Effect of carbon content on structural and mechanical properties of SiCN by atomistic simulations

Silicon carbonitride (SiCN) presents good performance on thermal stability and mechanical properties at high temperature. However, experiments still have problems to investigate the chemical structure of nanodomains and high temperature mechanical properties for SiCN. In this paper, atomistic simulations were used to generate amorphous SiCN with different carbon contents, the resulting structures show a tendency to include a “free carbon” phase when the carbon content increases. The calculated pair distributions, angular distributions and structure factor are comparable with experiments. Particularly, the first peaks of C–C and Si–C distributions become more significant when C content decreases, this is related to the variations of Si–C bonds near the graphene regions when the sizes of carbon phases change. The calculated Young's moduli are close to the experimental data and increase with increasing carbon content. The proposed atomic model can be used to predict the structural and mechanical properties of SiCN at different compositions.