Carbon fiber oxidation under high temperature by ReaxFF based molecular dynamics simulation
Linyuan Shi1 , Ximeng Wang1 , Nagi N. Mansour2 , Michael R. Tonks1 , Simon R. Phillpot1, *
1Materials Science and Engineering Department, University of Florida, Gainesville, FL 32601, USA
2NASA Ames Research Center, Moffett Field, CA 94035, USA
As a polymer-based ablator, the Phenolic Impregnated Carbon Ablator (PICA) material, a composite made of the resin matrix and carbon fiber, is widely used in Thermo Protection Systems (TPS) to protect space vehicles during atmospheric re-entry by resisting heat transport into the interior. Oxygen diffuses into the PICA materials and reacts with carbon fibers during the pyrolysis and ablation processes. The purpose of this study is to investigate the surface chemical reactions and structural changes of carbon fibers to provide larger scale models like phase field models with necessary parameters for developing a state-of-art model of PICA ablation and pyrolysis. The carbon fiber model is generated by a method developed by Desai et al [1], which combines kinetic Monte Carlo and molecular dynamics (MD) techniques. MD simulations based on a reactive-force-field (ReaxFF) potential were performed to investigate the oxidation in this carbon fiber model under high temperature. The influences of the oxygen concentration, the shape of the fiber and the temperature to carbon fiber oxidation are also studied in this research. The preliminary results of this simulation show the carbon fiber oxidation exhibits a temperature dependence and the major product during the reaction is carbon monoxide which is in good agreement with other simulations.
Keywords: Ablation, Carbon fiber, Phenolic Impregnator Carbon Ablator, Molecular Dynamics, ReaxFF
[1] Desai, S., Li, C., Shen, T., & Strachan, A. (2017). Molecular modeling of the microstructure evolution during carbon fiber processing. The Journal of chemical physics, 147(22), 224705.