A carbon fiber-aluminum silicon carbide composite material and its preparation process

Abstract

This invention relates to the field of silicon carbide composite material technology, specifically to a carbon fiber-aluminum silicon carbide composite material and its preparation process. By weight, it comprises the following components: 70-80 parts silicon carbide powder, 3-10 parts modified short-cut carbon fibers, 1-2 parts yttrium fluoride powder, 3-6 parts ZIF-8 (2-methylimidazolium zinc MOF), 3-5 parts alumina powder, 2-6 parts polyglycidyl methacrylate, 15-20 parts ethanol, 1-2 parts bisphenol A epoxy resin, 25-35 parts molten aluminum, and deionized water. In this invention, silicon carbide is used as the basic raw material for ceramics. By adding ZIF-8 material, the porosity of the silicon carbide ceramic is adjusted, increasing its compatibility with other composite materials and leveraging the overall excellent performance of the silicon carbide additives. The resulting carbon fiber-aluminum silicon carbide composite material exhibits advantages such as high wear resistance, high elastic modulus, and high strength.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide composite materials technology, specifically to a carbon fiber-aluminum silicon carbide composite material and its preparation process. Background Technology

[0002] Silicon carbide ceramics not only possess excellent room-temperature mechanical properties, such as high flexural strength, excellent oxidation resistance, good corrosion resistance, high wear resistance, and a low coefficient of friction, but also exhibit the best high-temperature mechanical properties (strength, creep resistance, etc.) among known ceramic materials. Materials sintered by hot pressing, pressureless sintering, and hot isostatic pressing can maintain their high-temperature strength up to 1600℃, making them the ceramic materials with the highest high-temperature strength. Their oxidation resistance is also the best among all non-oxide ceramics.

[0003] Silicon carbide is a compound with strong covalent bonds, and the ionic Si-C bond accounts for only about 12%. Silicon carbide ceramics, which use silicon carbide as the main raw material, also have the advantages of silicon carbide. Due to the many advantages inherent in silicon carbide, the application of silicon carbide ceramics is becoming more and more widespread.

[0004] To further enhance the performance of silicon carbide ceramics, materials other than silicon carbide are often added. For example, carbon fibers are added to toughen the silicon carbide ceramics, and alumina powder is added to further improve the strength and wear resistance of the silicon carbide ceramics. However, due to the inherent properties of the materials, the composite material cannot fully utilize the significant performance advantages of the original materials. For instance, the inert nature of carbon fibers and the limited number of surface-active groups result in insufficient bonding between the carbon fibers and the matrix material. Furthermore, the porosity of the silicon carbide surface itself does not provide a high enough loading capacity for the added composite material, leading to insufficient composite strength of the entire silicon carbide composite ceramic material. Therefore, addressing the problems mentioned in the background art, those skilled in the art propose a silicon carbide ceramic composite material that can efficiently combine with added materials, maximizing the performance advantages of the added materials. Simultaneously, it solves the problem of excessively high porosity in the ceramic, leading to increased brittleness, in an attempt to improve the composite capability. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon fiber-aluminum silicon carbide composite material and its preparation process to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A carbon fiber-aluminum silicon carbide composite material, by weight, comprises the following components: 70-80 parts silicon carbide powder, 3-10 parts modified short-cut carbon fiber, 1 part fluorinated yttrium powder, 3 parts ZIF-8 (2-methylimidazolium zinc MOF), 3 parts alumina powder, 2-6 parts polyglycidyl methacrylate, 15-20 parts ethanol, 1-2 parts bisphenol A epoxy resin, and an appropriate amount of deionized water;

[0008] The modified short-cut carbon fibers were prepared using the following method:

[0009] Short-cut carbon fibers were placed in a mixed solution of deionized water and hydrogen peroxide and treated with ultrasound for 20-30 minutes. The mass ratio of hydrogen peroxide to deionized water was 5:95, and the ultrasonic frequency was 20-25 kHz. After ultrasonic treatment, the carbon fibers were dried in an oven at 120°C for 2.5 hours to prepare modified short-cut carbon fibers.

[0010] A preparation process for a carbon fiber-aluminum silicon carbide composite material includes the following steps:

[0011] S1. Add silicon carbide powder, modified short-cut carbon fiber, yttrium fluoride powder, and ZIF-8 to deionized water to obtain mixed solution A;

[0012] S2. Add polyglycidyl methacrylate to ethanol, then add bisphenol A epoxy resin, and finally disperse the alumina powder into the ethanol by ultrasound to obtain solution B.

