CN113881875B - Three-dimensional framework structure metal reinforced aluminum matrix composite material and preparation method thereof - Google Patents

Abstract

The invention relates to a metal matrix composite material, in particular to a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure and a preparation method thereof. The volume fraction in the composite material is 30%-70%; it includes the following steps: S1: prepare the prefabricated block of the reinforcement by additive manufacturing technology; S2: melt the aluminum matrix under a protective atmosphere to obtain a metal aluminum melt; S3: make the reinforcement After the body prefabricated block is preheated and kept warm, it is placed in a press together with the mold, and the metal aluminum melt is poured into the mold, and the temperature of the press table is controlled to carry out pressure infiltration; S4: After the pressure is released, it is naturally cooled to room temperature to obtain Metal-reinforced aluminum matrix composites with three-dimensional skeleton structure. Compared with the prior art, the invention can improve the thermal conductivity of the aluminum-based composite material under the condition of obviously improving the strength and modulus of the composite material, and realize the improvement of the comprehensive performance of the aluminum-based composite material.

Description

Metal-reinforced aluminum matrix composite material with three-dimensional skeleton structure and preparation method thereof

technical field

The invention relates to a metal-based composite material, in particular to a metal-reinforced aluminum-based composite material with a three-dimensional skeleton structure and a preparation method thereof.

Background technique

With the rapid development of modern industry, higher and higher requirements are put forward for the comprehensive performance of modern new materials, that is, to realize the integration of material structure and function, especially in the fields of energy and aerospace, this demand is particularly urgent. The performance of a single material has gradually become difficult to meet the demand for comprehensive performance of materials in some fields.

As one of the most commonly used metals in industry, aluminum is often used as a good substitute for precious metal copper in the fields of power transportation and electronic products due to its low density, low cost, corrosion resistance, good thermal conductivity and easy recycling. Taste. However, due to its low strength and modulus, and there is no aluminum alloy that can maintain high thermal conductivity while having high strength, these shortcomings limit the application of metal aluminum in the fields of energy and functional materials. Therefore, the preparation of aluminum matrix composites with high strength and high thermal conductivity is one of the important ways to solve this problem.

At present, copper-aluminum composite materials are one of the important methods to achieve high thermal conductivity. The good thermal and electrical conductivity of copper is used to improve the overall thermal and electrical conductivity of composite materials. The strength of copper-aluminum composites can be improved by heat treatment, but the traditional composite material preparation technology cannot obtain uniformly distributed reinforcements, and thus cannot obtain composite materials with controllable properties.

The three-dimensional skeleton reinforcement can change the stress distribution state of the composite material, and the three-dimensional skeleton structure can realize the uniform and controllable distribution of the reinforcement, thereby improving or even regulating the mechanical properties, thermal conductivity and other comprehensive properties of the composite material. Due to the small and complex structure of the three-dimensional reinforcement, it is difficult to complete the preparation by traditional methods. At present, the preparation methods of composite materials mainly include rolling, welding, surface deposition, composite casting, powder sintering and other methods. However, these methods generally have problems such as long preparation period, weak interfacial bonding, and poor performance stability. High thermal conductivity aluminum matrix composite.

Contents of the invention

With the rapid development of additive manufacturing technology, small-sized, high-precision three-dimensional reinforcements can be quickly prepared by using selective laser melting technology for structural design through space modeling software. However, due to the immature manufacturing process, high porosity, and uncontrollable microstructure, this technology is still not widely used in the preparation of metal matrix composites. The invention combines the pressure infiltration method and the method of additive manufacturing to manufacture solid metal matrix composite materials, which reduces the porosity of the composite materials and limits the influence of the current shortcomings of additive manufacturing on the performance of the composite materials.

The object of the present invention is to provide a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure and a preparation method thereof in order to solve the above problems. This method combines the two technologies of selective laser melting and pressure infiltration, and composites the metal three-dimensional reinforcement precast block formed by selective laser melting with the aluminum matrix, which improves the strength and modulus of the material while improving the three-dimensional reinforcement aluminum matrix composite The thermal conductivity of the material realizes the structural and functional integration of the aluminum matrix composite material, that is, the combination of the strength and thermal conductivity of the aluminum matrix composite material is realized.

The object of the present invention is achieved through the following technical solutions:

The first aspect of the present invention provides a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure, the composite material is composed of a prefabricated block of a reinforcement body and an aluminum matrix, and the volume fraction of the reinforcement body in the aluminum matrix composite material is 30%- 70%, the reinforcement prefabricated block has a three-dimensional skeleton structure.

