Anomalous characteristics of the microcrystalline state of SiC fibres

Yajima, Seishi; Okamura, Koji; Matsuzawa, Takuro; Hasegawa, Yoshio; Shishido, Toetsu

doi:10.1038/279706a0

Cited by 116 publications

(33 citation statements)

References 6 publications

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“…It is important to note that due to the presence of excess oxygen and carbon, these fibers are more correctly classified as SiC-based fibers, rather than SiC fibers. The manufacturer's quoted composition for Nicalon™ NLM-202, which is close to figures given by Yajima [38] for pre-production fibers, is 65 % β-SiC with 23 % SiO 2 and 11 % free carbon. The microstructure of these fibers are of dispersed β-SiC crystallites of a few nanometers in size embedded in a continuum glassy silicon oxycarbide matrix (Si-O x -C y , where x+y is approximately 4).…”

Section: Sic Compositesupporting

confidence: 79%

Evaluation of neutron irradiated silicon carbide and silicon carbide composites

Newsome

Snead

Hinoki

et al. 2007

Journal of Nuclear Materials

141

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The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon™ Type-S, Hi-Nicalon™ or Sylramic™ fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10 25 n/m 2 (E>0.1 MeV) at 300, 500 and 800°C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing.Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon™ Type-S, while composites reinforced with Hi-Nicalon™ or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

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Section: Sic Compositesupporting

confidence: 79%

Evaluation of neutron irradiated silicon carbide and silicon carbide composites

Newsome

Snead

Hinoki

et al. 2007

Journal of Nuclear Materials

141

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“…Strength and creep resistance where not as expected either. Extensive study [43,[101][102][103][104][105][106][107][108][109][110][111][112] of these first generation fibers found that these fibers begin to lose their creep resistance and short-term strength at 1000…”

Section: Non-oxide (Sic) Fibersmentioning

confidence: 99%

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

Robertson¹

2015

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“…[1][2][3] Often, the ceramic contains unwanted oxygen, carbon or both. For example, the product obtained from the pyrolysis of PCS, a polydimethylsilane-derived polycarbosilane, [4][5][6] contains as much as 10-20% excess carbon and 10% oxygen. Likewise, polyvinylsilane (PVS) 7,8 gives carbon-rich ceramics (SiC C), while polymethylsilane (PMS) gives silicon-rich ceramic compositions (SiC Si).…”

Section: Introductionmentioning

confidence: 99%

Stoichiometric silicon carbide from borate‐catalyzed polymethylsilane–polyvinylsilane formulations

Boury

Bryson²,

Soula³

1999

Appl. Organometal. Chem.

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Polymethylsilane (PMS) and polyvinysilane (PVS) were prepared by Wurtz condensation of chlorosilanes and characterized by spectroscopy (1H, 13C and 29Si NMR, and infrared), viscosity and GPC analysis. Mixtures of the PMS and PVS were prepared and stabilized with 2,6‐di‐t‐butyl‐4‐methylphenol (BHT; 0.5 wt%) to which was added a catalytic amount of tris(trimethylsilyl)borate, B(OSiMe3)3 (BTMS; 2 wt% by weight). The resulting liquid materials were pyrolyzed to 950 °C and to 1400 °C under argon. The formulation, composed of 60% PMS / 40% PVS / 2% BTMS, was pyrolyzed and gives nearly stoichiometric silicon carbide in 73% yield. The pyrolyzate was analyzed spectroscopically at intermediate stages in order to study its thermal transformations and the influence of the boron catalyst. The ceramic obtained from the formulation 60% PMS / 40% PVS / 2% BTMS shows good stability at 1500 °C under oxygen. Copyright © 1999 John Wiley & Sons, Ltd.

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Anomalous characteristics of the microcrystalline state of SiC fibres

Cited by 116 publications

References 6 publications

Evaluation of neutron irradiated silicon carbide and silicon carbide composites

Evaluation of neutron irradiated silicon carbide and silicon carbide composites

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

Stoichiometric silicon carbide from borate‐catalyzed polymethylsilane–polyvinylsilane formulations

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