Deposition of Hermetic Carbon Coatings on Silica Fibers

1989 ◽  
Vol 172 ◽  
Author(s):  
R. G. Huff ◽  
F. V. DiMarcello ◽  
A. C. Hart ◽  
K. L. Walker
Keyword(s):  
Optical Fibers ◽  
Carbon Coating ◽  
Fiber Surface ◽  
Static Fatigue ◽  
Degradation Mechanisms ◽  
Forming Process ◽  
Deposition Rates ◽  
Carbon Coatings ◽  
Silica Fibers ◽  
Carbon Coated

AbstractCarbon coated optical fibers have recently been shown to have excellent resistance to both static fatigue and hydrogen induced losses. The deposition technique used to form the carbon coating strongly affects the coating's ability to resist these degradation mechanisms. The system developed by AT&T utilizes an atmospheric CVD chamber in which a hydrocarbon has is pyrolyzed on the fiber surface. The heat retained in the fiber from the fiber forming process is used to drive the reaction, and high draw speeds are typically used to attain the ˜900°C temperature required to deposit the hermetic form of the carbon coating. Deposition rates of ˜1μm/sec are required to produce the ˜500 Å coating.

Activation Energy for Strength Degradation of Fused Silica Optical Fibers

1998 ◽  
Vol 531 ◽  
Author(s):  
Yunn-Shin Shiue ◽  
M. John Matthewson
Keyword(s):  
Activation Energy ◽  
Optical Fibers ◽  
Pure Water ◽  
Strength Degradation ◽  
Fused Silica ◽  
Static Fatigue ◽  
Buffer Solution ◽  
Silica Fibers ◽  
Apparent Activation Energies ◽  
Stress Dependent

AbstractThe strength degradation behavior of fused silica optical fiber is well known to be sensitive to the temperature and an apparent activation energy can be determined. In addition, it has been observed that the activation energy also depends on the applied stress and the nature of the environment. However, no consistent model for this behavior has emerged. We propose a chemical kinetics model which accounts for the temperature dependence of the dissociation of water which predicts that degradation should be faster in pH 7 buffer than in pure water. Static fatigue of fused silica fibers in both water and pH 7 buffer solution has been carefully studied as a function of temperature to test the model. The apparent activation energies are stress dependent, and, while the dependency is not clear, different environments give different dependencies. These observations support the proposed model.

EPR Characterization of Carbon Coated Fiber

1989 ◽  
Vol 172 ◽  
Author(s):  
Daryl Inniss
Keyword(s):  
Optical Fibers ◽  
Active Sites ◽  
Hydrogen Permeation ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Static Fatigue ◽  
Paramagnetic Resonance ◽  
Intensity Measurements ◽  
Carbon Coated ◽  
G Value

AbstractAn amorphous carbon coating has been developed to improve the resistance of silica optical fibers to static fatigue and hydrogen permeation. The carbon coated optical fibers are characterized by electron paramagnetic resonance spectroscopy. A Lorentzian lineshape is observed, centered at the g value of 2.002. Intensity measurements as a function of temperature suggest that localized spin centers contribute to the spin resonance. It is shown that atmospheric control of the carbonaceous environment results in the removal of these EPR active sites.

Thermal stresses in carbon-coated optical fibers at low temperature

1997 ◽  
Vol 12 (9) ◽  
pp. 2493-2498 ◽  
Author(s):  
Sham-Tsong Shiue ◽  
Wen-Hao Lee
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Glass Fiber ◽  
Young’S Modulus ◽  
Optical Fibers ◽  
Poisson’S Ratio ◽  
Carbon Coating ◽  
Thermal Stresses ◽  
Poisson's Ratio ◽  
Carbon Coated

The thermal stresses in carbon-coated optical fibers at low temperature have been analyzed. The thermally induced lateral pressure in the glass fiber would produce microbending loss. In order to minimize such a microbending loss, the thickness, Young's modulus, and Poisson's ratio of the carbon coating should be decreased. On the other hand, the maximum thermal stress is the tangential stress in the carbon coating that occurs at the interface of the carbon coating and glass fiber. It was experimentally observed that if the maximum thermal stress is larger than the tensile strength of the carbon coating, the carbon coating will be broken along the axial direction. In order to minimize such a maximum thermal stress, the thickness of the carbon coating should be increased, but Young's modulus, thermal expansion coefficient, and Poisson's ratio of the carbon coating should be decreased. Finally, an optimal selection of the carbon coating for optical fiber is discussed.

Diffusion of Hydrogen Through Hermetic Carbon Films on Silica Fibers

1989 ◽  
Vol 172 ◽  
Author(s):  
P. J. Lemaire ◽  
K. L. Walker ◽  
K. S. Kranz ◽  
R. G. Huff ◽  
F. V. DiMarcello
Keyword(s):  
Optical Fibers ◽  
Elevated Temperatures ◽  
Optical Loss ◽  
Carbon Films ◽  
Accelerated Tests ◽  
Carbon Coatings ◽  
Silica Fibers ◽  
Defect Sites ◽  
Diffusion Of Hydrogen

AbstractRecent work has made it possible to deposit hermetic carbon coatings on optical fibers during the drawing process. These coatings are used to protect the silica portion of the fiber from undesirable loss increases and strength reductions caused by H2 and H2O, respectively. The hermetic properties of the carbon films have been evaluated using accelerated test conditions where the coated fibers are exposed to H2 at elevated temperatures and hydrogen pressures. In-situ spectral loss monitoring has made it possible to measure changes in the characteristic optical loss features associated with either molecular H2or with species such as OH which form when hydrogen reacts with defects in the silica. By using long lengths of fiber it is thus possible to optically measure the extremely small amounts of hydrogen that penetrate the carbon films during accelerated tests. At temperatures in the range of 100 to 145°C the diffusion of H2 is readily modeled using classical diffusion theories for a composite cylinder, allowing calculation of the diffusion coefficient and the solubility for H2 in the carbon. At higher temperatures the diffusing H2 is partially depleted by reaction with defects in the glass. For these conditions the inward diffusion of the H2 and its reaction at defect sites tend to balance each other, giving rise to a constant, but extremely low, concentration of H2 in the fiber.

