Analysis of High-Current Yield of Diamond-Based Field Emitters

1999 ◽  
Vol 558 ◽  
Author(s):  
Victor V. Zhimov ◽  
C. Lizzul Rinne ◽  
Gregory Wojak ◽  
John J. Hren
Keyword(s):  
Quantitative Estimate ◽  
Natural Diamond ◽  
Relative Effectiveness ◽  
Cvd Diamond ◽  
Current Yield ◽  
High Current ◽  
Diamond Coatings ◽  
Field Emitters ◽  
Maximum Current ◽  
First Time

Summary:The maximum emission currents of different diamond coatings were measured and compared quantitatively for the first time. Both the maximum current and the transconductance of field emission tips can be increased significantly by diamond coatings. A strong, nearly linear, dependence of Imax, on thickness was found. The relative effectiveness of CVD diamond, natural diamond, and nanodiamond can be characterized by values of ΔImax/ΔD and ΔVth/D. A quantitative estimate of the thermal conductivity of nanodiamond gave 2.71 W/cm K.

Effects of thickness and cycle parameters on fretting wear behavior of CVD diamond coatings on steel substrates

2010 ◽  
Vol 205 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Qiuping Wei ◽  
Z.M. Yu ◽  
Michael N.R. Ashfold ◽  
Z. Chen ◽  
L. Wang ◽  
...  
Keyword(s):  
Wear Behavior ◽  
Cvd Diamond ◽  
Fretting Wear ◽  
Diamond Coatings ◽  
Steel Substrates

Role of microstructure on the oxidation behavior of microwave plasma synthesized diamond and diamond-like carbon films

1990 ◽  
Vol 5 (11) ◽  
pp. 2445-2450 ◽  
Author(s):  
Rao R. Nimmagadda ◽  
A. Joshi ◽  
W. L. Hsu
Keyword(s):  
Oxidation Behavior ◽  
Microwave Plasma ◽  
Natural Diamond ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Gravimetric Analysis ◽  
Oxidation Rates

Oxidation kinetics of microwave plasma assisted CVD diamond and diamond-like carbon (DLC) films in flowing oxygen were evaluated in the temperature range of 500 to 750 °C and were compared with those of graphite and natural diamond. The diamond and DLC films were prepared using CH4/H2 ratios of 0.1, 0.25, 0.5, 1.0, and 2.0%. The films deposited at 0.1% ratio had a faceted crystalline structure with high sp3 content and as the ratio increased toward 2%, the films contained more and more fine crystalline sp2 bonded carbon. The oxidation rates were determined by thermal gravimetric analysis (TGA), which shows that the films deposited at ratios of 2, 1, and 0.5% oxidized at high rates and lie between the rates of natural diamond and graphite. The oxidation rate decreased with lower CH4/H2 ratio and the films deposited at 0.25 and 0.1% exhibited the lowest oxidation rates associated with the highest activation energies in the range of 293–285 kJ/mol · K. The oxidation behavior of microwave plasma assisted diamond films was similar to that of DC plasma assisted CVD diamond films. The results suggest that the same mechanism of oxidation is operational in both DC and microwave plasma assisted diamond films and is probably related to the microstructure and preferred orientation of the crystallites.

High-Current Pulsed Electron Treatment of Hypoeutectic Al–10Si Alloy

2017 ◽  
Vol 36 (1) ◽  
pp. 97-100 ◽  
Author(s):  
Lu Diankun ◽  
Gao Bo ◽  
Zhu Guanglin ◽  
Lv Jike ◽  
Hu Liang
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Beam Energy ◽  
High Current ◽  
Pulsed Electron Beam ◽  
Surface Nanocrystallization ◽  
Primary Si ◽  
Beam Energy Density ◽  
Eutectic Si ◽  
First Time