[0013] S3. Mix solution A from step S1 with solution B from step S2, add the mixture to a ball mill jar, add deionized water, and perform planetary ball milling.

[0014] S4. Place the solution after planetary ball milling in step S3 into an oven to dry, and obtain a mixed dry powder.

[0015] S5. Fill the mold with the dry powder from step S4, place the mold in a hydraulic press and hold it under pressure for a period of time to make a green body, place the green body in a high-temperature sintering furnace, and make a porous carbon fiber-silicon carbide ceramic green body under a nitrogen atmosphere.

[0016] S6. Self-made composite furnace. The furnace cavity is divided into upper and lower parts. The upper part is used to place the porous carbon fiber-silicon carbide ceramic green blanks prepared in step S5, and the lower part is used to place the aluminum liquid. After the green blanks and aluminum liquids are prepared and placed in the composite furnace, the composite furnace lid is locked, the mechanical pump is turned on to draw a vacuum, the vacuum is maintained for a period of time, the pressure is released, the finished product is taken out, and carbon fiber-aluminum silicon carbide composite material is made.

[0017] Preferably, the mass ratio of silicon carbide powder to deionized water in step S1 is 1:1.5-1:1.7.

[0018] Preferably, the ultrasonic frequency of the ultrasound in step S2 is 22-28 kHz.

[0019] Preferably, the planetary ball milling time in step S3 is 6-8 hours, and the drying temperature in step S4 is 85-90°C, and the drying time is 3-4 hours.

[0020] Preferably, in step S3, the ratio of the total mass of solution A and solution B to the mass of added deionized water is 1:1.8-1:2.2.

[0021] Preferably, in step S5, the dry powder is held at a pressure of 90-120 MPa in the hydraulic press for 10-25 min, and the green embryo is fired in a high-temperature sintering furnace at 2100-2300℃ for 5-7 h.

[0022] Preferably, in step S6, the pressure of the mechanical pump for evacuation is 80-100 Pa, and the vacuum holding time is 30-45 min.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The ceramic composite material prepared in this invention uses silicon carbide as the matrix material and adds carbon fiber and alumina. Carbon fiber can effectively improve the toughness of ceramic materials, alumina can improve the overall strength and wear resistance of ceramics, and yttrium fluoride powder is used as a sintering aid. The ceramic material prepared in this invention has the advantages of strong bending resistance, high elastic modulus and low coefficient of thermal expansion.

[0025] 2. In this invention, bisphenol A type epoxy resin is added as the resin matrix. The resin matrix can better highlight the excellent properties of high modulus, high strength, and low density of carbon fibers. The surface of short carbon fibers is oxidized by hydrogen peroxide and ultrasonic treatment, so that more active groups are attached to the surface of the short carbon fibers, which can better combine with the epoxy resin. In order to solve the problem that the polarity of alumina makes it difficult to disperse, the surface graft polymer poly(glycidyl methacrylate) is mixed with alumina. The surface graft polymer acts as an initiator to ensure that alumina is uniformly dispersed in the epoxy resin.

[0026] 3. In this invention, ZIF-8 (2-methylimidazolium zinc MOF) is added. As a highly efficient porous material, ZIF-8 can adjust the porosity of silica itself, which facilitates better adsorption of the materials (carbon fiber, alumina) that play a role in toughening, enhancing ceramic strength and improving wear resistance. This greatly improves the overall performance of the composite material. Finally, the pores are filled with molten aluminum to prevent the composite material from becoming brittle due to excessively large ceramic pores caused by the addition of the porous material (ZIF-8). Attached Figure Description

[0027] Figure 1 This is a process flow diagram for preparing carbon fiber-aluminum silicon carbide composite materials according to the present invention;

[0028] Figure 2 This is a sample appearance drawing of the present invention;

[0029] Figure 3 Metallographic image of the sample of this invention;

[0030] Figure 4 This is a scanning electron microscope energy dispersive spectroscopy (EDS) layered image of the present invention;

[0031] Figure 5 This is a scanning electron microscope energy dispersive spectroscopy (SEM) image of the elemental distribution of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1 to 5 The present invention provides:

[0034] A carbon fiber-aluminum silicon carbide composite material comprises the following components: silicon carbide powder, modified short-cut carbon fibers, fluorinated yttrium powder, ZIF-8 (2-methylimidazolium zinc MOF), alumina powder, polyglycidyl methacrylate, ethanol, bisphenol A type epoxy resin, molten aluminum, and an appropriate amount of deionized water.

