The influence of heat treatment on the ablation behavior of the C/Cx-SiCy composites tested by thin-blade under oxyacetylene torch

C/Cx-SiCy composites are one of the most promising counterparts of C/C composites as they maintain the mechanical strength of C/C composites while providing excellent anti-ablation properties at the same time. This paper reports that the composites could exhibit even better anti ablation properties after heat treatment. The materials were heat-treated and then tested with a thin-blade oxyacetylene torch without the protection of any coatings. The 1600 °C heat-treated thin-blade specimen could sustain the ablation of the oxyacetylene torch with a temperature of 1776 °C (80 °C higher than the original material without heat treatment) and a lower liner ablation rate (1.31 μm/s) than the original material (1.66 μm/s). An extreme ablation test was also conducted at around 2400 °C, and the 1600 °C heat-treated specimen exhibited a lower linear ablation rate (13 μm/s) than the original specimen (47 μm/s). The influence of the heat treatment on the crystallinity of the matrix is studied with the additional help of Raman spectroscopy and XPS. The ablation mechanism is discussed in detail, and the fluent condition of the thin-blade specimen is simulated. The paper also reports a different ablation behavior of the 1600 °C heat-treated specimen from the material without heat treatment to explain their excellent ablation property.