Preferably, the material of the reinforcement prefabricated block is Cu, W or Ti.

Preferably, the aluminum substrate is aluminum or aluminum alloy.

Preferably, the metal-reinforced aluminum matrix composite material with three-dimensional skeleton structure has a strength of 300-800 MPa, a modulus of 100-350 GPa, and an average thermal conductivity of 100-300 W/(m·K).

The second aspect of the present invention provides a method for preparing a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure, which is characterized in that it includes the following steps:

S1: Preparation of reinforced prefabricated blocks with three-dimensional skeleton structure by additive manufacturing technology;

S2: heating and melting the aluminum substrate under a protective atmosphere to obtain a metal aluminum melt;

S3: After preheating and keeping warm the reinforcement prefabricated block obtained in step S1, put it in a press together with the mold, pour the metal aluminum melt obtained in step S2 into the mold, control the temperature of the press table, and then press impregnation;

S4: naturally cool to room temperature after depressurization, and obtain the metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure.

Preferably, the additive manufacturing technology described in step S1 is preferably a selective laser melting technology, which can provide the highest manufacturing precision and can meet the design and manufacturing requirements of fine skeletons. At the same time, the surface of the material produced by the selective laser melting technology has a fine roughness, which is conducive to the formation of a tight interface bond during the pressure infiltration process, so its production has high precision, strong repeatability, and excellent efficiency. The manufacturing accuracy of this technology is 0.1mm, and a certain volume shrinkage will occur during the solidification process. Therefore, when using computer software for structural design, an allowance of about 5% needs to be added to ensure the dimensional accuracy of the three-dimensional reinforcement.

The preparation process of additive manufacturing can ensure that the reinforcement prefabricated block has high density and uniform microstructure.

Preferably, in the preparation process of the selective laser melting technology, the substrate on which the reinforcement prefabricated block is placed is made of the same material as the reinforcement prefabricated block.

Preferably, the preheating temperature of the substrate in the preparation process of the selective laser melting technology is 75-200°C.

Preferably, the power of the laser in the preparation process of the selective laser melting technology is 200-400W.

Preferably, the diameter of the laser beam in the preparation process of the selective laser melting technology is 0.1 mm.

Preferably, the scanning pitch in the preparation process of the selective laser melting technology is 0.05mm.

Preferably, the oxygen content in the preparation process of the selective laser melting technology is less than 1000ppm.

Preferably, the protective atmosphere in step S2 is nitrogen, helium or argon atmosphere.

Preferably, the heating and melting temperature in step S2 is 700-800°C.

Preferably, the preheating and holding in step S3 is preheating to 450-650° C. and holding for 1-3 hours. When preheating to above 450°C, a layer of black oxide will be formed on the surface of the reinforcement prefabricated block. Since this oxide will not have a serious impact on the interface reaction and will not block the infiltration channel of the metal aluminum melt, so No special surface treatment is required for the surface oxide.

Preferably, controlling the temperature of the press table in step S3 is to control the temperature of the press table to be greater than 200°C.

Preferably, the pressure of the pressure infiltration described in step S3 is 30-70 MPa, and the load holding time is 10-30s.

Preferably, the pressure of the pressure infiltration is 40-50 MPa.

Keeping the reinforcement prefabricated block dry during the preparation process is conducive to the formation of dense interfacial reaction products.

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

1. The present invention prepares a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure, which can improve the thermal conductivity of the aluminum matrix composite material while significantly improving the strength and modulus of the composite material, and realize the comprehensive performance of the aluminum matrix composite material improvement.

2. The present invention combines two technologies of selective laser melting and pressure infiltration. The method of additive manufacturing, that is, the selective laser melting technology, can realize the personalized production of the skeleton structure according to the actual production needs, and has the characteristics of high precision, repeatability and high production efficiency. The pressure infiltration technology is beneficial to the filling of the metal aluminum melt in the void of the three-dimensional skeleton reinforcement, and realizes the dense bonding of the interface of the aluminum matrix composite. The combination of the two technical methods can successfully manufacture solid high-density skeleton reinforcement composites with complex artificially designed geometric structures, and form a dense interfacial bond, realizing the precise control of the macroscopic morphology of composite reinforcements, thereby enabling regulation Comprehensive properties of composite materials.

3. The preparation method of the aluminum-based composite material used in the present invention is simple and feasible, with high preparation efficiency, low cost, and no pollution in the preparation process. The shape and various parameters of the reinforcement can be designed according to actual needs, and the design flexibility is high.

