阅读说明：本技术 一种高致密度石英/石英复合材料及其制备方法 (High-density quartz/quartz composite material and preparation method thereof ) 是由 郏保琪 李�瑞 黄慧 张雄军 于 2019-09-27 设计创作，主要内容包括：本发明公开一种高致密度石英/石英复合材料及其制备方法,该制备方法包括石英纤维编织物预处理；对石英纤维编织物数次真空浸渍和微波真空干燥；陶瓷化处理,最终得到石英/石英复合材料。本发明提供的制备方法制备周期短、工艺简单易操作、成本低,适用于大厚度纤维增强二氧化硅陶瓷复合材料的制备；该制备方法制备得到的复合材料致密度高、均匀性好、力学性能优异,可应用于天线罩及其他航空航天领域。(The invention discloses a high-density quartz/quartz composite material and a preparation method thereof, wherein the preparation method comprises the steps of pretreating a quartz fiber braided fabric; carrying out vacuum impregnation and microwave vacuum drying on the quartz fiber braided fabric for several times; and performing ceramic treatment to finally obtain the quartz/quartz composite material. The preparation method provided by the invention has the advantages of short preparation period, simple process, easy operation and low cost, and is suitable for preparing the large-thickness fiber reinforced silicon dioxide ceramic composite material; the composite material prepared by the preparation method has high density, good uniformity and excellent mechanical property, and can be applied to the fields of antenna covers and other aerospace.)

1. A preparation method of a high-density quartz/quartz composite material is characterized by comprising the following steps:

s1: soaking the quartz fiber braided fabric in an organic solvent, and airing;

S2: performing vacuum impregnation and microwave vacuum drying on the quartz fiber braided fabric subjected to the step S1, and repeating the vacuum impregnation and microwave vacuum drying processes for a plurality of times;

S3: and (4) performing ceramic treatment on the quartz fiber braided fabric subjected to the step S2 to obtain a silica matrix, and finally obtaining the quartz/quartz composite material.

2. the method according to claim 1, wherein in step S1, the organic solvent is at least one of acetone, absolute ethanol and xylene.

3. The method for preparing a high-density quartz/quartz composite material according to claim 1, wherein in the step S1, the soaking time is 3-5 h, and the soaking is repeated for 3 times.

4. The method for preparing a high-density quartz/quartz composite material according to claim 1, wherein in the step S2, the vacuum-impregnated impregnant is a silica sol solution with a mass fraction of 18-30 wt%.

5. The preparation method of the high-density quartz/quartz composite material according to claim 4, wherein the vacuum impregnation time is 12-16 h, and the temperature is room temperature.

6. The method for preparing a high-density quartz/quartz composite material according to claim 1, wherein in the step S2, the microwave frequency of the microwave vacuum drying is 2.35GHz, the vacuum degree is 0.01-10000 Pa, the microwave power is 2-30 kW, the temperature is 30-100 ℃, and the time is 10-30 min.

7. The method for preparing a high-density quartz/quartz composite material according to claims 4 to 6, wherein the vacuum impregnation and microwave vacuum drying process is repeated for 3 to 6 times.

8. The method for preparing a high-density quartz/quartz composite material according to claim 1, wherein in the step S3, the ceramization treatment is carried out by raising the temperature from room temperature to 800 ℃ within 2h, and then sintering at 800 ℃ for 1-1.5 h.

9. the high-density quartz/quartz composite material is characterized in that a quartz fiber braided fabric is used as a reinforcing phase, and silicon dioxide is used as a matrix; the volume fraction of the quartz fiber braided fabric in the composite material is 40-47%; the composite material can be applied to the fields of antenna covers and other aerospace.

10. The high-density quartz/quartz composite material according to claim 9, wherein the composite material has a density of 1.60 to 1.70g/cm ³ and a bending strength of 63.0 to 72.0 MPa.

Technical Field

The invention relates to the technical field of ceramic matrix composite materials and preparation thereof, in particular to a high-density quartz/quartz composite material and a preparation method thereof.

Background

The quartz fiber reinforced quartz ceramic composite material (quartz/quartz composite material) is a composite material with a series of excellent comprehensive properties such as heat insulation, wave transmission, higher mechanical strength, lower dielectric constant and loss, impact resistance, low density and the like, is widely applied to the fields of high-temperature wave transmission, heat insulation and the like, and is a main preferred material for manufacturing the radome.

