PIP (precursor infiltration and pyrolysis) rapid densification method of SiCf/SiC composite prefab

Abstract

The invention discloses a PIP (precursor infiltration and pyrolysis) rapid densification method of a SiCf / SiC composite prefab. The method includes a step of impregnating the SiCf / SiC composite prefabinto impregnation liquid, wherein the impregnation liquid is made by uniform mixing of 200-mesh polycarbosilane and analytically pure xylene. In different stages of a densification process, impregnation liquids different in mass ratio of polycarbosilane to xylene are adopted; in a first stage of the densification process, the mass ratio of polycarbosilane to xylene in the adopted impregnation liquid is 1:5-1:4; in a second stage, the mass ratio of polycarbosilane to xylene in the adopted impregnation liquid is 3:5-2:3; in a third stage, the mass ratio of polycarbosilane to xylene in the adopted impregnation liquid is 2:5-1:2. By adoption of the method, density of the prefab reaches 2.3g / cm<3>, a preparation period is shortened by 25% or more as compared with that of a traditional PIP process, and various performance indexes of the prefab are increased.

Description

technical field [0001] The invention relates to the field of densification of composite materials, in particular to a PIP rapid densification method of a SiCf / SiC composite material prefabricated body. Background technique [0002] SiCf / SiC composite material has excellent properties such as high temperature strength, light weight, good corrosion resistance and wear resistance, and its high temperature capability will improve engine performance, thrust-to-weight ratio and fuel consumption rate, and is the first choice for high-temperature structural parts of long-life aeroengines. Ideal material. The preparation methods of matrix SiC of SiCf / SiC composite materials include chemical vapor infiltration (CVI), reactive melt infiltration (RMI), and precursor impregnation pyrolysis (PIP), but chemical vapor infiltration (CVI) exists. The long period and easy formation of closed cells on the surface of the fiber lead to low final density; the reactive melt infiltration (RMI) meth...

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Problems solved by technology

When traditional PIP impregnation cracking uses carbosilane and xylene as the impregnation solution to densify the SiC matrix of the SiC fiber preform, a fixed concentration of the impregnation solution ratio and the same process parameters are used throughout the densification process, without considering polycarbonate. The relationship between the viscosity of the impregnation solution, the filling property and the pores of the preform at different mass ratios of silane and xylene, as well as the relationship between the holding time during pyrolysis and the conversion rate of the precursor polycarbosilane, resulting in PIP The preparation cycle of dipping and cracking is long and the cost is high

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