SiC颗粒含量对(Ti,Zr,Hf,Ta,Cr)(C,N)-SiC陶瓷力学性能及耐烧蚀性能的影响OA

Compared to conventional ultra-high temperature ceramics(UHTCs),multi-principal carbonitride UHTCs exhibit superior high-temperature stability and ablation resistance.However,the inherent brittleness of these materials poses a significant constraint on their widespread applications.To overcome this drawback,in this study,(Ti,Zr,Hf,Ta,Cr)(C,N)-SiC ceramics were fabricated by combining mechanical alloying/nitridation with spark plasma sintering through the introduction of second-phase SiC particles(SiCp)into the system,and influence of different SiCp contents on the mechanical properties and ablation resistance of the materials was systematically investigated.The results indicate that incorporation of SiCp effectively enhances the mechanical properties of the materials.When the volume fraction of SiCp reaches 20%,the fracture toughness achieves(5.18±0.24)MPa·m1/2,representing a substantial enhancement of 31.5%compared to the(Ti,Zr,Hf,Ta,Cr)(C,N)ceramic.This improvement in fracture toughness can be attributed to toughening mechanisms,including crack deflection and branching,owing to the introduction of SiCp.Further oxygen-acetylene ablation tests at 2100℃for 120 s demonstrate that incorporation of SiCp also significantly enhances the ablation resistance of the material.The optimal performance is achieved at a SiCp volume fraction of 20%,with a mass ablation of-0.92 mg/s and a linear ablation of-1.17 μm/s,outperforming most reported conventional UHTCs.The enhancement in ablation resistance can be attributed to the pinning effect exerted by a high-melting-point multicomponent oxide skeleton on the low-melting-point SiO2 phase,as well as the synergistic formation of a multicomponent dense oxide barrier that effectively suppresses oxygen diffusion.This work presents a strategy to resolve the intrinsic brittleness of multi-principal carbonitride UHTCs through the optimal incorporation of SiCp,which concurrently improves the mechanical properties and ablation resistance.These results provide a theoretical foundation and experimental data for the design of advanced thermal protection materials.