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Method for enhancing density of SiC/SiC ceramic matrix composite

A composite material and ceramic-based technology, applied in the field of composite materials, can solve the problems of long densification period, failure to meet practical application requirements, and high porosity, and achieve improved densification degree, good chemical compatibility, and short densification time. Effect

Active Publication Date: 2016-01-27
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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Problems solved by technology

At present, the method is mainly divided into isothermal and isobaric chemical vapor infiltration (ICVI) and temperature and pressure gradient chemical vapor infiltration (FCVI). The former mainly relies on the diffusion of reactants along the gap to form a ceramic matrix composite due to the densification process. Therefore, the densification period is long, the efficiency is low, and it is not easy to produce thick components, and the porosity of the latter is relatively high, which cannot meet the requirements of practical applications.
[0006] The Chinese patent application number CN104177113A discloses a SiC bonded ceramic matrix composite material and its preparation method, which is characterized in that ceramic powder is used as the base material, polycarbosilane-xylene is easily used as the binder, and the molded preform is formed. Combining polymer impregnation pyrolysis (PIP) and chemical vapor infiltration (CVI) to prepare high-density ceramic matrix composites, this method does not need to add sintering aids, and the high-temperature performance of the product is good, but the mixture needs to be prepared during the preparation process. Putting it into a special mold for compression molding, this method is more suitable for preparing simple composite material structural parts, for large and complex composite material components, this method does not have good operability
[0007] In the third issue of "Journal of Inorganic Materials" published in 2008, the "CVI+PIP" method mixed process was used to prepare low-cost C / SiC composite materials. The volume shrinkage of the pyrolysis product is small, and the pyrolysis product is relatively dense. However, since Ti is used as a metal active filler (density 4.54g / cm3), adding it to the interior of the composite material will increase the weight of the material. Due to the difference in thermal expansion coefficient between the TiC formed by the reaction of carbon components and the matrix SiC, it is easy to cause cracks inside the matrix

Method used

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  • Method for enhancing density of SiC/SiC ceramic matrix composite
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  • Method for enhancing density of SiC/SiC ceramic matrix composite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Embodiment 1: SiC / SiC composite material with porosity 20% (adopt chemical vapor infiltration method to make, SEM picture is as follows figure 1 Shown) Follow the steps below to process:

[0051] (1) Grinding and polishing the surface of the composite material, ultrasonic cleaning 3 times with deionized water, about 40 minutes each time, and then drying;

[0052] (2) Mix polycarbosilane with a molecular weight of 1500-1800 and SiC powder with a particle size of 1.5 μm in a mass ratio of 6:4, and ball mill for 24 hours to make a stable slurry;

[0053] (3) Pour the slurry or organic precursor solution prepared in (2) into the dipping tank, and then put the material treated in step (1) into the dipping tank, keeping the slurry or precursor solution submerged in the material. Seal the impregnation tank, vacuumize it, and impregnate it for 30 minutes at a vacuum degree of 8KPa, so that the slurry penetrates into the internal pores of the composite material;

[0054] (4) P...

Embodiment 2

[0068] Embodiment 2: The SiC / SiC composite material with a porosity of 20% is processed according to the following steps:

[0069] (1) Grinding and polishing the surface of the composite material, ultrasonic cleaning 3 times with deionized water, about 40 minutes each time, and then drying;

[0070] (2) Mix polycarbosilane with a molecular weight of 1500-1800 and SiC powder with a particle size of 1.5 μm in a mass ratio of 6.5:3.5, and ball mill for 24 hours to make a stable slurry;

[0071] (3) Pour the slurry or organic precursor solution prepared in (2) into the dipping tank, and then put the material treated in step (1) into the dipping tank, keeping the slurry or precursor solution submerged in the material. Seal the impregnation tank, vacuumize it, and impregnate it for 30 minutes at a vacuum degree of 8KPa, so that the slurry penetrates into the internal pores of the composite material;

[0072] (4) Put the vacuum-impregnated material into a curing furnace, and raise t...

Embodiment 3

[0077] Embodiment 3: The SiC / SiC composite material with a porosity of 20% is processed according to the following steps:

[0078] (1) Grinding and polishing the surface of the composite material, ultrasonic cleaning 3 times with deionized water, about 40 minutes each time, and then drying;

[0079] (2) Mix polycarbosilane with a molecular weight of 1500-1800 and SiC powder with a particle size of 1.5 μm in a mass ratio of 7:3, and ball mill for 24 hours to make a stable slurry;

[0080](3) Pour the slurry or organic precursor solution prepared in (2) into the dipping tank, and then put the material treated in step (1) into the dipping tank, keeping the slurry or precursor solution submerged in the material. Seal the impregnation tank, vacuumize it, and impregnate it for 30 minutes at a vacuum degree of 8KPa, so that the slurry penetrates into the internal pores of the composite material;

[0081] (4) Put the vacuum-impregnated material into a curing furnace, and raise the te...

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Abstract

The invention relates to a method for enhancing density of a SiC / SiC ceramic matrix composite. The method comprises the following steps: (1) a SiC / SiC ceramic matrix composite with a certain densification degree is immersed in slurry, in which an organic precursor and SiC powder are uniformly dispersed, and impregnation is carried out in an environment of 5-10 KPa vacuum degree for 20-50 min; (2) a material which has undergone vacuum impregnation is dried and the dried material undergoes cross-linking and curing; (3) the cross-linked and cured material undergoes pyrolysis treatment; and (4) the material which has undergone pyrolysis treatment further undergoes densification process in the atmosphere of a gaseous precursor containing Si and C elements by a chemical vapor infiltration technology while infiltration temperature is 850-1100 DEG C, pressure intensity is 10-20 KPa and infiltration time is 4-30 h. The method provided by the invention has advantages of simple operation, short densification time, good repeatability and high densification efficiency and has obvious advantages in the aspect of filling material voids. The method is a method with operability and development prospect.

Description

technical field [0001] The invention relates to a method for increasing the density of SiC / SiC ceramic matrix composite materials, belonging to the field of composite materials. Background technique [0002] Continuous fiber-reinforced ceramic matrix composites currently mainly include three categories: C / C, C / SiC, and SiC / SiC, which have low density, good mechanical properties, thermal and chemical stability, and radiation resistance. Aerospace, new energy, transportation and other fields have broad application prospects. Compared with C / C and C / SiC composite materials, SiC / SiC composite materials can be used for a long time in an oxidizing atmosphere because the reinforcement used is SiC fiber, and are mostly used in high-tech fields such as aerospace, such as Thermal protection parts entering the atmosphere, oxidation-resistant parts of aero-engines, etc. However, during the use of composite materials, the porosity of the material directly determines the various propert...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565
Inventor 董绍明廖春景张翔宇高乐
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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