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C/SiC composite has been widely used as a high‐temperature material for engineering components due to its excellent thermal properties. Facing the rapid development and threat of high‐energy laser, study on the ablation resistance under laser irradiation is strongly required. In this work, a continuous high‐energy laser was applied to explore the laser ablation behavior and mechanism of C/SiC composite. From the results, C/SiC composite shows different morphologies when irradiated at various laser power densities for 500 and 700 W/cm2. We divided the ablation area into three regions; the central, transition, and edge regions, where the formation of SiO2, SiO, and the breakage of carbon fiber were observed. The generated highly reflective SiO2 layer reduces the absorption of laser energy, which is beneficial to lower the back‐surface temperature and reduce the damage of composite. In addition, we put forward the ablation physical models and ablation mechanisms irradiated at different power densities. The work provides a basis for the laser ablation resistance of C/SiC composites under different conditions. [ABSTRACT FROM AUTHOR]

Graphite and SiO 2 composite was prepared by hot-pressing at 1300 °C for 3 h under a uniaxial load of 20 MPa. The ablation behavior of graphite and SiO 2 composite by high-intensity continuous laser was investigated. The X-ray diffraction, scanning electron microscopy, 3D-super-depth-digital microscopy, Raman spectroscopy and reflectivity were used to characterize the sample. The results show that under low laser power (500 W/cm 2 ), and no obvious damage appears, while just the irradiation area changes from grey to white and the reflectivity increases. With the laser power increasing, some heat-absorbing chemical reactions between graphite and SiO 2 occurred on the surface, and SiC was produced, which can increase the energy consumption of the surface and thus reduce the absorbed laser energy of the interior. Moreover, at the center of irradiation area, the formation of columnar structure graphite is beneficial to obstruct laser energy conduction from surface to interior material. [ABSTRACT FROM AUTHOR]

Abstract: Ultra high temperature ceramics (UHTCs) based composite ZrB2/20vol.% Cu was prepared by spark plasma sintering (SPS) at 1650C° for 3min. The ablation behavior of composite irradiated for 2–20s by 20MW/m2 high-intensity continuous laser was investigated. The phase and microstructure evolution of ZrB2/20vol.% Cu during ablation was demonstrated by XRD and SEM, respectively. The results reveal that no macroscopic damage but only one ablated layer with 40μm in thickness is observed even after being ablated for 20s. It implies that ZrB2/20vol.% Cu composite exhibits good ablation resistance against high-intensity continuous laser. The continuous Cu in composite evaporates preferentially, which impacts on the following ablation behavior. The generated ZrO2 at the spot center shows different forms such as closely packed nano-ZrO2, micron ZrO2 or melting ZrO2 for different ablation time. The melting ZrO2 is helpful to promote the ablation resistance of ZrB2/20vol.% Cu. [Copyright &y& Elsevier]