Pyrolytic conversion studies of blended polycarbosilane and polyaluminasilazane

Song, Li; Zhang, Yue

doi:10.1016/j.jnoncrysol.2011.11.035

Cited by 5 publications

(6 citation statements)

References 46 publications

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“…This broadening is a general phenomenon in solid-state 13 C-NMR spectra of polycarbosilane. 35,36,38,41 The methyl group was also indicated by the C-H peak ($0 ppm) in the 1 H-NMR spectra (Fig. 6(c): PCS).…”

Section: Solid-state Nmr Analysismentioning

confidence: 88%

“…( 5) The Si-C bond was formed. This is evident because the SiC 4 peak ($0 ppm) in the 29 Si-NMR spectra became broader and a slight Si 4 C bond tail ($21 ppm) 35 appeared in the 13 C-NMR spectra. The broadened SiC 4 peak is attributable to the inhomogeneously structured SiC 4 unit.…”

Section: Solid-state Nmr Analysismentioning

confidence: 96%

“…The chemical environments marked above the spectra are based on the spectra of known organic compounds and previous studies on PCSs. 31,[35][36][37][38][39][40][41][42][43][44][45] As can be seen in the 29 Si-NMR spectra, the initial PCS curve (Fig. 6(a): PCS) contained large peaks attributable to SiC 4 ($0 ppm) and HSiC 3 ($À17 ppm), as well weak peaks ascribable to OSiC 3 ($8 ppm) and Si-Si ($À38 ppm).…”

Section: Solid-state Nmr Analysismentioning

confidence: 99%

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Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

et al. 2014

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Section: Solid-state Nmr Analysismentioning

confidence: 88%

Section: Solid-state Nmr Analysismentioning

confidence: 96%

Section: Solid-state Nmr Analysismentioning

confidence: 99%

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Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

et al. 2014

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“…3 and 4 show the FTIR and NMR spectra, respectively, of the PCS bres before and aer iodisation at room temperature in an air atmosphere (the assignment of chemical bonds and environments marked in the gures are based on those reported in previous studies on PCS 15,17,[40][41][42][43][44][45][46][47][48] ). 3 and 4 show the FTIR and NMR spectra, respectively, of the PCS bres before and aer iodisation at room temperature in an air atmosphere (the assignment of chemical bonds and environments marked in the gures are based on those reported in previous studies on PCS 15,17,[40][41][42][43][44][45][46][47][48] ).…”

Section: Ceramic Yieldmentioning

confidence: 99%

“…Chemical structure changes of PCS Fig. 3 and 4 show the FTIR and NMR spectra, respectively, of the PCS bres before and aer iodisation at room temperature in an air atmosphere (the assignment of chemical bonds and environments marked in gures are based on those reported in previous studies on PCS 15,17,[40][41][42][43][44][45][46][47][48] ). There are a number of noteworthy changes in the spectra aer iodisation.…”

Section: Ceramic Yieldmentioning

confidence: 99%

Room temperature reaction of polycarbosilane with iodine under different atmospheres for polymer-derived silicon carbide fibres

et al. 2015

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The reaction of iodine with polycarbosilane (PCS) in air and N 2 atmospheres at room temperature was investigated with the goal of limiting oxygen uptake during iodine curing, in order to fabricate SiC fibres with low oxygen contents. The investigation shows that the PCS fibres are well cured by iodisation even at room temperature, regardless of the presence of oxygen in the atmosphere. Although it was previously reported that the amount of oxygen incorporated is affected proportionally by the processing temperature, when PCS fibres were iodised in air at room temperature, they contained significant amounts of oxygen owing to the very long processing time despite the low temperature. On the other hand, when iodised in a N 2 atmosphere, the fibres were successfully cured without oxygen uptake, thus demonstrating that iodisation under an oxygen-free atmosphere is a successful curing method for fabricating SiC fibres with low oxygen contents. During the cross-linking process, the iodine causes fragmentation of certain groups from the PCS polymer chains, which mostly contributes to the crosslinking between the chains, but leaves reactive sites that readily allow oxidation in air.

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Polymer‐Derived High‐Temperature Nonoxide Materials: A Review

Zhou

2023

Adv Eng Mater

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The synthesis of polymer-derived nonoxide materials such as carbides, borides, and nitrides started in the 1970s and slowly progressed into the 1980s, with silicon carbide (SiC) fibers as the prime examples. [1] In the 1990s, the research activities in this area became more intensive, with multiple efforts devoted to understanding the polymer-to-ceramic conversion mechanisms, resulting microstructures, and mechanical properties. In the 2000s, relying on the liquid precursor nature and advancement in chemistry, new techniques (e.g., electrospinning, coating, and precursor infiltration) and new precursors were introduced. Understanding of the crosslinking and thermal conversion process was improved. For example, SiC fibers were improved from amorphous silicon oxycarbide (SiOC) to low-oxygen SiC fibers and then to near-stoichiometric SiC fibers. SiC thin films of 8-190 μm thickness were reported in 2009. [2] These films can stand alone, and high mechanical properties and optoelectronic properties were achieved. Because of these advantages, they were proposed to be used in microelectromechanical systems (MEMS) and optoelectronic devices. In recent decades, additive manufacturing was used to form complex shapes. [3] Also, different one-pot precursor synthesis approaches were reported. [4] The pyrolyzed ceramic systems were frequently used in a powder format and can be further processed with traditional forming processes such as spark plasma sintering, hot pressing, thermal treatment, etc. [5,6] The advantages of using the polymerderived approach for such high-temperature nonoxide material formations involve several aspects. Compositions can be designed based on molecular-level interactions and conversion of polymeric precursors to composites. Through a synergistic selection and combination of polymer molecules of different architectures and additives, a large family of functional, structural, resilient, and versatile materials can be created. Pyrolysis conditions can also be varied to create different property systems. Species intermixing can be achieved at the true atomic level. It enables functional properties for inert systems and harsh environmental stability for far-from-equilibrium conditions. Additional advantages include low processing temperature (such as a few hundred degrees Celsius lower) and versatile shape achievement. The final materials can be fibers, coatings, membranes, powders, bulk parts, porous forms, infiltrating phases, and complex 3D-printed shapes, [3a] among others. Using the polymer-derived approach to form high-temperature ceramics also enables composition homogeneity and purity, thanks to the uniform mixing of different precursors and additives and high-purity chemical precursors. It can also create compositions that may be impossible with conventional routes, [7] such as sintering.The common challenges are as follows. Polymer-derived nonoxide composites are in a metastable state. At high temperatures, the composition and microstructure can continue to evolve and

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Pyrolytic conversion studies of blended polycarbosilane and polyaluminasilazane

Cited by 5 publications

References 46 publications

Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

Room temperature reaction of polycarbosilane with iodine under different atmospheres for polymer-derived silicon carbide fibres

Polymer‐Derived High‐Temperature Nonoxide Materials: A Review

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