The improvement on ablative properties of 1D high thermal conductivity carbon/carbon composites by constructing heterogeneous layered preforms

The 1D C/C reinforced by intermediate-phase pitch-based carbon fibers (CF_MP) has high thermal conductivity along the fiber direction, enabling rapid heat dissipation, which is crucial for enhancing the ablation resistance of C/C composites. However, the low mechanical properties between the bundles increase the risk of exfoliation damage. To address this issue, this work proposes introducing plain PAN-based carbon fiber (CF_PAN) cloth into the 1D CF_MP preform to construct CF_PAN and CF_MP heterogeneous layered preforms. A comparative study on the properties of C/C composites with different layups reveals that when the layup was CF_PAN/CF_MP/CF_MP, the inter-bundle bending strength and interlaminar shear strength increased by 174.53 % and 10.86 %. Meanwhile, the thermal conductivities reached 361.54 W/(m‧K) and 18.23 W/(m‧K) in the in-plane and out-of-plane directions, achieving a good balance between mechanical and thermal properties. Consequently, the composite exhibited optimal ablation resistance: the linear ablation rate and mass ablation rate were 0.74 mg/s and 3.3 μm/s after 60 s of ablation, 68.8 % and 34.3 % lower than those of 1D C/C, respectively, and the ablation surface temperature was only 2053 °C. The analysis suggests that the significantly improved ablation performance is mainly attributed to the enhanced interlaminar shear strength and efficient in-plane heat dissipation. This work provides guidance for preparing high performance ablation-resistant and high thermal conductivity C/C composites.