Understanding on interlaminar nano-reinforcement induced mechanical performance improvement of carbon/carbon composites after silicon infiltration

In structural materials research, lightweight composites for extreme environments are currently a hot issue. Although the layered architectural carbon/carbon (C/C) composites with pack cementation (PC) coatings are currently the most often viable option, free silicon penetration as a side effect of the PC process has the potential risk factors to damage the interlayer properties and hence greatly weaken the mechanical performance of the materials. Herein, the nanoscale enhancement technique is used to create a three-dimensional silicon carbide nanowire network/coating/matrix interlaminar structure to enhance the bonding strength between the coatings and the matrix. This strategy is employed in order to investigate the effect of interlaminar nano-reinforcement on the mechanical behavior of C/C composites after the silicon infiltration process. The mechanism of the influence of interlaminar reinforcement on the packing composition and stress distribution is investigated by using both experimental and multiscale modeling methodologies. Taking advantage of the improved interlayer bonding, the as-obtained composites do not only optimize the residual thermal stress concentration phenomenon caused by the high temperature treatment, but also promote a high level of interfacial shear strength, resulting in a simultaneous significant improvement in the strengthening of the load transfer and the toughening of the crack bridging. Thus, our approach contributes to a better understanding of the PC coating damage process while also providing novel insights into the creation of high-strength and lightweight structural materials. © 2022