Sintering densification behavior of silicon nitride (Si3N4) ceramics: A molecular dynamics study

HH Wang and XY Liu and M Chen and CG Bai and ZX Feng, CERAMICS INTERNATIONAL, 51, 59759-59769 (2025).

DOI: 10.1016/j.ceramint.2025.10.200

The densification mechanisms of silicon nitride (Si3N4) nanoparticles during sintering are systematically investigated at the atomic scale using molecular dynamics simulations. The results demonstrate that a smaller radius of curvature, inherent in finer nanoparticles and at sintering necks, significantly enhances atomic diffusion by reducing the activation energy, thereby accelerating neck formation and densification. Bimodal particle distributions further optimize this curvature effect, outperforming monodisperse systems in porosity reduction. The sintering process follows a two-stage mechanism: curvature-driven atomic transport dominates at low temperatures, while thermal activation prevails at high temperatures. Moreover, the introduction of vacancy defects markedly accelerates sintering kinetics, with a 5 % vacancy concentration reducing the diffusion onset temperature and a 10 % concentration enhancing mass transport efficiency across the entire temperature range. This study establishes a theoretical framework for defect-engineered sintering, demonstrating that synergistic control of particle architecture and vacancy concentration provides a transformative strategy for low-temperature, high-efficiency fabrication of high-performance Si3N4 ceramics.

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