阅读说明：本技术 一种碳纤维增强SiYOC复合材料及其制备方法 (Carbon fiber reinforced SiYOC composite material and preparation method thereof ) 是由 郭蕾 马青松 胡智瑜 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种碳纤维增强SiYOC复合材料及其制备方法,以三维碳纤维预制件为增强体,采用钇改性的硅树脂为先驱体,通过反复浸渍-固化-裂解获得C/SiYOC复合材料,该过程中以碳纤维预制件(三维编织物、毡体等)为骨架,在真空条件下浸渍Y改性的硅树脂先驱体,经热处理后使其交联固化,再进行高温裂解使先驱体转化为SiYOC陶瓷基体,经反复浸渍-固化-裂解后当本周期样品质量较上周期结束时样品质量增重不超过1％时得到C/SiYOC复合材料。本发明具有成本低廉、耐高温性能好且对设备要求低等优点,能有效提高C/SiOC复合材料的耐高温性能。(The invention discloses a carbon fiber reinforced SiYOC composite material and a preparation method thereof, wherein a three-dimensional carbon fiber prefabricated member is taken as a reinforcement body, yttrium modified silicon resin is taken as a precursor body, and the C/SiYOC composite material is obtained by repeated dipping-curing-cracking, wherein the carbon fiber prefabricated member (three-dimensional braided fabric, felt body and the like) is taken as a framework, a Y modified silicon resin precursor body is dipped under the vacuum condition, is subjected to heat treatment and then is crosslinked and cured, then high-temperature cracking is carried out to convert the precursor body into a SiYOC ceramic matrix, and the C/SiYOC composite material is obtained when the weight of a sample in the period is increased by not more than 1% compared with that of the sample at the end of the last period after repeated dipping-curing-cracking. The invention has the advantages of low cost, good high temperature resistance, low requirement on equipment and the like, and can effectively improve the high temperature resistance of the C/SiOC composite material.)

1. A preparation method of a carbon fiber reinforced SiYOC composite material is characterized by comprising the following steps: the method comprises the following steps:

1) dipping: preparing a carbon fiber prefabricated part, placing the carbon fiber prefabricated part under the vacuum condition with the pressure of less than 500Pa, and soaking the carbon fiber prefabricated part for 2-8h by using a Y-modified silicon resin precursor solution; the Y modified silicon resin precursor solution is a mixed sol of yttrium sol and silicon resin ethanol solution, wherein the yttrium sol is prepared from Y (NO)₃)₂·6H₂O in ethanol, Y (NO)₃)₂·6H₂The mass of O is 10-50% of the mass of the silicon resin, and the mass ratio of the silicon resin to the ethanol in the silicon resin ethanol solution is 2-5: 10;

2) and (3) curing: carrying out heat preservation on the carbon fiber prefabricated part soaked in the step to form gel, and then crosslinking and curing the carbon fiber prefabricated part subjected to gel at the temperature of 150-250 ℃ for 4-8 h;

3) cracking: performing pyrolysis on the carbon fiber prefabricated part subjected to crosslinking and curing in the previous step in an inert atmosphere, wherein the pyrolysis temperature is 1000-1200 ℃, and the pyrolysis time is 30-120 min;

repeating the dipping-curing-cracking cycle for multiple times until the weight of the sample is increased by no more than 1% when the cycle is finished compared with the weight of the sample when the cycle is finished, and finishing the preparation to obtain the carbon fiber reinforced SiYOC composite material.

2. The method of claim 1, wherein the carbon fiber reinforced SiYOC composite material is prepared by: the carbon fiber prefabricated part in the step 1) is one of a 2.5-dimensional braided fabric, a plain cloth laminated sewing prefabricated part, a three-dimensional needled felt, a three-dimensional four-way braided fabric, a three-dimensional five-way braided fabric or a three-dimensional six-way braided fabric.

3. The method of claim 1, wherein the carbon fiber reinforced SiYOC composite material is prepared by: the silicone resin in the step 1) is methyl silicone resin.

4. The method of claim 1, wherein the carbon fiber reinforced SiYOC composite material is prepared by: and 2) performing heat preservation on the carbon fiber prefabricated part impregnated in the step 2) to form gel, namely performing heat preservation on the carbon fiber prefabricated part impregnated in the step for 24-72 hours at the temperature of 60-80 ℃ to form gel.

5. The method of claim 1, wherein the carbon fiber reinforced SiYOC composite material is prepared by: the above dipping-curing-cracking cycle is repeated for a plurality of times, which means that the above dipping-curing-cracking cycle is repeated for 8-15 times.

6. A carbon fiber reinforced SiYOC composite material is characterized in that: obtained by a process for the preparation of a carbon fiber reinforced SiYOC composite as claimed in any one of claims 1 to 5.

Technical Field

The invention belongs to the technical field of high-temperature-resistant ceramic matrix composite materials, and particularly relates to a carbon fiber reinforced SiYOC composite material and a preparation method thereof.

Background

The rapid development in the aerospace field puts urgent demands on low cost, long service life and ultrahigh temperature of high-temperature structural materials. The carbon fiber reinforced ceramic matrix composite has excellent characteristics of high temperature resistance, high specific strength, corrosion resistance and the like, and is widely applied to surface thermal protection systems and propulsion systems of aerospace aircrafts. The carbon fiber reinforced Polysiloxane (PSO) converted SiOC (C/SiOC) composite material has the advantages of short flow, low cost and the like, and becomes a light high-temperature-resistant structural material with great application prospect.

