Chemical Liquid Vapor Deposition for High-Performance C/C Composites

Conspectus: As global competition in aerospace and hypersonic systems intensifies, the development of reliable high-temperature thermal structural materials has become increasingly critical. Carbon/carbon (C/C) composites are promising candidates for such applications due to their low density, low coefficient of thermal expansion, exceptional thermal shock resistance and excellent mechanical properties at elevated temperatures. However, their widespread use is limited by a pronounced tendency to oxidize in oxygen-containing environments above 370 °C, as well as susceptibility to mechanical erosion and ablation under extreme thermo-mechanical loads. To overcome these limitations, the introduction of silicon carbide (SiC) and ultrahigh temperature ceramics (UHTCs) into the carbon matrix has been identified as an effective approach for enhancing oxidation and ablation resistance of C/C composites.Conventional processes for fabricating C/C or ceramic-modified C/C composites, including chemical vapor infiltration (CVI), liquid impregnation carbonization (LIC), polymer infiltration and pyrolysis (PIP) and reactive melt infiltration (RMI), are often hampered by inherent shortcomings, such as long preparation cycles, the formation of closed pores, matrix cracking and nonuniform distribution of ceramic phases, which collectively compromise the performance and reliability of C/C composites. Impressively, chemical liquid vapor deposition (CLVD), also referred to in the literature as chemical liquid vapor infiltration (CLVI) or film boiling chemical vapor infiltration (FB-CVI), represents a highly efficient and scalable alternative. By combining the high permeability of liquid precursors with the controllability of vapor deposition, CLVD facilitates rapid and uniform densification through an axial thermal gradient design, significantly reducing process time from weeks to hours while avoiding pore closure.Our research group has leveraged CLVD technology to achieve high-efficiency preparation of C/C and ceramic-modified C/C composites, achieving significantly improved mechanical and ablation resistance properties. Furthermore, we have incorporated nanoscale reinforcements into matrix by CLVD, further enhancing the mechanical properties. In this Account, we focus on the progress and achievements of our team in the past 20 years and other teams regarding the use of CLVD technology for the preparation, matrix modification, and toughening of C/C composites. Meanwhile, we incorporate our latest thoughts, the prospects and challenges of CLVD technology. We believe that this Account offers a generalized and efficient methodology for the fabrication of advanced C/C composites and provides valuable theoretical and technical guidance for researchers engaged in thermal structural materials.