Aluminum alloy foil for temperature control element as well as preparation method and application of aluminum alloy foil

Abstract

The invention provides an aluminum alloy foil for a temperature control element as well as a preparation method and application of the aluminum alloy foil. The aluminum alloy foil comprises the following components in percentage by weight: 1.7 to 1.9 percent of Mn, 0.2 to 0.5 percent of Cr, 0.1 to 0.3 percent of Ti, 0.05 to 0.2 percent of V, 0.1 to 0.2 percent of Fe, 0.5 to 1.5 percent of Si, less than or equal to 0.2 percent of other inevitable impurity elements and the balance of Al; the preparation method comprises the steps that alloy raw materials are smelted and then poured into a copper mold with a water cooling system, an obtained cast ingot is subjected to cold rolling with the single-pass deformation of 20-40%, and then annealing and foil rolling are conducted. The aluminum alloy foil for the temperature control element, which is high in resistivity and easy to process, is obtained by adding metal elements in a specific proportion and casting a casting blank by adopting a copper mold in which cooling water is introduced, so that a large amount of effective elements are dissolved in a matrix, and by combining single-pass small cold rolling deformation, precipitation of the effective elements is reduced, and the aluminum alloy foil is suitable for a resistance heating element.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy foil material for a temperature control element, and a preparation method and application thereof. Background Art

[0002] Power batteries are the core components of new energy vehicles, affecting the performance of vehicles in all aspects. Temperature is an important factor affecting the working ability of lithium batteries. The most suitable working temperature of batteries is between 15 and 40 degrees Celsius. The working principle of lithium-ion batteries is essentially Li + It moves back and forth between liquid electrolytes, and is deintercalated and intercalated inside the positive and negative electrode materials. At low temperatures, the rate of lithium intercalation reaction of active materials on the electrode surface slows down and the lithium ion concentration inside the active materials decreases, which will cause the battery equilibrium potential to decrease, the internal resistance to increase, and the discharge capacity to decrease. In extreme low temperature conditions, the electrolyte may even freeze and the battery may not be able to discharge, which greatly affects the low temperature performance of the battery system, causing the power output performance of electric vehicles to decline and the range to decrease. In extremely cold conditions, it may even threaten the safety of battery use. To solve this problem, new energy vehicles use battery temperature control technology to keep the battery temperature within the optimal operating temperature range. At present, temperature control is mainly achieved by installing temperature control equipment in the battery pack. The temperature control equipment is mainly composed of heating elements and circuits, among which the heating element is the most important part. Common heating elements include variable resistance heating elements and constant resistance heating elements, the latter of which is usually a heating film composed of metal heating wires.

[0003] At present, the commonly used metal heating wire is steel foil, but steel foil needs to be processed into heating elements by chemical etching, which has a long process and causes great pollution. In addition, due to its high hardness, it is not suitable for mechanical processing. If aluminum foil is used instead, physical cutting can be used, which has high production efficiency and no pollution. However, the electrical conductivity of conventional aluminum alloy foil is 25-35MS / m, and the resistance is relatively small, which is far from the low conductivity of foil required for metal wire used in resistance heating elements. Summary of the invention

[0004] The main purpose of the present invention is to provide an aluminum alloy foil for a temperature control element, a preparation method and application thereof, so as to solve the problems in the prior art that metal steel foil and copper foil for temperature control elements are difficult to process and the aluminum foil product has high electrical conductivity.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, a method for preparing an aluminum alloy foil for a temperature control element is provided, wherein the components of the aluminum alloy foil include, by weight percentage: Mn 1.7-1.9%, Cr 0.2-0.5%, Ti 0.1-0.3%, V 0.05-0.2%, Fe 0.1-0.2%, Si 0.5-1.5%, other inevitable impurity elements ≤0.2wt.%, and the balance is Al; the preparation method comprises the following steps: step S1, smelting the alloy raw material according to the component ratio to obtain a melt; casting the melt into a copper mold with a water cooling system to obtain an ingot; step S2, milling the ingot and cold rolling it, the single-pass deformation of the cold rolling is 20-40%, to obtain an aluminum foil blank; step S3, annealing the aluminum foil blank to obtain an annealed blank; step S4, foil rolling the annealed blank to obtain an aluminum alloy foil for a temperature control element.

