Microstructure and High Temperature Mechanical Behavior of New Polymer Derived SiC Based Fibers

Berger, Marie‐Hélène; Hochet, Nicolas; Bunsell, Anthony R.

doi:10.1002/9780470294482.ch5

Cited by 6 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Raman parameter is the FWHH of "sp 3 -carbon" band and was obtained on spectra recorded at room-temperature on the surface of annealed fibers. The strengths are those measured during thermal treatments by Berger et al [21] . In fig.…”

Section: Correlation Between Raman Spectra and Microstructurementioning

confidence: 99%

“…Carbon was shown to lie on SiC grains in the NLM [6] and Hi [5] grades. In the SA fiber, carbon is found at grain boundaries triple points [21] , which implies it has strongly evolved and must be well organized, in rather big entities. Fig.…”

Section: Raman Spectroscopy and Sic Fibers Micro/nano-structurementioning

confidence: 99%

“…The thermal treatments were assumed to be equivalent to those performed by Berger et al [21] and Kumagawa et al [22] on, respectively, Hi and NLM fibers the strength of which they measured.…”

Section: Samples Preparationmentioning

confidence: 99%

“…3(b), each point corresponds to a given annealing temperature and a Raman parameter, either the wavenumber or the FWHH of "sp 3 -carbon" band, is given as a function of the high-temperature strength. The strength values for the annealing temperatures of the Raman investigated fibers were extrapolated from a sigmoïdal fit of Berger et al data [21] (Hi-Nicalon) and a exponential fit of Kumagawa et al data [22] (NLM-Nicalon).…”

Section: Correlation Between Raman Spectra and Microstructurementioning

confidence: 99%

“…±700 [3] 2970 [33] 1.4 [22,72] 1.2 ±0.09 [3] Hi 1.39 [21] 1.41 [5] 1.55 [81] 1.35 [82] 0.5 [21,33,72] e-5 [5] 5.4 [32] 4.5 [21] 2-15 [5,7] 5-20 $ [4] 3-5 [82] 1-30…”

Section: Fig 6 (A)mentioning

confidence: 99%

See 4 more Smart Citations

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Gouadec

Colomban

2001

Journal of the European Ceramic Society

View full text Add to dashboard Cite

The paper provides a comprehensive study on Raman spectroscopy versatility as a fast and non destructive tool for the prediction of the mechanical properties of SiC fibers derived from a polymeric precursor (NLM™, Hi™, Hi-S™, SA™ and Sylramic™ grades) or produced by CVD (SCS-6™ fiber), including in situ analysis in CMCs or MMCs. We show how the results of very simple spectra fitting are correlated with Young's modulus, tensile strength and microhardness. The reason why such a correlation exists, the common dependency of Raman signal and mechanical behavior to the micro/nanostructure of ceramics, is discussed. Keywords :SiC-fibers / Raman spectroscopy / Mechanical properties / Microstructure / Carbon ∂ Author to whom correspondence should be addressed Fax : 33 (0) 1 49 78 13 18 e-mail : colomban@glvt-cnrs.fr IntroductionThe reinforcement of ceramic materials by long ceramic fibers leads to low density and refractory materials, of high damage tolerance, that should be appropriate for metal alloys substitution in advanced engines (turbines) and waste treatment energy plants [1] . Ceramic fibers can also be incorporated directly in metal matrices to increase their high temperature mechanical properties [1] .SiC fibers, which are among the most stable fibers, have always been produced by the 3D reticulation of a polymeric precursor. This synthesis route leads to a high matter homogeneity and very smooth surfaces, the lack of defects explaining tensile strengths σ r as high as 3 GPa. SiC fibers have been widely studied, especially their aging [2][3][4][5][6][7] which evidenced that densification is linked to compositional changes (for instance the loss of some residual hydrogen [8] ). A peculiarity of ceramics issued from polymeric precursors is no impurities are concentrated at the grains boundaries. Abnormal grain growth is very common in the lack of such usual diffusion regulators [9] and the know-how of SiC fibers manufacturers consists in postponing the onset of SiC crystallization and grain growth, since a high correlation is anticipated with mechanical degradation. A close relationship has been evidenced, for instance, between the micro-hardness and short-range ordering in sol-gel prepared nanocrystalline oxides [10] and some authors have already pointed out fibers overall mechanical ability is governed by their microstructure [5,7,11] .The purpose of this paper is to try correlating, to the best extent possible, the tensile strength (σ r ), the Young's modulus (E) and the micro-hardness (μH) of different SiC fibers, either to Raman spectra or to "Raman Extensometry" S coefficient (measuring the straininduced shifts of Raman bands). Unlike most experimental methods intended to measure directly σ r and E, Raman analysis does not require extracting fibers from the matrix, either by mechanical grinding/crushing [12] or by chemical attack [13] . Only the most resistant fibers are extracted in the former case while fibers surface might be altered in the latter. Besides, it will always be difficult to extract...

