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通过Nd∶YAG激光辐照碳纤维/环氧树脂复合材料过程的高速摄像观测,得到了不同辐照功率密度下烧蚀过程中的主要现象。发现在低功率密度(50 W/cm2)下,主要是表面烧蚀机制,不会发生燃烧现象,在长时间辐照下,由于表层附近出现轻微的聚合物焦化分解,表面层出现粉末状和漂絮状的碳粉缓缓弥散空气中;在中等功率密度(300 W/cm2)下,体烧蚀机制占主要地位,内层分解气体喷出,在空气中点燃引起表面燃烧,主要燃烧表面聚合物;在高功率密度(4500 W/cm2)下是以表面烧蚀为主的质量迁移机制,在极短的时间(0.001 s)内表面层被破坏,瞬间燃烧,光斑中心出现喷射式的气化等离子体现象,并出现逐层烧蚀和各向异性热传导引起的烧蚀区形貌变形等现象。
The main phenomena of ablation process under different irradiation power densities were obtained by high-speed camera observation of Nd:YAG laser irradiated carbon fiber / epoxy composites. It has been found that at low power density (50 W / cm 2), the surface ablation mechanism is predominantly absent, and combustion does not occur. Under long-term irradiation, due to the slight coking decomposition of the polymer near the surface layer, The flocculent carbon powder diffuses slowly in the air. At medium power density (300 W / cm2), the bulk ablation mechanism is dominant, the inner decomposition gas is ejected and ignited in air to cause surface combustion. The main combustion surface Polymer is a mass transfer mechanism dominated by surface ablation at high power density (4500 W / cm 2). In a very short period of time (0.001 s), the surface layer is destroyed and burns instantaneously, and a jet-type Gasification plasma phenomenon, and there layer by layer ablation and anisotropic heat conduction caused by the morphological deformation of the ablation zone and so on.