Microfabrication of freestanding metal structures using graphite substrate

2003 ◽  
Vol 103 (1-2) ◽  
pp. 182-186 ◽  
Author(s):  
Olga V. Makarova ◽  
Derrick C. Mancini ◽  
Nicolaie Moldovan ◽  
Ralu Divan ◽  
Cha-Mei Tang ◽  
...  
Keyword(s):  
Graphite Substrate ◽  
Metal Structures

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

Determination of creep mechanisms in various silicon carbides via TEM

1986 ◽  
Vol 44 ◽  
pp. 484-487
Author(s):  
C. H. Carter ◽  
J. E. Lane ◽  
J. Bentley ◽  
R. F. Davis
Keyword(s):  
Heat Exchangers ◽  
Sintered Material ◽  
Polycrystalline Material ◽  
Chemical Vapor ◽  
Graphite Substrate ◽  
Second Phase ◽  
Reaction Bonding ◽  
Creep Mechanisms ◽  
Porous Sic

Silicon carbide (SiC) is the generic name for a material which is produced and fabricated by a number of processing routes. One of the three SiC materials investigated at NCSU is Norton Company's NC-430, which is produced by reaction-bonding of Si vapor with a porous SiC host which also contains free C. The Si combines with the free C to form additional SiC and a second phase of free Si. Chemical vapor deposition (CVD) of CH3SiCI3 onto a graphite substrate was employed to produce the second SiC investigated. This process yielded a theoretically dense polycrystalline material with highly oriented grains. The third SiC was a pressureless sintered material (SOHIO Hexoloy) which contains B and excess C as sintering additives. These materials are candidates for applications such as components for gas turbine, adiabatic diesel and sterling engines, recouperators and heat exchangers.

STOCHASTIC CALCULATION OF LIFETIME PREDICTION FOR COMPONENTS IN METAL STRUCTURES DUE TO THE GROWTH OF MICRODEFECTS

2020 ◽  
Vol 4 (97) ◽  
pp. 69-76
Author(s):  
IGOR N. SILVERSTOV
Keyword(s):  
Fatigue Strength ◽  
Fracture Mechanics ◽  
Stochastic Approach ◽  
Fatigue Curve ◽  
Probability Of Failure ◽  
Lifetime Prediction ◽  
Statistical Distributions ◽  
Metal Structures

A stochastic approach has been developed to evaluate fatigue strength using elements of the fracture mechanics. The article presents a method for determining the initial parameters of statistical distributions. It also considers the method for constructing a fatigue curve for a component of any size and configuration with any given probability of failure.

RECLAMATION AND CULVERT CROSSINGS MADE OF CORRUGATED PIPES ON SPAWNING STREAMS

2020 ◽  
pp. 68-77
Author(s):  
O.N. CHERNYKH ◽  
◽  
A.V. RBURLACHENKO
Keyword(s):  
Single Point ◽  
Experimental Studies ◽  
Fish Passage ◽  
Future Research ◽  
Fish Stocks ◽  
Metal Structures ◽  
Natural Reproduction ◽  
Spiral Shape ◽  
Corrugated Metal ◽  
Spawning Streams

Recommendations are presented for solving issues that arise in the design and operation of tubular transport crossings of corrugated metal structures through spawning streams while ensuring the safety and natural reproduction of fish stocks. There are discussed the results of experimental studies of culverts made of metal corrugated pipes with a normal and spiral shape of corrugation the bottom of which is buried and filled with suitable granular material to the level of the natural channel of a small watercourse. It is established that when 10% of the area of the corrugated pipe is occupied by stone filling, its throughput is reduced by about 10-12%. Based on the review of the existing literature and the results of laboratory experiments, data is provided to estimate the values of the roughness coefficients of the composite cross-section of a single-point junction and directions for future research on culvert reclamation are outlined. Studying of the structure of the velocity distribution in culverts can lead to the improved conditions for fish passage without installing special structural elements in the transit path of the fish passage structure.

Corrosion of Welded Metal Structures of Mining Equipment

2018 ◽  
Vol 69 (9) ◽  
pp. 2563-2566
Author(s):  
Dan Dobrota
Keyword(s):  
Carbon Concentration ◽  
Welded Joints ◽  
Construction Material ◽  
Working Environment ◽  
Mining Equipment ◽  
Metal Structures ◽  
Corrosion Phenomenon ◽  
Welding Regime ◽  
New Material ◽  
Initial Research

Mining equipment made of welded metal structures is strongly affected by the corrosion phenomenon due to the working conditions. Initial research has shown that the corrosion phenomenon is most pronounced in the area of cross-welded joints and welded T-shaped joints. In the researches, there was made a chemical analysis of the welded construction material used respectively of the new material and it was observed a reduction in carbon concentration in the material used, but also a substantial increase in the sulfur concentration compared to the new material. The pronounced corrosion of the metallic structure is influenced by the chemical composition change because the sulfur is a grafitizing and weakening element, and the decrease in carbon concentration causes a decrease in corrosion resistance. Also, the pronounced corrosion is due to the action of sulfurous acid (H2SO3) and hydrogen sulfide (H2S), elements that are present in the working environment of welded constructions. In order to achieve a reduction in the corrosion phenomenon, it is very important that the welded joints are made using the optimal parameters of the welding regime so as to obtain metallographic structure with finer granulations.

