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 comprises the following steps: (1) mixing and kneading the ceramic precursor polymer binder and penetrating agent powder to obtain (2) the sol prepared in the step (1) is coated on the surface of the C / C composite special-shaped part; (3) the C containing the sol coating prepared in the step (2) is / C Composite special-shaped parts are heated under vacuum or inert atmosphere to make the sol solidify and pyrolyze to form ceramic airgel. The infiltrating agent powder melts and fully infiltrates the special-shaped piece of C / C composite material to obtain the special-shaped piece of carbon / carbon-ceramic composite material. The method of the invention has good infiltration effect, hard coating, simple process and high utilization rate of infiltration material, and the mechanical properties of C / C composite special-shaped parts are greatly improved after being modified by the method.

Description

technical field [0001] The invention relates to the technical field of preparation of ceramic matrix composite materials, in particular to a gel infiltration ceramic modification method for special-shaped C / C composite materials. 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, etc., which are widely used in Manufacture throat liners for aero-engines and rockets, turbine blade components, space shuttle solid boosters, missile tip caps, heat exchangers, heat sinks for high-power electronics, and more. As thermal structural materials, C / C composites are generally used in high-temperature aerobic environments, but carbon materials are easily oxidized by air at higher temperatures. Studies have shown that C / C composites begin to be rapid...

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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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