Preparation method of carbon nanotube toughened silicon carbide ceramic

Abstract

The invention discloses a preparation method of carbon nanotube toughened silicon carbide ceramic, and belongs to the technical field of composite ceramic materials. The preparation method of the carbon nanotube toughened silicon carbide ceramic comprises the following steps: S1, uniformly mixing silicon carbide, carbon black, silicon nitride coated carbon nanotubes, water-soluble phenolic resin and pure water to obtain uniformly dispersed slurry with the solid content of 48-52%; S2, heating the slurry obtained in the step S1, evaporating to remove water to obtain a blocky material, carrying out dry pressing on the blocky material, and carrying out one-step molding to obtain a green body; S3, covering the surface of the green body with monatomic silicon, putting the green body into a vacuum high-pressure sintering furnace, heating to 1300-1400 DEG C, keeping the temperature for a certain period of time, and converting amorphous silicon nitride on the surface of the carbon nano tubes into hexagonal silicon nitride; and heating up to 1450-1500DEG C, and keeping the temperature for a certain period of time to obtain the carbon nanotube toughened silicon carbide ceramic; the fiber structure of the carbon nanotubes can be reserved in the reaction sintering process, the toughening effect of carbon fiber is fully exerted, and the performance of the composite ceramic material is enhanced.

Description

technical field [0001] The invention relates to a technology in the field of composite ceramic materials, in particular to a preparation method of carbon nanotube toughened silicon carbide ceramics. Background technique [0002] Silicon carbide is a crystalline substance with a diamond structure formed by the covalent bonding of carbon and silicon elements. It has many excellent properties, such as high hardness, high temperature resistance, corrosion resistance, high thermal conductivity, etc., and is used in corrosion, high temperature and aerospace. It has very superior performance under extreme conditions, so silicon carbide has become a widely used non-oxide ceramic material. [0003] Reaction sintering is the most common method for the preparation of silicon carbide ceramics. Silicon infiltrates into the green body containing silicon carbide and carbon black at high temperature, and reacts with carbon to form silicon carbide. This newly formed silicon carbide is combi...

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Problems solved by technology

However, reaction sintered silicon carbide ceramics contain a certain amount of free silicon, resulting in increased brittleness of silicon carbide ceramics.

In order to overcome the above defects, it is theoretically possible to add carbon fiber to the raw material, but it was not found that adding carbon fiber can improve the toughness of silicon carbide ceramics, because the carbon fiber reacts with liquid silicon to form silicon carbide during the reaction sintering process.

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