Titanium-aluminum-titanium three-layer metal composite material and preparation method and application thereof

Abstract

The invention discloses a titanium-aluminum-titanium three-layer metal composite material and a machining method and application thereof. The titanium-aluminum-titanium three-layer metal composite material comprises a middle metal layer, a first metal layer located on the upper surface of the middle metal layer and a second metal layer located on the lower surface of the middle metal layer, the first metal layer and the second metal layer are made of titanium plates or titanium alloy plates, and the middle metal layer is made of aluminum plates or aluminum alloy plates. The first metal layer, the middle metal layer and the second metal layer are formed through hot rolling, and metal atom diffusion layers are formed on bonding interfaces among the first metal layer, the second metal layer and the middle metal layer in the hot rolling process; the upper surface and the lower surface of the middle metal layer and the surfaces of the contact surfaces of the first metal layer, the second metal layer and the middle metal layer form rough surfaces with the average roughness of Ra3-5 through a texturing process, and the metal atom diffusion layer is diffused through the rough surfaces. The purpose of improving the material performance is achieved by improving the bonding interface between the titanium layer and the aluminum layer.

Description

Technical Field

[0001] The invention relates to the technical field of metal composite materials and processing thereof, and in particular to a titanium-aluminum-titanium three-layer metal composite material and a preparation method and application thereof. Background Art

[0002] Metal composite materials refer to composite materials formed by metallurgical bonding at the interface using composite technology or multiple metals with different chemical and mechanical properties. This material greatly improves the thermal expansion, strength, fracture toughness, impact toughness, wear resistance, electrical properties, magnetic properties and many other properties of single metal materials. There are many methods for producing metal composite materials, among which the most common solid-phase bonding methods are explosive welding and hot rolling.

[0003] At present, metal composite materials have been widely used in various fields such as construction, automobiles, ships, wind power, new energy, aerospace, etc. In addition, the global energy crisis has given rise to the demand for lightweight technology, and metal composite materials have become an irreplaceable choice in the application of some parts in the fields of electric vehicles, rail transportation, etc. With the development of the intelligent manufacturing industry, the demand for high-speed reciprocating parts with low density, high wear resistance, high rigidity and low cost is increasing, and metal composite materials can fully meet these needs.

[0004] However, the performance limitations of bimetallic composites and the difficulty in controlling the preparation cost have led researchers and the industry to actively explore new material combinations and preparation technologies in order to break through the existing limitations. In this context, trimetallic composites, as an innovative solution, have gradually entered people's field of vision and have shown great development potential and application value.

[0005] The titanium-aluminum-titanium three-layer composite material combines the high strength of titanium alloy with the lightweight characteristics of aluminum alloy, which greatly reduces the overall weight while ensuring strength. Titanium alloy itself has good corrosion resistance, and the aluminum layer has good thermal conductivity, which helps to quickly transfer and dissipate heat, so that the titanium-aluminum-titanium three-layer composite metal material can still remain stable in high temperature environments and is suitable for applications that require efficient heat dissipation; the titanium-aluminum-titanium three-layer composite metal material can be prepared by a variety of processes such as explosive compounding and rolling compounding, and has good processing performance, which provides convenience for its manufacture in various complex shapes and structures. The unique performance combination of the titanium-aluminum-titanium three-layer composite metal material makes it have broad application prospects in aerospace, automobile manufacturing, chemical equipment, and other fields. For example, in the aerospace field, it can be used to manufacture aircraft fuselages, wings and other components; in automobile manufacturing, it can be used to produce lightweight body structures and parts, or in the electronics field, it can be used to manufacture the shells and back panels of electronic products, and can also be used in the battery field. However, the preparation process of titanium-aluminum-titanium three-layer composite metal materials is relatively complicated, requiring multiple steps and precise control, which increases the production cost and difficulty of preparation, limiting its ability to be mass-produced; moreover, the interface bonding state between the titanium layer and the aluminum layer has a great influence on the overall performance of the material. If the interface bonding is poor, the strength and corrosion resistance of the material will be reduced. In addition, titanium-aluminum-titanium three-layer composite metal materials may produce microscopic defects such as holes and cracks. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a titanium-aluminum-titanium three-layer metal composite material, which improves the material properties by improving the bonding interface between the titanium and aluminum layers.

[0007] To solve the above problems, the technical solutions adopted in this application are as follows: The embodiment of the present application provides a titanium-aluminum-titanium three-layer metal composite material, including an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer, the plate materials for making the first metal layer and the second metal layer are titanium plates or titanium alloy plates, and the plate materials for making the intermediate metal layer are aluminum plates or aluminum alloy plates; the first metal layer, the intermediate metal layer, and the second metal layer are formed by hot rolling, and a metal atom diffusion layer is formed at the bonding interface between the first metal layer and the intermediate metal layer and at the bonding interface between the second metal layer and the intermediate metal layer during the hot rolling process; the upper and lower surfaces of the intermediate metal layer, the contact surface of the first metal layer and the intermediate metal layer, and the contact surface of the second metal layer and the intermediate metal layer are all formed into a rough surface with an average roughness of Ra3-5 through a texturing process, and the metal atom diffusion layer diffuses through the rough surface.

[0008] As a further preferred solution, in the embodiment of the present application, the thickness of the metal sheet used to make the first metal layer and the second metal layer is L 1 The thickness of the metal sheet used to make the intermediate metal layer is L 2 , where L 1 :L 2 =1:(2-4).

