The sandwich structure with ceramic matrix composites (CMCs) skin and carbon form (CF) core is the ideal thermal structural components with excellent thermal protective and lightweight properties in hypersonic vehicles. However, the temperature gradient and mismatch of thermal conductivity between CMC skin and CF core result in the thermal stress in sandwich structures. Therefore, core material CF with matching thermal conductivity have become very important to prevent cracks and debonding of the sandwich structure. In this work, carbon nanotubes (CNTs) reinforced carbon foam composites with different microstructure were fabricated using simple phenolic resin foaming followed by CVI process. The prepared CF display a very low density of 0.075 g/cm3 and a relatively high compressive strength of 1.65 MPa. By controlling the distribution position and content of CNTs the thermal conductivity of core materials CF/ CNTs (4.93 W·m− 1·K− 1 which is ~ 13 times higher than that of CF) can be regulated to compatibility with CMCs skin (3.5 ~ 6.0 W/m·K). And the thermal conductivity evolution mechanisms of the CF/CNTs from room temperature to 1200 ℃ were revealed. High interfacial thermal resistance by phonon scattering between the CF and CNTs blocks the solid conduction of materials at room temperature. With the increase of the temperature, radiative heat transfer between CF and CNTs becomes more violent and dominates the heat transfer path. The C/CMCs-CMCs sandwich structure was fabricated quickly by the in situ foaming method.

In situ construction of lightweight CF/CNTs with compatible thermal performance toward sandwich structures for hypersonic vehicles
    Abstract
    1 Introduction
    2 Experimental
        2.1 Preparation of carbon foam
        2.2 Growth of CNTs
        2.3 Characterizations
    3 Results and discussion
        3.1 Carbon foam
        3.2 Microstructure of CF/CNTs
        3.3 Heat transfer mechanisms
        3.4 C/CMCs-CMCs sandwich structure
    4 Conclusions
    References

• Bo-Wen Chen(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China) Corresponding author
• De-Wei Ni(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China)
• Fei-Yan Cai(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China)
• Chun-Jing Liao(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China)
• Hong-Da Wang(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China)
• Yu-Sheng Ding(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China)
• Shao-Ming Dong(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China) Corresponding author
• Qian Wang(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, University of Chinese Academy of Sciences, Beijing, China)
• Fu-Chen Liu(State Key Laboratory of High Performance Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China, University of Chinese Academy of Sciences, Beijing, China)