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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 Composite coatings consisting of flake graphite and SiO 2 fillers in a hyperbranched polycarbosilane (HBPCS) matrix were designed and prepared to meet the requirements of laser protection. The laser ablation behavior of the composite coatings were investigated. Control experiments were designed to study the performance of SiO 2 during laser irradiation. The results show that the introduction of SiO 2 changes the anti-laser protective mechanism and can improve the anti-laser property of the coating. High power laser irradiation results in pyrolysis of HBPCS and the formation of SiC particles. Chemical reactions between SiO 2 , graphite, and SiC play an important role in consuming energy, and provide an excellent cooling effect to the substrate, leading to decreased temperature. SiC particles formed on the surface of the laser ablation area act as a shield to prevent the laser from irradiating deeper layers of the coating. Due to the cooling effect and thermal stability of SiC, the proposed coating shows a good anti-laser property. [ABSTRACT FROM AUTHOR]