Selective laser melting formed graphene reinforced magnesium-based composite material and preparation method thereof

Abstract

The invention discloses a selective laser melting formed graphene reinforced magnesium-based composite material and a preparation method thereof, and belongs to the technical field of metal-based composite materials. The preparation method comprises the following steps: carrying out ultrasonic dispersion treatment on graphene in ethanol by using 1-pyrene butyric acid; performing liquid nitrogen cold quenching on the dispersed powder, spherical aluminum oxide and 1-pyrene butyric acid, and performing vacuum ball milling to obtain modified graphene; then the modified graphene, magnesium powder and 1-pyrene butyric acid are subjected to ball milling, and modified graphene-magnesium powder mixed powder is obtained; and finally, the modified graphene-magnesium powder mixed powder serves as a raw material, and the magnesium-based composite material is prepared through a selective laser melting forming technology. According to the preparation method, the product is directly manufactured on the basis of shortening the working time and reducing the cost, and the method is suitable for the fields of aeronautical manufacturing, machining, medical treatment, family consumption and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-based composite materials and relates to a magnesium-based composite material, in particular to a graphene-reinforced magnesium-based composite material formed by selective laser melting and a preparation method thereof. Background Art

[0002] Pure magnesium and traditional magnesium-based composite materials have obvious performance shortcomings. From the perspective of mechanical properties, pure magnesium has low strength and hardness, and is prone to deformation and damage when subjected to large loads. Although traditional magnesium-based composite materials have improved to a certain extent, they still cannot meet the stringent requirements of some high-end application scenarios for the mechanical properties of materials. Graphene, a two-dimensional material composed of carbon atoms, has shocked the materials science community with its unique structure and excellent performance since it was successfully separated in 2004. Its theoretical strength is as high as 130GPa, which is more than 100 times that of steel. It also has ultra-high electrical and thermal conductivity, with a thermal conductivity of up to 5300W / (m·K). Introducing graphene into magnesium-based composite materials can theoretically use its excellent mechanical properties to enhance the strength and hardness of the magnesium matrix, use its high electrical conductivity to improve the electrical properties of the composite material, and use its high thermal conductivity to improve the thermal stability of the material.

[0003] SLM technology, based on the principles of additive manufacturing, uses a high-energy laser beam to melt metal powder layer by layer according to a pre-designed three-dimensional model, directly producing parts with complex shapes. Compared to traditional manufacturing methods, SLM offers significant advantages. It eliminates the need for molds, significantly shortening product development cycles and manufacturing costs. SLM offers unique advantages in the preparation of graphene-reinforced magnesium-based composites. It enables precise control of the material's microstructure and composition distribution. By adjusting parameters such as laser power, scanning speed, and layer thickness, the distribution of graphene within the magnesium matrix can be manipulated, fully maximizing its reinforcing properties.

[0004] Selective laser melting of graphene-reinforced magnesium-based composites and their preparation methods have extremely important theoretical significance and practical value for promoting the development of magnesium-based composites and expanding their applications in high-end fields. This will also inject new vitality into the field of materials science and engineering and promote technological upgrading and innovative development in related industries.

[0005] CN118726789A discloses a method for preparing a graphite / graphene-reinforced magnesium-based composite material with high modulus, strength, and plasticity matching. The method uses a self-developed threaded twisting extrusion die to not only further disperse the reinforcement in the matrix during the extrusion process, but also applies three-dimensional compression and strong shear forces to the material, causing the reinforcement to be highly dispersed while undergoing strong plastic deformation, significantly refining the grains, and ultimately obtaining a graphite / graphene-reinforced magnesium-based composite material with high modulus, high strength, and high plasticity. CN116200623A discloses a method for preparing an oriented graphene-reinforced magnesium-based composite material. The method uses a process combining powder metallurgy and multi-stage continuous hot extrusion to achieve the oriented alignment of graphene in the magnesium matrix. The method utilizes the ultra-high thermal conductivity of graphene along the lamellar direction to significantly improve the thermal conductivity of the magnesium-based composite material, solving the problem of poor graphene orientation while also improving the mechanical properties of the composite material. CN117344183A relates to a copper oxide-modified graphene-reinforced magnesium-based composite material and a preparation method thereof. Copper oxide is used to modify the surface of graphene. Copper oxide is cheaper than precious metals such as nickel and silver, effectively reducing material costs.