However, because the SiOC ceramic matrix has a metastable ternary structure, phase separation and carbothermic reduction reaction can occur at high temperature, which leads to structural instability and performance reduction, and limits the high temperature resistance of the C/SiOC composite material. The structure of the ceramic matrix of SiOC converted from PSO can be modified to improve the thermal stability, wherein, the introduction of the heterogeneous element M into PSO molecules can not only give full play to the characteristics and advantages of PSO, but also uniformly regulate and control the fine structure of the ceramic matrix of SiOC on the molecular level or even the atomic level, and the applicability to the precursor impregnation cracking method for preparing the C/SiOC composite material is strong, and the high temperature resistance of the C/SiOC composite material can be improved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a carbon fiber reinforced SiYOC composite material and a preparation method thereof, namely a C/SiYOC composite material and a preparation method thereof, and the preparation method of the carbon fiber reinforced SiYOC composite material is simple in method, convenient to operate, low in cost and good in high temperature resistance. Yttrium has the characteristics of large atomic radius and long average bond path of Y-O bond, has strong oxygen affinity and is easy to form Y-O bond, Si-O-Y bond can be formed by introducing the Y-O-Y bond into SiOC ceramic to enhance the network strength of the SiOC ceramic, and Y with high melting point and without phase separation can be formed at high temperature₂SiO₅Or Y₂Si₂O₇And the high temperature resistance of the SiOC matrix and the C/SiOC composite material can be improved.

The preparation method of the carbon fiber reinforced SiYOC composite material comprises the following steps:

1) dipping: preparing a carbon fiber prefabricated part, placing the carbon fiber prefabricated part under the vacuum condition with the pressure of less than 500Pa, and soaking the carbon fiber prefabricated part for 2-8h by using a Y-modified silicon resin precursor solution;the Y modified silicon resin precursor solution is a mixed sol of yttrium sol and silicon resin ethanol solution, wherein the yttrium sol is prepared from Y (NO)₃)₂·6H₂O in ethanol, Y (NO)₃)₂·6H₂The mass of O is 10-50% of the mass of the silicon resin, and the mass ratio of the silicon resin to the ethanol in the silicon resin ethanol solution is (2-5): 10;

2) and (3) curing: carrying out heat preservation on the carbon fiber prefabricated part soaked in the step to form gel, and then crosslinking and curing the carbon fiber prefabricated part subjected to gel at the temperature of 150-250 ℃ for 4-8 h;

3) cracking: performing pyrolysis on the carbon fiber prefabricated part subjected to crosslinking and curing in the previous step in an inert atmosphere, wherein the pyrolysis temperature is 1000-1200 ℃, and the pyrolysis time is 30-120 min;

repeating the dipping-curing-cracking cycle for multiple times until the weight of the sample is increased by no more than 1% when the cycle is finished compared with the weight of the sample when the cycle is finished, and finishing the preparation to obtain the carbon fiber reinforced SiYOC composite material.

The carbon fiber prefabricated part in the step 1) is one of a 2.5-dimensional braided fabric, a plain cloth laminated sewing prefabricated part, a three-dimensional needled felt, a three-dimensional four-way braided fabric, a three-dimensional five-way braided fabric or a three-dimensional six-way braided fabric.

The silicone resin in step 1) is low molecular weight methyl silicone resin (MK), and MK is methyl silicone resin dissolved in toluene and has high SiO₂Content, after complete oxidation, 80% SiO₂Calculated as solid resin content.

And 2) performing heat preservation on the carbon fiber prefabricated part impregnated in the step 2) to form gel, namely performing heat preservation on the carbon fiber prefabricated part impregnated in the step for 24-72 hours at the temperature of 60-80 ℃ to form gel.

The above dipping-curing-cracking cycle is repeated for a plurality of times, preferably for 8 to 15 times.

The invention also relates to a carbon fiber reinforced SiYOC composite material prepared by the preparation method of the carbon fiber reinforced SiYOC composite material, under the condition of the same preparation process, the heat-resistant temperature of the C/SiYOC composite material in a low-pressure environment can be improved by more than 200 ℃ by the C/SiYOC composite material prepared by the invention, and the prepared C/SiYOC composite material has better high-temperature resistance.

Compared with the prior art, the invention has the following advantages:

1. the C/SiYOC composite material is prepared by modifying Y element, and yttrium has the characteristics of large ionic radius and long average bond path of Y-O bond, and has strong oxygen affinity and is easy to form Y-O bond. The SiOC ceramic is introduced into the SiOC ceramic, and Si-O-Y bonds are hopefully formed to enhance the network strength of the SiOC ceramic, so that the structural stability of the SiOC ceramic is improved. In high temperature environment, Y will consume O to form Y₂O₃，Y₂O₃Not only does not generate carbothermal reduction reaction with C, but also consumes SiO₂Forming Y with higher melting point and without phase separation₂SiO₅Or Y₂Si₂O₇. In addition, the micromolecular silicon resin and inorganic yttrium salt are subjected to hydrolysis-polycondensation reaction to generate a Y modified silicon resin precursor, so that the introduction amount of Y element can be increased, the gel yield is improved, the compactness of the C/SiYOC composite material is further improved, and the high temperature resistance of the C/SiYOC composite material is obviously improved while the mechanical property is not sacrificed.

2. The preparation method is simple, the operation is convenient, the cost is low, and the obtained C/SiYOC composite material can increase the long-life service temperature of the C/SiOC composite material under low pressure to more than 1500.

Drawings

FIG. 1 is a graph of load-displacement curves of the C/SiOC composite material prepared in example 1 of the present invention, which is tested for mechanical properties after heat treatment at different temperatures under low pressure conditions.

FIG. 2 is a graph of load-displacement curves for testing mechanical properties of the carbon fiber reinforced SiYOC (C/SiYOC) composite material prepared in example 1 of the present invention after heat treatment at different temperatures under low pressure conditions.

Detailed Description

The present invention is described in further detail below by way of examples, which should not be construed as limiting the invention thereto.