ZrB₂-20SiC (ZS20) composite and its derivatives doped with 5 vol% Sc₂O₃, Y₂O₃, and La₂O₃ were densified using hot press sintering to investigate the influence of rare earth oxides on their high temperature oxidation and ablation behavior. Isothermal oxidation testing at 1773 K indicate that rare earth oxides modification lowers activation energy and slightly accelerates weight gain during the initial phase. As oxidation progresses, the weight gain of ZS20 increases sharply. The sample doped with La₂O₃ (ZS20L5) exhibits the lowest oxidation weight gain, with a porosity of only 1.8 % after oxidation. Cyclic ablation tests at the middle-low temperature zones indicate that ZS20L5 exhibits the lowest linear and mass ablation rates. Thermodynamic analyses demonstrate that La₂O₃ preferentially reacts with SiO₂ to form La₂Si₂O₇, which demonstrates a more effective oxygen barrier property compared to ZrSiO₄. Additionally, La₂O₃ enhances the fluidity of the glass phase, effectively filling cracks, sealing pores, and blocking the penetration of oxygen.

Carbon-based materials, renowned for their low density, adjustable electrical conductivity, superior corrosion resistance and mechanical properties, and have found extensive applications in the field of electromagnetic wave absorption (EMWA). Despite their merits, the current EMWA and thermal insulation capabilities are not fully optimized, thereby restricting their applications in the aerospace sector. Herein, we introduce a combinatory methodology employing electrospinning followed by pyrolysis to in-situ integrate ZrO₂ and ZrB₂ nanoparticles onto the surface of carbon nanofibers, culminating in a flexible ZrO₂/ZrB₂/C nanofiber felt. The integration of ZrO₂ and ZrB₂ nanoparticles significantly augments impedance matching and promotes multifaceted scattering and interfacial polarization. Consequently, the ZrO₂/ZrB₂/C nanofiber felt demonstrates a minimum reflection loss (RL_min) of −54 dB and the effective absorption bandwidth (EAB, RL ≤ −10 dB) is 3.1 GHz. Moreover, the three-dimensional porous architecture and the presence of multiple heterogeneous interfaces endow the ZrO₂/ZrB₂/C nanofiber felt with an ultralow thermal conductivity of 0.016 W·m⁻¹·K⁻¹ at 1100 ℃, underscoring its exceptional potential for infrared stealth. This work shows considerable guiding significance for the design of bi-functional EMWA materials with ultralow thermal conductivity in aerospace field.