[0006] The common problem of graphene magnesium-based composite materials prepared by the above various methods is that the wettability between graphene and the magnesium matrix is poor, which makes it difficult for graphene to be evenly dispersed in the magnesium alloy, thereby affecting the mechanical properties of the composite material. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a graphene-reinforced magnesium-based composite material formed by selective laser melting and a preparation method thereof. The graphene-reinforced magnesium-based composite material prepared by the present invention greatly increases the graphene content, and the graphene is uniformly dispersed in the magnesium matrix, ultimately improving the mechanical properties of the composite material.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for preparing a graphene-reinforced magnesium-based composite material by selective laser melting, comprising the following steps:

[0010] 1) Graphene and 1-pyrenebutyric acid are uniformly dispersed in ethanol, and then freeze-dried to obtain a powder;

[0011] 2) placing the freeze-dried powder obtained in step 1), spherical alumina, and 1-pyrenebutyric acid in a ball mill, filling it with liquid nitrogen for quenching for a period of time, and then vacuum ball milling to obtain modified graphene;

[0012] 3) placing the modified graphene, high-purity spherical magnesium powder, and 1-pyrenebutyric acid in a ball mill, filling it with liquid nitrogen, submerging the grinding balls in the liquid nitrogen, ball milling, and vacuum drying to obtain a modified graphene-magnesium powder mixture;

[0013] 4) Using the modified graphene-magnesium powder mixture as a raw material for selective laser melting, performing selective laser melting under argon protection to obtain a selective laser melting-formed graphene reinforced magnesium-based composite material.

[0014] Furthermore, in the step 1), the mass ratio of graphene to 1-pyrenebutyric acid is 1:0.01-0.03.

[0015] Furthermore, in step 1), the ultrasonic dispersion time is 0.5-2 h, the freeze-drying temperature is -50°C-0°C, the vacuum degree is <0.1 mBar, and the freeze-drying time is 24-48 h.

[0016] Furthermore, in the step 2), the mass ratio of graphene to spherical alumina is 1:3-6, and the 1-pyrenebutyric acid is 1-3 wt% of the spherical alumina.

[0017] Furthermore, in step 2), the liquid nitrogen quenching time is 0.5-2 h, and the ball milling conditions are: ball-to-material ratio 5-7:1, rotation speed 200-300 rpm, and ball milling for 2-4 h.

[0018] Furthermore, in step 2), the particle size of the spherical alumina is 2-10 μm.

[0019] Furthermore, in step 3), the high-purity spherical magnesium powder has a magnesium content of 99.8% and a particle size of 48-60 μm. Strictly controlling the powder particle size is beneficial for reducing the surface roughness and quality of the selective laser melting formed parts.

[0020] Furthermore, in step 3), the mass ratio of modified graphene to high-purity magnesium powder is 1:4-7, and the content of 1-pyrenebutyric acid is 0.5-2 wt% of the mass of the magnesium powder.

[0021] Furthermore, in step 3), the ball milling conditions are: ball-to-material ratio 5-7:1, rotation speed 100-200 rpm, and ball milling for 1-3 hours. Improper control of the ball-to-material ratio, rotation speed, and time may damage the graphene structure, so strict control is required.

[0022] Furthermore, in step 3), the vacuum drying temperature is 50-60° C., and the drying time is 4-8 h.

[0023] Furthermore, in step 4), the laser power is 200-350 W, the scanning speed is 0.5-1.5 m / s, and the layer thickness is 0.02-0.05 mm.