[0006] Furthermore, in step S1, the smelting temperature is 750-800°C; and / or in the water cooling system, the temperature of the cooling water is 20-30°C, and the flow rate is 10-20 L / min; and / or the thickness of the ingot is 10-30 mm.

[0007] Furthermore, in step S2, during the milling, each surface of the ingot is milled by 2 to 6 mm; and / or the deformation amount of a single cold rolling pass is 20 to 30%.

[0008] Furthermore, in step S3, the heating rate of annealing is 60-70°C / h, the annealing temperature is 220-320°C, and the holding time is 1-2h.

[0009] Furthermore, in step S4, the deformation amount of a single pass of foil rolling is 10 to 35%, preferably 10 to 20%.

[0010] Furthermore, in the composition of the aluminum alloy foil, the sum of the weight percentages of Cr, V and Ti is ≤0.5%.

[0011] Furthermore, the area proportion of the second phase in the aluminum alloy foil is ≤5%, and the maximum size of the second phase is ≤3μm.

[0012] Furthermore, the electrical conductivity of the aluminum alloy foil at 20° C. is 12 to 14 MS / m, and the hardness of the aluminum alloy foil is 50 to 80 HV.

[0013] According to another aspect of the present invention, there is provided an aluminum alloy foil for a temperature control element, which is obtained using the above-mentioned preparation method of the present invention.

[0014] According to another aspect of the present invention, a power battery is provided, comprising a temperature control element, wherein a material of the temperature control element comprises the aluminum alloy foil for the temperature control element of the present invention.

[0015] The technical solution of the present invention is applied. First, by creatively adding elements such as Mn, Cr, Ti, and V, and controlling the addition ratio, the aluminum alloy foil has a larger resistance, which meets the heating characteristics of the temperature control element. By using the above elements that have a greater impact on the increase in the resistivity of the material, the material has the characteristics of low conductivity and high resistivity, and can be used in the temperature control system of the battery pack of new energy vehicles. Second, the copper mold with cooling water is used to cast the ingot. The copper mold can quickly conduct heat with the cooling water to achieve the purpose of melt cooling, so that a large amount of effective elements are dissolved in the matrix. Third, a single-pass small cold rolling deformation method is adopted to reduce the possibility of work hardening of the material as much as possible, thereby achieving the purpose of reducing the precipitation of effective elements, keeping the effective elements dissolved in the matrix in large quantities, giving full play to their role in increasing resistivity and reducing conductivity, and further reducing hardness, so as to obtain an aluminum alloy foil for temperature control elements that is easy to process, which is suitable for resistance heating elements. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0017] As described in the background of the present invention, there are problems in the prior art that metal steel foil and copper foil used for temperature control elements are difficult to process and that the electrical conductivity of aluminum foil products is relatively high. In order to solve the above problems, in a typical embodiment of the present invention, a preparation method of an aluminum alloy foil for a temperature control element is provided, wherein the components of the aluminum alloy foil include, by weight percentage: Mn 1.7-1.9%, Cr 0.2-0.5%, Ti 0.1-0.3%, V 0.05-0.2%, Fe 0.1-0.2%, Si 0.5-1.5%, other inevitable impurity elements ≤0.2wt.%, and the balance is Al; the preparation method comprises the following steps: step S1, smelting the alloy raw material according to the component ratio to obtain a melt; casting the melt into a copper mold with a water cooling system to obtain an ingot; step S2, milling the ingot and cold rolling it, the single-pass deformation of the cold rolling is 20-40%, to obtain an aluminum foil blank; step S3, annealing the aluminum foil blank to obtain an annealed blank; step S4, foil rolling the annealed blank to obtain an aluminum alloy foil for a temperature control element.

