8-series aluminum alloy foil as well as preparation method and application thereof

Abstract

The invention provides an 8-series aluminum alloy foil as well as a preparation method and application thereof. The preparation method comprises the steps that S1, raw materials of the 8-series aluminum alloy foil are subjected to smelting and cast rolling treatment, and a plate is obtained; s2, the plate is subjected to cold rolling treatment, and an aluminum foil blank is obtained; s3, the aluminum foil blank is subjected to foil rolling at the curling tension of 30 N / mm < 2 > to 45 N / mm < 2 > and the rolling speed of 500 m / min to 800 m / min, and an 8-series aluminum alloy foil is obtained; and the viscosity of rolling oil adopted for rolling the foil is 1.5 mm < 2 > / s to 2.5 mm < 2 > / s. The method is based on foil rolling process control of the aluminum foil blank and is combined with specific viscosity of rolling oil, so that the number of oil pit and pinhole defects caused by microcracks generated on the surface of the 8-series aluminum alloy foil in the rolling process is effectively reduced, and the surface appearance of the 8-series aluminum alloy foil is remarkably optimized.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloy foil and processing technology thereof, and in particular to an 8 series aluminum alloy foil, a preparation method and application thereof. Background Art

[0002] The application of aluminum foil is very extensive, covering many fields and industries. Among them, packaging aluminum foil is widely used in industrial and civilian fields such as aluminum foil for new energy lithium batteries, functional aluminum foil for new energy components, and pharmaceutical packaging due to its moisture-proof, airtight, light-shielding, and abrasion-resistant properties; battery aluminum foil can be used as a positive electrode current collector material for lithium-ion batteries. Due to its good conductivity and cost-effectiveness, it occupies an important position in battery manufacturing. Air-conditioning aluminum foil is used to manufacture air-conditioning heat exchanger fins. In the early days, plain foil was used. Later, hydrophilic foil and hydrophobic foil were developed to improve the surface performance of the fins and prevent condensation water from sticking. Electronic aluminum foil is a key material used in the electronics industry to manufacture wires, cables, capacitors, etc. Decorative aluminum foil is used as gold and silver wire, wallpaper, and decorative trademarks for various stationery prints and light industrial products. Insulating aluminum foil can reflect more than 93% of radiant heat because of its low solar absorption rate (solar radiation absorption coefficient), and can be used as an insulation material for buildings, vehicles, and ships.

[0003] At present, the commercial aluminum foil grades mainly include 1xxx, 3xxx, 5xxx and 8xxx (i.e. 1 series, 3 series, 5 series and 8 series). Among the commonly used aluminum alloy foil products, the 8 series aluminum alloy foil has become a hot spot for high-tech products and new product development in the fields of new energy lithium batteries, new energy components, medicines, food packaging, etc. due to its light weight, high strength, high conductivity, good processing performance and environmental protection characteristics. Its typical grades include 8021, 8079, 8006, 8011 and 8111. Among them, 8021 aluminum alloy foil has the characteristics of excellent moisture resistance, strong shading effect and strong blocking ability, safety and hygiene, good heat resistance, and a certain resistance to stress corrosion cracking, which is suitable for lithium battery soft pack aluminum foil. 8079 aluminum alloy foil is widely used in the fields of medicines, food packaging and lithium battery soft packs due to its high strength, good elongation and compressibility. 8011 aluminum alloy foil has excellent moisture resistance, light blocking and extremely high barrier ability. It is non-toxic and odorless, safe and hygienic, and is suitable for use in medicines, food packaging, radiators, etc.

[0004] 8 series aluminum alloy foil is mainly made by adjusting the composition and process of Al-Fe-Si alloy to make the processing and manufacturing of foil easier and less costly, while maintaining the required strength, cold deformation, diffusion resistance, sealing and coating properties. The main alloying elements of commercial 8xxx series aluminum alloy foil are Fe and Si, with the maximum content of Fe element reaching 2.0 (wt.)%, and the maximum content of Si element reaching 1.1 (wt.)%, so it is easy to form AlFeSi phase compound, and the foil has high strength, but it is easy to produce oil pits and pinhole defects caused by microcracks during the production process.

[0005] Based on this, how to optimize the preparation method of 8 series aluminum alloy foil to significantly reduce the oil pit pinhole defects on its surface, thereby reducing its pinhole rate and improving surface performance is one of the important technical problems that need to be solved in this field. Summary of the invention

[0006] The main purpose of the present invention is to provide an 8 series aluminum alloy foil, a surface morphology optimization method and application thereof, so as to solve the problem of poor surface morphology and limited application caused by excessive oil pits and pinhole defects on the surface of the 8 series aluminum alloy foil in the prior art.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing an 8 series aluminum alloy foil, comprising: step S1, smelting and casting the raw material of the 8 series aluminum alloy foil to obtain a plate; step S2, cold rolling the plate to obtain an aluminum foil blank; step S3, cold rolling the aluminum foil blank at 30N / mm 2 ~45N / mm 2 The foil is rolled at a curling tension of 500m / min to 800m / min to obtain an 8 series aluminum alloy foil; the viscosity of the rolling oil used in the foil rolling is 1.5mm 2 / s~2.5mm 2 / s.