[0024] Furthermore, the graphene content in the graphene-reinforced magnesium-based composite material prepared by the preparation method is 1-5wt%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a preparation method of graphene-reinforced magnesium-based composite materials formed by selective laser melting, which realizes the green and efficient forming of high-performance components based on additive manufacturing technology. Compared with traditional subtractive manufacturing processes, the material utilization rate is increased by more than 60% and the energy consumption is reduced by 40-50%. Its innovation lies in the use of a "ultrasonic dispersion-freeze drying-liquid nitrogen ball milling" collaborative process system to break through the technical bottleneck of low graphene dispersion content (≤3 wt%) in traditional magnesium-based composites. Specifically, it is manifested as follows: 1. Dispersion process upgrade: On the basis of ultrasonic dispersion of graphene in ethanol, freeze drying is introduced to form a porous skeleton structure, and liquid nitrogen quenching is combined to suppress the ball milling thermal effect, thereby achieving uniform dispersion of ultra-high content graphene; 2. Interface strengthening design: Through 1-pyrenebutyric acid molecular bridging and liquid nitrogen ball milling mechanical engagement, a strengthened and toughened interface of graphene-magnesium matrix is constructed; 3. Forming process innovation: Using selective laser melting (SLM) technology, by precisely controlling the laser power (200-350 W), scanning path and argon protective atmosphere, complex structural functional parts can be directly formed, which are suitable for aerospace, biomedicine, and precision electronics. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention will be further described below in conjunction with examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Various changes, modifications, substitutions and variations made by those skilled in the art without departing from the principles and purpose of the present invention to these examples should all be included within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a graphene-reinforced magnesium-based composite material by selective laser melting in this embodiment is as follows:

[0030] 1) Graphene and 1-pyrenebutyric acid were placed in a beaker at a mass ratio of 1:0.01. An appropriate amount of ethanol (a mass g / volume mL ratio of 1:100 can be used, the same below) was added and ultrasonically dispersed in an ultrasonic machine to obtain a dispersion. The dispersion was freeze-dried; the ultrasonic dispersion time was 0.5 h, the freeze-drying temperature was -50°C, and the freeze-drying time was 24 h.

[0031] 2) The freeze-dried powder from step 1), spherical alumina, and 1-pyrenebutyric acid were placed in a ball mill, filled with liquid nitrogen and quenched for a period of time, and then vacuum ball milled to obtain modified graphene; the mass ratio of graphene to spherical alumina was 1:6, the 1-pyrenebutyric acid was 1 wt% of the spherical alumina, the liquid nitrogen quenching time was 0.5 h, the ball-to-material ratio was 5:1, the rotation speed was 200 rpm, and the ball milling was performed for 2 h;

[0032] 3) The modified graphene, high-purity spherical magnesium powder (magnesium content 99.8%, the same below), and 1-pyrenebutyric acid were placed in a ball mill, filled with liquid nitrogen, and ball-milled to obtain a modified graphene-magnesium powder mixture, which was then vacuum-dried. The mass ratio of the modified graphene to the high-purity magnesium powder was 1:7, and the amount of 1-pyrenebutyric acid was 0.5 wt % of the mass of the magnesium powder. The milling balls were immersed in liquid nitrogen, with a ball-to-material ratio of 6:1, and the milling speed was 100 rpm for 2 h. The vacuum drying temperature was 50°C and the drying time was 8 h.

[0033] 4) Using the dried modified graphene-magnesium powder mixture as a raw material for selective laser melting, selective laser melting is performed under argon protection, with a laser power of 200 W, a scanning speed of 0.5 m / s, and a layer thickness of 0.02 mm.

[0034] The graphene content in the graphene-reinforced magnesium-based composite material prepared in this embodiment is 1.7 wt %.

[0035] Example 2

[0036] A method for preparing a graphene-reinforced magnesium-based composite material by selective laser melting in this embodiment is as follows:

[0037] 1) Graphene and 1-pyrenebutyric acid were placed in a beaker at a mass ratio of 1:0.03, and an appropriate amount of ethanol was added. The mixture was ultrasonically dispersed in an ultrasonic machine to obtain a dispersion, which was then freeze-dried. The ultrasonic dispersion time was 0.5 h, the freeze-drying temperature was -50°C, and the freeze-drying time was 24 h.

