Temperature-Dependent Oxidation Behavior of Silicon Carbide Surface: Reactive Molecular Dynamics Simulations

Area of Science:

• Materials Science
• Chemical Engineering
• Aerospace Engineering

Background:

• Silicon carbide (SiC) is vital for high-temperature applications, particularly in aircraft thermal protection systems.
• Understanding the oxidation mechanisms of SiC at elevated temperatures is critical for material design and performance.
• Existing knowledge gaps remain regarding the atomic-scale processes governing SiC oxidation.

Purpose of the Study:

• To investigate the high-temperature oxidation mechanism of silicon carbide (SiC) surfaces and interfaces.
• To analyze the influence of temperature and oxygen on silica (SiO2) growth and oxidation kinetics.
• To elucidate the atomic-scale chemical reaction processes and diffusion mechanisms involved in SiC oxidation.

Main Methods:

• Reactive molecular dynamics simulations were employed to model SiC oxidation.
• Simulations covered a temperature range of 300-2300 K.
• Analysis focused on silica growth, oxidation stages, and oxygen diffusion.

Main Results:

• SiC oxidation follows a passive mechanism, characterized by progressive silica layer growth.
• Three distinct oxidation processes were identified: initial adsorption, rapid Si/C oxidation, and interface oxidation.
• The oxidation rate is hindered by the diffusion barrier of oxygen through the silica layer, with activation energy increasing in later stages.

Conclusions:

• The study provides atomic-scale insights into SiC thermal oxidation behavior.
• Oxidation kinetics are influenced by both reaction rates and oxygen diffusion coefficients.
• Findings aid in the design of advanced ceramic materials for thermal protection applications.