[0009] As a further preferred solution, the average thickness of the metal atom diffusion layer described in the embodiment of the present application is 2.5-8.5 μm.

[0010] As a further preferred solution, the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application has a yield strength of 180-230 MPa, a tensile strength of 250-300 MPa, and an elongation after fracture of 16.2-26.7%.

[0011] The present application also provides a method for preparing a titanium-aluminum-titanium three-layer metal composite material, which uses a hot rolling process to composite the titanium-aluminum-titanium three-layer metal to obtain a composite plate, and controls the process parameters to improve the microstructure of the titanium-aluminum-titanium three-layer metal bonding interface to achieve the purpose of improving the performance of the metal composite plate and meet the application requirements. The preparation method includes the following steps: Material pretreatment: Take titanium or titanium alloy plate as the first metal layer plate and the second metal layer plate, take aluminum or aluminum alloy plate as the middle metal layer plate, clean the first metal layer plate, the second metal layer plate and the middle metal layer plate to remove surface stains; Roughening treatment: roughening the first metal layer, the second metal layer and the middle metal layer, and roughening one surface of the first metal layer, one surface of the second metal layer and the upper and lower surfaces of the middle metal layer to form a rough surface with an average roughness of Ra3-5; Preheating and heat preservation: preheating the first metal layer plate, the second metal layer plate and the middle metal layer plate after the texturing treatment to the rolling temperature and keeping them warm for a predetermined time; Hot rolling composite: After the preheated middle metal layer is fixed, the rough surface of the first metal layer and the rough surface of the second metal layer are respectively stacked on the middle metal layer, and a titanium-aluminum-titanium three-layer metal composite plate is formed by hot rolling once.

[0012] As a further preferred scheme, in the pretreatment step described in the embodiment of the present application, ultrasonic cleaning is adopted, and the cleaning medium is water at 40±5°C; after cleaning, the washing is carried out in an air-cut dryer, and the drying temperature is 76-85°C.

[0013] As a further preferred solution, in the roughening treatment step described in the embodiment of the present application, the treatment is performed by one of sand blasting, shot blasting, electric spark and laser.

[0014] As a further preferred scheme, in the preheating and insulation steps described in the embodiment of the present application, the preheating temperature is 495-550°C, and the insulation time is 2-5min; during the insulation process, argon gas is continuously introduced into the insulation furnace, and the gas flow rate is 1-5m³ / h.

[0015] As a further preferred solution, in the hot rolling composite step described in the embodiment of the present application, a single rolling treatment is adopted, the hot rolling temperature is 495-550°C, the rolling speed is 2-5m / min, and the reduction rate is 30-45%; argon protection is used during the rolling process.

[0016] As a further preferred scheme, the preparation method described in the embodiment of the present application also includes a post-processing step after hot-rolled composite, in which 0.2-0.5 mm is cut off from the head and tail of the titanium-aluminum-titanium three-layer metal composite plate, and it is straightened with an automatic straightening machine before cutting.

[0017] The titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application is used to manufacture battery bipolar plates.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. During the hot rolling process of the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application, a metal atomic diffusion layer will be formed between the first metal layer (titanium or titanium alloy) and the middle metal layer (aluminum or aluminum alloy), and between the second metal layer (also titanium or titanium alloy) and the middle metal layer; this diffusion layer is formed due to the mutual penetration of metal atoms under high temperature and pressure, which significantly enhances the bonding strength between different metal layers.

[0019] 2. The titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application is treated with a roughening process to process the contact surfaces of each metal layer so that the roughness of these surfaces reaches the range of Ra3-5; this rough surface morphology not only increases the contact area between the metal layers, but also provides more channels and anchor points for the diffusion of metal atoms; therefore, the metal atom diffusion layer can be formed more evenly, further improving the bonding quality and strength between the layers. In addition, the roughening treatment is also beneficial to removing the oxide layer on the surface of the metal layer plate, which is beneficial to the composite of dissimilar metal plates during the rolling process.

[0020] 3. In the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application, titanium and titanium alloys have excellent corrosion resistance, high strength and low density, while aluminum and aluminum alloys have good electrical conductivity, thermal conductivity and machinability. Therefore, this composite metal material has broad application prospects in aerospace, automobile manufacturing, electronics and other fields.

[0021] 4. In the preparation method of the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application, the microstructure of the titanium-aluminum-titanium three-layer metal bonding interface can be further improved by controlling the hot rolling process parameters, such as rolling temperature, rolling speed and reduction, and the optimization of this microstructure helps to improve the mechanical properties, corrosion resistance and heat resistance of the composite plate, thereby meeting various application requirements; by optimizing the coordination between the steps of material pretreatment, texturing treatment, preheating and insulation, and hot rolling composite, efficient and high-quality composite plate preparation is achieved, and the performance and application field of the composite plate are significantly improved.

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a flow chart of the preparation process of the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application.

[0025] Figure 2 This is a SEM image of the cross section of the titanium-aluminum-titanium three-layer metal composite material described in Example 1 of the present application.

[0026] Figure 3 This is a SEM image of the cross section of the titanium-aluminum-titanium three-layer metal composite material described in Example 2 of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] The term "comprising" and other equivalent descriptions involved in the specification and claims of this application are intended to cover non-exclusive inclusions, including both the contents clearly described in the specification and claims, and the steps or units that are not described in the specification and claims but are inherent in the product, method or structure.