[0018] Among them, Mn, Cr, Ti, and V have a greater impact on the resistivity of aluminum alloys, and adding them to aluminum alloys can significantly improve the resistivity. And the higher the solid solubility of these elements in the matrix, the greater the effect on improving the resistivity of the alloy. Therefore, the entire casting and processing process needs to be designed around reducing the precipitation of effective elements and improving the solid solubility of the finished product.

[0019] In order to improve the solid solubility of effective elements, the casting process of the present invention adopts a copper alloy material mold with fast heat conduction, and cooperates with an external water cooling system to accelerate cooling, so that the cooling rate of the melt in the casting process is greatly improved to increase the solid solution effect of the elements in the alloy. If the deformation amount of a single cold rolling pass is too large, it will lead to aggravated work hardening, increased precipitation of solid solution elements, and reduced resistivity of the finished foil, but if the deformation amount is too small, it will increase processing costs and reduce processing efficiency. Therefore, the present invention controls the deformation amount of a single cold rolling pass to 20-40%.

[0020] The main purpose of adding Si element is to improve the fluidity of the alloy and reduce the looseness and shrinkage defects caused by insufficient shrinkage compensation during the casting process; Ti element is not added as a refiner, but as an alloying element during the melting process. Its main purpose is to reduce the precipitation of Ti to form Al3Ti second phase. On the one hand, it can reduce the refinement effect of Ti element, and on the other hand, it can increase the solid solubility of Ti element, thereby increasing the resistivity of the alloy.

[0021] In summary, firstly, the present invention creatively adds Mn, Cr, Ti, V and other elements, and controls the addition ratio, so that the aluminum alloy foil has the heating characteristics of the temperature control element, controls the temperature control characteristics of the aluminum alloy, and uses the above-mentioned elements that have a greater impact on the increase in the resistivity of the material, so that the material has the characteristics of low conductivity and high resistivity, and can be used in the temperature control system of the battery pack of new energy vehicles. Secondly, the copper mold with cooling water is used to cast the ingot, and the copper mold can quickly conduct heat with the cooling water to achieve the purpose of melt cooling, so that the effective elements are dissolved in the matrix in large quantities. Thirdly, a single-pass small cold rolling deformation method is adopted to reduce the work hardening of the material as much as possible, thereby achieving the purpose of reducing the precipitation of effective elements, keeping the effective elements dissolved in the matrix in large quantities, giving full play to their role in increasing resistivity and reducing conductivity, and further reducing hardness, so as to obtain an aluminum alloy foil for temperature control elements that is easy to process, which is suitable for resistance heating elements.

[0022] In a preferred embodiment, in step S1, the smelting temperature is 750-800°C, which ensures good fluidity of the melt, reduces defects formed during the molding process, further improves the moldability and surface quality of the material, and can better ensure the solid solution effect of effective elements and avoid element volatilization caused by excessive temperature; and / or in the water cooling system, the water temperature of the cooling water is 20-30°C, and the flow rate is 10-20L / min. The optimized water cooling system design can cool the melt more quickly and evenly, increase the solid solubility of effective elements, and thus further improve the resistance characteristics of the foil; and / or the thickness of the ingot is 10-30mm, which can further reduce the tendency of element precipitation caused by the slow cooling rate in the core, which affects the uniformity of resistivity.

[0023] In the specific preparation process, the alloy raw materials may include 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent. The alloy raw materials are smelted and refined according to the component ratio. The refining includes stirring the smelted material for 3 to 8 minutes, degassing for 10 to 20 minutes, and standing for 3 to 8 minutes until the gas content of the melt is ≤0.13mL / 100g. This effectively reduces the gas content in the material, reduces the pores and cracks in the material, and makes the material have more suitable density and strength, thereby further improving the processing performance of the aluminum alloy foil.

