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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]

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]