Microtribological properties of hard amorphous carbon protective coatings for thin-film magnetic disks and heads

1997 ◽  
Vol 211 (4) ◽  
pp. 365-372 ◽  
Author(s):  
V N Koinkar ◽  
B Bhushan
Keyword(s):  
Amorphous Carbon ◽  
Carbon Coating ◽  
Protective Coatings ◽  
Ion Beam ◽  
Crystal Silicon ◽  
Carbon Coatings ◽  
Magnetic Disks ◽  
Hydrogenated Amorphous Carbon ◽  
Hydrogenated Amorphous ◽  
Cathodic Arc

For long durability of magnetic media and head sliders, protective overcoats of hydrogenated amorphous carbon (a-C:H) are generally used. In this study, microtribological studies of hydrogenated amorphous carbon coatings deposited on a single-crystal silicon using three different deposition techniques—sputtering, ion beam and cathodic arc—were studied using atomic force/friction force microscopy (AFM/FFM). Roughnesses of all coatings at two scan sizes of 1 μm × 1 μm and 10 μm × 10 μm are comparable. Surface topography of sputtered carbon coating shows some particulates on the surface. Cathodic arc carbon coating exhibits the lowest coefficient of friction value followed by ion beam and sputtered carbon coatings. Microscratch and wear resistance and nanohardness of cathodic arc carbon coating are superior to those of ion beam and sputtered carbon coatings. Cathodic arc deposited carbon coatings are potential candidates for magnetic disks and heads.

Electrochemical Properties of Carbon-Coated NbO2 as a Negative Electrode for Lithium-Ion Batteries

2016 ◽  
Vol 724 ◽  
pp. 87-91 ◽  
Author(s):  
Chang Su Kim ◽  
Yong Hoon Cho ◽  
Kyoung Soo Park ◽  
Soon Ki Jeong ◽  
Yang Soo Kim
Keyword(s):  
Electrochemical Properties ◽  
Lithium Ion Batteries ◽  
Ball Milling ◽  
Carbon Coating ◽  
Electrochemical Impedance ◽  
Active Material ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Transfer Resistance ◽  
Carbon Coated

We investigated the electrochemical properties of carbon-coated niobium dioxide (NbO2) as a negative electrode material for lithium-ion batteries. Carbon-coated NbO2 powders were synthesized by ball-milling using carbon nanotubes as the carbon source. The carbon-coated NbO2 samples were of smaller particle size compared to the pristine NbO2 samples. The carbon layers were coated non-uniformly on the NbO2 surface. The X-ray diffraction patterns confirmed that the inter-layer distances increased after carbon coating by ball-milling. This lead to decreased charge-transfer resistance, confirmed by electrochemical impedance spectroscopy, allowing electrons and lithium-ions to quickly transfer between the active material and electrolyte. Electrochemical performance, including capacity and initial coulombic efficiency, was therefore improved by carbon coating by ball-milling.

scholarly journals PROPERTIES OF NITROGEN-DOPED AMORPHOUS CARBON COATINGS OBTAINED BY IMPULSE VACUUM-ARC METHOD

2018 ◽  
Vol 59 (9) ◽  
pp. 68 ◽  
Author(s):  
Aleksandr I. Poplavskiy ◽  
Aleksandr Ya. Kolpakov ◽  
Marina E. Galkina ◽  
Igor Yu. Goncharov ◽  
Roman A. Lyubushkin ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Carbon Coating ◽  
Vacuum Arc ◽  
Internal Stresses ◽  
Structure And Properties ◽  
Carbon Coatings ◽  
Nitrogen Doped ◽  
Structure Surface ◽  
Amorphous Carbon Coatings ◽  
Carbon Plasma

The paper presents results of the research of the structure and properties of nitrogen-doped amorphous carbon coatings obtained in the vacuum from the flow of pulsed carbon plasma. The doping by nitrogen of carbon coating was determined to lead to increases in electrical conductivity, reductions of internal stresses, reduce of density, hardness and modulus, and to the change in structure, surface morphology and tribological characteristics.

In situ growth of Au–Ag bimetallic nanorings on optical fibers for enhanced plasmonic sensing

2020 ◽  
Vol 8 (22) ◽  
pp. 7552-7560 ◽  
Author(s):  
Se Shi ◽  
Anran Li ◽  
Renliang Huang ◽  
Jing Yu ◽  
Shuzhou Li ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Oxidation Resistance ◽  
Optical Fibers ◽  
Fiber Surface ◽  
Metal Deposition ◽  
In Situ Growth ◽  
Plasmonic Sensing

Au–Ag bimetallic nanorings were grown in situ on an optical fiber surface via bioinspired PDA, a synergetic GRR and metal deposition, which exhibited enhanced LSPR sensitivity and oxidation resistance.

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