CN115745642A

CN115745642A - Chopped fiber reinforced boron carbide ceramic sheet and preparation method and application thereof

Info

Publication number: CN115745642A
Application number: CN202211459048.XA
Authority: CN
Inventors: 张玉娣; 何维; 刘金水
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2022-11-21
Filing date: 2022-11-21
Publication date: 2023-03-07
Anticipated expiration: 2042-11-21
Also published as: CN115745642B

Abstract

The invention discloses a chopped fiber reinforced boron carbide ceramic sheet and a preparation method and application thereof. The preparation method can keep the integrity of the length of the chopped fiber in the final material so as to ensure the reinforcing and toughening effects.

Description

Chopped fiber reinforced boron carbide ceramic sheet and preparation method and application thereof

Technical Field

The invention relates to the technical field of ceramic sheets, in particular to a chopped fiber reinforced boron carbide ceramic sheet and a preparation method and application thereof.

Background

Boron carbide has low density, high modulus and high hardness, making it a major material for military armor and space applications. The single-phase boron carbide ceramic has low fracture toughness and poor external impact load resistance, and the exertion of the anti-elasticity performance is limited. The carbon fiber has comprehensive properties of high temperature resistance, low density, high strength and the like, and compared with boron carbide unidirectional ceramic, the boron carbide composite material prepared by using the carbon fiber as the reinforcing fiber has the advantages of high strength, high toughness, high hardness, good impact resistance and the like, and can improve the multi-strike resistance of the bulletproof material and the bulletproof performance of the bulletproof plate.

The existing short fiber reinforced boron carbide ceramic material is mostly prepared by mixing and ball-milling short carbon fibers, boron carbide powder and a corresponding dispersant, and then adopting a hot pressing or reaction sintering process, the short carbon fibers in the prepared composite material have large fiber damage due to the ball-milling, hot pressing and other processes, the fiber retention length in the composite material is only 50-250 microns, and the reinforcing and toughening effects of the composite material are obviously reduced.

Disclosure of Invention

The invention provides a chopped fiber reinforced boron carbide ceramic sheet and a preparation method and application thereof, which are used for overcoming the defects of poor reinforcing and toughening effects and the like caused by the fact that the length of fibers is damaged in the prior art.

In order to achieve the purpose, the invention provides a preparation method of a chopped fiber reinforced boron carbide ceramic sheet, which is characterized by comprising the following steps of:

s1: weighing the chopped fibers and the mixed solution I according to the mass ratio of 1; the mixed solution I is 0.5-2% of polyacrylamide aqueous solution or hydroxymethyl cellulose sodium aqueous solution; the two dispersants are soluble in water, and are economical and environment-friendly; in addition, the aqueous solutions of the two dispersants with low concentrations have high viscosity, can well disperse fibers, and are not easy to settle for a long time. When the concentration of the solution is too low, the viscosity is correspondingly reduced, and the fiber is easy to settle; too high concentration, large viscosity, poor fiber dispersion effect and easy agglomeration.

S2: weighing boron carbide powder and the mixed solution II according to the mass ratio of 1:5-1, and uniformly mixing to obtain slurry B; the mixed solution II is 0.5-2% of polyacrylamide aqueous solution or hydroxymethyl cellulose sodium aqueous solution; the two dispersants are soluble in water, economic and environment-friendly, and in addition, the low-concentration aqueous solutions of the two dispersants have higher viscosity, can well disperse powder and are not easy to settle for a long time. When the concentration of the solution is too low, the viscosity is correspondingly reduced, and the fiber is easy to settle; too high concentration, large viscosity, poor fiber dispersion effect and easy agglomeration.

S3: mixing the slurry A and the slurry B, and stirring to obtain mixed slurry;

s4: pouring the mixed slurry into a container with a flat bottom surface, placing the container on a vibration table, and vibrating for 10-30 min to uniformly spread the mixed slurry at the bottom of the container;

s5: the container is put into a drying oven to be dried for 4 to 8 hours at the low temperature of between 60 and 80 ℃, and then is continuously heated to between 120 and 150 ℃ to be dried for 2 to 4 hours, so as to obtain the chopped fiber reinforced boron carbide ceramic sheet _， The thickness of the sheet is controlled to be 0.5-2mm by controlling the mass of the slurry per unit area.

Preferably, in step S1, the chopped fibers are one of carbon fibers, silicon carbide fibers and alumina fibers.

