Molecular dynamics simulation on PyC interfacial failure mechanism and shear strength of SiC/SiC composites

Abstract

In this paper, a molecular dynamics simulation model was established for SiC/pyrolytic carbon (PyC)/SiC composites manufactured through a chemical vapor phase infiltration (CVI) process based on microscopic observation results to investigate the shear strength and failure mechanism of PyC interphase. The simulation results showed that due to the PyC interphase’s disordered structure, the carbon layer underwent non-planar shear, overlap, flip, and deflection during the shearing process, which increased the shear strength of the composites. In addition, when the strength of the PyC interphase was lower than the bonding strength with a fiber and matrix, failure was caused by the internal breakage of the PyC interphase; when the strength of the PyC interphase was higher than the bonding strength with a fiber or matrix, failure was caused by the debonding of the PyC interphase with a fiber or matrix.

Shear behavior of SiCf/SiC interface under the thermo-chemo-mechanical influence and machine-learning-based interfacial microstructure design

“…The thermal factor is implemented by ranging the interfacial temperature from 300 K to 1800 K, with a step of 300 K. The chemical factor is realized by constructing different coating interphases, including the bare SiC f /SiC interface, the SiC f /PyC/SiC interface, and the SiC f /BN/SiC interface. Although the real structure of commonly employed PyC or BN interphase is rather complex, its basic constituent is graphite or BN crystal [40]. Here, the PyC interphase and the BN interphase are mimicked by the three-layer graphite and the three-layer h-BN, respectively.…”