Research on the thermal conductivity and ablation performance of gradient 3D woven carbon/carbon composite

This paper presents a method to manufacture gradient three-dimensional (3D) orthogonal preforms by con-trolling fiber tension in the flexible oriented 3D woven process (FO3DWP). The method was then adopted to fabricate three groups of gradient and uniform 3D woven preforms in order to conduct fiber volume fraction analysis. The precursors were simultaneously prepared into carbon/carbon (C/C) composites by means of the precursor infiltration and pyrolysis (PIP) process. The experimental results demonstrated that the outer interlayer distance of the gradient C/C composite was smaller than the inner interlayer distance, leading to the increase of the pore distribution diameter in gradient C/C composites. Thermal conductivity test and ablation properties test were conducted experimentally via oxyacetylene flame and transient hot-wire test, respectively. The out-of-plane thermal and ablation rate of the gradient composites were found to be lower than the ones of uniform com-posites. Furthermore, both the ablation resistance and the thermal conductivity increased with increasing fiber volume fraction. During the ablation test, carbon fibers in the x- and y-yarn area were shown to be able to protect the matrix and interface from further ablation, compared with the z-yarn area. Those results, successfully demonstrating the thermophysical property improvement, proved great potential of the gradient 3D woven C/C composites in aerospace applications.