Oxygen-diffusion shielding: A novel mechanism governing the thermo-mechanical-oxidative behavior of C/SiC composites via In-situ CT

TY - JOUR

T1 - Oxygen-diffusion shielding

T2 - A novel mechanism governing the thermo-mechanical-oxidative behavior of C/SiC composites via In-situ CT

AU - Gu, Yongsheng

AU - Liu, Kangjia

AU - Lu, Wenke

AU - Wang, Zhijie

AU - Li, Xiaolong

AU - Chen, Yanfei

AU - Fang, Daining

N1 - Publisher Copyright: © 2026 Elsevier Ltd

PY - 2026/4/15

Y1 - 2026/4/15

N2 - While numerous studies have examined C/SiC composites under ultra-high temperatures in air, inert, or vacuum atmospheres, the actual service environment of hypersonic vehicles features ultra-high temperatures and low pressure. To address this gap, we analyzed the residual mechanical properties, surface morphology, and pore-structure evolution of C/SiC composites after exposure to different temperatures, pressures, and loads. Mechanical testing, SEM, and in-situ CT were jointly employed. The results show that, when the temperature increases from 1200 °C to 1400 °C, the average residual strength and modulus exhibit increases of approximately 4 % and 18 %, respectively. Increasing pressure from 5 kPa to 15 kPa and 25 kPa leads to progressive reductions in residual strength by about 8 % and 30 %, while the residual modulus increases modestly by approximately 3 % and 12 %, indicating distinct controlling mechanisms. Notably, at 1200 °C and 5 kPa, an oxygen-diffusion shielding effect was observed: low loads enhance residual strength and modulus by closing pores and suppressing oxygen diffusion, whereas high loads reopen pores and accelerate crack-tip oxidation. In-situ CT analysis further reveals that porosity and fractal dimension decrease at low stress levels before increasing again with increasing stress. Based on these observations, an oxygen-diffusion shielding model that incorporates pore closure and fractal characteristics and a coupled thermo-mechanical-oxidation predictive expression was developed. It accurately captures the three-dimensional dependence of degradation on temperature, pressure, and load, and successfully predicts experimental results at 1400 °C under different loading conditions.

AB - While numerous studies have examined C/SiC composites under ultra-high temperatures in air, inert, or vacuum atmospheres, the actual service environment of hypersonic vehicles features ultra-high temperatures and low pressure. To address this gap, we analyzed the residual mechanical properties, surface morphology, and pore-structure evolution of C/SiC composites after exposure to different temperatures, pressures, and loads. Mechanical testing, SEM, and in-situ CT were jointly employed. The results show that, when the temperature increases from 1200 °C to 1400 °C, the average residual strength and modulus exhibit increases of approximately 4 % and 18 %, respectively. Increasing pressure from 5 kPa to 15 kPa and 25 kPa leads to progressive reductions in residual strength by about 8 % and 30 %, while the residual modulus increases modestly by approximately 3 % and 12 %, indicating distinct controlling mechanisms. Notably, at 1200 °C and 5 kPa, an oxygen-diffusion shielding effect was observed: low loads enhance residual strength and modulus by closing pores and suppressing oxygen diffusion, whereas high loads reopen pores and accelerate crack-tip oxidation. In-situ CT analysis further reveals that porosity and fractal dimension decrease at low stress levels before increasing again with increasing stress. Based on these observations, an oxygen-diffusion shielding model that incorporates pore closure and fractal characteristics and a coupled thermo-mechanical-oxidation predictive expression was developed. It accurately captures the three-dimensional dependence of degradation on temperature, pressure, and load, and successfully predicts experimental results at 1400 °C under different loading conditions.

KW - In-situ CT

KW - Oxygen-diffusion shielding

KW - Pore-closure-fractal characteristics

KW - Residual mechanical properties

KW - Thermo-mechanical-oxidation coupling

UR - https://www.scopus.com/pages/publications/105028481391

U2 - 10.1016/j.corsci.2026.113665

DO - 10.1016/j.corsci.2026.113665

M3 - Article

AN - SCOPUS:105028481391

SN - 0010-938X

VL - 262

JO - Corrosion Science

JF - Corrosion Science

M1 - 113665

ER -