[0029] The embodiment of the present application provides a titanium-aluminum-titanium three-layer metal composite material, comprising an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer, the plate materials for making the first metal layer and the second metal layer are titanium plates or titanium alloy plates, and the plate materials for making the intermediate metal layer are aluminum plates or aluminum alloy plates; comprising an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer, the first metal layer and the second metal layer are titanium layers or titanium alloy layers, the intermediate metal layer is aluminum or aluminum alloy layers, the first metal layer, the intermediate metal layer The metal layer and the second metal layer are formed by hot rolling. The bonding interface between the first metal layer and the middle metal layer and the bonding interface between the second metal layer and the middle metal layer form a metal atom diffusion layer during the hot rolling process. The middle metal layer (aluminum or aluminum alloy layer) provides good electrical conductivity, thermal conductivity and lightweight characteristics. At the same time, aluminum and titanium can form a metallurgical bond under appropriate conditions to enhance the interlayer bonding strength. The middle metal layer (aluminum or aluminum alloy layer) can make the titanium-aluminum-titanium three-layer metal composite material lightweight while maintaining high strength and corrosion resistance, thereby improving the overall performance. The titanium or titanium alloy layer, as the first metal layer and the second metal layer, provides excellent corrosion resistance and high strength, and is a key component of the composite material performance. The titanium or titanium alloy layer is located on the upper and lower sides of the aluminum layer, forming a protective barrier to prevent the aluminum layer from being corroded. Through the hot rolling process, the three layers of metal are tightly combined together. Under high temperature and pressure, the metal atoms diffuse to form a metallurgical bond, which ensures the interlayer bonding strength, making it difficult for the composite material to delaminate when subjected to force, thereby improving the stability and reliability of the overall structure. The upper and lower surfaces of the intermediate metal layer, the contact surface of the first metal layer and the intermediate metal layer, and the contact surface of the second metal layer and the intermediate metal layer are all roughened to form a rough surface with a roughness of Ra3-5 through a texturing process, and the metal atom diffusion layer diffuses through the rough surface. Through the texturing process, a rough surface is formed on the contact surface of the first metal layer, the intermediate metal layer and the second metal layer, and this rough surface increases the contact area and mechanical bite force between the metal layers; promotes the diffusion of metal atoms during the hot rolling process, and further enhances the bonding strength between the layers.

[0030] The thickness of the metal sheet used to make the first metal layer, the second metal layer and the intermediate metal layer affects whether the hot rolling process can proceed smoothly. An overly thick titanium layer will increase the pressure and temperature required for hot rolling, while an overly thin aluminum layer is insufficient to form an effective metallurgical bond. In the embodiment of the present application, a thicker aluminum layer is provided to better fill the gaps between the titanium layers during the hot rolling process, forming a tighter metallurgical bond. This tight bond helps to improve the overall strength of the composite material. The thickness of the metal sheet used to make the first metal layer, the second metal layer and the intermediate metal layer will also affect the performance of the composite material. The titanium layer provides high strength and excellent corrosion resistance, while the aluminum layer gives the composite material good ductility and lightweight properties. The thickness ratio of the two metals titanium and aluminum can be well balanced to achieve the performance of the composite metal material, so that the composite material has both high strength and good toughness; the presence of the aluminum layer can better disperse the stress when the composite material is subjected to external force, avoiding damage caused by stress concentration. The density of aluminum is much lower than that of titanium, so increasing the thickness of the aluminum layer (within a reasonable range) helps to reduce the overall density of the composite material and achieve lightweight; at the same time, aluminum has good thermal conductivity. Therefore, in the embodiment of the present application, in order to form a close metallurgical bond and improve the mechanical properties, corrosion resistance, lightweight characteristics and thermal conductivity of the composite material, the thickness of the metal sheet used to make the first metal layer and the second metal layer is L 1 The thickness of the metal sheet used to make the intermediate metal layer is L 2 , where L 1 :L 2 =1:(2-4). In a preferred embodiment, L 1 :L 2 =1:3. The metal atom diffusion layer is the key to achieve metallurgical bonding between the titanium layer and the aluminum layer. A thin diffusion layer will lead to incomplete bonding, while a thick diffusion layer will introduce brittle phases or produce stress concentration, which is not conducive to improving the overall bonding strength. In addition, an overly thick diffusion layer may contain more brittle intermetallic compounds (such as TiAl 3 ), these compounds easily become the initiation points of cracks when subjected to stress, thereby reducing the toughness of the composite material. In addition, the thickness of the diffusion layer will also affect the corrosion resistance, lightweight and thermal conductivity of the metal composite material. In order to ensure sufficient diffusion and bonding between titanium atoms and aluminum atoms, improve the bonding strength between layers, and avoid brittle fracture caused by stress concentration, in some embodiments of the present application, the average thickness of the metal atom diffusion layer is 2.5-8.5μm. In a preferred embodiment, the average thickness of the metal atom diffusion layer is 4.2-6.7μm.

[0031] As a further preferred solution, the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application has a yield strength of 180-230 MPa, a tensile strength of 250-300 MPa, and an elongation after fracture of 16.2-26.7%.