[0008] Furthermore, in step S2, the metallographic structure of the aluminum foil blank includes a matrix phase and a second phase, wherein the area of ​​the second phase with a caliper diameter greater than 5 μm accounts for 2.0% to 4.0% of the metallographic structure, and the area of ​​the second phase with a caliper diameter greater than 3 μm accounts for 6.0% to 10.0% of the metallographic structure; preferably, the second phase is AlFe phase and / or AlFeSi phase.

[0009] Further, in step S3, the foil rolling includes the following steps: first foil rolling to obtain a first aluminum foil; second foil rolling to obtain a second aluminum foil; third foil rolling to obtain a third aluminum foil; preferably, the reduction rates of the first foil rolling, the second foil rolling and the third foil rolling are each independently 40% to 55%.

[0010] Furthermore, the linear roughness of the rollers used in the first foil rolling and the second foil rolling is independently 0.15 μm to 0.20 μm, and the linear roughness of the rollers used in the third foil rolling is 0.10 μm to 0.12 μm.

[0011] Furthermore, the maximum limit depth of microcracks on the surfaces of the first foil, the second foil and the third foil is 1.30 μm; the maximum maximum width of microcracks on the surfaces of the first foil, the second foil and the third foil is 21.5 μm; the maximum proportion of microcrack area on the surfaces of the first foil, the second foil and the third foil is 13.0%.

[0012] Furthermore, the rolling oil includes base oil, acid compounds, ester compounds and alcohol compounds, and the content of the acid compounds is 0.08% to 0.12%, the content of the ester compounds is 3.00% to 5.00%, and the content of the alcohol compounds is 0.50% to 12.00%.

[0013] Furthermore, step S2 also includes annealing the plate after cold rolling to obtain an aluminum foil blank; preferably, the annealing temperature is 200°C to 270°C, the heating rate is 30°C / h to 65°C / h, and the insulation time is 1.5h to 6h; more preferably, the heating method of the annealing is furnace heating.

[0014] A second aspect of the present invention provides an 8 series aluminum alloy foil, which is prepared by the above-mentioned method for preparing the 8 series aluminum alloy foil, and has a thickness of 35 μm to 45 μm.

[0015] Furthermore, the number of pinholes on the surface of 8 series aluminum alloy foil is 2 / 10,000 m 2 ~4 / 10,000 m 2 , the diameter of the pinhole is ≤0.05mm.

[0016] The third aspect of the present invention provides an application of the above-mentioned 8 series aluminum alloy foil as a packaging aluminum foil material in the fields of new energy, industrial and civil electrical equipment, food and medicine.

[0017] By applying the technical solution of the present invention, based on the foil rolling process control of the aluminum foil billet, it is achieved to control the limit depth, maximum width and area ratio of microcracks on the surface of the aluminum foil within a specified range, and combined with the specific viscosity of the rolling oil, the number of oil pits and pinhole defects caused by microcracks generated on the surface of the 8 series aluminum alloy foil during the rolling process is effectively reduced, and its surface morphology is significantly optimized so that its surface quality meets the product requirements in various fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 This is a scanning electron microscope photograph of the surface of the 8 series aluminum alloy foil obtained in Example 1. DETAILED DESCRIPTION

[0020] 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.

[0021] As described in the background technology, the 8 series aluminum alloy foil in the prior art has too many oil pits and pinholes on its surface, resulting in poor surface morphology and limited application. In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing 8 series aluminum alloy foil, including: step S1, smelting and casting the raw material of 8 series aluminum alloy foil to obtain a plate; step S2, cold rolling the plate to obtain an aluminum foil blank; step S3, cold rolling the aluminum foil blank at 30N / mm 2 ~45N / mm 2 The foil is rolled at a curling tension of 500m / min to 800m / min to obtain an 8 series aluminum alloy foil; the viscosity of the rolling oil used in the foil rolling is 1.5mm 2 / s~2.5mm 2 / s.

[0022] The present invention is based on the process parameter control of 8 series aluminum alloy foil during foil rolling, combined with the viscosity of the rolling oil used in the rolling process being 1.5mm 2 / s~2.5mm 2 / s, the problems of uneven deformation caused by too high rolling oil viscosity, too many defects caused by inability to carry away impurities, poor lubrication and many surface defects caused by too low rolling oil viscosity, etc. were successfully avoided. The generation of surface microcracks was effectively suppressed during the foil rolling (hereinafter referred to as foil rolling) process, thereby significantly reducing the number of oil pits and pinholes on the surface of the finished 8 series aluminum alloy foil caused by microcracks. Ultimately, the prepared 8 series aluminum alloy foil exhibited excellent surface properties, which was better adapted to the application needs of various fields.

