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实验研究了靶板表面有0.4Mach(1Mach=340m/s)切向空气气流、0.4Mach切向氮气气流和无气流时,976nm连续激光对碳纤维增强E-51环氧树脂复合材料的辐照效应,得到了该材料在不同功率密度下的烧蚀规律。实验结果表明:当样品发生剧烈热分解时,随热分解气体流出边界的固体颗粒对入射激光有屏蔽作用;切向气流一方面可以减弱这种屏蔽作用,有利于辐照区的烧蚀,另一方面对样品有冷却作用,不利于烧蚀;相比于氮气流,空气流有助于产物的燃烧,对下游附近区域产生明显的加热作用;切向空气气流的加载会明显提高扩散到样品表面的氧气浓度,导致碳纤维发生氧化烧蚀;三种气流状态下,当入射激光功率密度在100～800W/cm2范围内,随着功率密度的增大,激光能量的利用效率逐渐降低。
The effects of 976nm continuous laser on the carbon fiber reinforced E-51 epoxy composites were studied experimentally when the tangential air flow of 0.4Mach (1Mach = 340m / s), the tangential flow of nitrogen of 0.4Mach and the absence of air flow were observed on the surface of the target. The ablation law of the material at different power densities was obtained. Experimental results show that when the samples undergo intense thermal decomposition, solid particles that flow out of the boundary with pyrolysis gas have a shielding effect on incident laser light. On the one hand, the tangential gas flow can weaken the shielding effect and facilitate the ablation of the irradiated area. On the one hand, the cooling effect on the sample is not conducive to ablation; compared to the nitrogen flow, the air flow is helpful to the combustion of the product, which has obvious heating effect on the area near the downstream. The tangential air flow loading can obviously increase to the sample The oxygen concentration on the surface leads to the oxidative ablation of carbon fiber. With the increase of the power density, the laser energy efficiency decreases gradually with the incident laser power density in the range of 100 ~ 800W / cm2 under the three airflow conditions.