Experimental investigation on thermal ablation of carbon-fiber/epoxy composite irradiated by continuous wave laser

Abstract

The tests of carbon-fiber/epoxy composite laminates, subjected to a tangential gas-flow and 1070 nm continuous wave laser，are carried out to acquire the ablation laws of samples on the conditions of different gas-flow. Simultaneously, considered the images from camera of large dynamic range, the damage laws of samples are also obtained for various laser power densities. Experimental results reveal that, without airflow on sample surface, the smoke caused by laser heating can be quickly on fire which causes a burn damage on the surface of samples so that the mass loss is most of all. However, the tangential airflow can remove away the smoke which has a weakening effect on the energy of incidence laser. So the ablation depth has an obvious increase in laser irradiation area. Unlike airflow, nitrogen flow can obviously restrain oxidation ablation on surface so that the ablation damage in laser irradiation area is relatively not severe. On the other hand, as laser power density increases, the mass loss of samples continues to rise but isn’t proportional. And the ablation heat with the increase of power density shows a complex change. Below power density of 390 W/cm 2 , the mass loss mainly depends on the pyrolysis of epoxy while the ablation heat has a gradual decrease. Along with power density increasing but less than 1330 W/cm 2 , the oxidation ablation of carbon fibers will be a leading factor and the ablation heat shows a little increase. Above power density of 1330 W/cm 2 , the carbon fibers turn up the phenomenon of sublimation. What’s more, airflow removed effects will be enhanced in high temperature. In this case, the ablation heat again has a trend of decrease.