CVD-coated boron nitride on continuous silicon carbide fibres: structure and nanocomposition

Pippel, Eckhard; Woltersdorf, J.; Dietrich, D.; Stöckel, S.; Weise, K.; Marx, G.

doi:10.1016/s0955-2219(00)00062-5

Cited by 26 publications

(6 citation statements)

References 22 publications

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“…Darkfield (DF‐TEM) analysis of the BN layer (not shown) confirms the presence of nanometer‐scale crystallites. These observations support a previous suggestion that the as‐processed CVD‐BN structure actually consists of both turbostratic t‐BN and t‐C, shown schematically in Fig. (a).…”

Section: Resultssupporting

confidence: 91%

Intermediate Temperature Internal Oxidation of a SiC/SiCN Composite with a Polymer‐Derived Matrix

2016

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SiC-based composites exhibit oxidative embrittlement at intermediate temperatures. Although the mechanisms of internal oxidation in composites with initially hermetic matrices have been studied extensively, comparable studies on composites with semipermeable matrices, such as those produced by polymer infiltration and pyrolysis, have not been reported. The present article focuses on the latter class of composites, specifically a SiC f /SiCN m with a dual BN/Si 3 N 4 fiber coating. It describes detailed SEM and TEM analyses of the microstructure before and after oxidation in dry air or water vapor at 800°C. The results show that internal oxidation is more aggressive in water vapor and occurs appreciably even in the absence of an applied stress. The sequence of oxidation of the constituent phases appears to be consistent with the underlying thermodynamic hierarchy for the respective oxidation reactions. Notably, contrary to existing models based on preferential oxidation of BN coatings, oxidation occurs first on the SiC fiber surfaces and the Si 3 N 4 overcoat; crystalline BN remains even after significant fiber and matrix oxidation has occurred. The results are discussed in terms of rate-controlling kinetic processes, the effect of oxidant type, and applied stress.

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Section: Resultssupporting

confidence: 91%

Intermediate Temperature Internal Oxidation of a SiC/SiCN Composite with a Polymer‐Derived Matrix

2016

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“…Moreover, boron nitride coating on carbon fiber reinforcement is well accepted in ceramic matrix composites (CMCs) for enhancing the high-temperature strength and oxidation resistance. [32][33][34] In the backdrop of this scenario, the objective of the present study was to understand reactions and their mechanisms occurring at Al-BNNT interface to establish the suitability of BNNT as a potential reinforcement for aluminum matrix. It is emphasized that there is no study in open literature that addresses the issues of Al-BNNT or any other metal-BNNT composite system.…”

Section: Introductionmentioning

confidence: 99%

Insight into reactions and interface between boron nitride nanotube and aluminum

Lahiri

Singh

et al. 2012

J. Mater. Res.

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“…We suppose from this modified growth of the atomic sheets, that carbon atoms were at least partially incorporated into the lamellae. Otherwise, carbon impurities in hexagonal BN films are known to precipitate in small clusters with amorphous structure [11]. We observed by HRTEM amorphous clusters in the turbostratic matrix of samples with 20 at% carbon.…”

Section: Resultsmentioning

confidence: 67%

Structure and composition studies of chemical vapour-deposited BCN fibre coatings

Dietrich

Roll²,

Stöckel

et al. 2002

Analytical and Bioanalytical Chemistry

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The composition and structure of boron carbonitride (BCN) films were studied. The films were continuously deposited on fibres by atmospheric pressure CVD. The precursors were ammonia, trimethyl borate and toluene. The composition was determined by photoelectron spectra of boron 1s, nitrogen 1s, carbon 1s and oxygen 1s. By fixing the C 1s peak at 285 eV, the position of the B 1s peak and the N 1s peak in the BCN films was equal to BN films. The C content of the films increases from about 6 at% to 60 at%, leaving the stoichiometric boron/nitrogen ratio as well as the oxygen content below 10 at% unchanged. Generally, the carbon content in the films is lower than predicted by the precursor ratios. Obviously, the insertion of carbon into the film is decreased in the presence of ammonia, which is known to etch carbon. With a decreasing ammonia/toluene ratio, the undesired effect in the reaction is suppressed and the carbon deposition becomes considerable. Transmission electron microscopic studies were performed on cross-sections of the coated fibres. High-resolution images generally show a hexagonal turbostratic structure with different orientation preferences of the atomic lamellae similar to hexagonal turbostratic boron nitride and pyrolytic carbon. When a noticeable carbon concentration (20 at%) is reached, the atomic sheets become uniformly distributed in all directions in space.

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CVD-coated boron nitride on continuous silicon carbide fibres: structure and nanocomposition

Cited by 26 publications

References 22 publications

Intermediate Temperature Internal Oxidation of a SiC/SiCN Composite with a Polymer‐Derived Matrix

Intermediate Temperature Internal Oxidation of a SiC/SiCN Composite with a Polymer‐Derived Matrix

Insight into reactions and interface between boron nitride nanotube and aluminum

Structure and composition studies of chemical vapour-deposited BCN fibre coatings

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