Preparation method and application of modified SiCf/SiC ceramic-based composite material with SiC nanowires grown in situ

Abstract

The invention discloses a preparation method and application of a modified SiCf/SiC ceramic-based composite material with SiC nanowires grown in situ. The preparation method comprises the following steps: placing a graphite flake containing a metal coating and a carbon fiber preform into a chemical vapor deposition furnace under a non-contact condition; carrying out chemical vapor deposition to realize in-situ growth of the SiC nanowires on pores and the surface of a carbon fiber preform so as obtain a SiC fiber preform with the SiC nanowires; and carrying out chemical vapor deposition again to obtain a SiC matrix, thereby obtaining the SiC nanowire modified SiCf/SiC ceramic-based composite material. According to the invention, a metal catalyst is indirectly introduced, the metal catalyst is diffused to the surface and internal pores of the SiC fiber preform in a gas phase manner, catalyst distribution is more uniform, and the density of the SiC nanowires grown under catalysis is moderate; and the maximum crushing load of the obtained SiC nanowire-containing SiCf/SiC composite material can reach 1175.0 N, so compared with a SiC nanowire-modified SiCf/SiC ceramic-based composite material in the prior art, the crushing performance of the tubular SiCf/SiC composite material obtained by the preparation method disclosed by the invention 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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