Heat transfer mechanism of fiber reinforced composites processed by pulsed laser

Abstract

The generate principle and suppression method of thermal effect of silicon carbide fiber reinforced silicon carbide (SiC/SiC) in processing of nanosecond lasers with infrared band (fiber laser with maximum power of 20 W), visible light band (solid-state laser with maximum power of 4 W) and ultraviolet band (fiber laser with maximum power of 7 W) were studied. Firstly, the three-dimensional temperature field model was established to simulate the ablation process of SiC/SiC composites by pulsed laser. It was found that the SiC fiber bundle has a great influence on the energy distribution acting on the SiC/SiC composites, and the heat tends to transfer along the longitudinal direction of the fiber bundle. Secondly, nanosecond lasers with wavelengths of 1064, 532, and 355 nm were used for processing experiments in air and water environments respectively. The scanning power was set to 1.5–3 W, and the morphology quality of the microstructure after processing was analyzed. The results showed that: As the wavelength increases, the energy value of the pulsed laser increases, the oxidation and melt accumulation are more obvious, and the heat affected zone (HAZ) is larger. Besides that, the water solution can take away part of the heat and debris during the processing, reduce the accumulation of the melt, effectively avoid the processing damage caused by the thermal effect, and improve the quality of the microstructure.