Anti-corrosion method, magnesium-containing assembly and electronic device

Abstract

An anti-corrosion method, a magnesium-containing assembly and an electronic device. The anti-corrosion method is applied to a contact surface between a first structural part and a second structural part, and comprises: attaching a composite film (1) to the contact surface between the first structural part and the second structural part, wherein the composite film (1) comprises a glue film and mylar. The anti-corrosion method can achieve an efficient galvanic corrosion inhibition effect. The magnesium-containing assembly and the electronic device, which use the anti-corrosion method, have a good anti-corrosion effect.

Description

Anti-corrosion method, magnesium-containing component, and electronic equipment

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on April 28, 2023, with application number 202310485419.X and application name “Anti-corrosion method, magnesium-containing components and electronic equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of metal anti-corrosion, and in particular to an anti-corrosion method, a magnesium-containing component, and an electronic device. Background Art

[0003] As flexible foldable screen technology matures, flexible foldable terminal products have become a major trend. Foldable terminal products (such as foldable phones, foldable tablets, foldable computers, and other electronic devices) must meet high reliability, good operation experience, and good appearance to be accepted by consumers. However, foldable terminals currently have the problem of heavy weight that affects the user experience. To provide a better foldable device experience, weight reduction has become a key issue.

[0004] To reduce the weight of electronic devices, more and more structural parts are made of magnesium alloys. This inevitably causes magnesium alloys to come into contact with dissimilar metals (such as stainless steel fasteners and plates) and even be electrically connected. However, due to the large potential difference between magnesium alloys (approximately -2.363V) and steel (approximately -0.441V), magnesium alloys often suffer from severe galvanic corrosion, which not only affects the connection strength but also poses risks such as shaft jamming, foreign matter, and electrical connection failure. This problem also exists in folding devices. Therefore, while folding devices use magnesium alloys to reduce weight, how to prevent corrosion of magnesium alloys has become an important issue.

[0005] Summary of the Invention

[0006] In order to solve the above technical problems, the present application provides an anti-corrosion method, a magnesium-containing component, and an electronic device. The anti-corrosion method of the magnesium-containing structure can achieve high-efficiency anti-corrosion while maintaining high heat dissipation capacity of the structural component.

[0007] In a first aspect, the present application provides an anti-corrosion method applied to the contact surface between a first structural member and a second structural member, the anti-corrosion method comprising: attaching a composite film to the contact surface of the first structural member and the second structural member, the composite film comprising an adhesive film and Mylar.

[0008] According to the first aspect, the anti-corrosion method of the present application targets contact surfaces with severe galvanic corrosion, and performs directionally enhanced anti-corrosion by attaching a film / Mylar composite film to the contact surface, thereby achieving a high anti-corrosion effect.

[0009] According to the first aspect, or any implementation of the first aspect above, the thickness of the composite film is 0.01 mm to 0.1 mm. Such a thickness of the composite film is moderate, ensuring the anti-corrosion effect while not excessively occupying the space of the structural parts.

[0010] According to the first aspect, or any implementation of the first aspect above, the length of the composite film is at least 0.02 mm greater than the length of the contact surface, and the width of the composite film is at least 0.02 mm greater than the width of the contact surface. This allows the composite film to cover the contact surface, thereby ensuring an anti-corrosion effect and preventing corrosion at the edge of the contact surface.

[0011] According to the first aspect, or any implementation of the first aspect above, the first structural member is a magnesium-containing structural member, the second structural member is a steel structural member, the adhesive film in the composite film is attached to the first structural member, and the Mylar in the composite film faces the second structural member. This seals the magnesium alloy body, effectively blocking the ingress of corrosive media such as salt spray, and interrupting the ion path between the magnesium alloy structural member and the steel structural member, thereby preventing galvanic corrosion between the magnesium alloy structural member and the steel structural member.

