Effects of aligned carbon nanotube microcolumns on mechanical and thermal properties of C/SiC composites prepared by LA-CVI methods

Effect of initial density on thermal conductivity of new micro‐pipeline heat conduction C/SiC composites

“…The effective‐medium theory (EMT) proposed by Bruggeman indicated that k λ can be obtained by Equation 1,21 :where p is a parameter related to porosity.…”

“…The typical modeling process of Ref‐C/SiC and MPCF‐C/SiC was conducted in Dassault SIMULIA ABAQUS and the results are shown in Figure 7. The modeling process was also based on two premises: (a) ignoring the heat radiation and heat convection and (b) considering C/SiC as single entities which is similar to the theoretical calculation part in Section 3.2 1,22 . The specimens were set up at a continuous heating source, where heating temperature was kept constant at 500°C on the top surface of composites while the ambient temperature was set to 25°C as initial temperature.…”

“…The phonon total mean free path is sensitive to the material structure and phonon interactions, such as phonon-phonon and phonon-defect interactions. 28 According to the literature, 30 the relationship between temperature and mean free path can be summarized according to the formula: l ∝ 1 T , where l and T represent the mean free path and temperature, respectively. Therefore, the mean free path would decrease with temperature.…”

“…The modeling process was also based on two premises: (a) ignoring the heat radiation and heat convection and (b) considering C/SiC as single entities which is similar to the theoretical calculation part in Section 3.2. 1,22 The specimens were set up at a continuous heating source, where heating temperature was kept constant at 500°C on the top surface of composites while the ambient temperature was set to 25°C as initial temperature. The model size was set the same for the as-prepared composites with diameter and thickness of 12.7 and mm, respectively.…”

“…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 .…”