[0038] 2) The freeze-dried powder from step 1), spherical alumina, and 1-pyrenebutyric acid were placed in a ball mill, filled with liquid nitrogen and quenched for a period of time, and then vacuum ball milled to obtain modified graphene; the mass ratio of graphene to spherical alumina was 1:5, the 1-pyrenebutyric acid was 2 wt% of the spherical alumina, the liquid nitrogen quenching time was 1 hour, the ball-to-material ratio was 6:1, the rotation speed was 200 rpm, and the ball milling was carried out for 2 hours;

[0039] 3) placing the modified graphene, high-purity spherical magnesium powder, and 1-pyrenebutyric acid in a ball mill, filling the mill with liquid nitrogen, and ball milling to obtain a modified graphene-magnesium powder mixture, which was then vacuum-dried; the mass ratio of the modified graphene to the high-purity magnesium powder was 1:6, and the amount of 1-pyrenebutyric acid was 1.0 wt % of the mass of the magnesium powder; the milling balls were immersed in liquid nitrogen, the ball-to-material ratio was 6:1, the speed was 100 rpm, and the milling was carried out for 2 h; the vacuum drying temperature was 50°C, and the drying time was 8 h;

[0040] 4) The dried modified graphene-magnesium powder mixture was used as a raw material for selective laser melting (SLM) under argon protection, with a laser power of 250 W, a scanning speed of 1.0 m / s, and a layer thickness of 0.03 mm.

[0041] The graphene content in the graphene-reinforced magnesium-based composite material prepared in this example is 2.3 wt %.

[0042] Example 3

[0043] A method for preparing a graphene-reinforced magnesium-based composite material by selective laser melting in this embodiment is as follows:

[0044] 1) Graphene and 1-pyrenebutyric acid were placed in a beaker at a mass ratio of 1:0.01, an appropriate amount of ethanol was added, and the mixture was ultrasonically dispersed in an ultrasonic machine to obtain a dispersion. The dispersion was then freeze-dried; the ultrasonic dispersion time was 0.5 h, the freeze-drying temperature was -50°C, and the freeze-drying time was 24 h;

[0045] 2) The freeze-dried powder from step 1), spherical alumina, and 1-pyrenebutyric acid were placed in a ball mill, filled with liquid nitrogen and quenched for a period of time, and then vacuum ball milled to obtain modified graphene; the mass ratio of graphene to spherical alumina was 1:4, the 1-pyrenebutyric acid was 3 wt% of the spherical alumina, the liquid nitrogen quenching time was 2 h, the ball-to-material ratio was 7:1, the rotation speed was 200 rpm, and the ball milling was carried out for 2 h;

[0046] 3) placing the modified graphene, high-purity spherical magnesium powder, and 1-pyrenebutyric acid in a ball mill, filling the mill with liquid nitrogen, and milling to obtain a modified graphene-magnesium powder mixture, which was then vacuum-dried; the mass ratio of the modified graphene to the high-purity magnesium powder was 1:5, and the amount of 1-pyrenebutyric acid was 1.5 wt % of the mass of the magnesium powder; the milling balls were immersed in liquid nitrogen, the ball-to-material ratio was 6:1, the speed was 100 rpm, and the milling was carried out for 2 h; the vacuum drying temperature was 50°C, and the drying time was 8 h;

[0047] 4) The dried modified graphene-magnesium powder mixture was used as a raw material for selective laser melting (SLM) under argon protection, with a laser power of 350 W, a scanning speed of 1.5 m / s, and a layer thickness of 0.04 mm.

[0048] The graphene content in the graphene-reinforced magnesium-based composite material prepared in this example is 3.2 wt %.

[0049] Example 4

[0050] A method for preparing a graphene-reinforced magnesium-based composite material by selective laser melting in this embodiment is as follows:

[0051] 1) Graphene and 1-pyrenebutyric acid were placed in a beaker at a mass ratio of 1:0.03, and an appropriate amount of ethanol was added. The mixture was ultrasonically dispersed in an ultrasonic machine to obtain a dispersion, which was then freeze-dried. The ultrasonic dispersion time was 0.5 h, the freeze-drying temperature was -50°C, and the freeze-drying time was 24 h.

