Three-dimensional fiber prefabricated-part enhancement mullite composite and preparation method thereof

Abstract

The invention discloses a three-dimensional fiber prefabricated-part enhancement mullite composite and a preparation method thereof. The preparation method comprises impregnating three-dimensional fiber prefabricated parts in an A1203-SiO2 composite sol to be impregnated, dried and subjected to low-temperature thermal processing to obtain the A1203-SiO2 impregnated three-dimensional fiber prefabricated parts; repeating the process till the weight gaining of the A1203-SiO2 impregnated three-dimensional fiber prefabricated parts is lower than 1% to obtain three-dimensional fiber prefabricated-part first intermediates, performing medium-temperature thermal processing, subjecting the medium-temperature thermal processed three-dimensional fiber prefabricated-part first intermediates to impregnation, high-pressure processing, drying, low-temperature thermal processing and medium-temperature thermal processing, circulation the process till the weight gaining is lower than 1%, and performing high-temperature thermal treatment. According to the composite and the preparation method thereof, by three-stage thermal treatment, the compactness of the three-dimensional fiber prefabricated-part enhancement mullite can be further improved, and the mechanical performance and the oxidation resistance of the enhancement composite are enhanced.

Description

technical field [0001] The invention relates to the technical field of high temperature resistant fiber reinforced ceramic matrix composite materials, in particular to a three-dimensional fiber preform reinforced mullite composite material and a preparation method thereof. Background technique [0002] Mullite ceramics are made of Al 2 o 3 , SiO 2 The two-phase solid solution composed of it has low density, small thermal expansion coefficient, low thermal conductivity, good high temperature stability, and natural excellent oxidation resistance. In addition, as a high-temperature structural ceramic, the biggest feature of mullite is that its strength and toughness at 1300°C are 1.7 times that of room temperature, and its strength can still reach 90% of room temperature at 1500°C. It can also maintain good chemical stability and creep resistance. Therefore, in addition to being widely used as refractory materials for civil industrial kilns and high-temperature engineering ...

AI Technical Summary

Problems solved by technology

However, since the heat treatment temperature is only 1100-1200 °C, the degree of conversion of the sol to mullite is low, and the matrix composition is mainly loose and porous Al 2 o 3 -SiO 2 , resulting in unsatisfactory oxidation resistance of composite materials. After oxidation in air at 1300°C for 30 minutes, the maximum strength retention rate is only 80% (see Liu Haitao, Ma Qingsong, Xu Tianheng, Chen Shugang, Chen Chaohui, a three-dimensional carbon fiber fabric reinforced mullite Ceramics and their preparation methods, patent number: ZL201110086419.X, certificate number: No. 1131807; Liu Haitao, Ma Qingsong, Chen Shugang, Xu Tianheng, Chen Chaohui, a preparation method of three-dimensional carbon fiber fabric reinforced mullite ceramics, patent number: ZL201110086408 .1, certificate number: No. 1217697)

Based on the work of Liu Haitao, Dai Kewei increased the heat treatment temperature to 1400°C to obtain a dense matrix completely transformed into mullite, which significantly improved the oxidation resistance of the composite material, but found that each cycle was at 1400°C Heat treatment can easily lead to a high content of closed cells in the matrix, which is not conducive to the penetration of sol in subsequent cycles. After 18 cycles of "dipping-drying-heat treatment", the porosity of the composite material is 21-26%, and the bending strength is only 240MPa ( See Dai Kewei, Preparation and Properties of Mullite-Based Composite Materials Reinforced by Three-Dimensional Braided Carbon Fibers, Master Thesis of National University of Defense Technology, 2013)

[0007] Therefore, with high solid content Al 2 o 3 -SiO 2 Composite sol is used as raw material, and mullite composite materials reinforced with fiber three-dimensional preforms can be efficiently prepared by liquid phase method, but the porosity still needs to be further reduced to improve mechanical properties and oxidation resistance

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