[0023] Specifically, for the rolling process of aluminum alloy foil, in order to maintain the flatness of the aluminum alloy foil and prevent it from deforming during the rolling process, a certain tension, namely the curling tension, needs to be applied to control the curling degree of the metal foil. And its size has an important influence on the quality of the aluminum alloy foil, especially the surface morphology. If the tension is too large, cracks or deformation will appear on the surface of the aluminum alloy foil; if the tension is too small, it may cause it to curl during the rolling process, affecting the surface flatness and subsequent processing quality. The rolling speed is also an important factor affecting the alloy metallographic structure and surface morphology during the foil rolling process. When the rolling speed is low, the aluminum alloy foil has more time for dynamic recrystallization during the deformation process, thereby forming larger grains, and it is also more likely to produce surface defects such as cracks and folds; when the rolling speed is too high, it is very likely to cause uneven stress distribution inside the aluminum alloy foil, thereby causing uneven local plastic deformation, and then forming defects in the microstructure and surface morphology. Therefore, for the special aluminum alloy material of 8 series aluminum alloy, the inventors conducted a large number of experiments and coordinated the curling tension and rolling speed during the foil rolling process to 30N / mm respectively. 2 ~45N / mm 2 , 500m / min~800m / min, thereby realizing accurate control of microcracks and other defects that may occur on the surface of the foil during the foil rolling process from the perspective of rolling process parameters, thereby reducing the pinhole defect problem caused by microcracks.

[0024] It needs additional explanation that microcrack (oil pit) pinholes are caused by the connection between the bright surface microcracks and the deep concave parts of the dark surface waves, so controlling the generation and distribution of microcracks is conducive to reducing the generation of pinholes. Bright surface microcracks are related to the intrinsic quality of aluminum foil billets, rolling conditions, rolling processes and other factors. During cold rolling and foil rolling, the lubrication mechanism of rolling oil is a mixed lubrication composed of boundary lubrication and fluid lubrication. The rolling oil introduced into the roll bite will form periodically arranged microcracks (oil pits) perpendicular to the rolling furrows through the deformation of the aluminum surface. As the amount of interfacial rolling oil increases, the friction coefficient decreases, and the size of microcracks (oil pits) (such as depth, width, single volume, area and volume share, etc.) will gradually increase, and the initial rolling oil amount will tend to be constant after exceeding a certain level. The present invention reduces the amount of rolling oil flowing into the roller bite zone during rolling, that is, through the coordinated regulation of the rolling oil viscosity, rolling speed and curling tension, the effective control of microcrack generation is successfully achieved, thereby successfully reducing the number of oil pits and pinhole defects ultimately formed on the foil surface.

[0025] In particular, the preparation method provided by the present invention is universally applicable to aluminum alloys of various composition formulas, but the settings of the rolling oil viscosity, rolling speed and curling tension are additionally adapted to 8 series aluminum foil, and ultimately an 8 series aluminum alloy foil with excellent surface morphology is obtained.

[0026] And, unless otherwise specified, the viscosity in the present invention refers to the viscosity at room temperature. At the same time, cast-rolling is a continuous production process from liquid metal to finished product that combines the two traditional processes of casting and rolling. For the 8 series aluminum foil prepared by the present invention, the molding process realizes continuous coil production in the melting and casting link compared to the traditional hot-rolled slab, and eliminates the hot rolling process, which can effectively improve production efficiency and reduce costs. At the same time, due to the high cooling rate of cast-rolling, the solid solubility of Fe and Si elements in the alloy can be effectively increased, which is beneficial to the control of the number and size of the second phase in the microstructure of the cast-rolled slab.

[0027] At the same time, for the blank of 8 series aluminum foil, the excessive size of the second phase particles in its metallographic structure, or the high distribution ratio of the second phase greater than a certain size is a major reason for the high pinhole rate of the subsequent finished aluminum foil. Specifically, the larger second phase in the aluminum foil blank is easy to cause the discontinuity of the aluminum foil matrix structure, destroying the coherence relationship between the second phase and the matrix structure. At the same time, in the subsequent rolling and annealing, the size-invariable particles are formed, which usually have the characteristics of being distributed along the rolling direction to a certain extent. As the aluminum foil is continuously thinned, the matrix around the large-size second phase is cut and rolled to a greater extent, thereby increasing the probability of pinholes. Therefore, the inventor has conducted a large number of experiments, and in several typical embodiments, the metallographic structure of the aluminum foil blank in step S2 preferably includes a matrix phase and a second phase, wherein the area of ​​the second phase with a caliper diameter of more than 5 μm accounts for 2.0% to 4.0% in the metallographic structure, and the area of ​​the second phase with a caliper diameter of more than 3 μm accounts for 6.0% to 10.0% in the metallographic structure. Thus, the size distribution of the second phase in the aluminum foil blank is reasonably controlled, the continuity of the aluminum foil matrix structure is further protected, and the situation of it being cut during subsequent deformation is suppressed, thereby significantly improving the surface quality of the 8 series aluminum alloy foil. In several more typical embodiments, the second phase is AlFe phase and / or AlFeSi phase.

[0028] To avoid ambiguity, the "microcrack pinhole" in the present invention refers to the "surface pinhole defect caused by microcracks".

[0029] In several typical embodiments, the composition of the 8 series aluminum alloy foil includes Fe and Si, and in terms of weight percentage, the Fe element is 1.0% to 1.6%, and the Si element is 0.15% to 0.9%. In principle, the preparation method provided by the present invention is applicable to aluminum alloys that meet the composition requirements of the 8 series aluminum alloy foil, but in order to optimize the proportion of the second phase in the foil blank, the inventor has optimized the content of Fe and Si through a large number of experiments, so as to form less AlFeSi second phase and various impurity second phases, so as to more effectively ensure the surface morphology of the final 8 series aluminum alloy foil. In addition, when the Fe and Si content is too much, due to the high strength of the alloy matrix, it is easier to cause the maximum width and depth of the surface microcracks to increase. At the same time, after the aluminum foil is thinned to a certain extent, the number of pinholes caused by microcracks (oil pits) increases, and the surface morphology deteriorates.

