Chemical vapor infiltration (CVI) is used for manufacturing extreme-condition materials with enhanced properties. However, reactive surface gas interactions yielding material deposition into the porous system are not well-understood. As a part of our ongoing Department of Energy (DOE) project, we studied the dynamic properties of heterogeneous reactions between silicon carbide (SiC) and various hydrocarbon molecules during the CVI process. The precursors generated by the thermal breakdown of methyl trichlorosilane (MTS, CH3SiCl3) were studied in this work. The surface reaction consists of multiple steps. In the beginning, we focused on two reactions: the dissociation of Ethane and ethylene on the SiC surface. The Density Functional Theory-based Vienna ab initio Simulation Package (VASP) was used as the calculation tool. The reaction barrier for hydrogenation was calculated using the Transition State Search. Understanding the activation energy barriers related to the precursor molecules' adsorption, surface diffusion, and chemical reactions on the substrate is the key to optimizing CVI conditions to produce higher-quality materials in a shorter time.

This study investigates the decomposition mechanism of Methyl trichlorosilane during Silicon Carbide (SiC) deposition during Chemical Vapor Infiltration (CVI). High-performance applications require SiC-based ceramic matrix composites (CMCs); however, producing them presents challenges due to limited deposition rates, high energy consumption, and uneven coating quality. To overcome these challenges, a comprehensive understanding of the SiC formation mechanism is necessary. Modeling surface reactions of MTS decomposition on the SiC substrate using density functional theory (DFT) calculations with the Vienna Ab initio Simulation Package (VASP) is the key point of current research. 

 This study investigates the decomposition mechanism of Methyl trichlorosilane during Silicon Carbide deposition from Chemical Vapor Infiltration to produce SiC-based ceramic matrix composites. High-performance applications require SiC-based materials; however, producing them presents difficulties due to limited deposition rates, high energy consumption, and uneven coatings. To overcome these challenges, the mechanism of SiC formation needed to be understood completely. Modeling surface reactions of decomposition on the substrate using Density Functional Theory is the key point of current research. By focusing on the adsorption, reaction, and desorption mechanisms that control SiC development, our method incorporates quantum mechanical models. Using Transition State Theory, the study examines reaction routes and identifies key intermediates, including methyl and other hydrocarbon species. The findings expand our knowledge of the rate-limiting steps in MTS breakdown and offer guidance for refining CVI/CVD procedures, which could increase material quality and deposition efficiency for cutting-edge engineering applications.