[0012] According to the first aspect, or any implementation of the first aspect above, a chemical conversion film is formed on the surface of the first structural member. This provides overall corrosion protection for the non-contact, weakly corroded area between the first structural member and the second structural member using a thin salt-based chemical conversion film, thereby preserving the heat dissipation performance of the original metal material.

[0013] According to the first aspect, or any implementation of the first aspect above, the thickness of the chemical conversion film is less than or equal to 2 μm. This allows the chemical conversion film to have a moderate thickness, ensuring corrosion protection without excessively occupying space in the structural component.

[0014] According to the first aspect, or any implementation of the first aspect above, the chemical conversion film comprises phosphate and metal oxide. Since the phosphate chemical conversion film has high heat dissipation performance, it does not affect the heat dissipation capacity of the first structural member or the magnesium-containing component.

[0015] In a second aspect, the present application provides a magnesium-containing component, characterized in that it includes:

[0016] a middle frame, the middle frame comprising a main body and a first swing arm connected to the main body, the middle frame being made of magnesium alloy;

[0017] A rotating shaft, comprising a main body and a second swing arm connected to the main body, the rotating shaft being made of steel;

[0018] The middle frame is connected and fixed to the rotating shaft via the first swing arm and the second swing arm;

[0019] A composite film is attached to the contact surface between the first swing arm and the second swing arm, wherein the composite film includes an adhesive film and Mylar. The adhesive film in the composite film is attached to the surface of the first swing arm, and the Mylar in the composite film faces the second swing arm.

[0020] According to a second aspect, the magnesium-containing component of the present application targets areas of severe galvanic corrosion, namely the contact surface area between the middle frame and the rotating shaft (or between the first and second swing arms), by applying a film / Mylar composite film to the contact area to provide directional reinforcement and corrosion protection, thereby achieving a high corrosion protection effect. Furthermore, because the film in the composite film is attached to the surface of the first swing arm, the Mylar in the composite film faces the second swing arm. This can effectively seal the magnesium alloy middle frame body, effectively blocking the ingress of corrosive media such as salt spray, and isolating the ion path between the middle frame and the rotating shaft, thereby preventing galvanic corrosion between the middle frame and the rotating shaft.

[0021] According to the second aspect, or any implementation of the second aspect above, the thickness of the composite film is 0.01 mm to 0.1 mm. Such a thickness of the composite film is moderate, ensuring the anti-corrosion effect while not excessively occupying the space of the structural parts.

[0022] According to the second aspect, or any implementation of the second aspect above, the length of the composite film is at least 0.02 mm greater than the length of the contact surface, and the width of the composite film is at least 0.02 mm greater than the width of the contact surface. The width of the composite film is at least 0.02 mm greater than the width of the contact surface. This allows the composite film to cover the contact surface, thereby ensuring an anti-corrosion effect and preventing corrosion at the edge of the contact surface.

[0023] According to the second aspect, or any implementation of the second aspect above, a chemical conversion coating is formed on the surface of the middle frame or the middle frame body. This provides overall corrosion protection for the non-contact, weakly corroded area between the middle frame and the shaft using a thin salt-based chemical conversion coating, thereby preserving the heat dissipation performance of the original metal material.

[0024] According to the second aspect, or any implementation of the second aspect above, the thickness of the chemical conversion film is less than or equal to 2 μm. This allows the chemical conversion film to have a moderate thickness, ensuring corrosion protection without excessively occupying space in the structural component.

[0025] According to the second aspect, or any implementation of the second aspect above, the chemical conversion film comprises phosphate and metal oxide. Since the phosphate chemical conversion film has high heat dissipation performance, it does not affect the heat dissipation capacity of the first structural member or the magnesium-containing component.

[0026] According to the second aspect, or any implementation of the second aspect above, an anti-corrosion coating is formed on the surface of the first swing arm, and the composite film is attached to the anti-corrosion coating. This provides a better anti-corrosion effect by adding the anti-corrosion coating. The anti-corrosion coating can be any of various coatings commonly used in the art and can be formed using common methods.

