystallisation of the Co–Mo–W alloy, fractures appeared on the surface due to internal stresses.
The application of CMF reduced the fracture widths resulting from the increased concentration of electroactive particles at
the working electrode and the greater deposited alloy mass. Electrolyte motion under the influence of CMF caused an increase
in the percentage of the main ferromagnetic component (Co) in the alloy. 相似文献
128.
Farrell RA Kinahan NT Hansel S Stuen KO Petkov N Shaw MT West LE Djara V Dunne RJ Varona OG Gleeson PG Jung SJ Kim HY Koleśnik MM Lutz T Murray CP Holmes JD Nealey PF Duesberg GS Krstić V Morris MA 《Nanoscale》2012,4(10):3228-3236
Extending the resolution and spatial proximity of lithographic patterning below critical dimensions of 20 nm remains a key challenge with very-large-scale integration, especially if the persistent scaling of silicon electronic devices is sustained. One approach, which relies upon the directed self-assembly of block copolymers by chemical-epitaxy, is capable of achieving high density 1?:?1 patterning with critical dimensions approaching 5 nm. Herein, we outline an integration-favourable strategy for fabricating high areal density arrays of aligned silicon nanowires by directed self-assembly of a PS-b-PMMA block copolymer nanopatterns with a L(0) (pitch) of 42 nm, on chemically pre-patterned surfaces. Parallel arrays (5 × 10(6) wires per cm) of uni-directional and isolated silicon nanowires on insulator substrates with critical dimension ranging from 15 to 19 nm were fabricated by using precision plasma etch processes; with each stage monitored by electron microscopy. This step-by-step approach provides detailed information on interfacial oxide formation at the device silicon layer, the polystyrene profile during plasma etching, final critical dimension uniformity and line edge roughness variation nanowire during processing. The resulting silicon-nanowire array devices exhibit Schottky-type behaviour and a clear field-effect. The measured values for resistivity and specific contact resistance were ((2.6 ± 1.2) × 10(5)Ωcm) and ((240 ± 80) Ωcm(2)) respectively. These values are typical for intrinsic (un-doped) silicon when contacted by high work function metal albeit counterintuitive as the resistivity of the starting wafer (~10 Ωcm) is 4 orders of magnitude lower. In essence, the nanowires are so small and consist of so few atoms, that statistically, at the original doping level each nanowire contains less than a single dopant atom and consequently exhibits the electrical behaviour of the un-doped host material. Moreover this indicates that the processing successfully avoided unintentional doping. Therefore our approach permits tuning of the device steps to contact the nanowires functionality through careful selection of the initial bulk starting material and/or by means of post processing steps e.g. thermal annealing of metal contacts to produce high performance devices. We envision that such a controllable process, combined with the precision patterning of the aligned block copolymer nanopatterns, could prolong the scaling of nanoelectronics and potentially enable the fabrication of dense, parallel arrays of multi-gate field effect transistors. 相似文献
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