Fiber-reinforced composites with polymer-derived matrix: processing, matrix formation and properties

Cfiber/SiCfiller/Si–B–C–Nmatrix composites with extremely high thermal stability

“…Unlike the Si-B-C-N matrix within the filler-free CMC, which was severely damaged at 1700°C, the strength of the SiC filler /Si-B-C-N matrix within the C fiber /SiC filler /Si-B-C-N matrix CMC increased after heating at 1700°C (333 vs 406 MPa) [24]. Accordingly, the matrix was not obviously fractured at 1700°C by the stress which originated from the different CTE (SiC, 4.5-4.9 Â 10 À6°CÀ1 ) [36]. Fig.…”

“…The crystallization of the Si-B-C-N matrix became distinct at that temperature. The mismatch of the coefficient of thermal expansion (CTE) between the fiber and matrix (carbon, $0°C À1 ; Si-B-C-N, 3.1-3.5Â10 À6°CÀ1 ) induced thermal stresses within the CMC, which the damaged matrix could not sustain [32,36]. As a result, cracks formed throughout the CMC.…”

“…7a; maximum strength, 208 MPa). The strengths of carbon fiber-reinforced CMC made by PIP are usually low (125 MPa, 150-200 MPa) [36,39]. Ziegler et al reported that the bending strength of a C fiber /Si-C-N matrix CMC was lower than that of a SiC fiber /Si-C-N matrix CMC made using the same processing conditions (125 MPa vs 950 MPa) and attributed this to the formation of cracks which originated from the large difference in the CTE [36].…”

“…The strengths of carbon fiber-reinforced CMC made by PIP are usually low (125 MPa, 150-200 MPa) [36,39]. Ziegler et al reported that the bending strength of a C fiber /Si-C-N matrix CMC was lower than that of a SiC fiber /Si-C-N matrix CMC made using the same processing conditions (125 MPa vs 950 MPa) and attributed this to the formation of cracks which originated from the large difference in the CTE [36]. The application of thermally stable SiC fibers, such as Tyranno-SA, is expected to improve the mechanical properties of fiber-reinforced Si-B-C-N composites owing to the similar CTE values of SiC fibers (4Â10 À6°CÀ1 ) and the matrix [40].…”

New porous silicon carbide composite reinforced by intact high-strength carbon fibres

“…In the case of C/SiC there are broadly three processing routes with several modifications reported. 1,7-10 Chemical vapour infiltration (CVI) [11][12][13][14] as well as liquid polymer infiltration (LPI) [15][16][17][18] exhibit relatively high processing costs. Both methods lead to high-performance materials with stiff matrices.…”