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

Abstract

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.

(Nano)structure, skin/core and tension behaviour of polyamide fibres

“…9 In the case of Raman/Rayleigh images containing several hundred spectra, LabSpec 2.0 software was used. Raman images were recorded using the Infinity spectrometer with …”

“…8 Raman and Rayleigh imaging have helped in the identification of the skin/core (nano)structure. 9 Recently, the use of Raman spectroscopy has shown that a similar phenomenon occurs in polyaniline fibres spun in the gel state. Such a particular skin/core structure has been related to solvent evaporation and surface reaction.…”

Characterization of 4H-SiC grown on AlN/Si(100) by CVD

“…2), are corresponding to the diamond-like carbon and the graphitic carbon, respectively [10]. The diamond-like carbon occurs when C inhabits the Si site in the SiC lattice, which means the Si-vacancy (V Si ) more easily existing in the same position.…”

Comparison of 2-amino benzyl alcohol adsorption onto activated carbon, silicon carbide nanoparticle and silicon carbide nanoparticle loaded on activated carbon

“…The single, smooth and continuous curve of these compounds can be ascribed to the S 2 type, according to the Giles classification scheme. This type of curve is typical for micro-porous sorbents and was observed in the monolayer sorption on the microporous adsorbent [45].…”

“…The results of Boehm titration of silicon carbide particles in the present study (Table 1), indicate that the specific surface charge of the SiC powder was positive. On the other hand, Haval and Colomban [45] showed the existence of unsaturated hydrocarbons on the surface of silicon carbide particles. Also, the reaction of unsaturated hydrocarbons on silicon carbide nanoparticles with radical species generated from azo radical imitators has been reported [46].…”