A kind of in situ growth SiC nanowire modified SiC f Preparation method and application of /sic ceramic matrix composite material

Abstract

The invention discloses an in-situ growth SiC nanowire modified SiC f The preparation method and application of SiC ceramic matrix composite materials, the preparation method is to place the graphite sheet containing metal coating and the carbon fiber preform together in a chemical vapor deposition furnace without contact, and deposit it on the carbon fiber preform by chemical vapor deposition In-situ growth of SiC nanowires on the pores and surfaces to obtain SiC fiber preforms with SiC nanowires, and then obtain SiC matrix by chemical vapor deposition, that is, SiC nanowires modified SiC f / SiC ceramic matrix composite material, the present invention introduces the metal catalyst indirectly, and the metal catalyst diffuses to the surface and internal pores of the SiC fiber preform in the gas phase, the catalyst distribution is more uniform, and the SiC nanowire density of the catalyzed growth is moderate. The resulting SiC nanowire-containing SiC f / SiC composite material, the maximum crushing load can reach 1175.0N, and SiC nanowire modified SiC in the prior art f Compared with the SiC ceramic matrix composite material, the obtained tubular SiC of the present invention f The crush performance of / SiC composite material is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of preparation of ceramic matrix composite materials, and in particular relates to an in-situ grown SiC nanowire modified SiC f Preparation method and application of SiC ceramic matrix composites. Background technique [0002] Silicon carbide fiber reinforced silicon carbide matrix composites (SiC f / SiC) has the advantages of high strength, high thermal conductivity, small thermal expansion coefficient, small neutron absorption cross section, good radiation resistance, and low reaction rate with water to form hydrogen. It has great application potential in new nuclear fuel cladding materials and aerospace fields. It has attracted extensive attention from researchers all over the world, but as a ceramic matrix composite material, its inherent brittleness limits the application of this material in many high-end fields. In order to solve this problem, the second phase reinforcement material with excellent m...

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Problems solved by technology

There is no metal catalyst residue on the top of the nanowire grown by the catalyst-free process, but the growth of the nanowire is difficult and the preparation efficiency is relatively low

Although the method of introducing metal catalysts has many advantages, it also has many disadvantages: 1) the metal catalyst remains on the top of the growing nanowires, resulting in a decrease in the purity of the nanowires; Densification; 3) It is difficult to control the metal catalyst, too much metal catalyst remaining inside and on the surface of the composite material will reduce the performance of the material

[0005] Due to the above reasons, when the catalyst-free process is used to grow nanowires, the higher reaction temperature will reduce the mechanical properties of SiC fibers, and when the growth of SiC nanowires is insufficient, its effect on the strengthening and toughening of composite materials is not obvious; when When using the method of directly introducing metal catalysts to grow SiC nanowires in situ, due to the excessive growth of SiC nanowires and excessive metal catalyst residues, defects such as closed pores will be caused in the subsequent densification process, which will reduce the mechanical properties of the composite material.

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