In this work, pitch-based carbon fibers were utilized to reinforce silicon carbide (SiC) composites via reaction melting infiltration (RMI) method by controlling the reaction temperature and resin carbon content. Thermal conductivities and bending strengths of composites obtained under different preparation conditions were characterized by various analytical methods. Results showed the formation of SiC whiskers (SiCw) during RMI process according to vapor—solid (VS) mechanism. SiCw played an important role in toughening the Cpf/SiC composites due to crack bridging, crack deflection, and SiCw pull-out. Increase in reaction temperature during RMI process led to an initial increase in thermal conductivity along in-plane and thickness directions of composites, followed by a decline. At reaction temperature of 1600 °C, thermal conductivities along the in-plane and thickness directions were estimated to be 203.00 and 39.59 W/(m·K), respectively. Under these conditions, bending strength was recorded as 186.15±3.95 MPa. Increase in resin carbon content before RMI process led to the generation of more SiC matrix. Thermal conductivities along in-plane and thickness directions remained stable with desirable values of 175.79 and 38.86 W/(m·K), respectively. By comparison, optimal bending strength improved to 244.62±3.07 MPa. In sum, these findings look promising for future application of pitch-based carbon fibers for reinforcement of SiC ceramic composites.
Two-dimensional C/SiC composites have attracted increasing interests in recent years due to their low densities, high specific strengths, 1 elevated specific module, 2 and noncatastrophic mode of failure, 3 which made them promising thermal structural materials for applications in aerospace, aircraft braking, and space detection. 1,4,5 However, these harsh environments require them possessing not only thermal structural performances like load resistance, 2 but also functional properties such as high thermal conductivity, especially in thickness direction of the composites (about 5-12 W•m −1 •K −1 for now). 6-9 Therefore, C/SiC composites cannot serve as a functional materials for aerospace vehicle thermal discharge
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