Molecular dynamics simulations of the structure–property relationship in PCS-derived Si–C ceramics

Polycarbosilane (PCS) pyrolysis is a common method for synthesizing silicon carbide (SiC). However, the relationship between structure and properties during PCS pyrolysis is not well understood, and monitoring thermomechanical properties during the process is challenging. Few studies have examined the evolution of PCS performance during pyrolysis. Therefore, investigating the evolution of the structure–property relationship during PCS pyrolysis is essential. In this study, a reliable model was developed to track crosslinking, inorganic transformations, and gas release during PCS pyrolysis. Molecular dynamics (MD) simulations were used to elucidate the evolution of the structure–property relationship in PCS-derived Si–C ceramics. The results show a direct correlation between the microstructure and properties of Si–C ceramics, with our predictions closely matching experimental data. This indicates that these models can effectively estimate thermomechanical properties that are difficult to measure experimentally. Furthermore, our work offers a systematic approach to quantifying the structure–property relationship based on the primary reactions in the pyrolysis system, facilitating the tailoring of the structure to meet specific performance criteria.