[0035] The modified short-cut carbon fibers were prepared using the following method:

[0036] Short-cut carbon fibers were placed in a mixed solution of deionized water and hydrogen peroxide and treated with ultrasound for 25 minutes. The mass ratio of hydrogen peroxide to deionized water was 5:95, and the ultrasonic frequency was 23 kHz. After the ultrasonic treatment was completed, the carbon fibers were dried in an oven at 120°C for 2.5 hours to prepare modified short-cut carbon fibers.

[0037] Example 1

[0038] A preparation process for a carbon fiber-aluminum silicon carbide composite material includes the following steps:

[0039] S1. Add 70g silicon carbide powder, 3g modified short-cut carbon fiber, 1g yttrium fluoride powder and 3g ZIF-8 to 105g deionized water and stir to obtain mixed solution A;

[0040] S2. Add 2g of polyglycidyl methacrylate to 15g of ethanol, then add 1g of bisphenol A epoxy resin, and then disperse 3g of alumina powder into the above ethanol solution by ultrasonication at a frequency of 26kHz to obtain solution B.

[0041] S3. Mix solution A from step S1 with solution B from step S2, add the mixture to a ball mill jar, add 380g of deionized water, and ball mill for 7 hours.

[0042] S4. Place the solution after planetary ball milling in step S3 into an oven to dry, and obtain a mixed dry powder. The drying temperature is 85℃ and the drying time is 3h.

[0043] S5. Fill the mold with the dry powder from step S4, place the mold in a hydraulic press, hold it under pressure of 90MPa for 10 minutes to make a green body, place the green body in a high-temperature sintering furnace at 2100℃, and sinter it under a nitrogen atmosphere for 5 hours to make a porous carbon fiber-silicon carbide ceramic green body.

[0044] S6. Make a composite furnace. The furnace cavity is divided into upper and lower parts. The upper part is used to place the porous carbon fiber-silicon carbide ceramic green blanks prepared in step S5, and the lower part is used to place the aluminum liquid. The amount of aluminum liquid is 25g. After the green blanks and aluminum liquids are prepared and placed in the composite furnace, lock the composite furnace lid, turn on the mechanical pump to draw a vacuum. The vacuum pressure is 80Pa, and the vacuum is maintained for 30 minutes. Depressurize and take out the finished product.

[0045] Example 2

[0046] A preparation process for a carbon fiber-aluminum silicon carbide composite material includes the following steps:

[0047] S1. Add 75g silicon carbide powder, 7g modified short-cut carbon fiber, 1.5g yttrium fluoride powder and 4g ZIF-8 to 120g deionized water and stir to obtain mixed solution A;

[0048] S2. Add 4.5g of polyglycidyl methacrylate to 18g of ethanol, then add 1.6g of bisphenol A epoxy resin, and then disperse 4g of alumina powder into the above ethanol solution by ultrasonication at a frequency of 26kHz to obtain solution B.

[0049] S3. Mix solution A from step S1 with solution B from step S2 and add them to a ball mill jar. Add 430g of deionized water and ball mill for 7 hours.

[0050] S4. Place the solution after planetary ball milling in step S3 into an oven to dry, and obtain a mixed dry powder. The drying temperature is 87℃ and the drying time is 3.6h.

[0051] S5. Fill the mold with the dry powder from step S4, place the mold in a hydraulic press, hold it under pressure of 100MPa for 15 minutes to make a green body, and place the green body in a high-temperature sintering furnace at 2200℃ for 6 hours in a nitrogen atmosphere to make a porous carbon fiber-silicon carbide ceramic green body.

[0052] S6. Make a composite furnace. The furnace cavity is divided into upper and lower parts. The upper part is used to place the porous carbon fiber-silicon carbide ceramic green blanks prepared in step S5, and the lower part is used to place the aluminum liquid. The amount of aluminum liquid is 30g. After the green blanks and aluminum liquids are prepared and placed in the composite furnace, lock the composite furnace lid, turn on the mechanical pump to draw a vacuum. The vacuum pressure is 88Pa, and the vacuum is maintained for 37min. Depressurize and take out the finished product.

