Localized filtrating modification for fabricating gradient composites delivering lightweight and enhanced thermal protection

Composite materials with gradient structures are ideal candidates for high-temperature thermal protection systems of aerospace vehicles due to their unique properties within distinct regions. Herein, we report a novel method of localized filtrating modification (LFM) for fabricating gradient materials, offering a lightweight design and exceptional thermal protection performance. Notably, the gradient structure results in a density reduction of 37 % and a linear ablation rate of only 1.43 µm s⁻¹ after 120 s ablation, which is 75 % lower than that of uniform composites attributed to the reduced heat accumulation at the ablation center. Additionally, the particle refinement by LFM and the self-healing effect of the oxides of (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C prevent the failure of the produced oxide barrier layer. In this work, lightweight gradient composites that can withstand elevated temperatures with excellent thermophysical properties and ablation resistance are developed, providing a universal and adaptable strategy for the design and fabrication of advanced functional gradient materials.