At present, the quartz/quartz composite material is mainly prepared by a sol-gel process, namely, a quartz fiber braided fabric is prepared by repeatedly dipping silica sol for many times. Because the mass fraction of the silica sol solution is generally low and the dipping efficiency is low, when the method is used for preparing the quartz/quartz composite material, the method for repeatedly dipping, gelling and ceramizing needs dozens or even dozens of dipping and drying processes, the preparation period of the material is long, and the cost is high. Particularly, after multiple times of densification impregnation, silica sol is difficult to enter the internal pores of the composite material through re-impregnation, and particularly for a quartz fiber braided fabric with a relatively large thickness (equal to or larger than 25mm), the material density is difficult to increase, so that the composite material has the defects of low density, poor uniformity, insufficient mechanical property and the like.

Disclosure of Invention

The invention provides a high-density quartz/quartz composite material and a preparation method thereof, which are used for overcoming the defects that the material density is difficult to improve for a quartz fiber braided fabric with relatively large thickness in the prior art, so that the composite material has the defects of low density, poor uniformity, insufficient mechanical property and the like, the preparation of different thicknesses of the quartz fiber braided fabric is realized, particularly the density of the composite material with large thickness of the quartz fiber braided fabric is high, and the prepared composite material has the advantages of high density, good uniformity and excellent mechanical property.

in order to achieve the purpose, the invention provides a preparation method of a high-density quartz/quartz composite material, which comprises the following steps:

S1: soaking the quartz fiber braided fabric in an organic solvent, and airing;

s2: performing vacuum impregnation and microwave vacuum drying on the quartz fiber braided fabric subjected to the step S1, and repeating the vacuum impregnation and microwave vacuum drying processes for a plurality of times;

s3: and (4) performing ceramic treatment on the quartz fiber braided fabric subjected to the step S2 to obtain a silica matrix, and finally obtaining the quartz/quartz composite material.

in order to achieve the aim, the invention also provides a high-density quartz/quartz composite material, which takes a quartz fiber braided fabric as a reinforcing phase and silicon dioxide as a matrix; the volume fraction of the quartz fiber braided fabric in the composite material is 40-47%; the composite material can be applied to the fields of antenna covers and other aerospace.

Compared with the prior art, the invention has the beneficial effects that:

1. The preparation method of the high-density quartz/quartz composite material provided by the invention comprises the following steps of firstly, soaking a quartz fiber braided fabric to remove impurities such as dust, organisms and the like on the surface of the fiber; and then carrying out vacuum impregnation and microwave vacuum drying processes on the quartz fiber braided fabric for multiple times, and finally carrying out ceramic treatment to convert the silica sol into silicon dioxide to obtain the quartz/quartz composite material. According to the preparation method provided by the invention, after the quartz fiber braided fabric is pretreated and the silica sol is subjected to vacuum impregnation, the microwave vacuum drying process is adopted for drying, through the drying process, the composite material can be rapidly and uniformly heated, and a three-dimensional uniform cell skeleton structure can be formed in the material, and the structure is beneficial to the silica sol entering the material during re-impregnation, so that the material density is further improved, the material density gradient is reduced, and the densification times can be reduced. The preparation method provided by the invention has the advantages of short preparation period, simple process, easy operation, economy and environmental protection, and is suitable for preparing the large-thickness fiber reinforced silicon dioxide ceramic composite material.

2. The composite material prepared by the preparation method provided by the invention takes quartz fiber braided fabric as a reinforcing phase and takes silicon dioxide as a matrix; the volume fraction of the quartz fiber braided fabric in the composite material is 40-47%; the composite material can be applied to the fields of antenna covers and other aerospace. Meanwhile, the composite material has high density, good uniformity and excellent mechanical property.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

fig. 1 is a flow chart of a preparation method of the high-density quartz/quartz composite material provided by the invention.

the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

the drugs/reagents used are all commercially available without specific mention.

the invention provides a preparation method of a high-density quartz/quartz composite material, which is shown in figure 1 and comprises the following steps:

S1: soaking the quartz fiber braided fabric in an organic solvent to remove impurities such as dust, organisms and the like on the surface of the quartz fiber braided fabric, and airing for later use after soaking;

The knitting mode of the quartz fiber braided fabric is 2.5D knitting or three-dimensional multi-direction knitting.

The thickness of the quartz fiber braided fabric is that the quartz fiber braided fabric is braided into a proper shape and size according to the actual use requirement.

preferably, in the step S1, the organic solvent is at least one of acetone, absolute ethanol and xylene.