[0032] The present application also provides a method for preparing a titanium-aluminum-titanium three-layer metal composite material, which uses a hot rolling process to composite the titanium-aluminum-titanium three-layer metal to obtain a composite plate, and controls the process parameters to improve the microstructure of the titanium-aluminum-titanium three-layer metal bonding interface to achieve the purpose of improving the performance of the metal composite plate and meet the application requirements. The preparation method includes the following steps: Material pretreatment: Take titanium or titanium alloy plate as the first metal layer plate and the second metal layer plate, take aluminum or aluminum alloy plate as the middle metal layer plate, clean the first metal layer plate, the second metal layer plate and the middle metal layer plate to remove surface stains; Roughening treatment: roughening treatment is performed on the first metal layer plate, the second metal layer plate and the middle metal layer plate, and roughening treatment is performed on one surface of the first metal layer plate, one surface of the second metal layer plate and the upper and lower surfaces of the middle metal layer to form a rough surface with a roughness of Ra3-5; Preheating and heat preservation: preheating the first metal layer plate, the second metal layer plate and the middle metal layer plate after the texturing treatment to the rolling temperature and keeping them warm for a predetermined time; Hot rolling composite: After the preheated middle metal layer is fixed, the rough surface of the first metal layer and the rough surface of the second metal layer are respectively stacked on the middle metal layer, and a titanium-aluminum-titanium three-layer metal composite plate is formed by hot rolling once.

[0033] The appropriate cleaning medium temperature can ensure that the metal surface reaches the ideal cleanliness, which is crucial for subsequent texturing and hot rolling. In the pretreatment step described in the embodiment of the present application, ultrasonic cleaning is used, and the cleaning medium is 40±5℃ water; such a temperature can ensure that ultrasonic cleaning achieves the best cleaning efficiency, effectively removes stains, grease and other impurities on the metal surface, helps to avoid oxidation or corrosion of the metal surface due to overheating, protects the integrity of the metal surface, and provides a good foundation for subsequent texturing and hot rolling. In the embodiment of the present application, the direct effect of the drying temperature on the metal microstructure is limited, but too high a drying temperature will cause slight oxidation or thermal deformation of the metal surface, thereby affecting the quality and efficiency of hot rolling. Therefore, after cleaning, a wind shear dryer is used for drying, and the drying temperature is 76-85℃. The selection of the drying temperature also takes into account the avoidance of deformation or thermal stress of the metal due to overheating. Within this temperature range, the metal can maintain a stable shape and will not introduce additional defects due to the drying process; at the same time, a stable drying temperature also helps to maintain the continuity and stability of the production line and improve the overall production efficiency. In this scheme, the selection of medium temperature and drying temperature not only ensures the cleanliness and integrity of the metal surface, but also provides a good foundation for the subsequent hot rolling composite process, which helps to improve the performance and quality of the final composite plate.

[0034] In the preparation process of the titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application, the main purpose of the roughening treatment step is to form a rough surface with a roughness of Ra3-5 on one surface of the first metal layer, one surface of the second metal layer, and the upper and lower surfaces of the intermediate metal layer; this rough surface can enhance the mechanical bite between the metal layers, thereby promoting the formation of metallurgical bonding during the hot rolling composite process, and improving the bonding strength and overall performance of the composite plate. In the roughening treatment step described in the embodiment of the present application, one of sandblasting, shot peening, electric spark, and laser is used for treatment. Preferably, in some embodiments of the present application, sandblasting and shot peening are used for roughening treatment. When sandblasting is used, the sandblasting material is quartz sand. In order to effectively control the roughness of the rough surface, the sandblasting pressure is 0.1-0.3MPa, the nozzle is 60-100mm away from the surface of the metal layer to be treated, and the spray angle is 30-60°.

[0035] In this application, the main purpose of preheating is to make the metal layer plate reach a certain temperature uniformity before hot rolling, reduce the energy consumption during hot rolling, and also help to reduce the thermal stress during hot rolling and prevent the metal layer plate from deforming or cracking. Reasonable preheating helps the microstructure inside the metal to change, such as grain refinement, thereby improving the strength and toughness of the metal plate; it can reduce the probability of sintering, oxidation and peeling defects on the surface of the metal plate during hot rolling. Therefore, in the preheating and insulation steps described in the embodiment of the present application, the preheating temperature is 495-550℃. The purpose of insulation is to make the metal layer plate reach uniform heating at the preheating temperature and promote the completion of processes such as phase change. Reasonable insulation time can ensure the stability of the performance of the metal plate during hot rolling, avoid performance degradation caused by overheating or overcooling, and promote grain refinement, thereby improving the strength and toughness of the metal plate; it can also reduce energy consumption. Therefore, in the embodiments of the present application, the insulation time is 2-5min. During the insulation process, argon gas is continuously introduced into the insulation furnace. As an inert gas, argon gas protects the metal plate, prevents it from being oxidized at high temperatures, and keeps its surface clean and bright. Controlling the gas flow rate can not only protect the microstructure inside the metal from being destroyed to maintain its original performance, but also improve the quality of hot rolling and reduce defects caused by oxidation. In the embodiment of the present application, the gas flow rate is 1-5m³ / h.

