A hierarchically toughened ultra-high temperature ceramic matrix composite inspired by leaves and its preparation method

Abstract

The invention belongs to the field of ultra-high temperature ceramic-based composite materials, and specifically relates to a graded and toughened ultra-high-temperature ceramic-based composite material inspired by leaves and a preparation method thereof. First, carbon fibers are coated with a polyethersulfone coating, and then polyether Sulfone is used as carbon source to grow silicon carbide nanowires on carbon fibers to construct primary and secondary veins; secondly, impregnate carbon fibers grown with silicon carbide nanowires into ultra-high temperature ceramic slurry containing carbon nanotubes to construct tertiary veins , and dried to obtain a pre-sintered green body; finally, a hierarchically toughened ultra-high temperature ceramic matrix composite inspired by leaves was prepared by hot pressing and sintering. The special hierarchical structure of the present invention can change the direction of crack propagation, increase the propagation path of cracks, and absorb more fracture energy through mechanisms such as pulling out, debonding, and bridging of the first-level veins, second-level veins, and third-level veins. The prepared composite material has excellent thermal shock resistance and fracture resistance.

Description

technical field [0001] The invention belongs to the field of ultra-high-temperature ceramic-based composite materials, and in particular relates to a hierarchically toughened ultra-high-temperature ceramic-based composite material inspired by leaves. Background technique [0002] Due to their excellent high-temperature mechanical properties, oxidation resistance, wear resistance, and excellent chemical stability, ultra-high temperature ceramics are expected to be used in key parts of hypersonic aircraft (such as nose cones, leading edges of wings, and belly of the fuselage) . However, it has high brittleness, is very sensitive to cracks, has low fracture toughness (2-5MPa·√m), and low thermal shock resistance (critical temperature difference is 300-500°C). In order to improve the reliability of service in extreme environments (high temperature and oxygen atmosphere), it is urgent to improve the fracture resistance and thermal shock resistance of ultra-high temperature ceram...

AI Technical Summary

Problems solved by technology

[0004] In view of the low fracture resistance and thermal shock resistance of ultra-high temperature ceramics, inspired by leaves, carbon fiber is used as the primary vein (main vein), and silicon carbide nanowires are used as the secondary vein (parallel vein). Carbon nanotubes are used as tertiary leaf veins (reticular veins), and a hierarchically toughened ultra-high temperature ceramic matrix composite inspired by leaves is prepared. Excellent fracture resistance, thermal shock resistance, and good strength, in order to achieve the purpose of the present invention, through the following technical solutions:

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