[0024] For the purpose of removing the segregation layer on the surface of the ingot, in a preferred embodiment, in step S2, during the milling, each surface of the ingot is milled by 2 to 6 mm to remove the oxide layer and impurities on the surface and improve the subsequent processing efficiency; and / or the single-pass deformation amount of cold rolling is 20 to 30%. The preferred single-pass deformation amount can better maintain the solid solubility of effective elements, ensure the resistivity of the final product, and can also effectively reduce work hardening and improve the ductility of the material, so as to further improve the processing performance of the material and ensure the stability and reliability of the component during use.

[0025] In order to further reduce the precipitation of effective elements and reduce their solid solubility, which ultimately leads to a lower resistivity of the finished foil, in a preferred embodiment, in step S3, the heating rate of annealing is 60-70°C / h, the annealing temperature is 220-320°C, and the holding time is 1-2h. In addition, controlling the annealing temperature within the above range can also eliminate the internal stress generated during the cold rolling process, improve the mechanical properties of the material, optimize the microstructure of the material, enhance the plasticity and fatigue resistance of the material, and significantly improve the stability and reliability of the component during long-term use.

[0026] In a preferred embodiment, in step S4, the deformation amount of a single pass of foil rolling is 10-35%, preferably 10-20%. In the foil rolling step, controlling the deformation amount of a single pass within the above range can further reduce work hardening, so that the aluminum alloy foil has excellent forming performance, good mechanical properties and electrical conductivity, and further can make the material still maintain good thickness uniformity and surface quality when it reaches the foil state.

[0027] The thickness of the aluminum foil blank may be 0.2 to 0.4 mm, and the thickness of the aluminum alloy foil may be 0.03 to 0.06 mm.

[0028] In order to further control the size and proportion of the second phase in the foil within an appropriate range, in a preferred embodiment, in the composition of the aluminum alloy foil, the sum of the weight percentages of Cr, V and Ti is ≤0.5%, which can further reduce the formation of large-sized second phases caused by excessive Cr, Ti and V elements, and can also reduce the occurrence of broken strips and surface white line defects during the foil rolling process, so that the aluminum alloy foil has more suitable electrical conductivity and hardness.

[0029] As described above, the distribution of the second phase in the aluminum alloy foil will affect the conductivity and hardness of the aluminum alloy foil. In a preferred embodiment, the area proportion of the second phase in the aluminum alloy foil is ≤5%, and the maximum size of the second phase is ≤3μm, which is more conducive to the application of the aluminum alloy foil in temperature control elements.

[0030] In a preferred embodiment, the electrical conductivity of the aluminum alloy foil at 20°C is 12-14MS / m, and the hardness of the aluminum alloy foil is 50-80HV. The aluminum alloy foil has the characteristics of easy processing, low electrical conductivity, and high resistivity, and is suitable for the temperature control system of the battery pack of new energy vehicles, which can better meet the industry's strict requirements on material properties, and is suitable for the manufacture of temperature control components, which significantly improves the stability and reliability of the product.

[0031] In another typical embodiment of the present invention, there is also provided an aluminum alloy foil for a temperature control element, which is obtained using the above-mentioned preparation method of the present invention. The aluminum alloy foil has suitable conductive properties, is more conducive to application in power batteries, and provides a high-quality material solution for the temperature control element.

[0032] In another typical embodiment of the present invention, a power battery is provided, including a temperature control element, wherein the material of the temperature control element includes the aluminum alloy foil for the temperature control element of the present invention, which is beneficial to maintaining the temperature of the battery within the optimal operating temperature range and improving the stability and service life of the battery.

[0033] Typically, but not limiting, the composition of the aluminum alloy foil includes, by weight percentage: Mn 1.7%, 1.75%, 1.8%, 1.85%, 1.9% or a range consisting of any two of them, Cr 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5% or a range consisting of any two of them, Ti 0.1%, 0.15%, 0.2%, 0.25%, 0.3% or a range consisting of any two of them, V 0.05%, 0.1%, 0.15%, 0.2% or a range consisting of any two of them, Fe 0.1%, 0.12%, 0.15%, 0.18%, 0.2% or a range consisting of any two of them, Si 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5% or a range consisting of any two of them, other unavoidable impurity elements ≤ 0.2wt.%, and the balance is Al.