AbstractThis paper reports, for the first time, an analysis of the effect of high-current pulsed electron beam (HCPEB) on a hypoeutectic Al–10Si alloy. The Al–10Si alloy was treated by HCPEB in order to see the potential of this fairly recent technique in modifying its wear resistance. For the beam energy density of 3 J/cm2 used in the present work, the melting mode was operative and led to the formation of a “wavy” surface and the absence of mass primary Si phase and eutectic microstructure. The surface nanocrystallization of primary and eutectic Si phases led to the increase in macro-hardness of the top surface layer, and the wear resistance was drastically improved with a factor of 4.

scholarly journals Self-mated tribological systems based on multilayer micro/nanocrystalline CVD diamond coatings

Wear ◽  
2013 ◽  
Vol 303 (1-2) ◽  
pp. 225-234 ◽  
Author(s):  
E. Salgueiredo ◽  
C.S. Abreu ◽  
M. Amaral ◽  
F.J. Oliveira ◽  
J.R. Gomes ◽  
...  
Keyword(s):  
Cvd Diamond ◽  
Diamond Coatings

Analysis of Interlayer between WC–Co and CVD Diamond Film

2008 ◽  
Vol 375-376 ◽  
pp. 92-96 ◽  
Author(s):  
Wen Zhuang Lu ◽  
Dun Wen Zuo ◽  
Min Wang ◽  
Feng Xu
Keyword(s):  
Cutting Tools ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Diamond Coatings ◽  
X Ray Diffraction ◽  
Raman Scattering Spectroscopy ◽  
Electron Probe Micro Analyzer ◽  
Mechanical Bond ◽  
Cvd Diamond Coating ◽  
Better Than

Electroplated Cr, Ni and Cu were used as interlayer for chemical vapor deposition (CVD) diamond coating on WC–Co cemented carbide cutting tools. The electroplated interlayers were studied by Scanning Electron Microscope (SEM), Electron Probe Micro Analyzer (EPMA) and X-ray diffraction (XRD). The CVD diamond coatings were studied by SEM and Raman Scattering Spectroscopy (Raman). The experimental results show that there is diffusion bonded interface between electroplated layer and WC-Co substrate after H plasma treatment, the bond between electroplated layers and WC-Co substrate changes from mechanical bond to metallurgical bond and the adhesion becomes stronger. Electroplated Cr interlayer forms new phases of Cr3C2 and Cr7C3 under CVD conditions, while electroplated Ni and Cu interlayers do not form carbides under CVD conditions. Cr carbides have good chemical compatibility to diamond, and they are propitious to diamond nucleation and growth during the deposition period. The diamond crystal microstructure, diamond quality and adhesion on Cr interlayer are better than those on electroplated Ni and Cu interlayers.

Effects of CH4 Concentration on CVD Diamond Coatings Deposited on Cemented Carbide Cutting Cools

2006 ◽  
Vol 532-533 ◽  
pp. 480-483 ◽  
Author(s):  
Wen Zhuang Lu ◽  
Dun Wen Zuo ◽  
Min Wang ◽  
Feng Xu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Great Influence ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Cemented Carbide ◽  
Diamond Coatings ◽  
Ch4 Concentration

Chemical vapor deposition (CVD) diamond coatings were deposited on cemented carbide cutting cools by an electron-assisted hot filament chemical vapor deposition (EACVD) equipment developed by the authors. The CVD diamond coatings were studied by Scanning Electron Microscope (SEM) and Raman Scattering Spectroscopy (Raman). The experimental results show that CH4 concentration in the source gas performs great influence on the micro-structure, surface roughness, composition, residual stress and adhesion of the CVD diamond coatings. The increase of CH4 concentration results the change of diamond crystal from {111} orientation to {100} orientation, the decrease of the surface roughness and the increase of sp2 carbon in the CVD diamond coatings. A residual compressive stress exists in the CVD diamond coatings. The residual stress decreases with increasing CH4 concentration. A higher or lower CH4 concentration tends to reduce adhesion stress of the continuous CVD diamond coatings.

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