Preferably, in step S1, the chopped fibers have a length of 1 to 6mm.

Preferably, in step S1, the blending specifically comprises: the mixing mode of mechanical stirring and ultrasonic vibration is adopted, the mechanical stirring rotating speed is 600-1000rpm, the frequency of the ultrasonic vibration is 25-40KHz, and the time is 30-120 min.

Preferably, in step S2, the particle size of the boron carbide powder is 1 to 5 micrometers.

Preferably, in step S2, the blending manner specifically includes: the mixing mode of mechanical stirring and ultrasonic vibration is adopted, the mechanical stirring rotating speed is 600-1000rpm, the frequency of the ultrasonic vibration is 25-40KHz, and the time is 30-60 min.

Preferably, in step S3, the rotation speed of the stirring is 600-1000rpm, and the time is 10-60 min.

Preferably, in step S4, the frequency is 10-50Hz, the amplitude is 0.5-2mm, and the vibration time is 10-30 min.

In order to achieve the purpose, the invention also provides a chopped fiber reinforced boron carbide ceramic sheet prepared by the preparation method.

In order to achieve the purpose, the invention also provides an application of the chopped fiber reinforced boron carbide ceramic sheet, and the boron carbide ceramic sheet prepared by the preparation method or the boron carbide ceramic sheet is applied to a chopped carbon fiber reinforced boron carbide composite material, and can also be combined with a long fiber ceramic sheet to prepare a long and short fiber combined reinforced ceramic matrix composite material.

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

the preparation method of the chopped fiber reinforced boron carbide ceramic sheet provided by the invention adopts polyacrylamide or sodium hydroxymethyl cellulose as a dispersing agent, respectively and independently disperses chopped fibers and boron carbide powder, then the dispersing liquid of the chopped fibers and the boron carbide powder is mixed and stirred to form mixed slurry containing the chopped fibers and the boron carbide powder, the mixed slurry is poured into a container with a flat bottom surface, and then the slurry is spread and dried by adopting a vibration mode to obtain the chopped fiber reinforced boron carbide ceramic sheet. The invention adopts the combined mode of mechanical stirring and ultrasonic vibration to solve the problem of uniform dispersion of fibers and powder, the damage to the fibers in the dispersion process is smaller, compared with the traditional granulation, screening or ball milling dispersion process of the short fiber reinforced ceramic matrix composite, the invention keeps the length integrity of the short fiber, improves the toughening effect of the fibers in the material, and simultaneously, the slurry is quickly and uniformly spread and dried by the vibration mode to prepare the carbon fiber ceramic into a ceramic chip instead of directly preparing the ceramic chip into a block, thereby being beneficial to the preparation of short fiber reinforced boron carbide composite materials with different specifications and sizes, and simultaneously, the invention can also be used in combination with long fiber reinforced boron carbide ceramic chips or short fiber or long fiber reinforced ceramic chips of other systems to prepare ceramic matrix composite materials with different composition structures.

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 pictorial representation of a chopped fiber reinforced boron carbide ceramic sheet made in example 1;

FIG. 2 is a photomicrograph of the chopped fiber reinforced boron carbide ceramic sheet prepared in example 1.

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.

Example 1

The embodiment provides a preparation method of a chopped carbon fiber reinforced boron carbide ceramic sheet, which comprises the following steps:

mixing 0.5 mass percent of polyacrylamide solution with 6mm long chopped carbon fibers according to the mass ratio of 1.

Mixing 0.5 mass percent of polyacrylamide solution with 1 micron particle size boron carbide ceramic powder according to the mass ratio of 1.

The slurry A1 and B1 were mixed and further stirred for 60 minutes to obtain a uniform slurry containing carbon fibers and boron carbide ceramic powder. And pouring the uniformly dispersed solution into a container with a flat bottom surface, placing the container on a vibration table, and uniformly spreading the slurry at the bottom of the container after vibrating for 10 minutes. After the container is placed in an oven for drying at 60 ℃ for 4 hours, the temperature is continuously raised to 150 ℃ for drying for 2 hours, and the chopped carbon fiber reinforced boron carbide ceramic sheet is obtained, wherein macroscopic and microscopic images of the chopped carbon fiber reinforced boron carbide ceramic sheet are shown in fig. 1 and 2, as can be seen from fig. 1, the chopped carbon fiber reinforced silicon carbide ceramic sheet prepared in the embodiment has a flat surface, has no obvious defects of fiber agglomeration, holes visible to naked eyes and the like, has uniform fiber dispersion and basically no damage to the fiber length, and can be seen from the microscopic photograph of the chopped carbon fiber reinforced boron carbide ceramic sheet shown in fig. 2.

