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A supersonic multiphase flow was coupled with a ground simulation supersonic ablation test system to evaluate internal flow-field ablation/erosion performances of three-dimensional four-way braided carbon/carbon (C/C) composites. The results showed that the C/C composite mass and linear ablation rates were 0.0123 g/s and 0.0106 mm/s, respectively, in the supersonic inner flow-field ablation environment wherein kerosene and oxygen were completely burned. The overall material ablation was dominated by mechanical ablation accompanied by some C/CO 2 and C/H 2 O thermal oxidation ablations. With increasing oxygen enrichment, the composite mass and line ablation rates considerably increased to 0.0158 g/s and 0.0161 mm/s, respectively, in the 10%-oxygen-enriched internal flow-field ablation environment. And the composite thermal oxidation ablation was dominated by C/O 2 and supplemented by C/CO 2 and C/H 2 O reactions accompanied by rapid-airflow-induced mechanical erosion. In addition, the condensed-phase particle-induced erosion considerably reduced the C/C composite ablation resistance in the supersonic internal flow-field ablation environment. [ABSTRACT FROM AUTHOR]

In this study, C/C–SiC and C/C–SiC–ZrC composites were prepared via chemical vapor infiltration and polymer infiltration pyrolysis, and the ablation mechanism under hypersonic oxygen-rich environmental conditions was investigated. The C/C–SiC composites demonstrate an excellent ablation resistance in a hypersonic oxygen-rich environment with a relatively low temperature and speed of approximately 1800 K and 1100 m/s, respectively. It is only in the ablation center area with higher temperatures that a certain degree of thermochemical ablation was observed. The mass and linear ablation rates of C/C–SiC composites (0.027 g/s and 0.117 mm/s, respectively) showed a significant increase in a hypersonic oxygen-rich environment with a temperature and velocity of approximately 2050 K and 2000 m/s, respectively. The high-temperature ablation resistance of ZrC-modified C/C–SiC–ZrC composites improved significantly. However, the ZrC ceramic component had a considerable impact on the ablation resistance of the material. The structural integrity of C/C–20SiC–30ZrC composites was relatively high in hypersonic oxygen-rich environments with a jet temperature and velocity of 2050 K and 2000 m/s, respectively, and mass and linear ablation rates were 0.012 g/s and 0.015 mm/s, respectively. When the ZrC content increased by 40%, the ablation resistance of the composite reduced significantly, whereas the mass and linear ablation rates increased to 0.043 g/s and 0.130 mm/s, respectively. [ABSTRACT FROM AUTHOR]

A small-scale plasma ablation facility was employed to test the four-directional carbon/carbon (4D C/C) composites under high enthalpy multi-phase jet condition for ablation/erosion performance evaluation with the ablation flow field studied via computational fluid dynamics (CFD). The various ablation rates, ablation behavior and microstructure of the C/C specimens were investigated. The overall mass ablation rate was 0.05715 g·s−1 with 0.05550 mm·s−1and 0.01794 mm·s−1 axial linear ablation rate of inner and outer walls. In the radial direction, the linear ablation rates were 0.07794 and 0.00517 mm·s−1 for the inner and external diameter respectively. Ablation changes the inner wall of the annular specimen into an inverted horn shape, while the edge near the jet becomes rounded corners after the plasma procedure. The interface between the axial carbon rod and the matrix has visible ring fractures. Alumina particles are lodged in cracks and holes as a result of multiphase flow scouring. The regression rate of the composites can be considerably accelerated by particle erosion and the existence of inherent defects. The specimen ablation of top surface and inner wall is attributed to the coupling of the heterogeneous reaction and multiphase erosion. On the back wall of specimen, the regression is mainly caused by thermochemical ablation. [ABSTRACT FROM AUTHOR]

