Method for improving thickness uniformity of composite aluminum coating

Abstract

The invention relates to the technical field of composite aluminum coatings, in particular to a method for improving the thickness uniformity of a composite aluminum coating. Comprising the following steps that 1, evaporation structures are arranged, an airflow adjusting structure is arranged between the evaporation structures, and a preset angle is formed between the orientation of the airflow adjusting structure and the movement direction of aluminum steam in the evaporation structures; performing aluminum oxide bottoming on the base film in vacuum to form an aluminum oxide bottoming layer; 2, breaking vacuum, then opening an airflow adjusting structure, and carrying out evaporation on the surface of the aluminum oxide base layer to form an aluminum layer; and thus, the composite aluminum coating is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of composite aluminum coatings, in particular to a method for improving the thickness uniformity of composite aluminum coatings. Background Art

[0002] With the development of modern industry, composite aluminum foil has been widely used due to its excellent properties such as high conductivity and good barrier properties. Currently, composite aluminum foil is mainly produced through vacuum evaporation, specifically by depositing 1µm aluminum layers on the upper and lower surfaces of a 6µm PET base film, forming a "sandwich structure."

[0003] Specifically, during the vacuum evaporation process, aluminum wire is first introduced into a high-temperature evaporation boat, which is then heated to 1000-1200°C using electrical heating, thereby converting the solid aluminum into gaseous aluminum. Simultaneously, nitrogen is introduced into the diffusion channel of the aluminum vapor, causing the oxygen to react with the aluminum molecules, thereby generating metal compounds that are deposited on the surface of the base film, forming an auxiliary layer of a specific thickness. The auxiliary layer prepared in this way has the advantages of high density and strong corrosion resistance. Therefore, vacuum evaporation technology has become the most commonly used preparation technology for composite aluminum foil.

[0004] However, at present, vacuum evaporation technology has obvious defects, specifically the following problems: when using evaporation to aluminum-plate the composite aluminum current collector, the distribution of aluminum vapor in the evaporation chamber is not uniform, resulting in a situation where there is more in the middle and less on both sides. The final coating is thick in the middle and thin on both sides, which seriously affects the quality and performance stability of the composite aluminum foil.

[0005] Therefore, it is of great significance to solve the above problems and prepare a composite aluminum coating with uniform thickness. Summary of the Invention

[0006] The object of the present invention is to provide a method for improving the thickness uniformity of a composite aluminum coating to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for improving the thickness uniformity of a composite aluminum coating comprises the following steps: Step 1: Setting up an evaporation structure and an airflow regulating structure between the evaporation structures, with the direction of the airflow regulating structure forming a preset angle with the direction of movement of the aluminum vapor in the evaporation structure; applying an aluminum oxide primer to the base film under vacuum to form an aluminum oxide primer layer; Step 2: Break the vacuum, then open the airflow regulating structure, evaporate on the surface of the alumina base layer to form an aluminum layer, and obtain a composite aluminum coating.

[0008] More optimally, the evaporation structure includes N evaporation boats; N is a positive integer; the airflow adjustment structure is a gas curtain; the gas curtain is set as: on the left side of the first evaporation boat and on the right side of the Nth evaporation boat, and 2 to 8 evaporation boats are set between the first to Nth evaporation boats.

[0009] More optimally, when N is 20, the gas curtain is set as follows: on the left side of the 1st evaporation boat and on the right side of the 20th evaporation boat, between the 4th evaporation boat and the 5th evaporation boat, between the 8th evaporation boat and the 9th evaporation boat, and between the 16th evaporation boat and the 17th evaporation boat.

[0010] More optimally, the gas in the gas curtain is nitrogen; the pressure of the nitrogen is 0.2-0.6 MPa.

[0011] More optimally, the preset angle is 0-85°.

[0012] More optimally, the process parameters of the alumina primer are: the film-unwinding end of the base film is at 115~125N, the winding end is at 95~105N; the vacuum degree before opening is 4.5×10 -3 ~5.5×10 -3 Pa; winding speed is 280~300m / min; wire feeding speed is 300~350mm / min.

[0013] More optimally, the process parameters of the alumina primer are: the vacuum degree after opening is 4.5×10 -2 ~5.5×10 -2 Pa; the heating temperature of the evaporation boat is 1000~1200℃; the coating speed is 235~245m / min.