[0034] Typically but not limiting, in step S2, the deformation amount of a single cold rolling pass is 20%, 25%, 30%, 35%, 40% or a range consisting of any two of them.

[0035] Typically but not limiting, in step S3, the annealing temperature is 220°C, 240°C, 260°C, 280°C, 300°C, 320°C or a range consisting of any two of them, and the holding time is 1h, 1.2h, 1.5h, 1.8h, 2h or a range consisting of any two of them.

[0036] Typically but not limiting, in step S4, the deformation amount of the foil rolling in a single pass is 10%, 15%, 20%, 25%, 30%, 35% or a range consisting of any two of them.

[0037] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0038] Example 1

[0039] The ingredients are shown in Table 1. The preparation method is as follows:

[0040] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0041] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0042] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0043] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0044] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0045] Example 2

[0046] The ingredients are shown in Table 1. The preparation method is as follows:

[0047] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a crucible of a smelting furnace, heated to 800°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 20°C, the flow rate is 20L / min, and the thickness of the prepared ingot is 20mm.

[0048] (2) Milling process: milling the upper and lower surfaces of the above-mentioned ingot by 3 mm each to remove the segregation layer on the surface of the ingot.

[0049] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0050] (4) Annealing process: annealing the aluminum foil blank, with a heating rate of 60°C / h, an annealing temperature of 270°C, and a heat preservation time of 1.5h after the material reaches the temperature, to obtain an annealed blank.

[0051] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 20% to obtain an aluminum alloy foil.

[0052] Example 3

[0053] The ingredients are shown in Table 1. The preparation method is as follows:

[0054] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a crucible of a smelting furnace, heated to 800°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 20°C, the flow rate is 20L / min, and the thickness of the prepared ingot is 20mm.

[0055] (2) Milling process: milling the upper and lower surfaces of the above-mentioned ingot by 3 mm each to remove the segregation layer on the surface of the ingot.

[0056] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0057] (4) Annealing process: annealing the aluminum foil blank, with a heating rate of 60°C / h, an annealing temperature of 270°C, and a heat preservation time of 1.5h after the material reaches the temperature, to obtain an annealed blank.

[0058] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 20% to obtain an aluminum alloy foil.

[0059] Example 4

[0060] The ingredients are the same as in Example 1. The preparation method is as follows:

[0061] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0062] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0063] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 20%.

[0064] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0065] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0066] Example 5

[0067] The ingredients are the same as in Example 1. The preparation method is as follows:

[0068] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0069] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0070] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 30%.

[0071] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0072] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0073] Example 6

[0074] The ingredients are the same as in Example 1. The preparation method is as follows:

[0075] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0076] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0077] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 35%.

[0078] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0079] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0080] Example 7

[0081] The ingredients are the same as in Example 1. The preparation method is as follows:

[0082] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0083] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0084] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0085] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0086] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 10% to obtain an aluminum alloy foil.

[0087] Example 8

[0088] The ingredients are the same as in Example 1. The preparation method is as follows:

[0089] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0090] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0091] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0092] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0093] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 20% to obtain an aluminum alloy foil.

[0094] Example 9

[0095] The ingredients are the same as in Example 1. The preparation method is as follows:

[0096] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0097] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0098] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0099] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0100] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 35% to obtain an aluminum alloy foil.

[0101] Example 10

[0102] The ingredients are the same as in Example 1. The preparation method is as follows:

[0103] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 750°C for complete melting, stirred for 8 minutes, degassed for 10 minutes, and allowed to stand for 3 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water is 20°C, the flow rate is 20L / min, and the thickness of the prepared ingot is 10mm.

[0104] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0105] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0106] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0107] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0108] Embodiment 11

[0109] The ingredients are the same as in Example 1. The preparation method is as follows:

[0110] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 800°C for complete melting, stirred for 3 minutes, degassed for 20 minutes, and allowed to stand for 8 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 30°C, the flow rate is 10L / min, and the thickness of the prepared ingot is 30mm.

