Preparation method of boron carbide particle reinforced aluminum-based composite material

Abstract

The invention belongs to the field of inorganic materials, and particularly relates to a preparation method of a boron carbide particle reinforced aluminum-based composite material. The surface of boron carbide and the surface of aluminum are modified through the modifier, the molecular structure of the modifier prepared through the method contains two functional groups with different properties, the functional groups can chemically react with active groups on the surface of boron carbide, and chemical bonds are formed; amino groups and epoxy groups in the modifier have certain alkalinity and coordination ability, and react with aluminum at high temperature, so that the surface of the aluminum is nitrided or an aluminum-amine complex is formed, and therefore, a'bridge 'effect is achieved between the nano boron carbide and a matrix material, and the compatibility and binding force of the nano boron carbide and the matrix material are enhanced.

Description

Technical Field

[0001] The invention belongs to the field of inorganic materials, and in particular relates to a method for preparing a boron carbide particle reinforced aluminum-based composite material. Background Art

[0002] In the field of modern materials science, metal matrix composites have attracted much attention due to their unique combination of properties. Aluminum matrix composites have become one of the research hotspots due to their low density, good thermal and electrical conductivity, and excellent processing properties. Among them, boron carbide (B4C) particle reinforced aluminum matrix composites have shown great application potential due to the high hardness, high melting point, good chemical stability of boron carbide, and physical and chemical compatibility with aluminum matrix to a certain extent.

[0003] In the aerospace field, aircraft structural parts need to have high strength and low density to reduce their own weight, improve fuel efficiency and flight performance. Traditional aluminum alloy materials are gradually unable to meet the increasingly stringent design requirements in terms of strength. For example, in engine components, wing structures and other parts, the use of boron carbide particles to reinforce aluminum-based composite materials is expected to significantly improve the load-bearing capacity and fatigue resistance of components, thereby improving the reliability and safety of aircraft.

[0004] In the automotive industry, with the advancement of energy conservation and emission reduction policies and the pursuit of vehicle performance, key components such as automobile engine cylinders and pistons have put forward higher requirements for the heat resistance, wear resistance and strength of materials. The application of boron carbide particle reinforced aluminum-based composite materials can enable these components to effectively resist high-temperature wear and mechanical stress while maintaining a relatively light weight, extend the service life of components, and reduce automobile energy consumption.

[0005] However, the preparation of boron carbide particle reinforced aluminum-based composites still faces many challenges. Although traditional preparation methods such as powder metallurgy can better control the distribution of boron carbide particles, they have problems such as complex processes, high costs, and difficulty in preparing large-sized and complex-shaped parts. For example, during the powder mixing process, boron carbide particles tend to agglomerate, resulting in uneven dispersion in the aluminum matrix, which seriously affects the performance consistency and overall performance improvement of the composite material. Moreover, in the subsequent sintering process, a high temperature and high pressure environment is required, which not only increases equipment costs and energy consumption, but may also cause problems such as excessive oxidation of the aluminum matrix, reducing the quality of the material.

[0006] Melting and casting is also a common preparation method, but the wettability between boron carbide particles and aluminum liquid is poor, making it difficult for the particles to be evenly dispersed in the aluminum liquid, and segregation is prone to occur, which in turn forms defects inside the composite material and weakens the mechanical properties of the material. At the same time, during the solidification process, due to the large difference in thermal expansion coefficients between boron carbide particles and aluminum matrix, it is easy to generate large internal stress, causing cracking or deformation of the material, reducing the yield rate.

[0007] Therefore, it is of great practical significance and application value to develop a method for preparing boron carbide particle reinforced aluminum-based composite materials that can effectively solve the problems of boron carbide particle dispersion, wettability, and internal stress, and has a relatively simple process and controllable costs. Summary of the invention

[0008] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a method for preparing a boron carbide particle reinforced aluminum-based composite material. The present invention uses a modifier to modify the surface of boron carbide and aluminum, thereby playing a "bridge" role between nano boron carbide and the matrix material, thereby enhancing the compatibility and bonding strength of the two.

[0009] An object of the present invention is to provide a method for preparing a boron carbide particle reinforced aluminum-based composite material, which is characterized by comprising the following steps:

[0010] S1: Surface modification of boron carbide: Boron carbide powder is taken, and a surface modifier is added according to a weight ratio of boron carbide to surface modifier of 100-120:1, and the mixture is ball-milled and mixed to obtain modified boron carbide;

[0011] S2: Preparation of green embryo: Aluminum powder and modified boron carbide powder are mixed, and the boron carbide content is 5% to 10%; a binder is added, and the powder is mixed by ball milling for 20-28 hours; the mixed powder obtained after ball milling is passed through a 100 mesh sieve to ensure the uniformity of the particles.

[0012] S3: Preparation of composite materials: The pre-pressed green body is placed in a vacuum sintering furnace and sintered under an inert atmosphere.