[0030] On the basis of the above content, further, the cold rolling includes multi-pass cold rolling of at least three passes, and the total cold rolling rate is 95.0% to 96.5%, so as to more effectively break the second phase, refine the grains, and reduce the proportion of large sizes therein, so as to further reduce microcracks in the subsequent foil rolling process and improve the surface morphology of the final 8 series aluminum alloy foil.

[0031] In several typical implementations, in order to more accurately control the foil thickness and the number of surface defects, and also to make the deformation of the foil in all directions more uniform, it is preferred that in step S3, the foil rolling includes the following steps: first foil rolling to obtain a first aluminum foil; second foil rolling to obtain a second aluminum foil; third foil rolling to obtain a third aluminum foil. In order to better refine the grains, optimize the texture, and reduce internal and surface defects, the inventors have preferably selected the reduction rates of the first foil rolling, the second foil rolling, and the third foil rolling to be 40% to 55% independently after a large number of experiments.

[0032] In order to further improve the surface smoothness of the 8 series aluminum foil and reduce the number of oil pits and pinhole defects on its surface, the inventors have preferably, after a large number of experiments, selected the roller line roughness used for the first foil rolling and the second foil rolling to be independently 0.15μm to 0.20μm, and the roller line roughness used for the third foil rolling to be 0.10μm to 0.12μm.

[0033] Furthermore, after a large number of experiments, the inventors controlled the foil rolling process parameters and optimized the surfaces of the first foil, the second foil and the third foil, and the maximum value of the microcrack limit depth was 1.30μm; the maximum value of the maximum width of the microcracks on the surfaces of the first foil, the second foil and the third foil was 21.5μm; the maximum value of the microcrack area ratio on the surfaces of the first foil, the second foil and the third foil was 13.0%, thereby obtaining an aluminum alloy foil with better surface morphology.

[0034] In several typical embodiments, the limit depth of microcracks on the surface of the first foil is 0.95μm to 1.30μm, the maximum width of the microcracks is 15.5μm to 21.5μm, and the microcrack area accounts for 7.0% to 13.0%; and / or, the limit depth of microcracks on the surface of the second foil is 0.85μm to 1.25μm, the maximum width of the microcracks is 14.0μm to 18.5μm, and the microcrack area accounts for 5.5% to 11.0%; and / or, the limit depth of microcracks on the surface of the third foil is 0.75μm to 1.00μm, the maximum width of the microcracks is 11.5μm to 16.5μm, and the microcrack area accounts for 4.0% to 9.0%.

[0035] At present, for metal foils, pinhole defects can only be detected online when the aluminum foil is thinned to a level close to the finished product. Because it is close to the product terminal process, once the defect is found to exceed the technical quality requirements, it will lead to product downgrading, slitting to reduce the yield rate, or even the scrapping of the entire roll. Among the pinhole defects in aluminum foil, microcrack pinholes account for a very high proportion, especially for aluminum foil products with high alloy element content and single zero, double zero, and ultra-thin aluminum foil products. And microcracks, as mentioned above, are the main direct cause of oil pit pinholes. Therefore, in the above-mentioned embodiment of the present invention, it is preferred to adjust the foil rolling process parameters so that the ultimate depth, maximum width and area ratio of the surface microcracks of each pass are more accurately controlled, so as to more effectively predict and control the size and number of microcracks in the earlier passes, thereby more significantly suppressing the number of oil pit pinhole defects on the surface of the final 8 series aluminum alloy foil and improving its surface quality.

[0036] Furthermore, the rolling oil includes base oil, acid compounds, ester compounds and alcohol compounds, wherein the acid compounds play a role of lubrication and rust prevention in the rolling oil, and react with the aluminum oxide layer on the surface of the aluminum foil to form a protective film to prevent oxidation during the rolling process; the ester compounds can form a lubricating film on the surface to reduce friction and wear during the rolling process, and improve the surface properties of the aluminum foil to make it smoother and flatter; the alcohol substances can improve the internal structure of the aluminum foil to make it more uniform and dense. The inventors have collaboratively optimized the content of the acid compounds to be 0.08% to 0.12%, the content of the ester compounds to be 3.00% to 5.00%, and the content of the alcohol compounds to be 0.50% to 12.00% through a large number of experiments. Thereby, the optimization effects of the three are better exerted, and at the same time, the dark stripes caused by excessive reaction of the acid, the black spots caused by excessive esters, and especially the roller printing problems caused by excessive alcohols and decomposition are more effectively suppressed, and the surface properties of the obtained 8 series aluminum alloy foil are further optimized.

[0037] The present invention does not impose any restrictions on the specific formula of rolling oil and the specific types of each component in the formula, as long as it can meet the above content requirements. Exemplarily, the base oil used for rolling oil can be selected from one or more of mineral oil (such as kerosene), synthetic oil (such as polyalphaolefin, ester oil and polyether oil), vegetable oil, silicone oil and paraffin oil; acids can be selected from one or more of boric acid, fatty acid, organic phosphoric acid and sulfonic acid (such as lauric acid, stearic acid, etc.); esters can be selected from one or more of phosphate esters, sulfonic acid esters, fatty acid esters and polyol esters (such as methyl dodecanoate, methyl myristate and methyl hexadecanoate); alcohols can be selected from one or more of glycerol, ethylene glycol, polyethylene glycol and long-chain fatty alcohols. At the same time, other types of additives, such as antioxidants, antiwear agents, extreme pressure agents, etc., can be further added according to the specific rolling process and the quality requirements of aluminum foil to achieve better surface properties.

