Toward a Process-Based Molecular Model of SiC Membranes. 2. Reactive Dynamics Simulation of the Pyrolysis of Polymer Precursor To Form Amorphous SiC

In part 1 of this series we developed the reactive force field ReaxFF, choosing the parameters adjusted to fit quantum mechanics description of prototypical reactions. In the present paper we use ReaxFF for reactive dynamics (RD) simulation of thermal decomposition of a silicon-containing polymer, hydridopolycarbosilane (HPCS) over a wide range of temperature. Many properties of the material during its pyrolysis were computed and were found to be in good agreement with the experimental data. We then simulated pyrolysis of the HPCS under conditions that closely mimic the conditions of the fabrication of nanoporous SiC membranes to produce amorphous SiC material. Again, the computed properties of the SiC ceramic were found to be in good agreement with the experimental data. In particular, the ReaxFF RD simulations generate ceramic SiC that contains mostly Si-C bonds with some Si-Si and C-C bonds, consistent with experimental data. This indicates again the accuracy of the parameters of the ReaxFF determined in Part 1.