[0013] Furthermore, the surface modifier in step S1 is prepared by the following method:

[0014] Add 5 g of triethoxysilane (Si(OC2H5)3) to 50 mL of anhydrous ethanol and stir evenly; slowly add glycidol (1.5 g) at 60°C, and add 0.1 g of triethylamine as a catalyst; after stirring the reaction for 4 hours, add 2 mL of deionized water dropwise and continue stirring for 2 hours; remove the solvent by rotary evaporation, and purify the crude product by column chromatography to obtain a surface modifier containing amino and epoxy groups.

[0015] Furthermore, the mass ratio of triethoxysilane to glycidol is 2-4:1.

[0016] Furthermore, in step S1, the purity of the boron carbide powder is ≥98%, and the particle size is 0.5-5 μm.

[0017] Furthermore, in step S1, the particle size of the modified boron carbide powder is 30-50 nm.

[0018] Furthermore, in step S2, the purity of the aluminum powder is ≥99.5%, and the particle size is 10-50 nm; the ball milling medium is any one of ethanol or anhydrous ether, and the ball-to-material ratio is 10:1.

[0019] Furthermore, step S2 also includes placing the mixed powder in a mold and pre-pressing it by cold pressing technology, with a pressure of 100-300 MPa and a holding time of 3-10 minutes.

[0020] Furthermore, the specific process of calcination in step S3 is: adopting hot isostatic pressing process, the specific conditions are temperature 550-600° C., pressure 100-150 MPa, and insulation time 30-60 minutes.

[0021] Furthermore, the inert gas in step S3 is argon.

[0022] Furthermore, the binder in step S2 is any one of polyethylene glycol and paraffin.

[0023] Beneficial effects:

[0024] The modifier prepared by the present invention contains two functional groups of different properties in its molecular structure, which can react chemically with active groups (such as hydroxyl, carboxyl, etc.) on the surface of boron carbide to form chemical bonds; the amino and epoxy groups in the modifier have certain alkalinity and coordination ability, and react with aluminum at high temperature to nitride the aluminum surface or form an aluminum-amine complex, thereby playing a "bridge" role between nano boron carbide and the matrix material, enhancing the compatibility and bonding strength of the two. DETAILED DESCRIPTION

[0025] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and the concept of the present invention will be fully conveyed to those skilled in the art, and the present invention will only be limited by the claims.

[0026] It should be noted that the surface modifiers described in the following examples and comparative examples are prepared by the following method: 5 g of triethoxysilane (Si(OC2H5)3) is added to 50 mL of anhydrous ethanol and stirred evenly. At 60°C, glycidol (1.5 g) is slowly added dropwise, and 0.1 g of triethylamine is added as a catalyst. After stirring the reaction for 4 hours, 2 mL of deionized water is added dropwise, and stirring is continued for 2 hours. The solvent is removed by rotary evaporation, and the crude product is purified by column chromatography to obtain the surface modifier.

[0027] Example 1

[0028] Take boron carbide powder (purity ≥ 98%, particle size 0.5-5 μm), add surface modifier according to the weight ratio of boron carbide: surface modifier of 100:1, ball mill to a particle size of 30-50 nm, mix evenly to obtain modified boron carbide; mix aluminum powder and modified boron carbide powder, the content of modified boron carbide is 10%; add binder paraffin, mix the powder by ball milling, the ball milling medium is ethanol or anhydrous ether, the ball-to-material ratio is 10:1, and the ball milling time is 24 hours. The mixed powder after ball milling is placed in a mold and pre-pressed by cold pressing technology, the pressure is 160 MPa, and the holding time is 3 minutes. The pre-pressed green body is placed in a vacuum sintering furnace, and the hot isostatic pressing (HIP) process is used in an argon atmosphere to further improve the density of the material. The HIP conditions are a temperature of 600°C, a pressure of 120 MPa, and a holding time of 30 minutes.

[0029] Example 2

[0030] Take boron carbide powder (purity ≥ 98%, particle size 0.5-5 μm), add surface modifier according to the weight ratio of boron carbide: surface modifier of 100:1, ball mill to the particle size of 30-50nm, mix evenly to obtain modified boron carbide; mix aluminum powder and modified boron carbide powder, the content of modified boron carbide is 5%; add binder polyethylene glycol, mix the powder by ball milling, the ball milling medium is ethanol, the ball-to-material ratio is 10:1, and the ball milling time is 20 hours. The mixed powder after ball milling is placed in a mold and pre-pressed by cold pressing technology, the pressure is 100MPa, and the holding time is 10 minutes. The pre-pressed green body is placed in a vacuum sintering furnace, and the hot isostatic pressing (HIP) process is used in an argon atmosphere to further improve the density of the material. The HIP conditions are a temperature of 550°C, a pressure of 150MPa, and a holding time of 60 minutes.