Description of drawings

Fig. 1 is a three-dimensional structure schematic diagram of a three-dimensional reinforcement prefabricated block designed in Example 1 of the present invention;

Fig. 2 is a bimetal composite interface diagram of a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure prepared in Example 1 of the present invention;

Fig. 3 is a scanning electron microscope image of a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure prepared in Example 1 of the present invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

In the following examples, the aluminum used is AL99.70 high-purity aluminum produced by Zhengdi Metal Materials Co., Ltd.; the copper powder used is a spherical powder with a purity ≥ 99.99% produced by Zhuyu New Material Technology Co., Ltd Copper powder, CAS No. 7440-50-8; the titanium powder used is HYF-Ti spherical titanium powder produced by Chengdu Huayin Powder Technology Co., Ltd.; the tungsten powder used is Beijing Xingrongyuan Technology Co., Ltd. The brand of production is W99.9 high-purity spherical tungsten powder, and the aluminum-zinc alloy used is 7075 aluminum alloy.

Example 1

A metal-reinforced aluminum-matrix composite material with a three-dimensional skeleton structure. The composite material is composed of a reinforcement prefabricated block and an aluminum matrix. The volume fraction of the aluminum matrix in the composite material is 30%-70%, and the reinforcement prefabricated block has a three-dimensional skeleton structure.

More specifically, in this example:

Aluminum is selected as the aluminum matrix, and pure copper powder is used as the preparation material of the reinforcement prefabricated block.

Firstly, the UG/NX computer 3D modeling software is used to design and simulate the structure of the 3D skeleton reinforcement to preliminarily confirm the stability and feasibility of the reinforcement. As shown in Fig. 1, it can be seen that the volume fraction of the skeleton designed in this embodiment is 33%, and the size of the structural unit is finer, which can give full play to the processing advantages of the selective laser melting technology. Use Magics 3D slicing software to pre-process the 3D model, then use pure copper powder as raw material, and use selective laser melting technology to add material to the 3D reinforcement. Under the action of the focused laser beam, the copper powder is melted and then re-solidified, layer by layer. A prefabricated block of pure copper reinforcement with a three-dimensional skeleton structure is produced. During the manufacturing process, the substrate with the same material as the reinforcement prefabricated block is preheated to 200°C, the power of the laser is selected as 400W, the diameter of the laser beam is about 0.1mm, the scanning distance is about 0.05mm, and the oxygen content is required to be less than 1000ppm. Since the manufacturing accuracy of this technology is about 0.1 mm, and a certain volume shrinkage will occur during the solidification process, it is necessary to add about 5% margin to ensure the dimensional accuracy of the three-dimensional reinforcement when using computer software for structural design.

Weigh 8 kg of metal aluminum ingots and a refining agent with a mass fraction of 0.5% of the metal aluminum ingots. The refining agent can be produced by Yongkang Qixin Trading Co., Ltd. to settle impurities in the aluminum ingots, and heat them in a furnace to After standing at 800°C for 12 hours to remove foam on the surface of the molten aluminum, a protective atmosphere of argon gas was introduced to obtain a metal aluminum melt for pressure infiltration.

Place the reinforcement prefabricated block in a box-type high-temperature furnace to preheat to 550°C, keep it warm for 1 hour after reaching the preheating temperature, and place the prefabricated block together with the mold at the correct position of the press. The obtained metal aluminum melt is poured into the cavity of the mold, the temperature of the press table is controlled to be higher than 200° C., and then the pressure infiltration is carried out. The pressure applied during pressure infiltration was 50 MPa, and the load holding time was 30 s. After the pressure was released, it was naturally cooled to room temperature to obtain a metal-reinforced aluminum matrix composite ingot with a three-dimensional skeleton structure. As shown in Figure 2 and Figure 3, it can be seen from Figure 2 that the copper-aluminum interface in the aluminum-based composite material prepared in this embodiment is tightly bonded, and there is no obvious metallurgical defect; it can be seen from Figure 3 that the aluminum alloy prepared in this embodiment Dendrite interfacial reaction products exist at the interface of matrix composites, which are copper-aluminum intermetallic compounds.

The pure copper three-dimensional skeleton structure reinforced aluminum matrix composite material prepared in this example has a yield strength of 340MPa and a modulus of 142GPa without heat treatment, which is improved compared with pure copper and pure aluminum. At the same time, The average thermal conductivity of the aluminum-based composite material is 234W/(m·K), which achieves high thermal conductivity while increasing the strength.