[0027] According to the second aspect, or any implementation of the second aspect above, the first swing arm and the second swing arm are connected and fixed by fasteners, glue dispensing, or snap-fitting. This connection structure is simple and low in cost.

[0028] According to the second aspect, or any implementation of the second aspect above, the fastener is made of a material with a potential difference with magnesium that is less than a set value. This prevents galvanic corrosion between the fastener and the middle frame. The set value is the maximum potential difference between the two without galvanic corrosion, which can be determined based on the specific material and is not specifically limited here.

[0029] According to the second aspect, or any implementation of the second aspect above, an anti-corrosion coating is formed on the surface of the fastener by electrophoresis or physical vapor deposition. This prevents galvanic corrosion between the fastener and the middle frame. The anti-corrosion coating can be any coating commonly used in the art and can be formed using common methods.

[0030] In a third aspect, the present application provides an electronic device comprising the magnesium-containing component described in the second aspect.

[0031] According to the third aspect, the magnesium-containing component adopts the anti-corrosion method of the first aspect of the present application, and thus has good anti-corrosion effect and excellent heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application when in a flattened state:

[0033] FIG2 is a schematic diagram of the structure of the electronic device shown in FIG1 in an intermediate state:

[0034] FIG3 is a schematic diagram of the structure of the electronic device shown in FIG1 when it is in a closed state:

[0035] FIG4 is a schematic structural diagram of another electronic device provided by an embodiment of the present application in an intermediate state:

[0036] FIG5 is a schematic diagram showing the principle of galvanic corrosion between magnesium alloy and steel;

[0037] FIG6 is a schematic diagram of galvanic corrosion occurring when magnesium alloy contacts steel in electronic equipment;

[0038] FIG7 is a schematic diagram showing the principle of preventing galvanic corrosion between magnesium alloy and steel according to an embodiment of the present application;

[0039] FIG8 is a schematic structural diagram of a middle frame and a rotating shaft provided in an embodiment of the present application;

[0040] FIG9 is a cross-sectional schematic diagram of the middle frame and the rotating shaft after being connected according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] The term "and / or" in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0043] In the description and claims of the embodiments of this application, the terms "first" and "second" are used to distinguish different objects, rather than to describe a specific order of objects. For example, the terms "first target object" and "second target object" are used to distinguish different objects, rather than to describe a specific order of objects.

[0044] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0045] In the description of the embodiments of this application, unless otherwise specified, "multiple" means two or more. For example, "multiple processing units" means two or more processing units; "multiple systems" means two or more systems.

[0046] The present invention provides an electronic device, including but not limited to foldable mobile phones, foldable tablet computers, foldable game consoles, foldable personal digital assistants (PDAs), and other terminal devices with folding functions. The present invention does not limit the specific form of the terminal devices.

[0047] As shown in Figures 1 to 3, the electronic device 100 includes a housing 10, a folding hinge 20, and a flexible display screen 30. The folding hinge 20 can be deformed to allow the first housing 11 and the second housing 12 to fold or unfold relative to each other. As shown in Figure 1, the first housing 11 and the second housing 12 can unfold relative to each other to a flattened state, so that the electronic device 100 is in a flattened state. Exemplarily, when the first housing 11 and the second housing 12 are in the flattened state, the two can be approximately 180° (slight deviations are also allowed, such as 165°, 177°, or 185°). As shown in Figure 2, the first housing 11 and the second housing 12 can rotate relative to each other (expand or fold) to an intermediate state, so that the electronic device 100 is in an intermediate state. As shown in Figure 3, the first housing 11 and the second housing 12 can be folded relative to each other to a closed state, so that the electronic device 100 is in a closed state. Exemplarily, when the first housing 11 and the second housing 12 are in the closed state, the two can be completely closed together to be parallel to each other (slight deviations are also allowed). 2 can be any state between the flattened state and the closed state. Therefore, the electronic device 100 can switch between the flattened state and the closed state by deforming the folding hinge 20.