[0036] In the hot rolling composite step described in the embodiment of the present application, the selection of hot rolling temperature has an important influence on the organization and performance of the titanium-aluminum-titanium three-layer metal material. Controlling the hot rolling temperature can ensure that the material obtains good plasticity and deformation ability during the rolling process; when the rolling temperature is appropriately increased, the deformation resistance of the material is reduced, and the plasticity is enhanced, which is conducive to obtaining a more uniform microstructure and better interface bonding strength; it can also promote the dynamic recrystallization of the material, refine the grains, and improve the mechanical properties and corrosion resistance of the material. Therefore, in a specific embodiment, the hot rolling temperature is 495-550℃; preferably, the hot rolling temperature is set to 500-520℃. The rolling speed is one of the key factors affecting the rolling effect and performance of the titanium-aluminum-titanium three-layer metal material. A reasonable rolling speed helps the material to form a stable deformation zone between the rollers and reduce the internal defects of the material caused by uneven speed. At the same time, a suitable rolling speed is conducive to heat conduction and heat dissipation inside the material, avoiding excessive temperature from causing material performance degradation. Therefore, in order to ensure that the metal layer is subjected to uniform pressure and friction during the rolling process of the material, and obtains the ideal microstructure and mechanical properties, the rolling speed is controlled to be 2-5m / min. The reduction rate mainly affects the interface bonding strength and mechanical properties of the titanium-aluminum-titanium three-layer metal material; with the increase of the reduction rate, the deformation degree inside the material increases, which is conducive to the close bonding of the interface and the homogenization of the microstructure; a higher reduction rate can also improve the tensile strength and yield strength of the material, but too high a reduction rate will cause too many defects and residual stresses inside the material, affecting the overall performance of the material. Therefore, in order to ensure that the material obtains good interface bonding and mechanical properties, in the embodiment of the present application, the reduction rate is controlled to be 30-45%. Argon protection is used during the rolling process, which can effectively prevent the material from reacting with oxygen, nitrogen, etc. in the air at high temperature, resulting in a decrease in material performance. Argon, as an inert gas, can provide an oxygen-free and nitrogen-free rolling environment to ensure that the material is rolled during the rolling process. The original chemical composition and microstructure of the material are maintained.

[0037] In this application, preheating is an important step before hot rolling. The selection of preheating temperature needs to comprehensively consider the properties, thickness and other characteristics of the material. The preheating temperature should be set to ensure that not only the titanium plate (titanium alloy plate) and the aluminum plate (aluminum alloy plate) are fully preheated, but also to ensure that the performance of the metal plate does not decrease due to excessive preheating temperature. Insufficient preheating may lead to insufficient material temperature during the rolling process, thereby affecting the plastic deformation ability and the quality of the finished product. The rolling temperature setting should ensure that the material is fully plastically deformed and will not cause the metal plate to overburn or performance degradation due to excessively high temperature. The control and adjustment of the preheating temperature and the rolling temperature jointly determine the temperature state and organizational evolution of the metal plate during the hot rolling forming process. The preheating temperature can provide a basis for the rolling temperature. Insufficient preheating will lead to insufficient material temperature during the rolling process, thus affecting the plastic deformation ability of the metal sheet and the quality of the finished product; the rolling temperature is a further adjustment and optimization of the preheating temperature to ensure that the material can obtain the best performance during the hot rolling process. The synergistic effect of the preheating temperature and the rolling temperature can significantly improve the plastic deformation ability and finished product quality of the material. By reasonably setting these two temperature parameters, it can be ensured that the material is fully plastically deformed during the hot rolling process and forms a good metallurgical bond. In an embodiment of the present application, the preheating temperature T1 and the hot rolling temperature T2 satisfy the relationship, T1=T2±20℃. Preferably, the preheating temperature T1 and the hot rolling temperature T2 satisfy the relationship: T1=T2+15℃.

[0038] As a further preferred scheme, the preparation method described in the embodiment of the present application also includes a post-processing step after hot-rolled composite, in which 0.2-0.5 mm is cut off from the head and tail of the titanium-aluminum-titanium three-layer metal composite plate, and it is straightened with an automatic straightening machine before cutting.

[0039] The titanium-aluminum-titanium three-layer metal composite material described in the embodiment of the present application is used to manufacture battery bipolar plates.

[0040] Example 1

[0041] The present embodiment provides a titanium-aluminum-titanium three-layer metal composite material, including an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer. The plate materials for making the first metal layer and the second metal layer are TA1 titanium plates with a thickness of 0.6 mm, and the plate materials for making the intermediate metal layer are 6013 aluminum plates with a thickness of 1.8 mm. The first metal layer, the intermediate metal layer, and the second metal layer are formed by hot rolling, and a metal atom diffusion layer is formed at the bonding interface between the first metal layer and the intermediate metal layer and at the bonding interface between the second metal layer and the intermediate metal layer during the hot rolling process; the upper and lower surfaces of the intermediate metal layer, the contact surface of the first metal layer and the intermediate metal layer, and the contact surface of the second metal layer and the intermediate metal layer are all formed into a rough surface with an average roughness of Ra4 through a texturing process, and the metal atom diffusion layer diffuses through the rough surface.

[0042] like Figure 1 As shown, the preparation method of the titanium-aluminum-titanium three-layer metal composite material comprises the following steps: Material pretreatment: Take two TA1 titanium plates as the first metal layer and the second metal layer, and take 6013 aluminum plate as the middle metal layer. Use ultrasonic cleaning to clean the two TA1 titanium plates and 6013 aluminum plates. The cleaning medium is 42°C water to remove surface stains. After cleaning, dry at 80°C. Roughening treatment: one surface of each TA1 titanium plate is roughened, and both surfaces of the 6013 aluminum plate are roughened, respectively forming a rough surface with an average roughness of Ra3; Preheating and insulation: Preheat the TA1 titanium plate and 6013 aluminum plate after texturing to 510℃ and keep them warm for 3 minutes; 99.9% argon gas is used for protection during the insulation process, and the air flow rate is controlled at 3m³ / h; Hot rolling composite: After the preheated 6013 aluminum plate is fixed, the rough surfaces of two TA1 titanium plates are stacked on the upper and lower surfaces of the 6013 aluminum plate, and a titanium-aluminum-titanium three-layer metal composite plate is formed by hot rolling at a time. The rolling temperature is 500°C, the rolling speed is 3m / min, and the pressing amount is 35%. A titanium-aluminum-titanium three-layer metal composite material with a thickness of 2.0mm is obtained.