[0014] In a further approach, a gas curtain is installed within the evaporation boat. The position, number, and pressure of the gas curtains are adjusted according to the distribution of the aluminum vapor. This allows the aluminum vapor to move within the gas curtains and prevent them from concentrating in the center, thereby achieving uniform deposition on the base film. Simultaneously, the gas ejected from the gas curtains cools the base film, reducing strain caused by the vapor heat.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention controls the flow direction of aluminum vapor by setting a gas curtain in part of the evaporation boat, thereby ensuring a more uniform thickness distribution of the aluminum coating on the membrane surface, so that the fluctuation of the sheet resistance along the width direction of the membrane surface is smaller; (2) The present invention sets a gas curtain in part of the evaporation boat, and the gas (nitrogen) cools the base film, thereby reducing the stress caused by the heat on the film surface. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0017] Example 1: A method for improving the thickness uniformity of a composite aluminum coating, comprising the following steps: Step 1: Set up 20 evaporation boats, and set up gas curtains in some of the 20 evaporation boats, including: setting up a gas curtain on the left side of the first evaporation boat, setting up a gas curtain in the middle of the fourth and fifth evaporation boats, setting up a gas curtain in the middle of the eighth and ninth evaporation boats, setting up a gas curtain in the middle of the sixteenth and seventeenth evaporation boats, and setting up a gas curtain on the right side of the 20th evaporation boat; the direction of the gas curtain is at a preset angle of 42° with the movement direction of the aluminum vapor in the evaporation boat; fix the base film to the winding trolley, retract and release the film, adjust the tension (120N at the film release end and 100N at the rewinding end), and then set the vacuum degree before opening to 5×10 -3 Pa, start the winding trolley and control the winding speed to 300m / min; at the same time, heat the evaporation boat at 1200℃ to feed aluminum wire at a wire feeding speed of 300mm / min, start the oxygen intake, and coat the base film surface with aluminum oxide at a coating speed of 240m / min to form an aluminum oxide base layer; after the vacuum degree is controlled to be 5×10 -2 Pa; Step 2: Break the vacuum, then open the gas curtain, set the nitrogen supply to start, set the nitrogen pressure to 0.2 MPa, and evaporate on the surface of the alumina base layer in the same way as above to form an aluminum layer to obtain a composite aluminum coating.

[0018] Example 2: A method for improving the thickness uniformity of a composite aluminum coating. The difference from Example 1 is that in step 2, the nitrogen pressure is set to 0.4 MPa, and the other conditions are the same as those in Example 1.

[0019] Example 3: A method for improving the thickness uniformity of a composite aluminum coating. The difference from Example 1 is that in step 2, the nitrogen pressure is set to 0.6 MPa, and the other conditions are the same as those in Example 1.

[0020] Example 4: A method for improving the thickness uniformity of a composite aluminum coating. The difference from Example 2 is that in step 1, a gas curtain is set on the left side of the first evaporation boat, a gas curtain is set between the second and third evaporation boats, a gas curtain is set between the eighteenth and nineteenth evaporation boats, and a gas curtain is set on the right side of the 20th evaporation boat. The other conditions are the same as those in Example 2.

[0021] Example 5: A method for improving the thickness uniformity of a composite aluminum coating. The difference from Example 2 is that in step 1, a gas curtain is set on the left side of the first evaporation boat, a gas curtain is set between the seventh and eighth evaporation boats, a gas curtain is set between the thirteenth and fourteenth evaporation boats, and a gas curtain is set on the right side of the 20th evaporation boat. The other conditions are the same as those in Example 2.

[0022] Comparative Example 1: Based on Example 1, aluminum plating was performed by a single evaporation method without setting any gas curtain. The other processes remained unchanged, specifically as follows: Step 1: Fix the base film to the winding trolley, and then retract and release the film. Adjust the tension (120N for the film release end and 100N for the rewinding end). After the winding trolley enters the evaporation chamber, set the vacuum degree before opening to 5×10 -3 Pa, start the winding trolley and control the winding speed to 300m / min; at the same time, heat the evaporation boat at 1200℃ to feed aluminum wire at a wire feeding speed of 300mm / min, start the oxygen intake, and coat the base film surface with aluminum oxide at a coating speed of 240m / min to form an aluminum oxide base layer; after the vacuum degree is controlled to be 5×10 -2 Pa; Step 2: Break the vacuum, and vapor-deposit on the surface of the alumina base layer in the same manner as above to form an aluminum layer to obtain a composite aluminum coating.

