High-temperature chemistry of the conversion of siloxanes to silicon carbide

Burns, Gary T.; Taylor, Richard B.; Xu, Youren; Zangvil, Avigdor; Zank, Gregg A.

doi:10.1021/cm00024a035

Cited by 157 publications

(148 citation statements)

References 4 publications

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“…It can be attributed to the release of cyclic D-oligomers that formed during the synthesis of ladder-like silsesquioxanes as a by-product. In addition, a mass loss associated with the release of residual solvent and EtOH/ H 2 O from ongoing polycondensation reaction should be observed at this temperature [11,14,21,44]. High impact on loss of mass in this area is the number of D groups in the starting xerogel-it increases with the quantity (Fig.…”

Section: Resultsmentioning

confidence: 95%

“…Many routs can be employed to achieve black glasses [7][8][9][10]. Depending on desired outcome-final product properties, a variety of preceramic materials with different function groups can be used-like methyl, ethyl, and vinyl [11][12][13][14]. Changing the precursor can lead to formation of different black glasses, e.g., materials with or without free carbon phase [5,7,15,35].…”

Section: Introductionmentioning

confidence: 99%

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Thermal evolution of ladder-like silsesquioxanes during formation of black glasses

Jeleń

Szumera

Gawęda

et al. 2017

J Therm Anal Calorim

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Pyrolysis of ladder-like silsesquioxanes in oxygen-free atmosphere leads to the formation of silicon oxycarbides (black glasses). Black glasses are materials of amorphous silica structure where some amount of O 2-ions were replaced by C 4-ions. This exchange leads to local increase in bonds density and therefore improvement in mechanical, thermal, and chemical properties. Thanks to this modification, silicon oxycarbide glasses can be used in a variety of applications like: protective coatings and interconnectors in solid oxide fuel cells. Xerogels were prepared by sol-gel method, and ladder-like silsesquioxanes were used as precursors. Samples were burned at 200-1000°C in inert atmosphere. Structural studies in the middle infrared range (MIR) and SEM with EDX confirmed the presence of SiOC bonds in obtained materials. MIR analysis of solid samples together with TG/dTG measurements allowed defining the process for the formation of black glasses.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Thermal evolution of ladder-like silsesquioxanes during formation of black glasses

Jeleń

Szumera

Gawęda

et al. 2017

J Therm Anal Calorim

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“…Such Si−O−C ceramics have a white color, while conventional Si−O−C ceramics with excess carbon have a black color. [1][2][3] It is also becoming apparent that such white Si−O−C ceramics exhibit photoluminescence (PL) at the visible wavelength region under excitation by UV light. Various kinds of Si−O−C ceramics were synthesized by various methods, and many mechanisms have been proposed to explain the observed PL bands.…”

Section: Author(s) All Article Content Except Where Otherwise Notedmentioning

confidence: 99%

Investigation of photoluminescence of Si−O−C(−H) ceramics at an early stage of decarbonization by using high energy excitation

et al. 2014

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Si−O−C(−H) ceramics with reduced carbon contents were prepared by pyrolyzing polysiloxane particles in hydrogen at temperatures of 750, 800 and 850 °C. Under HeCd laser irradiation (325 nm), the obtained ceramics show broad spectra peaking at 400–415 nm. On the other hand, the excitation on the higher energy region by an ArF excimer laser (193 nm) induces new PL bands located at short wavelength region of 300 and 355 nm. Such high energy PL bands appear prominently in the ceramics synthesized at 750 °C, and are minor in ceramics synthesized at 800 and 850 °C.

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“…Since the pioneering work on polycarbosilane by Yajima et al [13,14], many Si-based polymeric precursors such as polysiloxanes, polysilanes, polysilazanes, polycarbosilanes have been prepared to fabricate a range of ceramic compositions [22,23]. These polymers, upon controlled pyrolysis, yield ceramic residue through the elimination of organic moieties by breaking of C-H bonds and releasing H 2 , CH 4 or other volatile compounds [22,24,25].…”

Section: Introductionmentioning

confidence: 99%

Processing of polysiloxane-derived porous ceramics: a review

Kumar

Kim

2010

Science and Technology of Advanced Materials

112

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Because of the unique combination of their attractive properties, porous ceramics are considered as candidate materials for several engineering applications. The production of porous ceramics from polysiloxane precursors offers advantages in terms of simple processing methodology, low processing cost, and easy control over porosity and other properties of the resultant ceramics. Therefore, considerable research has been conducted to produce various Si(O)C-based ceramics from polysiloxane precursors by employing different processing strategies. The complete potential of these materials can only be achieved when properties are tailored for a specific application, whereas the control over these properties is highly dependent on the processing route. This review deals with processing strategies of polysiloxane-derived porous ceramics. The essential features of processing strategies-replica, sacrificial template, direct foaming and reaction techniques-are explained and the available literature reports are thoroughly reviewed with particular regard to the critical issues that affect pore characteristics. A short note on the cross-linking methods of polysiloxanes is also provided. The potential of each processing strategy on porosity and strength of the resultant SiC or SiOC ceramics is outlined.

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High-temperature chemistry of the conversion of siloxanes to silicon carbide

Cited by 157 publications

References 4 publications

Thermal evolution of ladder-like silsesquioxanes during formation of black glasses

Thermal evolution of ladder-like silsesquioxanes during formation of black glasses

Investigation of photoluminescence of Si−O−C(−H) ceramics at an early stage of decarbonization by using high energy excitation

Processing of polysiloxane-derived porous ceramics: a review

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