Green aqueous coordination chemistry enables size-programmable zirconium carbide powders and high-performance ultra-high-temperature composites

This work reports a green, low-temperature and all-aqueous strategy for synthesizing high-purity zirconium carbide powders with precisely controllable particle sizes. Common sugar molecules serve as a sustainable carbon source, forming a zirconium–glucose coordination precursor. This molecular-level pre-organization facilitates efficient carbothermal conversion, enabling phase-pure ZrC to be obtained at 1400℃. By regulating the hydrothermal conditions, the particle size of ZrC can be continuously tailored from 70 nm to 1 µm. The resulting size-designable powders are further assembled into a micro–nano binary graded system and utilized to carbon-fiber-reinforced ZrC-SiC composites. Despite a low density of 2.41 g/cm³, the composites exhibit a flexural strength exceeding 380 MPa and a fracture toughness of 14.63 MPa·m^1/2, demonstrating excellent ablation resistance under oxyacetylene flame ablation at 1850℃. These results reveal an unconventional pathway that integrates sugar-derived aqueous coordination chemistry with ultra-high-temperature ceramic manufacturing, providing a novel approach for producing high-performance ZrC powders and extreme-environment structural composites.