Modelling of inhomogeneous mixing of plasma species in argon–steam arc discharge for broad range of operating conditions

Carbon nanotubes have a lot of applications in mechanical fields. This is because nanomaterials have many superior mechanical properties such as very high strength-to-weight ratio, high modulus-to-weight ratio, high corrosion resistance, and super intelligence properties, which make them as smart materials. One of these attractive applications is the use of carbon nanotubes in vehicle brake friction material. Therefore, the fabrication and testing processes of these nanomaterials should be performed carefully to evaluate their mechanical, tribological, and noise properties. In this paper, friction material mixed with carbon nanotubes have been fabricated with different carbon nanotube contents and the same fabrication parameters. The carbon nanotubes have been produced using the conventional submerged arc discharge technique. The produced friction materials have been cut into pieces with standard sizes and then tested mechanically and tribologically. The results of tests have illustrated that the addition of carbon nanotubes into the friction materials could improve their mechanical properties (hardness, strength, and modulus) and also could enhance their tribological properties (wear rate and friction coefficient). Moreover, the tests showed that the presence of carbon nanotubes in friction materials could reduce the noise, vibration of the friction materials, and reduce the temperature rise due to the effect of friction, which means that the carbon nanotubes could raise the thermal conductivity of friction material, while the friction coefficient has stayed within the allowable standard limits (0.35–0.45). Surface morphology shows that the presence of carbon nanotubes in the friction materials could help to avoid surface friction cracks or fins within the normal operating conditions. The good combination of mechanical and tribological properties was obtained at 0.5% carbon nanotubes.

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Preparation of Metal Nitride Particles Using Arc Discharge in Liquid Nitrogen

Nanomaterials ◽

10.3390/nano11092214 ◽

2021 ◽

Vol 11 (9) ◽

pp. 2214

Author(s):

Yoon Sik Park ◽

Satoshi Kodama ◽

Hidetoshi Sekiguchi

Keyword(s):

Electron Microscope ◽

Liquid Nitrogen ◽

Field Emission ◽

Arc Discharge ◽

Standard Free Energy ◽

Operating Conditions ◽

Experimental Conditions ◽

Metal Nitride ◽

Reactive Material ◽

Power Mode

A simple process to synthesize metal nitride particles was proposed using submerged arc discharge plasma in liquid nitrogen. Gibbs standard free energy was considered for the selection of the nitride-forming materials. In this study, titanium (Ti) and aluminum (Al) electrodes were used as raw materials for nitride particle preparation. Liquid nitrogen acted as a dielectric medium as well as a nitridation source in this process. A copper electrode was also used as a non-reactive material for comparison with the reactive Ti and Al electrodes. As the operating conditions of the experiments, the arc discharge current was varied from 5 A (low-power mode) to 30 A (high-power mode). The formation of titanium nitride (TiN) and aluminum nitride (AlN) was confirmed in the particles prepared in all experimental conditions by X-ray powder diffraction (XRD). The observation using a field emission scanning electron microscope (FE-SEM) and a field emission transmission electron microscope (FE-TEM) indicated that the synthesized TiN particles showed a cubic morphology, whereas AlN particles containing unreacted Al showed a spherical morphology. The experiments using different metal electrode configurations showed that the anode generated most of the particles in this process. Based on the obtained results, a particle formation mechanism was proposed.

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Synthesis of Single and Multi Walled Carbon Nanotubes by Improved Arc Discharge Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.510-511.124 ◽

2012 ◽

Vol 510-511 ◽

pp. 124-131 ◽

Cited By ~ 1

Author(s):

S. Sami-Ullah ◽

S.M.H. Waqar ◽

F. Hussain ◽

A. Ali

Keyword(s):

Arc Discharge ◽

Low Cost ◽

Operating Conditions ◽

Small Scale ◽

Discharge Process ◽

Scale Production ◽

Noteworthy Feature ◽

Multi Walled Carbon Nanotubes ◽

Swcnts And Mwcnts ◽

Walled Carbon Nanotubes

This paper presents the development of a laboratory scale setup for the production of CNTs by arc discharge process in an argon gas environment. The main problem with the existing lab scale production setups is the cleaning of the chamber and this problem is resolved in presented work by placing a circular metal sheet inside the chamber, which is removed after the synthesis, thus allowing easy cleaning and recovery of the produced CNTs. The most noteworthy feature of the presented setup is its low cost, hence offering for the first time the synthesis of economical CNTs on small scale. In addition to offering better control over operating conditions and hence the quality of CNTs, another unique feature of the developed setup is its capability to synthesize SWCNTs and MWCNTs with versatile range of diameters. Significant quantity of CNTs using the developed setup were produced and characterized by using Scanning Electron microscope (SEM) and few results are reported.

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Cathodoluminescence of Catalyst Crystallites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055667 ◽

1982 ◽

Vol 40 ◽

pp. 664-665

Author(s):

E.D. Boyes ◽

P.L. Gai ◽

D.B. Darby ◽

C. Warwick

Keyword(s):

Defect Density ◽

Chemical Properties ◽

Operating Conditions ◽

Semiconductor Materials ◽

Environmental Cell ◽

High Resolution Structure ◽

Commercially Important ◽

Crystallographic Defects ◽

Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

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Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096230 ◽

1972 ◽

Vol 30 ◽

pp. 596-597

Author(s):

David A. Ansley

Keyword(s):

Spherical Aberration ◽

Focal Length ◽

Chromatic Aberration ◽

Spatial Filter ◽

Operating Conditions ◽

Objective Lens ◽

List Type ◽

Spatial Filters ◽

Transmission Electron ◽

Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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Preparation and characterization of thin films of carbon nitride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136891 ◽

1995 ◽

Vol 53 ◽

pp. 104-105

Author(s):

L. Wan ◽

R. F. Egerton

Keyword(s):

Carbon Nitride ◽

Arc Discharge ◽

Ion Beam ◽

Chemical Vapor ◽

Reactive Sputtering ◽

Vacuum Arc ◽

Specimen Preparation ◽

Bonding Structure ◽

Electron Energy Loss

INTRODUCTION Recently, a new compound carbon nitride (CNx) has captured the attention of materials scientists, resulting from the prediction of a metastable crystal structure β-C3N4. Calculations showed that the mechanical properties of β-C3N4 are close to those of diamond. Various methods, including high pressure synthesis, ion beam deposition, chemical vapor deposition, plasma enhanced evaporation, and reactive sputtering, have been used in an attempt to make this compound. In this paper, we present the results of electron energy loss spectroscopy (EELS) analysis of composition and bonding structure of CNX films deposited by two different methods.SPECIMEN PREPARATION Specimens were prepared by arc-discharge evaporation and reactive sputtering. The apparatus for evaporation is similar to the traditional setup of vacuum arc-discharge evaporation, but working in a 0.05 torr ambient of nitrogen or ammonia. A bias was applied between the carbon source and the substrate in order to generate more ions and electrons and change their energy. During deposition, this bias causes a secondary discharge between the source and the substrate.

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Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169791 ◽

1994 ◽

Vol 52 ◽

pp. 412-413

Author(s):

M. Pan

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Structural Damage ◽

Low Dose ◽

Dynamic Range ◽

High Resolution Electron Microscopy ◽

Operating Conditions ◽

Digital Data ◽

Ccd Cameras ◽

Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

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