ACID/BASE Interactions with Silicon Carbide Fiber

1989 ◽  
Vol 170 ◽  
Author(s):  
Sheldon P. Wesson ◽  
Ronald E. Allred
Keyword(s):  
Silicon Carbide ◽  
Thermal Treatment ◽  
Thermal Desorption ◽  
Photoelectron Spectroscopy ◽  
Organic Contaminants ◽  
Fiber Surface ◽  
Glow Discharge Plasma ◽  
Silicon Carbide Fiber ◽  
Acid Base ◽  
Surface Energetics

AbstractSilicon carbide fiber surfaces were analyzed by programmed thermal desorption and inverse gas chromatography, using Lewis acids and bases as probe adsorbates to compare the effect of RF glow discharge plasma and thermal treatment on surface energetics. Changes in surface acid/base character were correlated with wetting data, surface titrations, and surface chemical composition deduced from x-ray photoelectron spectroscopy. Thermal treatment did not alter fiber surface energetics significantly. Plasma treatment rendered the surface more acidic and more basic. XPS and thermal desorption analysis indicate that the plasma removed: strongly adsorbed organic contaminants, exposing and activating the underlying glassy surface.

Use of Blended Precursors of Poly(vinylsilane) in Polycarbosilane for Silicon Carbide Fiber Synthesis with Radiation Curing

1999 ◽  
Vol 82 (4) ◽  
pp. 1045-1051 ◽  
Author(s):  
Masaki Narisawa ◽  
Akira Idesaki ◽  
Shuhei Kitano ◽  
Kiyohito Okamura ◽  
Masaki Sugimoto ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Silicon Carbide Fiber ◽  
Radiation Curing

Oxidation of silicon carbide and the formation of silica polymorphs

2006 ◽  
Vol 21 (10) ◽  
pp. 2550-2563 ◽  
Author(s):  
Maxime J-F. Guinel ◽  
M. Grant Norton
Keyword(s):  
Silicon Carbide ◽  
Photoelectron Spectroscopy ◽  
Polycrystalline Silicon ◽  
Ambient Pressure ◽  
Silicon Oxycarbide ◽  
Oxide Scales ◽  
X Ray ◽  
Transmission Electron ◽  
Polycrystalline Silicon Carbide ◽  
Crystalline Films

The oxidation of both single crystal and relatively pure polycrystalline silicon carbide, between 973 and 2053 K, resulted in the formation of cristobalite, quartz, or tridymite, which are the stable crystalline polymorphs of silica (SiO2) at ambient pressure. The oxide scales were found to be pure SiO2 with no contamination resulting from the oxidizing environment. The only variable affecting the occurrence of a specific polymorph was the oxidation temperature. Cristobalite was formed at temperatures ≥1673 K, tridymite between 1073 and 1573 K, and quartz formed at 973 K. The polymorphs were determined using electron diffraction in a transmission electron microscope. These results were further confirmed using infrared and Raman spectroscopies. Cristobalite was observed to grow in a spherulitic fashion from amorphous silica. This was not the case for tridymite and quartz, which appeared to grow as oriented crystalline films. The presence of a thin silicon oxycarbide interlayer was detected at the interface between the SiC substrate and the crystalline silica using x-ray photoelectron spectroscopy.

Probing a Gas/Liquid Acid-Base Reaction by X-ray Photoelectron Spectroscopy

2013 ◽  
Vol 52 (34) ◽  
pp. 8904-8907 ◽  
Author(s):  
Inga Niedermaier ◽  
Nicola Taccardi ◽  
Peter Wasserscheid ◽  
Florian Maier ◽  
Hans-Peter Steinrück
Keyword(s):  
Photoelectron Spectroscopy ◽  
Acid Base ◽  
Liquid Acid ◽  
X Ray

Structural and Spectroscopic Assessment of Er3+-Activated SiO2-HfO2 Glass Ceramics Planar Waveguides

2008 ◽  
Vol 55 ◽  
pp. 56-61
Author(s):  
L. Minati ◽  
Giorgio Speranza ◽  
Yoann Jestin ◽  
Cristina Armellini ◽  
Andrea Chiappini ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Spinodal Decomposition ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Emission Spectra ◽  
Planar Waveguides ◽  
Material Structure ◽  
Crystalline Environment ◽  
Concentration Threshold

Two series of xHfO2 - (100-x) SiO2 (x=10, 20, 30 mol%) glass-ceramics planar waveguides doped with 0.3 mol% Er3+ ions were prepared by the sol-gel route. A thermal treatment at 1000°C was applied to the second series of samples to nucleate HfO2 crystals. The waveguides were analyzed by X-ray photoelectron spectroscopy to study the effect of the Hf concentration and of the annealing on the material structure. XPS shows that in the first series of samples a Hf concentration threshold exists. Above this threshold the material undergoes a spinodal decomposition with formation of HfO2 rich domains. In the second series of samples the presence of thermal treatment lowers the concentration threshold so that the phase separation occurs also at a Hf concentration of 10%mol. In the waveguides where spinodal decomposition in present, the emission spectra from the Er3+ ions reveal a sensible narrowing of the 4I13/2 → 4I15/2 line. This demonstrates the presence of a crystalline environment for the Er3+ ions since the inhomogeneous broadening due to the disordered glassy network is suppressed. These results may have important implications for the fabrication of photonic devices with increased efficiency.

Surface Treatment of PMIA Fibers with Sub-Atmospheric Pressure Dielectric Barrier Glow Discharge Plasma

2014 ◽  
Vol 1048 ◽  
pp. 72-76
Author(s):  
Huan Da Zheng ◽  
Juan Zhang ◽  
Bing Du ◽  
Qu Fu Wei ◽  
Lai Jiu Zheng
Keyword(s):  
Glow Discharge ◽  
Atmospheric Pressure ◽  
Chemical Structure ◽  
Surface Characterization ◽  
Discharge Plasma ◽  
Treatment Time ◽  
Fiber Surface ◽  
Glow Discharge Plasma ◽  
Dielectric Barrier ◽  
Ft Ir

Meta-aramid fibers were treated by sub-atmospheric pressure dielectric barrier glow discharge plasma. The effect of plasma treatment time on the fiber surface physical and chemical properties was studied by using surface characterization techniques. Scanning electron microscopy (SEM) was performed to determine the surface morphology changes. FT-IR spectroscopy measurements were performed to investigate the change of chemical structure. Dynamic contact angle analysis (DCAA) was used to examine the changes of the fiber surface wettability. SEM analysis showed that there was obvious crack along the fibers’ axial direction present on the fiber surface, which resulted in the better wetting behavior of the plasma-treated PMIA fiber. FT-IR analysis showed that plasma had little effect on the chemical structure of PMIA fibers. DCAA analysis showed that the wettability of the samples could be improved with the treatment time increasing. In addition, a slight decrease in breaking strength was observed at the treatment time ranging from 60 to 180 s in comparison with the untreated sample.

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