Example 2

A metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure. The composite material is composed of a reinforcement prefabricated block and an aluminum matrix. The volume fraction of the reinforcement in the composite material is 30%-70%. The reinforcement prefabricated block has a three-dimensional skeleton structure.

More specifically, in this example:

Aluminum is selected as the aluminum matrix, and pure titanium powder is used as the preparation material of the reinforcement prefabricated block.

Firstly, the UG/NX computer 3D modeling software is used to design and simulate the structure of the 3D skeleton reinforcement to preliminarily confirm the stability and feasibility of the reinforcement. The volume fraction of the skeleton designed in this embodiment is 30%, and the size of the structural unit is relatively fine, which can give full play to the processing advantages of the selective laser melting technology. Use Magics 3D slicing software to pre-process the 3D model, then use pure titanium powder as raw material, and use selective laser melting technology to add material to the 3D reinforcement. Under the action of the focused laser beam, the titanium powder is melted and then re-solidified, layer by layer. A prefabricated block of pure titanium reinforcement with a three-dimensional skeleton structure is manufactured. During the manufacturing process, the substrate with the same material as the reinforcement prefabricated block is preheated to 75°C, the power of the laser is selected as 200W, the diameter of the laser beam is about 0.1mm, the scanning distance is about 0.05mm, and the oxygen content is required to be less than 1000ppm. Since the manufacturing accuracy of this technology is about 0.1 mm, and a certain volume shrinkage will occur during the solidification process, it is necessary to add about 5% margin to ensure the dimensional accuracy of the three-dimensional reinforcement when using computer software for structural design.

Weigh 8 kilograms of metal aluminum ingots, and a refining agent with a mass fraction of 0.5% metal aluminum ingots, produced by Yongkang Qixin Trading Co., Ltd., used to settle impurities in aluminum ingots, and put them into a furnace and heat them to 700°C , After standing still for 12 hours to remove foam on the surface of the aluminum liquid, a nitrogen protective atmosphere was introduced to obtain a metal aluminum melt for pressure infiltration.

Place the reinforcement prefabricated block in a box-type high-temperature furnace to preheat to 650°C, keep warm for 3 hours after reaching the preheating temperature, and place the prefabricated block together with the mold at the correct position of the press. The obtained metal aluminum melt is poured into the cavity of the mold, the temperature of the press table is controlled to be higher than 200° C., and then the pressure infiltration is carried out. The pressure applied in the pressure infiltration is 70MPa, and the load holding time is 10s. After the pressure is released, it is naturally cooled to room temperature to obtain a metal-reinforced aluminum matrix composite ingot with a three-dimensional skeleton structure. In the aluminum-based composite material prepared in this example, the titanium-aluminum interface is closely bonded, and there is no obvious metallurgical defect; the aluminum-based composite material prepared in this example has a dendritic interface reaction product at the interface, which is a titanium-aluminum intermetallic compound.

The pure titanium three-dimensional skeleton structure reinforced aluminum matrix composite material prepared in this example has a yield strength of 345MPa and a modulus of 120GPa without heat treatment, which is improved compared with pure titanium and pure aluminum. At the same time , the average thermal conductivity of the aluminum matrix composite material is 150W/(m·K), while improving the strength, a higher thermal conductivity is achieved.

Example 3

A metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure. The composite material is composed of a reinforcement prefabricated block and an aluminum matrix. The volume fraction of the reinforcement in the composite material is 30%-70%. The reinforcement prefabricated block has a three-dimensional skeleton structure.

More specifically, in this example:

Al-Zn alloy is selected as the aluminum matrix, and pure tungsten powder is used as the preparation material of the reinforcement prefabricated block.

Firstly, the UG/NX computer 3D modeling software is used to design and simulate the structure of the 3D skeleton reinforcement to preliminarily confirm the stability and feasibility of the reinforcement. The volume fraction of the skeleton designed in this embodiment is 70%, and the size of the structural unit is relatively fine, which can give full play to the processing advantages of the selective laser melting technology. Use Magics 3D slicing software to pre-process the 3D model, then use pure tungsten powder as raw material, and use selective laser melting technology to add material to the 3D reinforcement. Under the action of the focused laser beam, the tungsten powder is melted and then re-solidified, layer by layer. A prefabricated block of pure tungsten reinforcement with a three-dimensional skeleton structure is produced. During the manufacturing process, the substrate with the same material as the reinforcement prefabricated block is preheated to 120°C, the power of the laser is selected as 250W, the diameter of the laser beam is about 0.1mm, the scanning distance is about 0.05mm, and the oxygen content is required to be less than 1000ppm. Since the manufacturing accuracy of this technology is about 0.1 mm, and a certain volume shrinkage will occur during the solidification process, it is necessary to add about 5% margin to ensure the dimensional accuracy of the three-dimensional reinforcement when using computer software for structural design.