[0111] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0112] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0113] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0114] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0115] Example 12

[0116] The ingredients are the same as in Example 1. The preparation method is as follows:

[0117] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0118] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 2 mm each to remove the segregation layer on the surface of the ingot.

[0119] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0120] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0121] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0122] Example 13

[0123] The ingredients are the same as in Example 1. The preparation method is as follows:

[0124] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0125] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 6 mm each to remove the segregation layer on the surface of the ingot.

[0126] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0127] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 65°C / h and an annealing temperature of 270°C. The material is kept at the temperature for 1.5 h to obtain an annealed blank.

[0128] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0129] Embodiment 14

[0130] The ingredients are the same as in Example 1. The preparation method is as follows:

[0131] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0132] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0133] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0134] (4) Annealing process: annealing the aluminum foil blank, with a heating rate of 60°C / h, an annealing temperature of 220°C, and a heat preservation time of 2h after the material reaches the temperature, to obtain an annealed blank.

[0135] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0136] Embodiment 15

[0137] The ingredients are the same as in Example 1. The preparation method is as follows:

[0138] (1) Casting process: 99.75% industrial pure aluminum, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-V master alloy, Al-Si master alloy and iron agent are placed in a melting furnace crucible, heated to 780°C for complete melting, stirred for 5 minutes, degassed for 15 minutes, and then allowed to stand for 5 minutes. The gas content of the melt is measured to be 0.10mL / 100g (≤0.13mL / 100g). The melt is then cast into a copper square mold with a water cooling system, the cooling water temperature is 25°C, the flow rate is 15L / min, and the thickness of the prepared ingot is 20mm.

[0139] (2) Milling process: mill the upper and lower surfaces of the above-mentioned ingot by 4 mm each to remove the segregation layer on the surface of the ingot.

[0140] (3) Cold rolling process: The ingot is rolled to a thickness of 0.3 mm using a cold rolling mill to obtain an aluminum foil blank, and the deformation amount of a single cold rolling pass is 25%.

[0141] (4) Annealing process: annealing the aluminum foil blank at a heating rate of 70°C / h and an annealing temperature of 320°C. After the material reaches the temperature, the insulation time is 1h to obtain an annealed blank.

[0142] (5) Foil rolling process: The annealed billet is rolled to 0.04 mm using a foil rolling mill, with a single-pass deformation of 15% to obtain an aluminum alloy foil.

[0143] Comparative Example 1

[0144] The difference from Example 1 is that the copper square mold used in the casting process does not have a water cooling system.

[0145] Comparative Example 2

[0146] The difference from Example 1 is that the deformation amount of a single cold rolling pass in the cold rolling process is 15%; and the annealing temperature in the annealing process is 200° C. and the temperature is kept for 1 hour.

[0147] Comparative Example 3

[0148] The difference from Example 1 is that the deformation amount of a single cold rolling pass in the cold rolling process is 45%; and the annealing temperature in the annealing process is 350° C. and the temperature is kept for 2 hours.

[0149] The aluminum alloy foils prepared in the above examples and comparative examples were subjected to performance tests, and the results are shown in Table 2.

[0150] Test method:

[0151] Phase 2: Microscopic observation.

[0152] Conductivity: At room temperature (20°C ± 5), a four-probe resistance tester was used to measure the resistance of the aluminum foil sample, and the conductivity of the aluminum foil sample was calculated by taking the conductivity as the reciprocal of the resistance.

[0153] Hardness: At room temperature (20℃±5), the hardness of the aluminum foil sample was tested using a micro Vickers hardness tester in accordance with GB / T4340.1.