[0023] Test Experiment 1: The composite aluminum coatings prepared in Examples 1 to 5 and Comparative Example 1 were subjected to performance testing: Thickness test: The composite aluminum coatings prepared in Examples 1 to 5 and Comparative Example 1 were tested using a Mahr thickness gauge. Ten points were measured at even intervals along the width (1600 mm) from left to right on the film surface. The test results are shown in Table 1.

[0024] Test Experiment 2: The composite aluminum coatings prepared in Examples 1-5 and Comparative Example 1 were subjected to performance testing: Surface sheet resistance test: Referring to GB / T 22638.6-2016, a four-probe resistivity tester was used. The number of sheet resistance tests was determined based on the lateral width of the product. One point was tested every 100 mm, for a total of 10 points. The test results are shown in Table 2.

[0025] Detection Experiment 3: The performance of a composite aluminum coating prepared in Examples 1 to 5 and Comparative Example 1 was tested: Residual stress test: The residual stress of the composite current collector was tested by using the μ-360s X-ray residual stress tester of QUANTUM Quantum Scientific Instrument Trading (Beijing) Co., Ltd. The specific operation is as follows: the cut sample is placed in the test chamber, and the sample is irradiated with X-rays. After a single angle of incidence, a complete Debye ring is obtained using a two-dimensional detector. The change in the interplanar spacing under stress and the corresponding stress are calculated by comparing the difference between the Debye ring without stress and the deformed Debye ring under stress. After applying stress, the changes in the Debye ring before and after a single incidence are analyzed, and the residual stress data can be obtained through the residual stress analysis software; the test results are shown in Table 3;

[0026] Results Analysis: Tables 1-3 above show that using a gas curtain can control the flow direction of aluminum vapor, resulting in uniform deposition of aluminum vapor on the base film. Example 2 achieved the best results. Positioning the gas curtain near the edge ensured consistent thickness at both ends and the center, minimizing thickness fluctuations. Low nitrogen pressure caused the aluminum vapor to move toward the center near the film surface, while high pressure caused the film surface to vibrate. Furthermore, the cooling effect of the nitrogen reduced residual stress on the film surface.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for improving the thickness uniformity of a composite aluminum coating, characterized in that: The following steps are involved: Step 1: Setting up an evaporation structure and an airflow regulating structure between the evaporation structures, with the direction of the airflow regulating structure forming a preset angle with the direction of movement of the aluminum vapor in the evaporation structure; applying an aluminum oxide primer to the base film under vacuum to form an aluminum oxide primer layer; Step 2: Break the vacuum, then open the airflow regulating structure, evaporate on the surface of the alumina base layer to form an aluminum layer, and obtain a composite aluminum coating.

2. The method for improving the thickness uniformity of a composite aluminum coating according to claim 1, wherein: The evaporation structure includes N evaporation boats; N is a positive integer; the airflow adjustment structure is a gas curtain; the gas curtain is set as follows: on the left side of the first evaporation boat and on the right side of the Nth evaporation boat, and 2 to 8 evaporation boats are set between the first to Nth evaporation boats.

3. The method for improving the thickness uniformity of a composite aluminum coating according to claim 2, wherein: When N is 20, the gas curtain is set as follows: on the left side of the 1st evaporation boat and on the right side of the 20th evaporation boat, between the 4th evaporation boat and the 5th evaporation boat, between the 8th evaporation boat and the 9th evaporation boat, and between the 16th evaporation boat and the 17th evaporation boat.

4. The method for improving the thickness uniformity of a composite aluminum coating according to claim 2, wherein: The gas in the gas curtain is nitrogen; the pressure of the nitrogen is 0.2~0.6MPa.

5. The method for improving the thickness uniformity of a composite aluminum coating according to claim 1, wherein: The preset angle is 0~85°.

6. The method for improving the thickness uniformity of a composite aluminum coating according to claim 2, wherein: The process parameters of the aluminum oxide primer are as follows: the film-unwinding end of the base film is at 115~125N, the winding end is at 95~105N; the vacuum degree before opening is 4.5×10 -3 ~5.5×10 -3 Pa; winding speed is 280~300m / min; wire feeding speed is 300~350mm / min.

7. The method for improving the thickness uniformity of a composite aluminum coating according to claim 2, wherein: The process parameters of the alumina bottoming are: vacuum degree after opening is 4.5×10 -2 ~5.5×10 -2 Pa; the heating temperature of the evaporation boat is 1000~1200℃; the coating speed is 235~245m / min.

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