[0043] The performance of the titanium-aluminum-titanium three-layer metal composite material described in the above Example 1 was tested, and the specific test items and the adopted test methods / standards are shown in Table 1 below. Figure 2 This is a cross-sectional SEM image of the titanium-aluminum-titanium three-layer metal composite material described in this embodiment. Figure 2 It shows that there is a metal atom diffusion layer at the titanium-aluminum bonding interface with a thickness of 3.92μm.

[0044] Table 1: Performance test results of the titanium-aluminum-titanium three-layer metal composite material of Example 1 Serial number Test items Test method / standard Test results 1 Interface bonding strength (MPa) GB / T 228.1-2021 26.5 2 Tensile strength (MPa) GB / T 228.1-2021 259.30 3 Yield strength (MPa) GB / T 228.1-2021 191.45 4 Elastic modulus (MPa) GB / T 228.1-2021 84 5 Density (g / cm³) GBT20042.6-2024 3.472 6 Resistance (µΩ·cm) GBT20042.6-2024 17.1 7 Corrosion current density (μA / cm²) GBT20042.6-2024 0.27 Based on the above Example 1, the effect of the roughness of the rough surface on the performance of the metal atom diffusion layer and the titanium-aluminum-titanium three-layer metal composite material was further explored, and different roughnesses were set, while other conditions remained the same as in Example 1. The specific settings and comparison results are shown in Table 2.

[0045] Table 2: Effect of roughness of rough surface on the properties of metal atom diffusion layer and titanium-aluminum-titanium three-layer metal composite material Serial number Average roughness of rough surface (Ra) Thickness of metal atom diffusion layer (μm) Interface bonding strength (MPa) Tensile strength (MPa) Yield strength (MPa) 1 0 0.79 18.2 221.23 166.23 2 1 1.13 19.4 237.89 170.78 3 2 2.43 21.9 256.45 172.45 4 3 3.92 26.5 259.30 191.45 5 4 5.27 27.4 268.76 194.89 6 5 6.46 26.3 252.98 189.34 7 6 8.14 23.1 248.30 182.99 8 7 8.98 21.6 245.67 176.67 The results in the above table show that the rough interface helps more atoms to diffuse, because the unevenness on the interface provides more diffusion channels and contact areas, therefore, as the roughness value increases, the thickness of the diffusion layer also increases. Although the roughness of the rough surface is large, after the thicker diffusion layer is formed, the roughness causes the diffusion rate to be limited, and defects such as cracks or delamination will be generated during the hot rolling process, which will cause the interface bonding force between the metal layers of the composite metal material to decrease, thereby affecting its processing performance and forming performance. The titanium-aluminum-titanium three-layer metal composite material described in this application has a yield strength of 180-230MPa and a tensile strength of 250-300MPa when meeting the application requirements, and the interface bonding force should be greater than 24 MPa, therefore, in the embodiments of the present application, the average roughness of the rough surface is controlled to Ra3-5.

[0046] On the basis of the above-mentioned Example 1, the effect of preheating temperature on the titanium-aluminum-titanium three-layer metal composite material was further discussed, and different preheating temperatures were set, while other conditions remained the same as those in Example 1. See Table 3 for specific preheating temperature settings and comparison results.

[0047] Table 3: Effect of preheating temperature on the properties of titanium-aluminum-titanium three-layer metal composites Serial number Preheating temperature (℃) Thickness of metal atom diffusion layer (μm) Interface bonding strength (MPa) Tensile strength (MPa) Yield strength (MPa) 1 450 1.01 19.4 228.7 194.0 2 460 1.73 21.7 242.4 193.1 3 475 2.71 24.2 261.2 193.3 4 490 3.35 25.8 259.1 195.2 5 500 3.90 27.2 264.1 192.4 6 520 4.31 29.4 261.2 195.3 7 550 3.46 26.1 259.3 193.0 8 560 5.98 23.1 247.9 192.4 The results in the above table show that as the preheating temperature increases, the mobility of titanium and aluminum atoms increases and the diffusion rate significantly accelerates, thereby promoting atoms to cross the interface and form a thicker diffusion layer. However, too high a preheating temperature may lead to the formation of brittle intermetallic compounds (such as TiAl 3 ), these compounds will significantly weaken the interface bonding strength. In addition, too high a temperature may also cause grain coarsening or local melting, further reducing the mechanical properties of the material. When the preheating temperature is controlled at 475-550℃, the various properties of the metal composite material can meet the application requirements.

[0048] On the basis of the above-mentioned Example 1, the influence of hot rolling temperature, rolling speed and reduction ratio on the performance was further discussed, and different hot rolling temperatures, rolling speeds and reduction ratios were set, but other conditions remained the same as in Example 1. The specific hot rolling temperature, rolling speed and reduction ratio settings and the comparison results are shown in Table 4.

