Understanding the ultra-high-temperature mechanical behaviors of advanced two-dimensional carbon-carbon composites

Advanced carbon-carbon composites (C/Cs) are tailored materials exhibiting properties designed to fit the end demands. However, as a kind of fiber reinforced materials, C/Cs have complex internal structures and various manufacturing defects which evolve with temperature. In addition, the micro-nano structures of the carbon fiber reinforcements and graphite matrix are susceptible to the thermal and graphitizing treatments. All these result in the complicated mechanical behaviors of C/Cs. Several experimental studies have been reported, but the mechanical parameters coupled together cannot be separated. Thus, the mechanical behaviors of C/Cs have yet been well understood. In the present work, theoretical models for the coefficient of thermal expansion, Young's modulus, and tensile strength of 2D C/Cs are established based on the mechanical mechanisms revealed in the ultra-high-temperature experiments. The mechanical behaviors of 2D plain-weave PAN based C/Cs at elevated temperatures are then studied. The factors contributing to the mechanical behaviors are separated and characterized quantitatively.