Graphene Converted from the Photoresist Material on Polycrystalline Nickel Substrate

ABSTRACTBilayer nickel membranes have been prepared using electrodeposition to grow polycrystalline nickel on a nanocrystalline nickel substrate. When hydrogen is charged from the nano-Ni side of the nano-Ni and poly-Ni composite membrane, the permeation current increases rapidly, then the membrane releases hydrogen faster during decay. When hydrogen is charged from the poly-Ni side of the same composite membrane, the permeation current rises gradually and takes a longer time to reach steady state. Also the permeability of nano-poly-Ni membrane is eight times higher than that of poly-nano-Ni membrane. The diffusivity for the nano-Ni side charging in a nano-poly-Ni membrane is two times higher than that of poly-Ni side charging of the same membrane. The diffusivity and permeability of nano-poly-Ni membranes are smaller than those for nano-Ni membranes, but larger than those for poly-Ni membranes. Using this anisotropic behavior, one can manipulate hydrogen permeation through composite membranes. A hydrogen permeation model for bilayer membranes is proposed to simulate diffusion in a nano-Ni and poly-Ni bilayer membrane in two-directions of charging. The experimental data is in good qualitative agreement with the model.

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expansion with a heterodyne laser interferometer (laser probe). Demodulation is obtained with specific electronics. The magnitude and phase of the surface vibration are given with a second lock-in amplifier (lock-in amplifier 1) and stored in a microcomputer that also drives the scanning units. With this multi-acquisition microscope, the typical duration of an experiment in order to obtain a set of five low noise images is about 15 minutes. The resolution of the SThEM is given by the size at the photothermal source (radius of the optical beam: 5 /xm here). 4.1. Application to the study of thin films The first example concerns the observation of subsurface thin layers. In order to demonstrate the capacity for subsurface investigation we successively vapour deposited a 200 nm thick SiC>2 and 100 nm thick aluminium layers onto a polycrystalline nickel substrate (Fig. 8a). The bright strip on the right part of the image (Fig. 8b) reveals the presence of the subsurface SiC>2 layer which is optically invisible. This image has been obtained at 220 kHz modulation frequency of the excitation beam. The image contrast corresponds to about 25° phase shift. As the SThEM makes it possible to observe the subsurface we decided to use it for the detection of thin films delamination. We used a 1 /xm thick DLC film deposited on a steel substrate. Several lines of Vickers indentations were performed under an applied load of 4.5N. A different spacing (25 to 140 pim) between indentations has been taken for each line. The SEM and thermoelastic images of the indentations spaced 25 /xm are shown in Fig. 9. Due to the film delamination, an optically invisible bright area between the indentations (Fig. 9a) was observed by the SThEM at 100 kHz operating frequency (Fig. 9b). It is an indication of the excessive heating resulting from the film delamination. The latter is due to the tensile residual stresses which develop around each indentation. The bright area (film delamination) could not be detected both in the case of a single indentation or when the spacing between indentations was higher than 40 /xm. In the latter case

Adhesion Aspects of Thin Films, Volume 1 ◽

10.1201/b11971-32 ◽

2014 ◽

pp. 210-212

Keyword(s):

Thin Films ◽

Steel Substrate ◽

Modulation Frequency ◽

Low Noise ◽

Nickel Substrate ◽

Polycrystalline Nickel ◽

Excitation Beam ◽

The Right ◽

Lock In ◽

Bright Area

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Thin Pyrolytic Graphite Films for Electron Microscope Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065183 ◽

1971 ◽

Vol 29 ◽

pp. 226-227 ◽

Cited By ~ 1

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.

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The Microstructure of Nickel Oxide Scales

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097144 ◽

1981 ◽

Vol 39 ◽

pp. 86-87

Author(s):

M. T. Tinker ◽

L. W. Hobbs

Keyword(s):

Electron Microscopy ◽

Nickel Oxide ◽

Ion Beam ◽

Oxide Scales ◽

Nickel Substrate ◽

Outward Diffusion ◽

Transmission Electron ◽

Nickel Substrates ◽

Nickel Base ◽

Technological Interest

There is considerable technological interest in oxidation of nickel because of the importance of nickel-base superalloys in high-temperature oxidizing environments. NiO scales on nickel grow classically, by outward diffusion of nickel through the scale, and are among the most studied of oxidation systems. We report here the first extensive characterization by transmission electron microscopy of nickel oxide scales formed on bulk nickel substrates and sectioned both parallel and transversely to the Ni/NiO interface.Electrochemically-polished nickel sheet of 99.995% purity was oxidized at 1273 K in 0.1 MPa oxygen partial pressure for times between 5 s and 25 h. Parallel sections were produced using a combination of electropolishing of the nickel substrate and ion-beam thinning of the scale to any desired depth in the scale. Transverse sections were prepared by encasing stacked strips of oxidized nickel sheet in epoxy resin, sectioning transversely and ion-beam thinning until thin area spanning one or more interfaces was obtained.

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Voids in Quenched Nickel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101074 ◽

1968 ◽

Vol 26 ◽

pp. 266-267

Author(s):

J. J. Laidler

Keyword(s):

Electron Beam ◽

Ambient Temperature ◽

Cooling Rate ◽

Three Dimensional ◽

Cooling Curve ◽

Polycrystalline Nickel ◽

Quenching Temperature ◽

Long Tail ◽

Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

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