[0049] Table 4: Effects of hot rolling temperature, rolling speed and reduction ratio on the properties of titanium-aluminum-titanium three-layer metal composites Serial number Hot rolling temperature (℃) Thickness of metal atom diffusion layer (μm) Interface bonding strength (MPa) Tensile strength (MPa) Yield strength (MPa) 1 460 0.98 18.7 238.76 174.23 2 480 1.43 20.9 242.34 180.78 3 495 2.53 25.4 259.12 191.56 4 510 3.41 27.1 261.89 192.99 5 520 4.22 29.1 257.45 194.67 6 530 3.53 29.7 260.67 189.34 7 540 3.31 28.3 252.98 178.12 8 550 4.14 25.6 246.54 171.87 On the basis of the above-mentioned Example 1, the effect of rolling speed on the performance of the titanium-aluminum-titanium three-layer metal composite plate was further discussed, and different rolling speeds were set, while other conditions remained the same as in Example 1. See Table 5 for specific rolling speed settings and performance test results.

[0050] Table 5: Effect of rolling speed on the properties of titanium-aluminum-titanium three-layer metal composites Serial number Rolling speed (m / min) Thickness of metal atom diffusion layer (μm) Interface bonding strength (MPa) Tensile strength (MPa) Yield strength (MPa) 1 1 3.63 26.9 258.53 193.91 2 2 4.50 28.4 262.79 191.23 3 3 3.92 26.5 259.30 191.45 4 4 3.91 25.5 261.82 193.27 5 5 3.53 24.7 257.77 191.18 6 6 2.18 19.9 237.18 179.4 The results in the above table show that lower rolling speed prolongs the residence time of the material at high temperature, which is conducive to the full diffusion of atoms, thereby increasing the thickness of the diffusion layer, promoting metallurgical bonding at the interface, reducing interface defects, and improving interface bonding strength; but too low a speed (<2m / s) will lead to increased interface oxidation, which will inhibit effective diffusion, resulting in too long a pressing time, low production efficiency, and difficulty in adapting to industrial production. Higher rolling speeds will shorten the diffusion time, resulting in a thinner diffusion layer, and introduce microcracks or brittle phases due to shear stress and deformation heat, weakening the interface bonding strength.

[0051] On the basis of the above-mentioned Example 1, the effect of the reduction ratio on the performance was further discussed, and different reduction ratios were set, but other conditions remained the same as in Example 1. See Table 6 for the specific reduction ratio settings and performance test results.

[0052] Table 6: Effect of reduction rate on the properties of titanium-aluminum-titanium three-layer metal composites Serial number Reduction rate (%) Thickness of metal atom diffusion layer (μm) Interface bonding strength (MPa) Tensile strength (MPa) Yield strength (MPa) 1 25 1.19 20.1 251.89 180.20 2 30 3.21 25.1 258.23 181.37 3 35 3.92 26.5 259.30 191.45 4 40 5.21 26.7 263.22 193.15 5 45 4.49 25.4 261.21 191.23 6 50 3.67 21.1 247.82 178.91 The results in the above table show that when the reduction rate is low, the plastic deformation at the interface is small, and the power of atomic diffusion is insufficient, resulting in a thin diffusion layer thickness; at the same time, it is difficult to achieve full contact and metallurgical bonding at the interface, resulting in low interface bonding strength. As the reduction rate increases, sufficient plastic deformation can be provided to promote full diffusion of atoms at the interface, thereby increasing the thickness of the diffusion layer; at the same time, atomic diffusion and metallurgical bonding are promoted, significantly improving the interface bonding strength. When the reduction rate is too high, although the plastic deformation increases, it also leads to excessive temperature rise or uneven deformation at the interface, inhibiting atomic diffusion; at the same time, too high a reduction rate will cause excessive shear stress and micro defects at the interface, weakening the interface bonding strength.

[0053] Example 2

[0054] The present embodiment provides a titanium-aluminum-titanium three-layer metal composite material, including an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer. The plate materials for making the first metal layer and the second metal layer are TA1 titanium plates with a thickness of 0.8 mm, and the plate materials for making the intermediate metal layer are 6013 aluminum plates with a thickness of 2.0 mm. The first metal layer, the intermediate metal layer, and the second metal layer are formed by hot rolling, and a metal atom diffusion layer is formed at the bonding interface between the first metal layer and the intermediate metal layer and at the bonding interface between the second metal layer and the intermediate metal layer during the hot rolling process; the upper and lower surfaces of the intermediate metal layer, the contact surface of the first metal layer and the intermediate metal layer, and the contact surface of the second metal layer and the intermediate metal layer are all roughened to form a rough surface with an average roughness of Ra5, and the metal atom diffusion layer diffuses through the rough surface.

[0055] The preparation method of the titanium-aluminum-titanium three-layer metal composite material comprises the following steps: Material pretreatment: Take two TA1 titanium plates as the first metal layer and the second metal layer, and take 6013 aluminum plate as the middle metal layer. Use ultrasonic cleaning to clean the two TA1 titanium plates and 6013 aluminum plates. The cleaning medium is 42°C water to remove surface stains. After cleaning, dry at 80°C. Roughening treatment: one surface of each TA1 titanium plate is roughened, and both surfaces of the 6013 aluminum plate are roughened, respectively forming a rough surface with an average roughness of Ra3; Preheating and insulation: Preheat the TA1 titanium plate and 6013 aluminum plate after texturing to 520℃ and keep them warm for 2 minutes; 99.9% argon gas is used for protection during the insulation process, and the air flow rate is controlled at 5m³ / h; Hot rolling composite: After the preheated 6013 aluminum plate is fixed, the rough surfaces of two TA1 titanium plates are stacked on the upper and lower surfaces of the 6013 aluminum plate, and a titanium-aluminum-titanium three-layer metal composite plate is formed by hot rolling at a time. The rolling temperature is 510°C, the rolling speed is 5m / min, and the pressing amount is 45%. A titanium-aluminum-titanium three-layer metal composite material with a thickness of 2.1mm is obtained.