[0053] Example 3

[0054] A preparation process for a carbon fiber-aluminum silicon carbide composite material includes the following steps:

[0055] S1. Add 80g of silicon carbide powder, 10g of modified short-cut carbon fiber, 2g of yttrium fluoride powder and 6g of ZIF-8 to 136g of deionized water and stir to obtain mixed solution A;

[0056] S2. Add 6g of polyglycidyl methacrylate to 20g of ethanol, then add 2g of bisphenol A epoxy resin, and then disperse 5g of alumina powder into the above ethanol solution by ultrasonication at a frequency of 26kHz to obtain solution B.

[0057] S3. Mix solution A from step S1 with solution B from step S2 and add them to a ball mill jar. Add 520g of deionized water and ball mill for 7 hours.

[0058] S4. Place the solution after planetary ball milling in step S3 into an oven to dry, and obtain a mixed dry powder. The drying temperature is 90℃ and the drying time is 4h.

[0059] S5. Fill the mold with the dry powder from step S4, place the mold in a hydraulic press, hold it under pressure of 120MPa for 25 minutes to make a green body, and place the green body in a high-temperature sintering furnace at 2300℃ for 7 hours in a nitrogen atmosphere to make a porous carbon fiber-silicon carbide ceramic green body.

[0060] S6. Make a composite furnace. The furnace cavity is divided into upper and lower parts. The upper part is used to place the porous carbon fiber-silicon carbide ceramic green blanks prepared in step S5, and the lower part is used to place the aluminum liquid. The amount of aluminum liquid is 35g. After the green blanks and aluminum liquids are prepared and placed in the composite furnace, lock the composite furnace lid, turn on the mechanical pump to draw a vacuum. The vacuum pressure is 100Pa, and the vacuum is maintained for 45 minutes. Depressurize and take out the finished product.

[0061] Comparative Example 1

[0062] The difference between Comparative Example 1 and Example 1 is that step S1 was changed, and the modified chopped carbon fiber added in step S1 was replaced with conventional chopped carbon fiber. The remaining steps are exactly the same as in Example 1.

[0063] Comparative Example 2

[0064] The difference between Comparative Example 2 and Example 1 is that step S1 was omitted, thus eliminating the addition of ZIF-8. The remaining steps are exactly the same as in Example 1.

[0065] Comparative Example 3

[0066] The difference between Comparative Example 3 and Example 1 is that step S6 was omitted, and the aluminum liquid and ceramic green body were calcined in a vacuum environment instead of calcining in an atmospheric pressure environment. The remaining steps are exactly the same as those in Example 1.

[0067] Comparative Example 4

[0068] The difference between Comparative Example 4 and Example 1 is that not only was the modified short-cut carbon fiber added in step S1 replaced with conventional short-cut carbon fiber, but the addition of ZIF-8 was also omitted. Finally, the calcination of aluminum liquid and ceramic green body under vacuum was changed to calcination under normal pressure. The remaining steps were exactly the same as in Example 1.

[0069] Seven carbon fiber-aluminum silicon carbide composite materials were prepared using the seven methods described above. Their density (g / cm³), flexural strength (MPa), elastic modulus (GPa), thermal conductivity (W / m K), and coefficient of linear expansion (10⁻⁶@25℃) were then tested, and the data are shown in Table 1 below.

[0070] Table 1

[0071]