Preferably, the soaking time is 3-5 h, and the soaking is repeated for 3 times to ensure that impurities such as dust and organisms on the surface of the quartz fiber braided fabric are removed completely.

S2: performing vacuum impregnation and microwave vacuum drying on the quartz fiber braided fabric subjected to the step S1, and repeating the vacuum impregnation and microwave vacuum drying processes for a plurality of times;

Preferably, the vacuum impregnation impregnant is a silica sol solution with the mass fraction of 18-30 wt%, and is preferably 22%. And injecting the silica sol solution in a vacuum injection mode. The microwave vacuum drying method is adopted to prepare the silicon dioxide matrix, and the solvent in the silica sol solution is uniformly distributed (the solvent is uniformly distributed, namely no agglomeration and precipitation exist, and serious density gradient of the prepared matrix material can not occur), so that the prepared silicon dioxide matrix is uniform, the microwave vacuum drying can complete the densification process at relatively low temperature, the quartz fiber braided fabric can be protected from being damaged, and the near-size forming advantage is achieved.

Preferably, the vacuum impregnation time is 12-16 h, preferably 16h, and the temperature is room temperature.

Preferably, the microwave frequency of the microwave vacuum drying is 2.35GHz, the vacuum degree is 0.01-10000 Pa, the microwave power is 2-30 kW, the temperature is controlled to be 30-100 ℃ by adjusting the microwave power, and the time is 20-30 min; preferably, the microwave frequency is 2.35GHz, the vacuum degree is 10-1000 Pa, the microwave power is adjusted, the temperature is controlled, and the drying is carried out for 25min under the condition of 75 ℃, so that the material is prevented from cracking.

Preferably, the vacuum impregnation and microwave vacuum drying processes are repeated for 3-6 times until weight is not increased any more. And introducing a silicon dioxide matrix into the quartz fiber braided fabric through multiple vacuum impregnation and microwave vacuum drying processes to achieve certain density, so as to form the high-density quartz fiber braided fabric reinforced-silicon dioxide ceramic composite material.

S3: and (4) performing ceramic treatment on the quartz fiber braided fabric subjected to the step S2 to obtain a silica matrix, and finally obtaining the quartz/quartz composite material.

Preferably, in the step S3, the ceramization treatment is to heat the temperature from room temperature to 800 ℃ within 2 hours, then perform heat preservation sintering at 800 ℃ for 1-1.5 hours, cool the temperature to room temperature with a furnace, and take out the temperature. The sintering temperature is set to 800 ℃, so that the damage of the high temperature to the quartz fiber braided fabric reinforcement is reduced to the maximum extent on the premise of ensuring that the generated silica ceramic matrix is generated, and the quartz fiber braided fabric reinforcement has a more obvious reinforcement effect. The temperature rise rate is increased from room temperature to 800 ℃ within 2h, the interior and the outer surface of the material are heated uniformly, and cracks caused by thermal stress are avoided.

According to the preparation method provided by the invention, after the quartz fiber braided fabric is pretreated and the silica sol is subjected to vacuum impregnation, the microwave vacuum drying process is adopted for drying, through the drying process, the composite material can be rapidly and uniformly heated, and a three-dimensional uniform cell skeleton structure can be formed in the material, and the structure is beneficial to the silica sol entering the material during re-impregnation, so that the density of the material is further improved, the density gradient of the material is reduced, the densification frequency is reduced, and the enhanced quartz/quartz composite material with uniform density is obtained. The preparation method provided by the invention has the advantages of short preparation period, simple process, easy operation, economy and environmental protection.

The invention also provides a high-density quartz/quartz composite material, which takes a quartz fiber braided fabric as a reinforcing phase and takes silicon dioxide as a matrix; the volume fraction of the quartz fiber braided fabric in the composite material is 40-47%; the composite material can be applied to the fields of antenna covers and other aerospace. A large number of tests prove that when the volume fraction of the quartz fiber braided fabric adopted by the reinforcing phase is 40-47%, the composite material has excellent mechanical strength and high temperature resistance, and can well meet the application requirements of the quartz/quartz composite material in the fields of antenna covers and other aerospace. Meanwhile, the composite material has high density, good uniformity and excellent mechanical property.

Preferably, the density of the composite material is 1.60-1.70 g/cm ³, and the bending strength is 63.0-72.0 MPa.