• C/C-SiC composite material thermal performance and ablation characteristicsis investigated under two heat flux conditions, 3593.54 kW·m−2 and 5644.86 kW·m−2, followed by calibration and CFD results. • The material ablation rates and back temperature curve are obtained. • The post-test ablation surface is divided into three ablation regions for analysis, compared with virgin material, as well as cross section of specimen. A small-scale plasma ablation facility was employed to test the C/C-SiC composite material for investigating the thermal performance and ablation characteristics under two heat flux conditions, 3593.54 kW·m−2 and 5644.86 kW·m−2. The morphology of post-test specimens was analyzed with the ablation rates calculated. The average mass ablation rates of two group specimens were 0.01735 and 0.10620 g·s−1 respectively with average linear ablation rate of 0.00680 and 0.09407 mm·s−1. Specimen surface could be divided into three regions with typical layered structure characteristics. For the stagnation point ablation test, the structural deformation in the ablation surface area featured in vertical layering and lateral regionality, forming an ablation pit near the stagnation point. In the center region, sublimation occured primarily, accompanied by a serious jet scouring of the molten liquid phase, as well as a small amount of oxidation reaction; Jet erosion with thermal sublimation was the main factor for the mass loss in the transitional region; Thermochemical reactions were mainly carried out in the marginal region. The SiO 2 generated from the thermochemical reaction of the material filled the interspace well and prevented the thermochemical reaction from penetrating deeper through the crack. The protective layer in the molten state with high viscosity reduced the damage of the high-speed jet impact material. [ABSTRACT FROM AUTHOR]

This study investigates the ablation resistance of C/C–SiC composites using the ground simulation internal flow‐field supersonic oxygen‐rich ablation test technology. The microstructure evolution and ablation mechanism of the composites in a supersonic oxygen‐rich environment were explored by examining the macroscopic and microscopic ablation morphologies of the composites before and after the test. The results demonstrate that C/C–SiC composites exhibit excellent ablation resistance, with mass and linear ablation rates of.46 × 10−2 g/s and.42 × 10−2 mm/s, respectively, after 120 s of ablation in a low gas temperature and high oxygen‐rich ablation thermal environment. As the gas temperature increases, the mass and linear ablation rates of C/C–SiC composites gradually increase, even though the oxygen enrichment within the gas components decreases. When the gas temperature reaches 2178–2491 K, the mass and linear ablation rates increase to 1.31 × 10−2 g/s and.84 × 10−2 mm/s, respectively. Furthermore, at high temperatures above 2650 K, the mass and linear ablation rates of the composites exhibit a geometric multiple increase, reaching 4.73 × 10−2 g/s and 1.89 × 10−2 mm/s, respectively. These findings indicate that the ablation resistance of C/C–SiC composites in the supersonic oxygen‐rich ablation environment is more sensitive to gas temperature than oxygen enrichment. The main factors contributing to the increased ablation rate of C/C–SiC composites in the supersonic oxygen‐rich ablation process include the formation of a glass SiO2 oxide film, transition to molten SiO2, erosion of molten SiO2, and high‐temperature sublimation of the SiC matrix. [ABSTRACT FROM AUTHOR]

A self-designed oxygen-kerosene ablation system was employed to research the ablation properties of silicone rubber-based insulation material under different oxygen-rich conditions, that is, 0%, 5.00%, 7.71%, 17.01%, and 18.50%. The morphology of posttest specimens was analyzed via a scanning electron microscope (SEM), and the ablation rates were calculated. Experimental results showed that when the particle concentration was a fixed value, the mass and the linear ablation rates increased first and then decreased with the rise of oxygen content; the maximum values were 0.572 g/s and 0.933 mm/s, respectively. Under high oxygen-rich conditions, the formation of silicone rubber restricted the further increase of the ablation rates, filling more gaps of the reaction layer with liquid silicone rubber. Meanwhile, the thickness of the liquid glass layer attached to the surface was increased, which acted as a buffer against the impacts and erosion of particles and retarded the consumption and recession of materials. Excess oxygen spread to the edge of the ablation pit and reacted. Finally, these led to the increase in diameter of the ablation pit and the decrease of two types of ablation rates. [ABSTRACT FROM AUTHOR]