Ablation mechanisms of bulk Nb4AlC3 ceramics at 1600–2200 °C in nitrogen plasma flame

Abstract

MAX phase ceramics are promising thermal protection materials due to their excellent anti-oxidation and ablation resistance. This paper systematically investigates the ablation behaviors of Nb₄AlC₃ ceramics in nitrogen plasma flames at 1600–2200 °C. By analyzing changes in ablation rate, microstructure, and elemental composition of the surface and cross-section, the ablation evolution mechanism of Nb₄AlC₃ ceramics is elucidated. As the ablation temperature increased from 1600 °C to 2200 °C, the linear ablation rate increased from 4.17 to 12.8 μm/s, while the mass ablation rate increased from −4.12 to 22 mg/s. The surface of the ablated Nb₄AlC₃ underwent decomposition and oxidation reactions, forming oxides (NbO₂, Nb₂O₅, and Al₂O₃) on the surface. Simultaneously, NbO₂ reacted with Al₂O₃ to form molten AlNbO₄, which adhered to the surface and provided protection to the substrate. With increasing ablation temperature, O atoms continuously diffused into the matrix, resulting in a higher O content in the near-subsurface area. These findings indicate that Nb₄AlC₃ ceramics can withstand plasma flame erosion up to 2200 °C, exhibiting excellent ablation resistance. Therefore, Nb₄AlC₃ ceramics have significant potential as thermal protection materials.