Abstract: This study presents a structural-induced orientation strategy to fabricate cost-effective two-dimensional carbon/carbon composites with superior unidirectional thermal conductivity. By employing low-cost polyacrylonitrile-based carbon fibers and optimizing reinforcement architecture, the carbon matrix is guided to form highly oriented lamellar structures along the fiber axis, creating efficient thermal conduction pathways. Systematic investigation demonstrates that unidirectional fabric reinforcement significantly outperforms plain weave fabric in inducing matrix orientation, with thermal conductivity strongly dependent on the fiber volume ratio between orthogonal directions. The optimized material achieves an exceptional X-direction thermal conductivity of 400 W m^-1 K^-1 at a fiber volume ratio of 5:1. Cross-scale finite element modeling reveals that the oriented carbon matrix possesses an extraordinary intrinsic thermal conductivity of 1945 W m^-1 K^-1, substantially surpassing conventional carbon matrices and demonstrating its dominant role in heat conduction. The established model provides important insights into the heat transfer mechanisms within these architectural composites. This innovative approach simultaneously reduces raw material costs by nearly two orders of magnitude compared to conventional materials using mesophase pitch-based carbon fibers, successfully overcoming the traditional cost-performance limitations. The work provides valuable theoretical insights and practical guidance for developing next-generation thermal management materials.

Key words: 2D-C/C composites, Carbon matrix, Induced orientation, Thermal response