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High-Temperature Oxidation of SiC-Based Composite: Rate Constant Calculation from ReaxFF MD Simulations, Part II

Evidence and attribution

Authority of statements

Prose sections below (Summary, Methods, Findings, etc.) are curated summaries of the publication identified by doi, title, and pdf_path in the front matter above. They are not new primary claims by this wiki.

For definitive numerical values, reaction schemes, and interpretations, use the peer-reviewed article (and optional records under normalized/papers/ when present)—not this page alone.

Summary

Part II of a two-part study uses ReaxFF reactive molecular dynamics trajectories to build rate models for thermal protection system (TPS) chemistry: oxidation of silicon carbide by O₂ and H₂O and combustion/pyrolysis of an EPDM polymer model. The work connects atomistic transport and reaction events to Arrhenius parameters for comparison with experiment and with phenomenological multiscale models (abstract and introduction, pages 1–2 of the extract).

Methods

1 — MD application: Reactive molecular dynamics uses a Si/C/H/O ReaxFF parameterization trained to ab initio data (Part I referenced in the text; papers/Newsome_JPCC_2013.pdf, normalized/extracts/2013newsome-venue-jp307680t_p1-2.txt). Trajectories underpin rate models for SiC oxidation by O\(_2\) and H\(_2\)O and for EPDM combustion vs pyrolysis via Arrhenius fits. N/A — full LAMMPS settings (ensemble, timestep, thermostat/barostat, cell sizes, production durations, temperature grids) are not reproduced from the short extract; read “Details of computational approach” in the PDF for the definitive protocol.

2 — Force-field training: N/A — Part I carries the primary parameterization/validation narrative relative to this Part II rate-theory focus.

3 — Static QM / DFT-only: N/A — central method is ReaxFF MD plus phenomenological rate fits (Deal–Grove–style transport picture referenced in the abstract/introduction).

Electric field / enhanced sampling: N/A — not stated in the indexed opening for this kinetics extraction workflow.

System / boundaries / ensemble / pressure (ReaxFF production MD): N/A — normalized/extracts/2013newsome-venue-jp307680t_p1-2.txt does not restate slab/composite atom counts, 3D periodic boundary conditions, whether trajectories use NVT vs NPT, or any GPa/bar pressure targets—see papers/Newsome_JPCC_2013.pdf Methods.

Findings

Outcomes and mechanisms: O\(_2\) oxidizes SiC more efficiently than H\(_2\)O in the simulations; transport activation barriers fall roughly in the 40–70 kJ/mol range for O\(_2\) and 125–150 kJ/mol for H\(_2\)O. Oxidizer attack builds a SiO\(_2\)-rich surface while O inserts between Si–C bonds and C migrates into a carbonaceous region (abstract).

Comparisons: EPDM combustion and pyrolysis simulations yield activation barriers near 183 kJ/mol and 213 kJ/mol, respectively, compared to experimental polymer literature near ~100–250 kJ/mol for both channels (abstract).

Sensitivity / design levers: Temperature enters through Arrhenius extraction across the MD trajectory sets; full temperature/pressure matrices and mixture (O\(_2\), H\(_2\)O, mixtures) handling appear later in the PDF than the indexed opening.

Limitations and outlook: Part II depends on Part I FF validation and trajectory ensembles; Arrhenius extraction from finite MD windows can be sensitive to model and sampling choices (see discussion in the article).

Corpus honesty: This summary is anchored to normalized/extracts/2013newsome-venue-jp307680t_p1-2.txt (early pages); quantitative fits, uncertainties, and figure-level mechanisms require the full J. Phys. Chem. C article (DOI 10.1021/jp307680t).

Limitations

Part II depends on Part I force-field validation and trajectory ensembles; Arrhenius extraction from short MD windows can be sensitive to model and sampling. The extract covers early pages only; full temperature/pressure matrices and uncertainty quantification appear later in the PDF. Repository automation maps this stable paper_id to normalized/papers/2013newsome-venue-jp307680t.json and the repo-relative pdf_path. Where extraction_quality is partial, the tracked PDF and DOI remain the quantitative authority over short local extracts.

Relevance to group

Co-authored with Adri van Duin; demonstrates ReaxFF for aerospace ablation/oxidation chemistry and quantitative kinetics extraction aligned with the group’s reactive MD and parameterization line.

Citations and evidence anchors

  • Abstract and introduction: contribution statement, barrier ranges, EPDM Arrhenius values, J. Phys. Chem. C framing (extract pages 1–2).
  • DOI: 10.1021/jp307680t (footer of extract).