Method for preparing thick-walled ceramic-matrix composite material through mechanical processing assisted CVI (Chemical Vapor Infiltration)

Abstract

The invention relates to a method for preparing ceramic-matrix composite material thick-walled parts (thickness is not smaller than 5mm) by a mechanical processing assisted CVI (Chemical Vapor Infiltration) method. The method comprises the following steps: carrying out interface layer deposition on a preform in a graphite furnace; carrying out densification treatment on the preform by a CVI method, and taking out the preform after the relative density of the preform reaches 20% to 65%; carrying out micropore processing on the preform by using a mechanical processing method, so as to dredge a transmission channel for a gaseous precursor; and carrying out cyclic deposition, thereby obtaining a ceramic-matrix composite material. The method has the advantages that the intrinsic pore structure of the preform is improved, the density gradient of the composite material is lowered, and the problem that the density of the ceramic-matrix composite material thick-walled parts (thickness is not smaller than 5mm) is uneven is effectively solved; the overall mechanical properties of the composite material are improved; and the speed of densification is increased, and the preparation cycle is shortened.

Description

technical field [0001] The invention belongs to the field of CVI preparation of ceramic matrix composite materials, and in particular relates to a method for preparing thick-walled ceramic matrix composite materials with mechanical processing assisted CVI. The gaseous precursor diffusion channel inside the preform enables the formation of multi-scale mass transfer channels in the porous body: intra-bundle holes, inter-bundle holes and processing holes, thereby improving the compactness and density of ceramic matrix composite thick-walled parts (≥5mm). Density uniformity to achieve high density and high strength preparation of ceramic matrix composites. Background technique [0002] Ceramic matrix composites can meet the requirements of long life below 1650°C, limited life below 20000°C, and instantaneous life below 2800°C. Thermal systems, cruise missile engines, liquid and solid rocket engines and other weapons and equipment fields have broad prospects for promotion and ap...

AI Technical Summary

Problems solved by technology

In US Patent 4580524, the FCVI method is used to prepare ceramic matrix composites, which can effectively shorten the densification process and improve the density uniformity. However, the heating of each area in the preform mainly depends on heat conduction, resulting in insufficient densification of the cold surface of the preform.

In the German patent DE4142261, the isothermal pressure gradient CVI process is used to prepare porous structure composite materials, which effectively improves the gas transmission capacity, but there is still the problem of uneven densification

Literature "MicrowaveHeatedChemicalVaporInfiltration: DensificationMechanismofSiC f / SiCComposites.DavidJaglin, JonBinner, andBalaVaidhyanathan.TheAmericanCeramicSociety, 2006,9:2710-2717"proposed the use of microwave pyrolysis to densify SiC f / SiC composite material, this process can make the average density of the composite material reach 50%, and the center density of the composite material reach 73% within 24 hours, speed up the densification rate of the prefabricated body, and improve the density uniformity, but the process is harmful to the equipment The requirements are relatively high, and it is still in the experimental stage

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