SiC fiber-glass matrix composite

Fig. 4.24. Plot of partial debond stress, oJJ, as a function of debond length, f, for untreated SiC fiber-glass matrix composite. After Kim et al. (1991).

Numerical treatment of Eq. (4.104) gives Zmax values for the different composite systems as shown in Table 4.3. It is worth emphasizing that for the SiC fiber-glass matrix composites, z, ax values are very small relative to values, irrespective of the fiber surface treatments and when compared to other epoxy matrix based composites. 

Fig. 4.28. Comparisons between experiments and theory of (a) maximum debond stress, crj, and (b) initial frictional pull-out stress for SiC fiber-glass matrix composites (O) untreated fibers ( ) acid treated...

Specific results are calculated for SiC fiber-glass matrix composites with the elastic constants given in Table 4.1. A constant embedded fiber length L = 2.0 mm, and constant radii a = 0.2 mm and B = 2.0 mm are considered with varying matrix radius b. The stress distributions along the axial direction shown in Fig. 4.31 are predicted based on micromechanics analysis, which are essentially similar to those obtained by FE analysis for the two extremes of fiber volume fraction, V[, shown in Fig. 4.32. The corresponding FAS distribution calculated based on Eqs. (4.90) and (4.120), and IFSS at the fiber-matrix interface of Eqs. (4.93) and (4.132) are plotted along the axial direction in Fig. 4.32. 

To evaluate the stability of the debond process, the instability parameter, z,nax, is compared, z ax values calculated based on Eqs. (4.104) and (4.139) respectively for fiber pull-out and fiber push-out give z ax = 6-5, 6.2 mm for coated steel wire-epoxy matrix and z ax = 0.5, 0.49 mm for the untreated SiC-fiber-glass matrix composite... 

Fig. 4.39. Comparisons of initial debond stress,

Carbon fiber glass matrix composites were intensively studied in the 1970s [77, 78] and SiC fiber composites in the 1980s [79, 80], In both cases the fabrication method is essentially the same. Fiber tows or fabrics are first immersed in a glass powder suspension, and the powder-containing fiber sheets are stacked ready to be hot-pressed into laminates. 

Ceramic fibers can be coated with ceramic slurries and hot-pressed to make dense fiber reinforced ceramic- or glass-matrix composites, Alternatively, continuous ceramic fibers can be combined with other fibers, whiskers, or powders and formed into porous shapes used for insulation (e.g., space-shuttle tiles) or subsequently infiltrated by CVD techniques to form fiber reinforced ceramic matrix composites without hot-pressing. For example, Nextel-SiC composites made by infiltration are being considered for applications such as heat exchangers and radiant gas burner tubes [210]. 

Sun, E.Y., Nutt, S.R. and Brennan, J.J. (1994). Interfacial microstructure and chemistry of SiC/BN dual-coated Nicalon-fiber reinforced glass-ceramic matrix composites. J. Am. Ceram. Soc. 77, 1329-1239. 

J. J. Brennan, Interfacial Studies of SiC Fiber Reinforced Glass-Ceramic Matrix Composites, Final Report R87-917546-4 on ONR Contract N00014-82-C-0096, October, 1987. 

Figure 8.71 Micrograph showing a fully-bridged matrix crack in a SiC fiber-reinforced glass-ceramic matrix composite width of field 550 p,m. (From D. B. Marshall and A. G. Evans, 1985, reproduced courtesy of The American Ceramic Society, Westerville, OH.)...

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