A Predictive Model of the Impact of the Skidding System on Forest Soil in Severe Climatic Conditions

2020 ◽  
pp. 131-144
Author(s):  
S.E. Rudov ◽  
◽  
V.Ya. Shapiro ◽  
O.I. Grigoreva ◽  
I.V. Grigorev ◽  
...  
Keyword(s):  
Forest Soil ◽  
Warm Season ◽  
Climatic Conditions ◽  
Soil Freezing ◽  
Class Iii ◽  
Freezing And Thawing ◽  
Metal Structures ◽  
Rapid Adjustment ◽  
Soil Freezing And Thawing ◽  
The Impact

In the Russian Federation logging operations are traditionally carried out in winter. This is due to the predominance of areas with swamped and water-logged (class III and IV) soils in the forest fund, where work of forestry equipment is difficult, and sometimes impossible in the warm season. The work of logging companies in the forests of the cryolithozone, characterized by a sharply continental climate, with severe frosts in winter, is hampered by the fact that forest machines are not recommended to operate at temperatures below –40 °C due to the high probability of breaking of metal structures and hydraulic system. At the same time, in the warm season, most of the cutting areas on cryosolic soils become difficult to pass for heavy forest machines. It turns out that the convenient period for logging in the forests of the cryolithozone is quite small. This results in the need of work in the so-called off-season period, when the air temperature becomes positive, and the thawing processes of the soil top layer begin. The same applies to the logging companies not operating in the conditions of cryosolic soils, for instance, in the Leningrad, Novgorod, Pskov, Vologda regions, etc. The observed climate warming has led to a significant reduction in the sustained period of winter logging. Frequent temperature transitions around 0 °C in winter, autumn and spring necessitate to work during the off-season too, while cutting areas thaw. In bad seasonal and climatic conditions, which primarily include off-season periods in general and permafrost in particular, it is very difficult to take into account in mathematical models features of soil freezing and thawing and their effect on the destruction nature. The article shows that the development of long-term predictive models of indicators of cyclic interaction between the skidding system and forest soil in adverse climatic conditions of off-season logging operations in order to improve their reliability requires rapid adjustment of the calculated parameters based on the actual experimental data at a given step of the cycles.

On corrosion damage and its connection with non-metal inclusions in elements of pipe metal structures of NPP

2020 ◽  
pp. 148-156
Author(s):  
A. S. Mitrofanov ◽  
Ye. A. Krainyuk ◽  
S. V. Gozhenko ◽  
V. N. Voyevodin ◽  
R. L. Vasilenko
Keyword(s):  
Corrosion Damage ◽  
Metal Structures ◽  
Pipe Metal

scholarly journals Mechanisms of construction machines and selection of steels for the manufacture of welded metal structures

2020 ◽  
Vol 1001 ◽  
pp. 012012
Author(s):  
Alexander Scherbakov ◽  
Anna Babanina ◽  
Elena Solovyeva ◽  
Maxim Aleksandrovskiy
Keyword(s):  
Metal Structures ◽  
Selection Of

scholarly journals Ultra-Narrow Metallic Nano-Trenches Realized by Wet Etching and Critical Point Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 783
Author(s):  
Jeeyoon Jeong ◽  
Hyosim Yang ◽  
Seondo Park ◽  
Yun Daniel Park ◽  
Dai-Sik Kim
Keyword(s):  
Critical Point ◽  
Terahertz Spectroscopy ◽  
High Surface ◽  
Wet Etching ◽  
Drying Process ◽  
Metal Structures ◽  
Critical Point Drying ◽  
Metal Insulator Metal ◽  
Gap Width ◽  
Optical Structure

A metallic nano-trench is a unique optical structure capable of ultrasensitive detection of molecules, active modulation as well as potential electrochemical applications. Recently, wet-etching the dielectrics of metal–insulator–metal structures has emerged as a reliable method of creating optically active metallic nano-trenches with a gap width of 10 nm or less, opening a new venue for studying the dynamics of nanoconfined molecules. Yet, the high surface tension of water in the process of drying leaves the nano-trenches vulnerable to collapsing, limiting the achievable width to no less than 5 nm. In this work, we overcome the technical limit and realize metallic nano-trenches with widths as small as 1.5 nm. The critical point drying technique significantly alleviates the stress applied to the gap in the drying process, keeping the ultra-narrow gap from collapsing. Terahertz spectroscopy of the trenches clearly reveals the signature of successful wet etching of the dielectrics without apparent damage to the gap. We expect that our work will enable various optical and electrochemical studies at a few-molecules-thick level.

scholarly journals Thermoelectric current in a graphene Cooper pair splitter

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Z. B. Tan ◽  
A. Laitinen ◽  
N. S. Kirsanov ◽  
A. Galda ◽  
V. M. Vinokur ◽  
...  
Keyword(s):  
Cooper Pair ◽  
Theoretical Description ◽  
Seebeck Effect ◽  
Normal Metal ◽  
Electric Voltage ◽  
Power Generators ◽  
Metal Structures ◽  
Fundamental Phenomenon ◽  
Non Local ◽  
Cooper Pair Splitting

AbstractGeneration of electric voltage in a conductor by applying a temperature gradient is a fundamental phenomenon called the Seebeck effect. This effect and its inverse is widely exploited in diverse applications ranging from thermoelectric power generators to temperature sensing. Recently, a possibility of thermoelectricity arising from the interplay of the non-local Cooper pair splitting and the elastic co-tunneling in the hybrid normal metal-superconductor-normal metal structures was predicted. Here, we report the observation of the non-local Seebeck effect in a graphene-based Cooper pair splitting device comprising two quantum dots connected to an aluminum superconductor and present a theoretical description of this phenomenon. The observed non-local Seebeck effect offers an efficient tool for producing entangled electrons.

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