[0052] 2) The freeze-dried powder from step 1), spherical alumina, and 1-pyrenebutyric acid were placed in a ball mill, filled with liquid nitrogen and quenched for a period of time, and then vacuum ball milled to obtain modified graphene; the mass ratio of graphene to spherical alumina was 1:3, the 1-pyrenebutyric acid was 3 wt% of the spherical alumina, the liquid nitrogen quenching time was 2 h, the ball-to-material ratio was 7:1, the rotation speed was 200 rpm, and the ball milling was carried out for 2 h;

[0053] 3) placing the modified graphene, high-purity spherical magnesium powder, and 1-pyrenebutyric acid in a ball mill, filling the mill with liquid nitrogen, and milling to obtain a modified graphene-magnesium powder mixture, which was then vacuum-dried. The mass ratio of the modified graphene to the high-purity magnesium powder was 1:4, and the amount of 1-pyrenebutyric acid was 2.0 wt % of the mass of the magnesium powder. The milling balls were immersed in liquid nitrogen, the ball-to-material ratio was 6:1, the speed was 100 rpm, and the milling was carried out for 2 h. The vacuum drying temperature was 50°C and the drying time was 8 h.

[0054] 4) The dried modified graphene-magnesium powder mixture was used as a raw material for selective laser melting (SLM) under argon protection, with a laser power of 250 W, a scanning speed of 1.0 m / s, and a layer thickness of 0.05 mm.

[0055] The graphene content in the graphene-reinforced magnesium-based composite material prepared in this example is 4.8 wt %.

[0056] The room temperature mechanical properties of the graphene magnesium-based composite materials obtained in Examples 1-4 are detailed in Table 1.

[0057] Table 1 Room temperature mechanical properties of graphene magnesium-based composite materials obtained in Examples 1 to 4

[0058]

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting, characterized in that: The following steps are involved: 1) Graphene and 1-pyrenebutyric acid are uniformly dispersed in ethanol, and then freeze-dried to obtain a powder; 2) placing the freeze-dried powder obtained in step 1), spherical alumina, and 1-pyrenebutyric acid in a ball mill, filling it with liquid nitrogen for quenching for a period of time, and then vacuum ball milling to obtain modified graphene; 3) placing the modified graphene, high-purity spherical magnesium powder, and 1-pyrenebutyric acid in a ball mill, filling it with liquid nitrogen, submerging the grinding balls in the liquid nitrogen, ball milling, and vacuum drying to obtain a modified graphene-magnesium powder mixture; 4) Using the modified graphene-magnesium powder mixture as a raw material for selective laser melting, performing selective laser melting under argon protection to obtain a selective laser melting-formed graphene reinforced magnesium-based composite material.

2. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, characterized in that: In the step 1), the mass ratio of graphene to 1-pyrenebutyric acid is 1:0.01-0.

03.

3. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In the step 1), the ultrasonic dispersion time is 0.5-2 h, the freeze-drying temperature is -50°C-0°C, the vacuum degree is <0.1 mBar, and the freeze-drying time is 24-48 h.

4. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In the step 2), the mass ratio of graphene to spherical alumina is 1:3-6, and the 1-pyrenebutyric acid is 1-3 wt% of the spherical alumina.

5. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In the step 2), the liquid nitrogen quenching time is 0.5-2 h, and the ball milling conditions are: ball-to-material ratio 5-7:1, rotation speed 200-300 rpm, and ball milling for 2-4 h.

6. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In step 3), the high-purity spherical magnesium powder has a magnesium content of 99.8% and a particle size of 48-60 μm.

7. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In the step 3), the mass ratio of modified graphene to high-purity magnesium powder is 1:4-7, and the content of 1-pyrenebutyric acid is 0.5-2 wt% of the mass of the magnesium powder.

8. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In step 3), the ball milling conditions are: ball-to-material ratio 5-7:1, rotation speed 100-200 rpm, and ball milling 1-3 h.

9. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: In step 4), the laser power is 200-350 W, the scanning speed is 0.5-1.5 m / s, and the layer thickness is 0.02-0.05 mm.

10. The method for preparing graphene-reinforced magnesium-based composite materials by selective laser melting according to claim 1, wherein: The graphene content in the graphene-reinforced magnesium-based composite material prepared by the preparation method is 1-5 wt%.

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