Gel to Glass Transformation of Methyltriethoxysilane:  A Silicon Oxycarbide Glass Precursor Investigated Using Vibrational Spectroscopy

2005 ◽  
Vol 17 (17) ◽  
pp. 4468-4473 ◽  
Author(s):  
Arnold Desmartin Chomel ◽  
Philip Dempsey ◽  
Jerôme Latournerie ◽  
Djamila Hourlier-Bahloul ◽  
Upali A. Jayasooriya
Keyword(s):  
Vibrational Spectroscopy ◽  
Silicon Oxycarbide ◽  
Glass Transformation ◽  
Oxycarbide Glass

Silicon oxycarbide glasses: Part II. Structure and properties

1991 ◽  
Vol 6 (12) ◽  
pp. 2723-2734 ◽  
Author(s):  
Gary M. Renlund ◽  
Svante Prochazka ◽  
Robert H. Doremus
Keyword(s):  
Silicon Carbide ◽  
Coefficient Of Thermal Expansion ◽  
Random Network ◽  
Silicon Oxycarbide ◽  
Index Of Refraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silicon Oxycarbide Glasses ◽  
Oxycarbide Glass ◽  
Silicon Oxygen

Silicon oxycarbide glass is formed by the pyrolysis of silicone resins and contains only silicon, oxygen, and carbon. The glass remains amorphous in x-ray diffraction to 1400 °C and shows no features in transmission electron micrographs (TEM) after heating to this temperature. After heating at higher temperature (1500–1650 °C) silicon carbide lines develop in x-ray diffraction, and fine crystalline regions of silicon carbide and graphite are found in TEM and electron diffraction. XPS shows that silicon-oxygen bonds in the glass are similar to those in amorphous and crystalline silicates; some silicons are bonded to both oxygen and carbon. Carbon is bonded to either silicon or carbon; there are no carbon-oxygen bonds in the glass. Infrared spectra are consistent with these conclusions and show silicon-oxygen and silicon-carbon vibrations, but none from carbon-oxygen bonds. 29Si-NMR shows evidence for four different bonding groups around silicon. The silicon oxycarbide structure deduced from these results is a random network of silicon-oxygen tetrahedra, with some silicons bonded to one or two carbons substituted for oxygen; these carbons are in turn tetrahedrally bonded to other silicon atoms. There are very small regions of carbon-carbon bonds only, which are not bonded in the network. This “free” carbon colors the glass black. When the glass is heated above 1400 °C this network composite rearranges in tiny regions to graphite and silicon carbide crystals. The density, coefficient of thermal expansion, hardness, elastic modulus, index of refraction, and viscosity of the silicon oxycarbide glasses are all somewhat higher than these properties in vitreous silica, probably because the silicon-carbide bonds in the network of the oxycarbide lead to a tighter, more closely packed structure. The oxycarbide glass is highly stable to temperatures up to 1600 °C and higher, because oxygen and water diffuse slowly in it.

Synthesis and characterization of boron silicon oxycarbide glass fibers

2012 ◽  
Vol 358 (2) ◽  
pp. 155-162 ◽  
Author(s):  
A. Tamayo ◽  
R. Peña-Alonso ◽  
F. Rubio ◽  
J. Rubio ◽  
J.L. Oteo
Keyword(s):  
Glass Fibers ◽  
Silicon Oxycarbide ◽  
Synthesis And Characterization ◽  
Oxycarbide Glass

The Role of Si-H Functionality in Oxycarbide Glass Synthesis

1992 ◽  
Vol 271 ◽  
Author(s):  
Anant K. Singh ◽  
Carlo G. Pantano
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Analysis ◽  
Carbon Concentration ◽  
Mas Nmr ◽  
Silicon Oxycarbide ◽  
Total Carbon ◽  
Primary Interest ◽  
Hydrolysis And Condensation ◽  
Oxycarbide Glass

ABSTRACTSilicon oxycarbide gels and glasses were synthesized using various ratios of methyldimethoxysilane and TEOS. These gels and glasses were compared with those made from methyltrimethoxysilane and TEOS. The effect of the Si-H functionality in the methyldimethoxysilane was of primary interest. Hydrolysis and condensation processes were monitored using 1H and 29Si-NMR spectroscopy. The structures and the oxycarbide fractions of the glasses, obtained after heating the gels to 900°C in flowing argon, were investigated with 29si-MAS NMR. The total carbon and silicon contents of the glasses were determined using chemical analysis. The glasses covered the range of carbon concentration from ∼1 to 15%, while the silicon concentrations were constant at about 40%. The concentration of the oxycarbide species was enhanced in the glasses synthesized with the Si-H functionality in the precursor.

Changes in structure and in mechanical properties during the pyrolysis conversion of crosslinked polymethylsiloxane and polymethylphenylsiloxane resins to silicon oxycarbide glass

2015 ◽  
Vol 41 (5) ◽  
pp. 6237-6247 ◽  
Author(s):  
Martin Černý ◽  
Zdeněk Chlup ◽  
Adam Strachota ◽  
Martina Halasová ◽  
Šárka Rýglová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Silicon Oxycarbide ◽  
Oxycarbide Glass

MoSi2 Ceramic Foam Prepared by Polymer Pyrolysis

2005 ◽  
Vol 287 ◽  
pp. 129-134
Author(s):  
J.W. Paek ◽  
Beom Seob Kim ◽  
Deug Joong Kim
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Glass Matrix ◽  
Filler Content ◽  
Silicon Oxycarbide ◽  
Ceramic Foam ◽  
Ceramic Foams ◽  
Oxycarbide Glass ◽  
Polymer Pyrolysis ◽  
Curing Of Polymer

Ceramic foams containing MoSi2 were prepared by a self-blowing process of poly-silsesquioxane with MoSi2 as filler. Ceramic foams prepared by polymer pyrolysis were composed of MoSi2 and silicon oxycarbide glass matrix. Densities, pore sizes and mechanical properties of ceramic foams were depended on the filler content and heating rate for curing of polymer. Depending on the foaming condition, ceramic foams with a density of 1.2∼0.4 and a compressive strength of 3∼30 MPa were obtained.

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