[0038] In order to match the raw materials and cold rolling process of the 8 series aluminum alloy foil, it is preferred that step S2 also includes annealing the plate after cold rolling to obtain an aluminum foil blank, so as to more effectively reduce the proportion of the second phase in its metallographic structure. After a large number of experiments, the inventor further preferred that the annealing temperature be 200°C to 270°C, the heating rate be 30°C / h to 65°C / h, and the holding time be 1.5h to 6h, and under these conditions, an 8 series aluminum alloy foil with a lower proportion of the second phase and better surface properties was obtained. It is more preferred that the heating method of the annealing treatment be furnace heating, so as to further improve the comprehensive performance of the 8 series aluminum alloy foil.

[0039] The second aspect of the present invention provides an 8 series aluminum alloy foil, which is prepared by the above-mentioned preparation method of the 8 series aluminum alloy foil, and the thickness of the 8 series aluminum alloy foil is 35μm to 45μm. The 8 series aluminum alloy foil prepared by the above-mentioned preparation method has a more suitable thickness and better surface properties.

[0040] Furthermore, the number of pinholes on the surface of 8 series aluminum alloy foil is 0 / 10,000 m 2 ~4 / 10,000 m 2 The diameter of the pinhole is ≤0.05mm, that is, there are fewer surface defects. Compared with the traditional 8021 and 8079 aluminum foils, the 8 series aluminum alloy foil prepared by the present invention has high strength and excellent formability.

[0041] The third aspect of the present invention provides an application of the above-mentioned 8 series aluminum alloy foil as a packaging aluminum foil material in the fields of new energy, industrial and civil electrical equipment, food and medicine. The 8 series aluminum alloy foil obtained by the present invention has excellent surface morphology and can better meet the application requirements of the above-mentioned fields.

[0042] 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.

[0043] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Example 1

[0045] A method for preparing 8 series aluminum alloy foil:

[0046] Step S1: Using raw materials with an Fe content of 1.6%, an Si content of 0.15% and the balance of Al as raw materials, the alloy raw materials are smelted, cast and rolled to obtain a plate with a thickness of 7 mm.

[0047] Step S2: The obtained sheet is cold-rolled to obtain a cold-rolled sheet with a thickness of 0.34 mm (i.e., the total cold-rolling rate is 95.1%), and then intermediate annealing is performed at an annealing temperature of 240°C and a furnace heating rate of 45°C / h. After the billet reaches the temperature, it is kept warm for 4 hours, i.e., the aluminum foil billet. The metal structure of the aluminum foil billet is an equiaxed crystal structure, and the second phase area with a size greater than 3μm accounts for 6.2%, and the second phase area with a size greater than 5μm accounts for 2.8%.

[0048] Step S3: Before foil rolling, the viscosity of the rolling oil used for foil rolling is prepared to be 2.1 mm 2 / s, which uses kerosene as the base oil, and adds 0.09% of lauric acid, 3.8% of methyl hexadecanoate and 10.0% of dodecanol based on the total weight of the rolling oil.

[0049] The obtained aluminum foil blank was subjected to three passes of foil rolling, and the thickness change was 0.34mm→0.16mm→0.070mm→0.035mm (i.e., the reduction rates of the three passes of foil rolling were 52.9%, 56.3% and 50.0% respectively), and the curling tension of the three passes of foil rolling was controlled at 35N / mm 2 The rolling speed is controlled at 650m / min. The line roughness of the rollers used in the first two passes of foil rolling is 0.19μm, and the roughness of the rollers used in the third pass of foil rolling is 0.12μm. At the same time:

[0050] The ultimate depth of microcracks on the foil surface after the first foil rolling is 0.96 μm, the maximum width of microcracks is 15.8 μm, and the microcrack area accounts for 7.9%;

[0051] The ultimate depth of microcracks on the foil surface after the second foil rolling is 0.89 μm, the maximum width of microcracks is 14.2 μm, and the microcrack area accounts for 5.9%;

[0052] After the third foil rolling, the ultimate depth of microcracks on the foil surface is 0.77 μm, the maximum width of microcracks is 11.8 μm, and the microcrack area accounts for 4.3%.

[0053] Step S4: After slitting, the obtained aluminum foil is subjected to finished product degreasing annealing, and finally an 8 series aluminum alloy foil is obtained, the thickness of which is 35 μm, and the number of oil pits and pinholes on the surface is 3 / 10,000 m 2 .

[0054] The surface morphology of the obtained 8 series aluminum alloy foil was tested by scanning electron microscope. Figure 1 , which shows the microscopic morphology of the pinhole, and it can be seen that its diameter is about 0.05 mm. At the same time, it can be seen from the figure that the surface flatness of the 8 series aluminum alloy foil obtained in this embodiment is high, and the number of microcrack pinholes and oil pits is small.

