Determination of material properties for short fibre reinforced C/C-SiC

Abstract

Abstract. Determining the mechanical properties of short fibre reinforced CMC using standard sized coupons has always been a challenge due to a high statistical scattering of the measured values. Although the random orientation of short fibres results in a quasi-isotropic material behavior of 2D-structures with a sufficiently large volume, the small volume typical for test coupons usually results in a non-isotropic fibre orientation in the tested volume. This paper describes a method for manufacturing unidirectional oriented short fibre reinforced CMC materials and presents material properties of UD-C/C-SiC. After verifying the fibre orientation of the CMC using micro-computed tomography, coupons were extracted to determine the orthotropic material properties. These orthotropic material properties were then used to predict the properties of C/C-SiC with randomly distributed short fibres. To validate the method, micro-computed tomography is used to quantitatively determine the fibre orientation within coupons extracted from randomly distributed short fibre C/C-SiC. After mechanical three-point-bending tests, the measured stiffness and bending strength is compared with the predicted properties. Finally, the data are used to devise a method suited for reducing the inherent large spread of material properties associated with the measurement of CMC materials with randomly distributed short fibres.

A novel approach for manufacturing of layered, ultra-refractory composites using pliable, short fibre-reinforced ceramic sheets

“…In fact, Ref. [62] demonstrates that compared to the identical material made of randomly orientated chopped fibres, the unidirectional material has a 50% increase in the flexural strength. No visible difference in the pull-out was found between the samples with different amounts of the fibres (20, 35, and 50 vol%).…”

Fiber orientation dependence of tribological behavior of short carbon fiber reinforced ceramic matrix composites

“…No references were found on modeling of the PIP process for CMCs, though experimental studies on this manufacturing process have been reported. Studies on polycarbosilanederived SiC ceramic 25 and SiC/SiC composite 26,27 have shown that porosity decreases and mechanical properties improve with the increasing number of PIP cycles. Zhu et al 28 show that increasing pyrolysis temperature and the concentration of SiC fillers in polycarbosilane polymer result in improved mechanical properties in two-dimensional Carbon/ SiC (C/SiC) composites fabricated using the PIP process.…”

“…Previous research revealed that distinctly different friction and wear performance were presented in carbon fiber reinforced carbon (C/C) composites with different carbon fiber orientations 26 . Currently, researchers have tried to design fiber orientations of C/C‐SiC composites for further development of mechanical properties and oxidation properties 27–30 . According to Ref.…”

“…26 Currently, researchers have tried to design fiber orientations of C/C-SiC composites for further development of mechanical properties and oxidation properties. [27][28][29][30] According to Ref. [27], significantly enhanced bending strength and stiffness were achieved in unidirectional C/C-SiC composites, when loading occurred in the direction of fiber alignment.…”

“…[27][28][29][30] According to Ref. [27], significantly enhanced bending strength and stiffness were achieved in unidirectional C/C-SiC composites, when loading occurred in the direction of fiber alignment. However, till date, the tribological properties of C/C-SiC composites with different carbon fiber orientation have been rarely studied.…”