A gel infiltration ceramic modification method for special-shaped parts of c/c composite materials

Abstract

The invention discloses a gel infiltration ceramic modification method for C / C composite special-shaped parts, which includes the following steps: (1) Mix and knead ceramic precursor polymer binder and infiltration agent powder to obtain The sol in which the penetrant powder is evenly dispersed; (2) Coat the sol prepared in step (1) on the surface of the C / C composite special-shaped parts; (3) Apply the C containing sol coating prepared in step (2) / C composite special-shaped parts are heated under vacuum or in an inert atmosphere to solidify the sol and pyrolyze it to form a ceramic aerogel. After the temperature reaches 40 to 100°C above the melting point of the penetrant powder, the heat is maintained to make the gel in The infiltration agent powder is melted and fully infiltrated into C / C composite special-shaped parts to obtain carbon / carbon-ceramic composite special-shaped parts. The method of the present invention has good infiltration effect, the coating is not easy to fall off, the process is simple, and the utilization rate of infiltration materials is high. The mechanical properties of C / C composite special-shaped parts are greatly improved after being modified by this method.

Description

Technical field [0001] The invention relates to the technical field of ceramic matrix composite material preparation, and in particular to a gel infiltration ceramic modification method for C / C composite special-shaped parts. Background technique [0002] C / C composite materials have a series of excellent properties such as high specific strength, high specific modulus and fracture toughness, superior ablation resistance, excellent friction and wear properties, thermal shock resistance and good chemical stability. They are widely used in Manufacturing of throat liners for aero engines and rockets, turbine blade components, space shuttle solid boosters, missile end caps, heat exchangers, heat sinks for high-power electronic devices, etc. As thermal structural materials, C / C composite materials are generally used in high-temperature aerobic environments. However, carbon materials are easily oxidized by air at higher temperatures. Research shows that C / C composite materials be...

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Problems solved by technology

However, it needs to be pointed out that many C / C composites that need to be modified are not regular structures, but special-shaped parts with complex structures, such as rocket engine nozzles

The traditional RMI method has certain defects in the ceramic modification of such C / C composite materials: first, the infiltrant block or powder cannot be placed evenly on the special-shaped C / C composite material, and the carbon / carbon obtained after RMI -The texture of the ceramic composite is uneven, which may lead to a decrease in its ablation resistance and mechanical properties, which affects the reliability of the material; second, in order to obtain a carbon / carbon-ceramic composite with a uniform structure, if the C / C composite Too much infiltration agent on the special-shaped parts may cause the carbon fiber in the composite material to be ceramicized, which will cause the C / C composite special-shaped parts to become brittle and deteriorate their mechanical properties; third, the traditional RMI method is difficult to be able to C / C Partial ceramic modification of C composite materials; finally, too much infiltration agent leads to waste of raw materials and may also cause irreversible pollution to the high-temperature sintering furnace, affecting the service life of the high-temperature sintering furnace

However, this method is not only cumbersome, but also only suitable for workpieces with a small angle between the coating and the horizontal plane during the sintering process, otherwise the coating will easily fall off on the composite material during the process, and the surface morphology of special-shaped parts is often varied , so the use of this method has great limitations; and in the process of infiltration, the infiltration agent preferentially reacts with epoxy resin pyrolytic carbon to form a ceramic layer, which not only leads to the loss of infiltration raw materials, but also needs to be further removed in the subsequent process The ceramic layer formed on the surface of the composite material hinders the flow of the infiltration agent melt during infiltration, resulting in the inability of the infiltration reaction to continue

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