Multiscale Investigation of Carbon Fiber Oxidation Kinetics: Bridging Atomistic Simulation and a Finite-Rate Reaction Model

H Tian and XT Niu and XZ Jiang and GB Cai and RZ Li, JOURNAL OF PHYSICAL CHEMISTRY C, 127, 19947-19962 (2023).

DOI: 10.1021/acs.jpcc.3c03148

Carbon fibers (CFs) have wide applications in spacecraft thermal protection systems because of their high mechanical strength and low ablation rate. As a thermally resistant material, obtaining carbon fiber's oxidation kinetics under extreme temperatures is crucial for predicting its ablation behavior. However, the CF oxidation kinetics under extreme temperatures are still unclear. Here, we propose an approach for building a macroscale applicable finite-rate CF oxidation model based on atomistic simulations. In the microscale, the carbines on the CF surface are discovered to serve as active sites that adsorb O atoms while determining the overall oxidation rate. The capital reaction paths including O-2 adsorption, surface complex transformation, and CO and CO2 desorption are revealed by tracking atoms' states. With reaction paths and reaction coefficients determined from atomistic simulations, a finite-rate model is established at temperatures ranging from 2750 to 3750 K. This model is capable of illustrating the high-temperature CO- predominant phenomenon. Also, its steady-state output is applied to predict the graphite ablation rate, which shows excellent agreement with previous flow-tube experiment results. This CF/O-2 finite-rate model is applicable to high-temperature scenarios, and this research provides a new guideline for building CF/oxidative-component surface chemistry models from atomistic simulations..

Return to Publications page