[0154] Table 1

[0155] Weight percentage Mn Cr Ti V Fe Si Other impurity elements Al Cr+V+Ti Example 1 1.8 0.25 0.15 0.1 0.15 1 0.1 margin 0.5 Example 2 1.7 0.2 0.1 0.05 0.1 0.5 0.1 margin 0.35 Example 3 1.9 0.5 0.3 0.2 0.2 1.5 0.1 margin 1

[0156] Table 2

[0157]

[0158]

[0159] As can be seen from the above, compared with the comparative example, the embodiments of the present invention creatively add elements such as Mn, Cr, Ti, V, etc., and control the addition ratio, so that the aluminum alloy foil has a larger resistance, which meets the heating characteristics of the temperature control element. By using the above elements that have a greater impact on the increase in the resistivity of the material, the material has the characteristics of low conductivity and high resistivity, and can be used in the temperature control system of the battery pack of new energy vehicles. In addition, a copper mold with cooling water is used to cast the ingot. The copper mold can quickly conduct heat with the cooling water to achieve the purpose of melt cooling, so that a large amount of effective elements are dissolved in the matrix. In addition, a single-pass small cold rolling deformation method is adopted to minimize the possibility of work hardening of the material, thereby achieving the purpose of reducing the precipitation of effective elements, keeping the effective elements dissolved in the matrix in large quantities, giving full play to their role in increasing resistivity and reducing conductivity, and further reducing hardness, so as to obtain an easy-to-process aluminum alloy foil for temperature control elements, which is suitable for resistance heating elements.

[0160] In addition, it can be seen that when each process parameter is within the preferred range of the present invention, the overall effect is better.

[0161] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy foil for a temperature control element, characterized in that: The aluminum alloy foil comprises, by weight percentage, 1.7-1.9% Mn, 0.2-0.5% Cr, 0.1-0.3% Ti, 0.05-0.2% V, 0.1-0.2% Fe, 0.5-1.5% Si, and other unavoidable impurity elements ≤ 0.2wt.%, with the balance being Al. The preparation method comprises the following steps: Step S1, smelting the alloy raw materials according to the composition ratio to obtain a melt; casting the melt into a copper mold with a water cooling system to obtain an ingot; Step S2, milling the ingot and then cold rolling it, wherein the deformation amount of a single cold rolling is 20-40%, to obtain an aluminum foil blank; Step S3, annealing the aluminum foil blank to obtain an annealed blank; Step S4, foil rolling the annealed blank to obtain the aluminum alloy foil for the temperature control element.

2. The preparation method according to claim 1, characterized in that: In the step S1, The smelting temperature is 750-800°C; and / or In the water cooling system, the temperature of the cooling water is 20-30°C and the flow rate is 10-20 L / min; and / or The thickness of the ingot is 10 to 30 mm.

3. The preparation method according to claim 1 or 2, characterized in that: In the step S2, in the milling, each surface of the ingot is milled by 2 to 6 mm; and / or the deformation amount of a single pass of the cold rolling is 20 to 30%.

4. The preparation method according to any one of claims 1 to 3, characterized in that In the step S3, the heating rate of the annealing is 60-70°C / h, the annealing temperature is 220-320°C, and the holding time is 1-2h.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step S4, the deformation amount of the foil rolling in a single pass is 10-35%, preferably 10-20%.

6. The preparation method according to any one of claims 1 to 5, characterized in that In the composition of the aluminum alloy foil, the sum of the weight percentages of Cr, V and Ti is ≤0.5%.

7. The preparation method according to any one of claims 1 to 6, characterized in that The area proportion of the second phase in the aluminum alloy foil is ≤5%, and the maximum size of the second phase is ≤3 μm.

8. The preparation method according to any one of claims 1 to 7, characterized in that The electrical conductivity of the aluminum alloy foil at 20° C. is 12 to 14 MS / m, and the hardness of the aluminum alloy foil is 50 to 80 HV.

9. An aluminum alloy foil for a temperature control element, characterized in that: The method according to any one of claims 1 to 8 is used.

10. A power battery, comprising a temperature control element, characterized in that: The material of the temperature control element includes the aluminum alloy foil for the temperature control element according to claim 9.

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