[0072] As can be seen from the data in Table 1, the carbon fiber-aluminum silicon carbide composite materials prepared in Examples 1, 2, and 3 have the advantages of high flexural strength, high elastic modulus, and low coefficient of linear expansion. In Comparative Example 1, short-cut carbon fibers were directly added. Compared with modified short-cut carbon fibers, short-cut carbon fibers contain fewer active groups, resulting in weaker bonding with the resin matrix and ZIF-8. This leads to a decrease in the overall toughness of the composite material, which is directly manifested in a decrease in flexural strength and elastic modulus. In addition, ZIF-8 is used in this application as a material to adjust the porosity of silicon carbide, which plays a good load-bearing role and is used to bind the alumina and carbon fiber materials in the entire composite material, making the overall strength and toughness of the composite material higher. In Comparative Example 2, due to the lack of ZIF-8, the flexural strength and elastic modulus of the composite material are lower. The modulus is also significantly reduced. In this application, in order to better integrate the alumina and carbon fiber in the composite material, ZIF-8 porous material is used. Due to the characteristics of porous materials, the porosity of the composite material increases, the brittleness of the composite material increases, and it is more prone to expansion when heated. Therefore, by using molten aluminum in a vacuum environment, the molten aluminum can more easily enter the pores of the ZIF-8 material, blocking the pores of the composite material, improving the overall strength and bending resistance of the composite material, and reducing the linear expansion coefficient of the load material. As can be seen from Comparative Example 3, under normal pressure, molten aluminum does not easily enter the pores of ZIF-8, the entire ceramic composite material has more pores, and the bending resistance and expansion resistance are reduced. After molten aluminum is used for composite, the overall bending resistance of the composite material is effectively improved and the linear expansion coefficient is reduced.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A carbon fiber-aluminum silicon carbide composite material, characterized by, By mass parts, including the following components: 70-80 parts of silicon carbide powder, 3-10 parts of modified short carbon fiber, 1-2 parts of yttrium fluoride powder, 3-6 parts of ZIF-8, 3-5 parts of alumina powder, 2-6 parts of poly glycidyl methacrylate, 15-20 parts of ethanol, 1-2 parts of bisphenol A type epoxy resin, 25-35 parts of aluminum liquid and a proper amount of deionized water; The modified short carbon fiber is prepared by the following method: The short carbon fiber is put into a mixed solution of deionized water and hydrogen peroxide, and is treated by ultrasonic wave for 20-30 min, the mass ratio of hydrogen peroxide to deionized water is 5:95, the ultrasonic frequency of the ultrasonic wave is 20-25 kHz, after the ultrasonic treatment, the short carbon fiber is put into an oven at 120 DEG C and is dried for 2.5 h to prepare the modified short carbon fiber; The preparation process of the carbon fiber-aluminum silicon carbide composite material comprises the following steps: S1, the silicon carbide powder, the modified short carbon fiber and the yttrium fluoride powder and ZIF-8 are put into the deionized water to obtain a mixed solution A; S2, the poly glycidyl methacrylate is added into the ethanol, then the bisphenol A type epoxy resin is added, and then the alumina powder is dispersed into the ethanol by ultrasonic wave to obtain a solution B; S3, the solution A in step S1 and the solution B in step S2 are mixed with each other and are added into a ball mill tank, deionized water is added, and planetary ball milling is carried out; S4, the solution after the planetary ball milling in step S3 is put into an oven for drying to obtain a mixed dry powder; S5, the dry powder in step S4 is filled into a mold, the mold is put into a hydraulic machine, and is kept for a period of time to prepare a green body, the green body is placed in a high temperature sintering furnace to prepare a porous carbon fiber-silicon carbide ceramic green body under nitrogen atmosphere; S6, a self-made composite furnace is used, the furnace cavity of the composite furnace is divided into upper and lower parts, the upper part is used for placing the porous carbon fiber-silicon carbide ceramic green body prepared in step S5, and the lower part is used for placing the aluminum liquid, after the green body and the aluminum liquid are prepared and placed in the composite furnace, the cover of the composite furnace is locked, a mechanical pump is opened to extract vacuum, the vacuum is kept for a period of time, the pressure is released, and the finished product is taken out to prepare the carbon fiber-aluminum silicon carbide composite material.

2. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The mass ratio of the silicon carbide powder to the deionized water in step S1 is 1:1.5-1:1.

7.

3. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The ultrasonic frequency of the ultrasonic wave in step S2 is 22-28 kHz.

4. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The time of the planetary ball milling in step S3 is 6-8 h, the drying temperature in step S4 is 85-90 DEG C, and the drying time is 3-4 h.

5. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The mass ratio of the total mass of the solution A and the solution B to the mass of the added deionized water in step S3 is 1:1.8-1:2.

2.

6. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The pressure of the dry powder in the hydraulic machine in step S5 is 90-120 MPa, the pressure keeping time is 10-25 min, and the green body is sintered in the high temperature sintering furnace at a temperature of 2100-2300 DEG C for 5-7 h.

7. The carbon fiber-aluminum silicon carbide composite material of claim 1, wherein: The pressure of the mechanical pump for extracting vacuum in step S6 is 80-100 Pa, and the vacuum keeping time is 30-45 min.

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