ChemInform Abstract: Comparison of Microwave Hybrid and Conventional Heating of Preceramic Polymers to Form Silicon Carbide and Silicon Oxycarbide Ceramics.

ChemInform ◽  
2000 ◽  
Vol 31 (43) ◽  
pp. no-no
Author(s):  
Gene A. Danko ◽  
Richard Silberglitt ◽  
Paolo Colombo ◽  
Eckhard Pippel ◽  
Joerg Woltersdorf
Keyword(s):  
Silicon Carbide ◽  
Silicon Oxycarbide ◽  
Conventional Heating ◽  
Preceramic Polymers

Comparison of Microwave Hybrid and Conventional Heating of Preceramic Polymers to Form Silicon Carbide and Silicon Oxycarbide Ceramics

2004 ◽  
Vol 83 (7) ◽  
pp. 1617-1625 ◽  
Author(s):  
Gene A. Danko ◽  
Richard Silberglitt ◽  
Paolo Colombo ◽  
Eckhard Pippel ◽  
Jörg Woltersdorf
Keyword(s):  
Silicon Carbide ◽  
Silicon Oxycarbide ◽  
Conventional Heating ◽  
Preceramic Polymers

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.

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.

Sintered silicon nitride/nano-silicon carbide materials based on preceramic polymers and ceramic powder

2012 ◽  
Vol 32 (9) ◽  
pp. 1893-1899 ◽  
Author(s):  
Ulrich Degenhardt ◽  
Frank Stegner ◽  
Christian Liebscher ◽  
Uwe Glatzel ◽  
Karl Berroth ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Ceramic Powder ◽  
Preceramic Polymers ◽  
Nano Silicon ◽  
Sintered Silicon

Composites Obtained from Alumina and Polymer Derived Ceramic

2018 ◽  
Vol 912 ◽  
pp. 141-146 ◽  
Author(s):  
Glauson Aparecido Ferreira Machado ◽  
Rosa Maria Rocha ◽  
Ana Helena Almeida Bressiani
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Linear Shrinkage ◽  
Density Variation ◽  
Silicon Oxycarbide ◽  
Alternative Route ◽  
Preceramic Polymer ◽  
Pure Alumina ◽  
Polymer Derived Ceramic ◽  
Alumina Composites

Alumina-mullite composites with low shrinkage can be made by reaction bond using mixtures of alumina, aluminum and silicon carbide. In this work, an alternative route is used to produce alumina composites with low shrinkage. Here alumina samples containing additions of 10 and 20 wt% of a preceramic polymer were warm-pressed and treated in the range of 900 -1500°C to produce alumina based composites. The obtained composites were analyzed by linear shrinkage and compared to pure alumina samples sintered at the same temperature range. It were also evaluated the density variation and crystalline phases formed during heat treatment of alumina composites. Results showed that alumina-silicon oxycarbide and alumina-mullite composites were obtained with lower shrinkage than pure alumina samples.

SiC Platelets Synthesized by Powder-Heating Technique

2007 ◽  
Vol 336-338 ◽  
pp. 939-941
Author(s):  
Yong Qiang Meng ◽  
Zhi Min Bai ◽  
Chang Hong Dai ◽  
Bao Bao Zhang
Keyword(s):  
Silicon Carbide ◽  
Reaction Time ◽  
Carbon Black ◽  
Raw Materials ◽  
Low Cost ◽  
Average Diameter ◽  
New Method ◽  
Conventional Heating ◽  
High Yield ◽  
Sio2 Powder

A new method for producing silicon carbide platelets with low cost and high yield was introduced. The silicon carbide platelets were synthesized by powder-heating techniques with carbon black and SiO2 powder as raw materials and CoCl2 as catalyst. The starting mixtures were heated at a temperature in the range of 1800-2000°C for the duration of about 2-4h to produce substantially completely unagglomerated silicon carbide platelets with a thickness of 5-20μm and the average diameter of 50-200μm. Compared to the conventional heating, the powder-heating technique is advantageous of less investment on equipment, easy to manufacture and convenient to operate. Furthermore, it is very suitable for realizing the scaled production because of the lower synthesizing temperature, shorter reaction time and greater output.

Fabrication of Foam-Type Porous Silicon Carbide without Cracks and Hollow Struts

2016 ◽  
Vol 369 ◽  
pp. 48-52
Author(s):  
Jeong Won Bang ◽  
Soo Ryong Kim ◽  
Young Hee Kim ◽  
Dong Geun Shin ◽  
Yoon Joo Lee ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Porous Silicon ◽  
Silicon Oxycarbide ◽  
X Ray Diffraction ◽  
Porous Silicon Carbide ◽  
Air Atmosphere ◽  
Sic Ceramics ◽  
Sic Ceramic ◽  
Curing Condition ◽  
Porous Sic

Foam-type porous silicon carbide (SiC) ceramics without cracks and hollow struts were fabricated using the polymer replica method with polycarbosilane (PCS) and polyurethane (PU) foam as the starting materials. The synthesized porous SiC was analyzed using X-ray diffraction and scanning electron microscopy. The results revealed that a porous SiC ceramic structure was formed with a dense framework at a low temperature of 1200°C. During the heat-treatment process, the PCS experienced an organic–inorganic transformation and then converted to the SiC ceramics. It was determined that the organic–inorganic transformation of PCS, which was the stage of silicon oxycarbide formation, is affected by the curing condition. In this study, the optimum curing condition was determined to be an air atmosphere at 200°C for 7 h.

Crystalline silicon oxycarbide: Is there a native oxide for silicon carbide?

2004 ◽  
Vol 84 (24) ◽  
pp. 4845-4847 ◽  
Author(s):  
Cesar R. S. da Silva ◽  
João F. Justo ◽  
Inés Pereyra
Keyword(s):  
Silicon Carbide ◽  
Crystalline Silicon ◽  
Silicon Oxycarbide ◽  
Native Oxide
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