[0055] Example 2

[0056] A method for preparing 8 series aluminum alloy foil:

[0057] Step S1: Using raw materials with an Fe content of 1.0%, an Si content of 0.9% and the balance of Al as raw materials, the alloy raw materials are smelted, cast and rolled to obtain a plate with a thickness of 7.2 mm.

[0058] Step S2: The obtained sheet is cold-rolled to obtain a cold-rolled sheet with a thickness of 0.28 mm (i.e., the total cold-rolling rate is 96.1%), and then intermediate annealing is performed at an annealing temperature of 250°C and a furnace heating rate of 40°C / h. After the billet reaches the temperature, it is kept warm for 5 hours, i.e., the aluminum foil billet. The metal structure of the aluminum foil billet is an equiaxed crystal structure, and the second phase area with a size greater than 3μm accounts for 8.5%, and the second phase area with a size greater than 5μm accounts for 3.2%.

[0059] Step S3: Before foil rolling, the viscosity of the rolling oil used for foil rolling is prepared to be 2.0 mm 2 / s, which uses kerosene as the base oil, and adds 0.12% of lauric acid, 5.0% of methyl hexadecanoate and 5.0% of dodecanol based on the total weight of the rolling oil.

[0060] The obtained aluminum foil blank was subjected to three passes of foil rolling, and the thickness change was 0.28mm→0.17mm→0.080mm→0.045mm (i.e., the reduction rates of the three passes of foil rolling were 50.0%, 52.9% and 43.8% respectively), and the curling tension of the three passes of foil rolling was controlled at 42N / mm 2 The rolling speed is controlled at 700m / min. The line roughness of the rolls used in the first two passes of foil rolling is 0.16μm, and the roughness of the rolls used in the third pass of foil rolling is 0.12μm. At the same time:

[0061] The ultimate depth of microcracks on the foil surface after the first foil rolling is 0.98 μm, the maximum width of microcracks is 16.1 μm, and the microcrack area accounts for 8.7%;

[0062] The ultimate depth of microcracks on the foil surface after the second foil rolling is 0.88μm, the maximum width of microcracks is 14.5μm, and the microcrack area accounts for 6.2%;

[0063] After the third foil rolling, the microcrack limit depth on the foil surface is 0.78 μm, the maximum microcrack width is 12.0 μm, and the microcrack area accounts for 4.7%. The above structural characteristics are shown in Tables 1 and 2.

[0064] Step S4: After slitting, the obtained aluminum foil is subjected to finished product degreasing annealing, and finally an 8 series aluminum alloy foil is obtained, the thickness of which is 45 μm, and the number of oil pits and pinholes on the surface is 2 / 10,000 m 2 .

[0065] Example 3

[0066] A method for preparing 8 series aluminum alloy foil:

[0067] The difference between this embodiment and embodiment 1 is only that the alloy raw materials are different, specifically: the raw materials are 0.8% Fe element content, 1.0% Si element content, and the balance is Al.

[0068] Example 4

[0069] A method for preparing 8 series aluminum alloy foil:

[0070] The difference between this embodiment and embodiment 1 is only that the alloy raw materials are different, specifically: the raw materials are 1.8% Fe element content, 0.12% Si element content, and the balance is Al.

[0071] Example 5

[0072] A method for preparing 8 series aluminum alloy foil:

[0073] The only difference between this embodiment and embodiment 1 is that in step S1, the casting parameters are controlled to obtain a plate with a thickness of 6.2 mm; and step S2: the obtained plate is further cold-rolled to obtain a cold-rolled plate with a thickness of 0.34 mm (i.e., the total cold rolling rate is 94.5%), followed by intermediate annealing, the annealing temperature is 180°C, the furnace heating rate is 25°C / h, and the billet is kept warm for 7 hours after reaching the temperature, i.e., the aluminum foil billet.

[0074] Example 6

[0075] A method for preparing 8 series aluminum alloy foil:

[0076] The only difference between this embodiment and embodiment 2 is that in step S1, the casting parameters are controlled to obtain a plate with a thickness of 8.2 mm; and step S2: the obtained plate is further cold rolled to obtain a cold-rolled plate with a thickness of 0.28 mm (that is, the total cold rolling rate is 96.6%), and then intermediate annealing is performed, the annealing temperature is 300°C, the furnace heating rate is 75°C / h, and the billet is kept warm for 1 hour after reaching the temperature, that is, the aluminum foil billet.

[0077] Example 7

[0078] A method for preparing 8 series aluminum alloy foil:

[0079] The only difference between this embodiment and embodiment 1 is that the intermediate annealing treatment in step S2 is not performed, but the plate obtained by cold rolling is directly used as a foil blank for subsequent foil rolling treatment.

[0080] Example 8

[0081] A method for preparing 8 series aluminum alloy foil:

[0082] The only difference between this embodiment and embodiment 1 is that in step S3, the thickness of the foil rolling changes, that is, the reduction rate of the three foil rolling passes. Specifically: the obtained aluminum foil billet is subjected to three foil rolling passes, and the thickness changes as follows: 0.340mm→0.209mm→0.128mm→0.035mm (that is, the reduction rates of the three foil rolling passes are 38.5%, 38.5% and 72.7%, respectively).