show abstract

Section: Correlation Between Raman Spectra and Microstructurementioning

confidence: 99%

Section: Raman Spectroscopy and Sic Fibers Micro/nano-structurementioning

confidence: 99%

Section: Samples Preparationmentioning

confidence: 99%

Section: Correlation Between Raman Spectra and Microstructurementioning

confidence: 99%

“…±700 [3] 2970 [33] 1.4 [22,72] 1.2 ±0.09 [3] Hi 1.39 [21] 1.41 [5] 1.55 [81] 1.35 [82] 0.5 [21,33,72] e-5 [5] 5.4 [32] 4.5 [21] 2-15 [5,7] 5-20 $ [4] 3-5 [82] 1-30…”

Section: Fig 6 (A)mentioning

confidence: 99%

See 3 more Smart Citations

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Gouadec

Colomban

2001

Journal of the European Ceramic Society

View full text Add to dashboard Cite

show abstract

Analysis of Strain and Stress in Ceramic, Polymer and Metal Matrix Composites by Raman Spectroscopy

Colomban¹

2002

Adv. Eng. Mater.

View full text Add to dashboard Cite

Raman scattering is a unique tool providing information on the structure and short‐range order of matter. Stress‐induced Raman shifts can be used to determine the stress/strain in films, fibres, particulate composites and, more generally, in any phase a few microns or more in scale. Quantitative results follow from a wavenumber calibration as a function of tensile strains or pressures applied to reference fibres or crystals. Furthermore, if the material is coloured, (near) resonant Raman scattering occurs, which enhances the scattered light intensity and simplifies the spectra – especially for harmonics – but drastically reduces the analysed volume (in‐depth penetration ∼10–100 nm). This paper discusses the effective and potential advantages/drawbacks of Raman micro‐spectrometry technique. The procedures to improve the sensitivity, the legibility and the reliability will be addressed. Examples will be chosen among (aramid, C, SiC) fibre‐ reinforced ceramic (CMCs), polymer (PMCs) or metal matrix (MMCs) composites.

show abstract

Skin/bulk nanostructure and corrosion of SiC‐based fibres: a surface Rayleigh and Raman study

Havel¹,

Colomban²

2003

J Raman Spectroscopy

View full text Add to dashboard Cite

SiC-based fibres are complex systems of nanophases. Raman imaging of polished Tyranno SA3 fibre (UBE Industry) sections indicated that carbon species have different concentrations, natures and short-range order on the fibre core and surface, which results from the production process. The monitoring of the fibre's skin/bulk nanostructure, composition and geometry was performed on sections by Raman and Rayleigh microspectrometry. Owing to the weak light penetration in these materials, Rayleigh diffusion can map the surface geometry. The spatial correlation model applied to the LO SiC Raman mode at ca 969 cm −1 allowed us to estimate the size variation of the small SiC crystallites across the fibre. A model based on the I D /I G Raman peak ratio was used to calculate and map the size distribution of the carbon moieties. The position of the D Raman peak at ca 1620 cm −1 , which is correlated with the graphite in-plane lattice contraction or expansion, allowed us to identify the intercalant ions. The fibre's core, which contains non-aromatic carbon moieties, is corroded much faster than the periphery under an alkaline and oxidative environment (modelled by molten NaNO 3 and LiNO 3 ). This is considered to be linked to the nature of these carbon moieties and to their location (at triple points and grain boundaries), which constitutes a direct diffusion pathway.

show abstract

Microstructure and High Temperature Mechanical Behavior of New Polymer Derived SiC Based Fibers

Cited by 6 publications

References 0 publications

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Analysis of Strain and Stress in Ceramic, Polymer and Metal Matrix Composites by Raman Spectroscopy

Skin/bulk nanostructure and corrosion of SiC‐based fibres: a surface Rayleigh and Raman study

Contact Info

Product

Resources

About