Example 2

The embodiment provides a preparation method of a chopped silicon carbide fiber reinforced boron carbide ceramic sheet, which comprises the following steps:

mixing a sodium carboxymethylcellulose solution with the mass fraction of 2% with 1mm long-short cut silicon carbide fibers according to the mass ratio of 1.

Mixing the sodium carboxymethyl cellulose solution with the mass fraction of 2% with the boron carbide ceramic powder with the particle size of 5 microns according to the mass ratio of 1:5, and stirring for 60 minutes by adopting a mechanical stirring and ultrasonic vibration mixing mode to obtain the uniformly dispersed boron carbide slurry B2.

And mixing the slurry A2 and the slurry B2, and further stirring for 30 minutes to obtain uniform slurry containing the silicon carbide fibers and the boron carbide ceramic powder. And pouring the uniformly dispersed solution into a container with a flat bottom surface, placing the container on a vibration table, and uniformly spreading the slurry on the bottom of the container after vibrating for 30 minutes. And (3) drying the container in an oven at the temperature of 80 ℃ for 8 hours, and then continuously raising the temperature to 120 ℃ for drying for 4 hours to obtain the chopped silicon carbide fiber reinforced boron carbide ceramic sheet.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A preparation method of a chopped fiber reinforced boron carbide ceramic sheet is characterized by comprising the following steps:

s1: weighing the chopped fibers and the mixed solution I according to the mass ratio of 1; the mixed solution I is 0.5-2% of polyacrylamide solution or sodium carboxymethyl cellulose solution;

s2: weighing boron carbide powder and the mixed solution II according to the mass ratio of 1:2-1, and uniformly mixing to obtain slurry B; the mixed solution II is 0.5-2% of polyacrylamide solution or sodium carboxymethyl cellulose solution;

s3: mixing the slurry A and the slurry B, and stirring to obtain mixed slurry;

s4: pouring the mixed slurry into a container with a flat bottom surface, placing the container on a vibration table, and vibrating to uniformly spread the mixed slurry on the bottom of the container;

s5: and (3) drying the container in a drying oven at the low temperature of 60-80 ℃ for 4-8 h, and then continuously heating to 120-150 ℃ for drying for 2-4 h to obtain the chopped fiber reinforced boron carbide ceramic sheet.

2. The production method according to claim 1, wherein in step S1, the chopped fiber is one of a carbon fiber, a silicon carbide fiber and an alumina fiber.

3. The method according to claim 1, wherein the chopped fibers have a length of 1 to 6mm in step S1.

4. The preparation method according to claim 1, wherein in step S1, the blending specifically comprises:

the mixing mode of mechanical stirring and ultrasonic vibration is adopted, the rotating speed of the mechanical stirring is controlled to be 600-1000rpm, the frequency of the ultrasonic vibration is 25-40KHz, and the time is 30-120 min.

5. The production method according to claim 1, wherein in step S2, the boron carbide powder has a particle size of 1 to 5 μm.

6. The preparation method according to claim 1, wherein in step S2, the blending specifically comprises:

the mixing mode of mechanical stirring and ultrasonic vibration is adopted, the rotating speed is controlled to be 600-1000rpm, the frequency of the ultrasonic vibration is 25-40KHz, and the time is 30-60 min.

7. The method according to claim 1, wherein in step S3, the mechanical stirring is performed at a speed of 600 to 1000rpm for 10 to 60min.

8. The method of claim 1, wherein in step S4, the vibration has a frequency of 10 to 50Hz, an amplitude of 0.5 to 2mm, and a vibration time of 10 to 30min.

9. A chopped fiber reinforced boron carbide ceramic sheet prepared by the preparation method of any one of claims 1 to 8.

10. The use of a chopped strand fiber reinforced boron carbide ceramic sheet, characterized in that the boron carbide ceramic sheet prepared by the preparation method according to any one of claims 1 to 8 or the boron carbide ceramic sheet according to claim 9 is applied to a chopped strand fiber reinforced ceramic matrix composite.