[0048] In some embodiments, the flexible display screen 30 is used to display images. Exemplarily, the flexible display screen 30 can be an organic light emitting diode (OLED) display screen, an active matrix organic light emitting diode (AMOLED) display screen, a mini organic light emitting diode (OLED) display screen, a micro organic light-emitting diode (OLED) display screen, a micro organic light-emitting diode (OLED) display screen, or a quantum dot light emitting diode (QLED) display screen.

[0049] The flexible display 30 includes a first non-bending portion 31, a bending portion 32, and a second non-bending portion 33, arranged in sequence. The flexible display 30 is fixed to the housing 10. For example, the flexible display 30 can be bonded to the housing 10 via an adhesive layer. The first non-bending portion 31 of the flexible display 30 is fixed to the first housing 11, and the second non-bending portion 33 is fixed to the second housing 12. During the relative folding or unfolding of the first and second housings 11, 12, the bending portion 32 deforms. As shown in FIG1 , when the first and second housings 11, 12 are flattened, the flexible display 30 is in a flattened configuration. As shown in FIG2 , when the first and second housings 11, 12 are in an intermediate configuration, the flexible display 30 is in a configuration intermediate between the flattened and closed configurations. As shown in FIG3 , when the first and second housings 11, 12 are in a closed configuration, the flexible display 30 is in a closed configuration. When the electronic device 100 is in the closed configuration, the flexible display 30 is located outside the housing 10 and can be generally U-shaped.

[0050] In this embodiment, the flexible display screen 30 can be unfolded or folded along with the folding hinge 20. When the electronic device 100 is in a flat state, the flexible display screen 30 is in a flat state and can display full screen, so that the electronic device 100 has a larger display area and improves the user's viewing experience. When the electronic device 100 is in a closed state, the planar size of the electronic device 100 is smaller (having a smaller width dimension), making it easier for the user to carry and store.

[0051] As shown in Figure 4, the electronic device 100 includes a housing 10, a folding hinge 20 and a flexible screen 30. The flexible screen 30 is fixed to a side surface of the housing 10. The electronic device 100 can be folded along its center. When the foldable phone is in a folded state, that is, the folding angle of the foldable phone is 0, the size of the foldable phone can be reduced; when the foldable phone is in a flattened state, that is, the folding angle of the foldable phone is 180°, the flexible screen 30 is in a state of maximum display area, and the user can operate on the flexible screen 30. It should be noted that the folding angle refers to the angle between the left and right parts of the foldable phone. The difference from the electronic device shown in Figures 1 to 3 is that when the electronic device 100 in Figure 4 is in a closed state, the flexible display screen 30 is located on the inner side of the housing 10.

[0052] In order to facilitate a clear description of the technical solution of the embodiment of the present application, as shown in Figure 4, three directions can be defined, namely the length direction of the foldable mobile phone (X direction, also called the first direction), the width direction of the foldable mobile phone (Y direction, also called the second direction) and the thickness direction of the foldable mobile phone (Z direction, also called the third direction).

[0053] In addition, in the embodiments of the present application, "up", "down", "left" and "right" refer to the directions determined with reference to the user's hands when the foldable mobile phone is in a flattened state and the user holds the foldable mobile phone with both hands and the flexible screen 30 faces the user.

[0054] It will be appreciated that this embodiment is described using the example of "the rotation center of the electronic device 100 being parallel to the length direction of the electronic device 100." In this case, the electronic device 100 can rotate left and right, and the folding and unfolding of the electronic device 100 affects the width dimension of the electronic device 100. In other embodiments, the rotation center of the electronic device 100 may also be parallel to the width direction of the electronic device 100. In this case, the electronic device 100 can rotate up and down, and the folding and unfolding of the electronic device 100 affects the length dimension of the electronic device 100.