Weigh 8 kg of Al-Zn alloy, and a refining agent with a mass fraction of 0.5% Al-Zn alloy, produced by Yongkang Qixin Trading Co., Ltd., used to settle impurities in Al-Zn alloy, put it into a furnace and heat it to 750 ℃, after standing still for 12 hours to remove foam on the surface of the molten aluminum, a helium protective atmosphere was introduced to obtain a metal aluminum melt for pressure infiltration.

Place the reinforcement prefabricated block in a box-type high-temperature furnace to preheat to 600°C, keep warm for 3 hours after reaching the preheating temperature, and place the prefabricated block together with the mold at the correct position of the press. The obtained metal aluminum melt is poured into the cavity of the mold, the temperature of the press table is controlled to be higher than 200° C., and then the pressure infiltration is carried out. The pressure applied in the pressure infiltration is 40MPa, and the load holding time is 25s. After the pressure is released, it is naturally cooled to room temperature to obtain a metal-reinforced aluminum matrix composite ingot with a three-dimensional skeleton structure. The tungsten-aluminum interface in the aluminum-based composite material prepared in this example is closely bonded, and there is no obvious metallurgical defect; the dendritic interfacial reaction product exists at the interface of the aluminum-based composite material prepared in this example, which is a tungsten-aluminum intermetallic compound.

The pure tungsten three-dimensional skeleton structure reinforced aluminum matrix composite material prepared in this example has a yield strength of 800MPa and a modulus of 350GPa without heat treatment, which is improved compared with pure tungsten and pure aluminum. At the same time , the average thermal conductivity of the aluminum matrix composite material is 180W/(m·K), while improving the strength, a higher thermal conductivity is achieved.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (5)

1. A method for preparing a metal-reinforced aluminum-matrix composite with a three-dimensional skeleton structure, characterized in that the method combines two techniques of selective laser melting and pressure infiltration, specifically comprising the following steps: S1: Preparation of reinforcement prefabricated blocks with three-dimensional skeleton structure by additive manufacturing technology; additive manufacturing technology is selective laser melting technology; S2: heating and melting the aluminum substrate under a protective atmosphere to obtain a metal aluminum melt; S3: Preheat the reinforcement prefabricated block obtained in step S1 to 450-650°C and keep it warm for 1-3 hours, then place it in a press together with the mold, pour the metal aluminum melt obtained in step S2 into the mold, and control the pressure The temperature of the machine table top is higher than 200°C, and then pressure infiltration is carried out; the pressure of pressure infiltration is 30-70MPa, and the load holding time is 10-30s; S4: naturally cool to room temperature after depressurization, and obtain the three-dimensional skeleton structure metal Reinforced aluminum matrix composites; The volume fraction of the reinforcement in the aluminum matrix composite is 30%-70%; The material of the reinforcement prefabricated block is Cu, W or Ti; the strength of the three-dimensional skeleton structure metal reinforced aluminum matrix composite material is 300-800MPa, the modulus is 100-350GPa, and the average thermal conductivity is 100-300W /(m•K). 2 . The method for preparing a metal-reinforced aluminum matrix composite with a three-dimensional skeleton structure according to claim 1 , wherein the aluminum matrix is aluminum or an aluminum alloy. 3 . 3. The preparation method of a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure according to claim 1, wherein the preparation process parameters of the selective laser melting technique are as follows: (i) The substrate on which the reinforced prefabricated block is placed is made of the same material as the reinforced prefabricated block; (ii) The preheating temperature of the substrate is 75-200°C; (iii) The power of the laser is 200-400W; (iv) The diameter of the laser beam is 0.1mm; (v) The scanning distance is 0.05mm; (vi) The oxygen content is less than 1000 ppm. 4. A method for preparing a metal-reinforced aluminum matrix composite with a three-dimensional skeleton structure according to claim 1, wherein step S2 comprises the following steps: (i) The protective atmosphere is a nitrogen, helium or argon atmosphere; (ii) The heating and melting temperature is 700-800°C. 5 . The method for preparing a metal-reinforced aluminum matrix composite material with a three-dimensional skeleton structure according to claim 1 , wherein the pressure of the pressure infiltration is 40-50 MPa.

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