[0083] Example 9

[0084] A method for preparing 8 series aluminum alloy foil:

[0085] The only difference between this embodiment and embodiment 1 is that in step S3, the thickness of the foil rolling changes, that is, the reduction rate of the three foil rolling passes. Specifically: the obtained aluminum foil billet is subjected to three foil rolling passes, and the thickness changes as follows: 0.340mm→0.136mm→0.054mm→0.035mm (that is, the reduction rates of the three foil rolling passes are 60.0%, 60.0% and 35.7% respectively).

[0086] Example 10

[0087] A method for preparing 8 series aluminum alloy foil:

[0088] The difference between this embodiment and embodiment 1 is that in step S3, the thickness of the foil rolling changes. Specifically, the obtained aluminum foil billet is subjected to two foil rolling passes, and the thickness changes from 0.340 mm to 0.106 mm to 0.035 mm (i.e., the reduction ratios of the two foil rolling passes are both 68.8%).

[0089] Embodiment 11

[0090] A method for preparing 8 series aluminum alloy foil:

[0091] The difference between this embodiment and embodiment 1 is that in step S3, the line roughness of the rollers used in the three foil rollings is different. Specifically, the line roughness of the rollers used in the first and second foil rollings is 0.12 μm, and the roughness of the rollers used in the third foil rolling is 0.15 μm. The surface structural characteristics of the foil obtained after each foil rolling are shown in Tables 1 and 2.

[0092] Example 12

[0093] A method for preparing 8 series aluminum alloy foil:

[0094] The difference between this embodiment and embodiment 1 is that in step S3, the line roughness of the rollers used in the three foil rollings is different. Specifically, the line roughness of the rollers used in the first and second foil rollings is 0.22 μm, and the roughness of the rollers used in the third foil rolling is 0.08 μm. The surface structural characteristics of the foil obtained after each foil rolling are shown in Tables 1 and 2.

[0095] Embodiment 13

[0096] A method for preparing 8 series aluminum alloy foil:

[0097] The difference between this embodiment and embodiment 1 is that the rolling oil formula used in step S3 is different, specifically: kerosene is used as the base oil, and 0.05% of lauric acid, 2.5% of methyl hexadecanoate and 13.0% of dodecanol are added to the total weight of the rolling oil, and the viscosity remains unchanged. The surface structural characteristics of the foil obtained after each foil rolling are shown in Tables 1 and 2.

[0098] Embodiment 14

[0099] A method for preparing 8 series aluminum alloy foil:

[0100] The difference between this embodiment and embodiment 1 is that the rolling oil formula used in step S3 is different, specifically: kerosene is used as the base oil, and 1.50% of lauric acid, 8.0% of methyl hexadecanoate and 0.3% of dodecanol are added to the total weight of the rolling oil, and the viscosity remains unchanged. The surface structural characteristics of the foil obtained after each foil rolling are shown in Tables 1 and 2.

[0101] Comparative Example 1

[0102] A method for preparing 8 series aluminum alloy foil:

[0103] The difference between this comparative example and Example 1 is that in step S3, the conditions of the three foil rolling are specifically: the curling tension of the three foil rolling is controlled at 28N / mm 2, the rolling speed is controlled at 850m / min.

[0104] Comparative Example 2

[0105] A method for preparing 8 series aluminum alloy foil:

[0106] The difference between this comparative example and Example 1 is that in step S3, the conditions of the three foil rolling are as follows: the curling tension of the three foil rolling is controlled at 50N / mm 2 , the rolling speed is controlled at 450m / min.

[0107] Comparative Example 3

[0108] A method for preparing 8 series aluminum alloy foil:

[0109] The difference between this comparative example and Example 1 is that the rolling oil formula used in step S3 is changed to make its viscosity 1.2 mm 2 / s. The surface structural characteristics of the foil obtained after each foil rolling are shown in Tables 1 and 2.

[0110] Test Method

[0111] Second phase area ratio: The test is carried out using an optical microscope, and its evaluation and calculation are based on GB / T 3246.1-2024 "Test methods for microstructure of deformed aluminum and aluminum alloy products Part 1: Microstructure test methods".

[0112] Microcracks: The detection of microcracks is measured by ultra-depth microscope and optical profiler, where the ultra-depth microscope characterizes the distribution of microcracks, calculates the area ratio and measures the maximum width, while the optical profiler realizes the measurement and statistics of the limit depth data of microcracks on the surface of aluminum foil under 2D and 3D morphology. In order to avoid errors, the foils in the preparation process of each embodiment and comparative example are sampled and tested 10 times, and the maximum value is taken as the test result value of the limit depth, maximum width and area ratio of microcracks on its surface.

[0113] Number of pinholes: After pinholes are determined using the online pinhole detection equipment on the production line, the morphology and energy spectrum are analyzed using a scanning electron microscope. The type of pinholes is confirmed to be microcrack pinholes based on the results of the scanning electron microscope. The quality requirements for pinhole defects refer to the provisions of "3.5.1" and "3.5.2" in "GB / T 3198-2020 Aluminum and Aluminum Alloy Foil". The pinhole diameters on the foil surface obtained in the embodiments of the present invention are all ≤0.05mm. The evaluation and calculation of pinholes are based on GB / T 22638.2-2016 "Aluminum Foil Test Methods Part 2: Pinhole Detection".

[0114] The above performance tests were performed on the aluminum alloy foils obtained in the embodiments and comparative examples, and the obtained results are shown in Table 1 and Table 2, respectively.