[0056] The performance of the titanium-aluminum-titanium three-layer metal composite material described in the above Example 2 was tested, and the specific test items and the adopted test methods / standards are shown in Table 7 below. Figure 3 This is a cross-sectional SEM image of the titanium-aluminum-titanium three-layer metal composite material described in this embodiment. Figure 3 It shows that there is a metal atom diffusion layer at the titanium-aluminum bonding interface with a thickness of 5.43μm.

[0057] The performance of the titanium-aluminum-titanium three-layer metal composite material described in the above Example 2 was tested, and the specific test items and the adopted test methods / standards are shown in Table 7 below.

[0058] Table 7: Performance test results of the titanium-aluminum-titanium three-layer metal composite material described in Example 2 Serial number Test items Test methods / standards used Test results 1 Interface bonding strength (MPa) GB / T 228.1-2021 26.2 2 Tensile strength (MPa) GB / T 228.1-2021 260.01 3 Yield strength (MPa) GB / T 228.1-2021 194.30 4 Elastic modulus (MPa) GB / T 228.1-2021 86 5 Density (g / cm³) GBT20042.6-2024 3.463 6 Resistance (µΩ·cm) GBT20042.6-2024 17.3 7 Corrosion current density (μA / cm²) GBT20042.6-2024 0.26 The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A titanium-aluminum-titanium three-layer metal composite material, characterized in that: It includes an intermediate metal layer, a first metal layer located on the upper surface of the intermediate metal layer, and a second metal layer located on the lower surface of the intermediate metal layer. The plates for making the first metal layer and the second metal layer are titanium plates or titanium alloy plates, and the plates for making the intermediate metal layer are aluminum plates or aluminum alloy plates. The first metal layer, the intermediate metal layer, and the second metal layer are formed by hot rolling, and a metal atom diffusion layer is formed at the bonding interface between the first metal layer and the intermediate metal layer, and at the bonding interface between the second metal layer and the intermediate metal layer during the hot rolling process. The upper and lower surfaces of the intermediate metal layer, the contact surface of the first metal layer and the intermediate metal layer, and the contact surface of the second metal layer and the intermediate metal layer are all roughened to form a rough surface with an average roughness of Ra3-5, and the metal atom diffusion layer diffuses through the rough surface.

2. The titanium-aluminum-titanium three-layer metal composite material according to claim 1, characterized in that: The thickness of the metal sheet used to make the first metal layer and the second metal layer is L1, and the thickness of the metal sheet used to make the intermediate metal layer is L2, wherein L1:L2=1:(2-4).

3. The titanium-aluminum-titanium three-layer metal composite material according to claim 1, characterized in that: The average thickness of the metal atom diffusion layer is 2.5-8.5 μm.

4. The titanium-aluminum-titanium three-layer metal composite material according to claim 1, characterized in that: Its yield strength is 180-230MPa, tensile strength is 250-300MPa, and elongation after fracture is 16.2-26.7%.

5. A method for preparing the titanium-aluminum-titanium three-layer metal composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Material pretreatment: Take titanium or titanium alloy plate as the first metal layer plate and the second metal layer plate, take aluminum or aluminum alloy plate as the middle metal layer plate, clean the first metal layer plate, the second metal layer plate and the middle metal layer plate to remove surface stains; Roughening treatment: roughening the first metal layer, the second metal layer and the middle metal layer, and roughening one surface of the first metal layer, one surface of the second metal layer and the upper and lower surfaces of the middle metal layer to form a rough surface with an average roughness of Ra3-5; Preheating and heat preservation: preheating the first metal layer plate, the second metal layer plate and the middle metal layer plate after the texturing treatment to the rolling temperature and keeping them at the temperature for a predetermined time; Hot rolling composite: After the preheated middle metal layer is fixed, the rough surface of the first metal layer and the rough surface of the second metal layer are respectively stacked on the middle metal layer, and a titanium-aluminum-titanium three-layer metal composite plate is formed by hot rolling once.

6. The preparation method according to claim 5, characterized in that: In the pretreatment step, ultrasonic cleaning is adopted, and the cleaning medium is water at 40±5°C; after cleaning, the cleaning is carried out using an air shear dryer, and the drying temperature is 76-85°C.

7. The preparation method according to claim 5, characterized in that: In the preheating and insulation steps, the preheating temperature is 475-550° C., and the insulation time is 2-5 min. During the insulation process, argon gas is continuously introduced into the insulation furnace at a gas flow rate of 1-5 m³ / h.

8. The preparation method according to claim 5, characterized in that: In the hot rolling composite step, a single rolling process is adopted, the hot rolling temperature is 495-530° C., the rolling speed is 2-5 m / min, and the reduction rate is 30-45%; argon protection is adopted during the rolling process.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The method also includes a post-processing step after hot rolling and cladding, in which 0.2-0.5 mm is cut off from the head and tail of the titanium-aluminum-titanium three-layer metal composite plate, and the plate is straightened with an automatic straightening machine before cutting.

10. Use of the titanium-aluminum-titanium three-layer metal composite material according to any one of claims 1 to 4 in manufacturing battery bipolar plates.

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