[0031] Example 3

[0032] Take boron carbide powder (purity ≥ 98%, particle size 0.5-5 μm), add surface modifier according to the weight ratio of boron carbide: surface modifier of 120:1, ball mill to particle size of 30-50 nm, mix evenly to obtain modified boron carbide; mix aluminum powder and modified boron carbide powder, the content of modified boron carbide is 10%; add binder polyethylene glycol and paraffin, mix the powder by ball milling, the ball milling medium is ethanol or anhydrous ether, the ball-to-material ratio is 10:1, and the ball milling time is 28 hours. The mixed powder after ball milling is placed in a mold, and pre-pressed by cold pressing technology, the pressure is 300 MPa, and the holding time is 10 minutes. The pre-pressed green body is placed in a vacuum sintering furnace, and the hot isostatic pressing (HIP) process is used in an argon atmosphere to further improve the density of the material. The HIP conditions are temperature 600°C, pressure 150 MPa, and holding time is 30 minutes.

[0033] Example 4

[0034] Take boron carbide powder (purity ≥ 98%, particle size 0.5-5 μm), add surface modifier according to the weight ratio of boron carbide: surface modifier of 110:1, ball mill to a particle size of 30-50 nm, mix evenly to obtain modified boron carbide; mix aluminum powder and modified boron carbide powder, the content of modified boron carbide is 8%; add binder polyethylene glycol and paraffin, mix the powder by ball milling, the ball milling medium is ethanol or anhydrous ether, the ball-to-material ratio is 10:1, and the ball milling time is 24 hours. The mixed powder after ball milling is placed in a mold and pre-pressed by cold pressing technology, the pressure is 180 MPa, and the holding time is 6 minutes. The pre-pressed green body is placed in a vacuum sintering furnace, and the hot isostatic pressing (HIP) process is used in an argon atmosphere to further improve the density of the material. The HIP conditions are a temperature of 550°C, a pressure of 130 MPa, and a holding time of 45 minutes.

[0035] Using Archimedes' principle, the composite material sample is immersed in a liquid of known density, the volume of the displaced liquid is measured, and the density is calculated.

[0036] The fracture morphology of the composite material of the present invention was observed and analyzed by a field emission scanning electron microscope (model: JSM-7800F, Jeol, Japan). In order to increase the conductivity, the samples were gold-sprayed before analysis with a thickness of 10 nm. The equipment voltage was 12 KV and the vacuum chamber pressure was 4.45 × 10 -4 Pa.

[0037] The hardness test was conducted on an HVS-1000Z automatic turret digital display micro-Vickers hardness tester (Shanghai Wanheng Precision Instrument Co., Ltd.). The experimental loading load was 1000g and the loading time was 10s. In order to remove the processing marks on the surface of the impregnated sample during the wire cutting process, the samples were all inlaid by a metallographic sample inlay machine and polished by a polishing machine before the hardness test. Each sample was tested at 9 random points and the average value was taken. The room temperature tensile test was conducted using an Instron universal testing machine. The relevant test results are shown in the following table:

[0038] Example <![CDATA[Density (g / cm 3 )]]> Microhardness(HV) Tensile strength(MPa) Example 1 2.71 128.6 188.6 Example 2 2.85 136.3 189.3 Example 3 2.79 144.5 179.9 Example 4 2.81 120.3 178.6

[0039] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for preparing a boron carbide particle reinforced aluminum-based composite material, characterized in that: The steps include: S1: Surface modification of boron carbide: Boron carbide powder is taken, and a surface modifier is added according to a weight ratio of boron carbide to surface modifier of 100-120:1, and the mixture is ball-milled and mixed to obtain modified boron carbide; S2: Preparation of green embryo: mixing aluminum powder and modified boron carbide powder, wherein the boron carbide content is 5% to 10%; adding a binder, and mixing the powder by ball milling for 20 to 28 hours; and passing the mixed powder obtained after ball milling through a 100 mesh sieve to ensure the uniformity of the particles; S3: Preparation of composite materials: The pre-pressed green body is placed in a vacuum sintering furnace and sintered under an inert atmosphere.

2. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The surface modifier in step S1 is prepared by the following method: adding triethoxysilane to anhydrous ethanol and stirring evenly; slowly adding glycidol dropwise and adding triethylamine as a catalyst; stirring, adding deionized water dropwise, and continuing stirring for 2 hours; removing the solvent by rotary evaporation, and purifying the crude product by column chromatography.

3. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 2, characterized in that: The mass ratio of triethoxysilane to glycidol is 2-4:

1.

4. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: In step S1, the purity of the boron carbide powder is ≥98%, and the particle size is 0.5-5 μm.

5. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The particle size of the modified boron carbide powder in step S1 is 30-50 nm.

6. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: In step S2, the purity of the aluminum powder is ≥99.5%, and the particle size is 10-50 nm; the ball milling medium is either ethanol or anhydrous ether, and the ball-to-material ratio is 10:

1.

7. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: Step S2 also includes placing the mixed powder in a mold and pre-pressing it using cold pressing technology at a pressure of 100-300 MPa for a holding time of 3-10 minutes.

8. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The specific process of calcination in step S3 is: adopting hot isostatic pressing process, temperature 550-600° C., pressure 100-150 MPa, and insulation time of 30 to 60 minutes.

9. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The inert gas in step S3 is argon.

10. The method for preparing a boron carbide particle reinforced aluminum-based composite material according to claim 1, characterized in that: The binder in step S2 is any one of polyethylene glycol and paraffin.