Investigations on the oxidation behavior and removal mechanism of SiC/SiC composites by multi-pulse femtosecond laser ablation

SiC/SiC (SiC fiber-reinforced SiC matrix) composites have superior performance, making them promising candidates as one of the best materials for high-temperature components in aerospace applications. This investigation analyzed the morphology, structure, composition, and plasma state of multi-pulse femtosecond laser ablated SiC/SiC composites from multiple perspectives using various static and in situ characterization methods. Further, the oxidation behavior and removal mechanism of SiC/SiC composites were studied qualitatively and quantitatively. The results indicated that the ablation products of multi-pulse femtosecond laser ablation of SiC/SiC composites were mainly SiO2 and plasma deposits. The heat accumulation effect and oxidation degree at the ablation locations were enhanced accordingly as the effective ablation number or energy density increased, and the main shape of the products also changed regularly. At the same time, the material removal mechanism changed from non-thermal removal dominated to the equilibrium stage and then to thermal removal dominated. The detailed analysis of the oxidation behavior of each component in SiC/SiC composites enabled the controlled ablation of femtosecond lasers targeting the oxidation process of SiC/SiC composites. Besides, 1MPa N2 could improve the processing efficiency of femtosecond laser for the depth and width of the groove by a maximum of about 90.40% and 104.02% in this study, respectively. Ultimately, the range of laser process parameters corresponding to multi-pulse femtosecond laser ablation of SiC/SiC composites without thermal removal as dominant was determined.