[0115] Table 1

[0116]

[0117]

[0118] Table 2

[0119]

[0120] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the optimization of the surface morphology of the 8 series aluminum alloy foil, and the number of microcracks and pinholes on the surface of the obtained 8 series aluminum alloy foil is significantly reduced, so that it can be used as a packaging material to meet the application of various fields.

[0121] Specifically, when the number of foil rolling passes is reduced and the pass reduction rate is too large, the deformation during rolling is uneven, which can easily lead to surface microcracks, wrinkles and other defects on the aluminum foil surface, which in turn leads to an increase in microcrack pinholes in the finished aluminum foil. If the rolling speed is too high, it will affect the lubrication state in the rolling deformation zone, causing poor lubrication in the rolling deformation zone, reducing the oil film thickness, etc., thereby increasing the surface roughness and microcrack degree of the aluminum foil. During the rolling process of the aluminum foil, if the tension is too small, it will cause wrinkling and ridge formation on the material surface, as well as problems such as interlayer penetration on the coil end surface. However, when the coiling tension is too large, the grain changes faster, the local grains are coarse and the deformation is not coordinated, which will lead to a significant increase in the number of microcracks and pinholes on the aluminum foil surface, and even cause belt breakage in severe cases. In addition, excessive tension will also cause the inside of the foil coil to be loose and the outside to be tight, resulting in a folding phenomenon, which is the so-called "bird's nest" defect.

[0122] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0123] 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 8 series aluminum alloy foil, characterized in that: include: Step S1, melting and casting the raw material of the 8 series aluminum alloy foil to obtain a plate; Step S2, cold rolling the plate to obtain an aluminum foil blank; Step S3, the aluminum foil blank is subjected to a pressure of 30 N / mm 2 ~45N / mm 2 The 8 series aluminum alloy foil is obtained by rolling the foil at a curling tension of 500 m / min to 800 m / min. The rolling oil viscosity used in the foil rolling is 1.5 mm 2 / s~2.5mm 2 / s.

2. The method for preparing the 8 series aluminum alloy foil according to claim 1, characterized in that: In step S2, the metallographic structure of the aluminum foil blank includes a matrix phase and a second phase, wherein the area of ​​the second phase with a caliper diameter greater than 5 μm accounts for 2.0% to 4.0% of the metallographic structure, and the area of ​​the second phase with a caliper diameter greater than 3 μm accounts for 6.0% to 10.0% of the metallographic structure; Preferably, the second phase is an AlFe phase and / or an AlFeSi phase.

3. The method for preparing the 8 series aluminum alloy foil according to claim 1 or 2, characterized in that: In step S3, the foil rolling includes the following steps performed in sequence: The first foil material is rolled to obtain a first aluminum foil; The second foil material is rolled to obtain a second aluminum foil; The third foil material is rolled to obtain a third aluminum foil; Preferably, the reduction ratios of the first foil rolling, the second foil rolling and the third foil rolling are each independently 40% to 55%.

4. The method for preparing the 8 series aluminum alloy foil according to claim 3, characterized in that: The linear roughness Ra of the rolls used in the first foil rolling and the second foil rolling is independently 0.15 μm to 0.20 μm, and the linear roughness Ra of the rolls used in the third foil rolling is 0.10 μm to 0.12 μm.

5. The method for preparing the 8 series aluminum alloy foil according to claim 3 or 4, characterized in that: The maximum limit depth of microcracks on the surfaces of the first foil, the second foil, and the third foil is 1.30 μm; The maximum value of the maximum width of microcracks on the surfaces of the first foil, the second foil, and the third foil is 21.5 μm; The maximum value of the micro-crack area ratio on the surfaces of the first foil, the second foil and the third foil is 13.0%.

6. The method for preparing the 8 series aluminum alloy foil according to any one of claims 1 to 5, characterized in that: The rolling oil comprises base oil, acid compounds, ester compounds and alcohol compounds, wherein the content of the acid compounds is 0.08% to 0.12%, the content of the ester compounds is 3.00% to 5.00%, and the content of the alcohol compounds is 0.50% to 12.00%.

7. The method for preparing the 8 series aluminum alloy foil according to any one of claims 1 to 6, characterized in that: Step S2 also includes annealing the plate after the cold rolling process to obtain the aluminum foil blank; Preferably, the annealing treatment temperature is 200°C to 270°C, the heating rate is 30°C / h to 65°C / h, and the holding time is 1.5h to 6h; More preferably, the annealing treatment is performed by heating the temperature in a furnace.

8. An 8 series aluminum alloy foil, characterized in that: The 8 series aluminum alloy foil is prepared by the method for preparing the 8 series aluminum alloy foil according to any one of claims 1 to 7, and the thickness of the 8 series aluminum alloy foil is 35 μm to 45 μm.

9. The 8 series aluminum alloy foil according to claim 8, characterized in that: The number of pinholes on the surface of the 8 series aluminum alloy foil is 2 / 10,000 m 2 ~4 / 10,000 m 2 , the diameter of the pinhole is ≤0.05mm.

10. Use of the 8 series aluminum alloy foil material according to claim 8 or 9 as a packaging aluminum foil material in the fields of new energy, industrial and civil electrical equipment, food and medicine.

Images