Yifan Fu, Xin Lin, Junjie Pan Zezhong Wang, Xilong Yu

DOI Number: N/A

Conference number: HiSST-2025-296

Carbon fiber-reinforced silicon carbide (C/SiC) composites are essential for the thermal protection systems of reusable hypersonic vehicles. Their high-temperature performance relies on a protective silica (SiO₂) layer, but this can be compromised by a sudden, hazardous increase in surface temperature, known as “temperature jump”. The complex gas-surface interaction mechanisms driving this phenomenon remain inadequately understood. This study presents an experimental investigation of the temperature jump mechanism on a C/SiC composite. Experiments were conducted in a 1.2 MW plasma wind tunnel under high-enthalpy (42.8 MJ/kg) conditions. A designed two-stage thermal loading procedure successfully induced a temperature jump from ~2000 K to ~2400 K.By employing a multi-diagnostic approach combining pyrometry, Scanning Electron Microscopy (SEM), Optical Emission Spectroscopy (OES), and quantitative Laser Absorption Spectroscopy (LAS), the gas-surface interactions were probed. The results demonstrate that the temperature jump is associated with a transition from a passive to an active oxidation regime. SEM analysis confirmed the failure of the protective SiO₂ layer, exposing the underlying material to aggressive ablation. The time-resolved LAS measurements revealed a synchronous and sharp increase in both the translational temperature and the number densities of near-body O and N atoms. This increase in reactant density is attributed to a reduced net consumption rate during active oxidation. Concurrently, OES registered a surge in emission
from reaction products (Si, CN), corroborating the shift to a vigorous ablation mode. By integrating time-resolved, quantitative measurements of reactant densities with spectral monitoring of reaction products and detailed microstructural analysis, this work offers new insights on the temperature jump phenomenon, providing valuable data to advance the understanding and predictive modeling of C/SiC materials in extreme aerothermal environments.

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In Categories: 1.Events, 1.HiSST 2025
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