[0055] To reduce the weight of the electronic devices shown in Figures 1-4, a common method currently used is to use magnesium alloy for the middle frame, which reduces the overall weight of the device compared to steel. However, the hinge or shaft, a key mechanism in foldable devices, still requires steel for strength and other reasons. The middle frame needs to be connected and secured to the hinge. As previously mentioned, when magnesium alloy and steel come into contact, the potential difference between the magnesium alloy (approximately -2.363V) and steel (approximately -0.441V) is large. This can lead to severe galvanic corrosion between the contact surface of the middle frame and the hinge, which not only affects the connection strength but also poses risks such as hinge jamming, foreign matter, and electrical connection failure.

[0056] Figure 5 is a schematic diagram of the principle of galvanic corrosion. Taking steel / iron as an example of a metal in contact with a magnesium alloy, as shown in Figure 5, galvanic corrosion requires three conditions: first, a sufficient potential difference, second, an electron pathway, and third, an ion pathway. For magnesium as the anode and iron as the cathode, a sufficient potential difference exists between the two, and galvanic corrosion occurs when both an electron pathway and an ion pathway exist.

[0057] Figure 6 is a schematic diagram of galvanic corrosion occurring when magnesium alloy contacts steel in electronic equipment. As shown in Figure 6, in electronic equipment such as folding devices, galvanic corrosion is likely to occur when a structural member made of magnesium alloy (such as a middle frame) contacts a structural member made of steel (such as a rotating shaft). This is because: first, there is a large potential difference between the magnesium alloy middle frame and the steel rotating shaft; second, there is an electrical connection requirement between the magnesium alloy middle frame and the steel rotating shaft (in order to discharge, an electrical connection needs to be formed between the middle frame and the rotating shaft). This has already met the two requirements for galvanic corrosion. Therefore, when the device is in a salt spray environment, because the salt spray environment provides the third condition for galvanic corrosion (the presence of an ion path), galvanic corrosion is very likely to occur between the magnesium alloy middle frame and the steel rotating shaft in the salt spray environment.

[0058] To overcome this problem, the current main approach is to use a fully encapsulated polymer coating for overall corrosion protection (e.g., electrophoresis, spray painting, etc.). However, this approach has the following problems: on the one hand, it has limited inhibitory effect on galvanic corrosion; on the other hand, the fully encapsulated polymer coating can have an adverse effect on non-magnesium / steel contact areas, significantly reducing the heat dissipation capacity of the magnesium alloy.

[0059] Based on this, the embodiment of the present application proposes a corrosion protection method for magnesium-containing structural parts and magnesium-containing structural parts for application in the folding device of the embodiment of the present application, thereby having good corrosion protection effect while using magnesium alloy materials to reduce the weight of the equipment and without affecting the heat dissipation capacity of the magnesium-containing structural parts.

[0060] Figure 7 is a schematic diagram of the principle of preventing galvanic corrosion between magnesium alloy and steel in an embodiment of the present application. As shown in Figure 7, in order to prevent galvanic corrosion between a structural part made of magnesium alloy (such as a middle frame) and a structural part made of steel (such as a rotating shaft) in an embodiment of the present application, the following method can be used:

[0061] First, a composite film 1 composed of a film and Mylar is attached to the contact surface between a structural part made of a magnesium alloy (such as a middle frame) and a structural part made of steel (such as a rotating shaft), wherein one side of the film is in contact with the structural part made of the magnesium alloy, and the other side of the Mylar is in contact with the structural part made of the steel. This is because if it is attached to a structural part made of steel, the effect of preventing galvanic corrosion will be weakened, and the magnesium alloy body will be at risk of chemical corrosion. The film side of the film / Mylar composite film 1 is attached to the surface of the magnesium alloy, which can seal the magnesium alloy body, thereby effectively blocking the entry of corrosive media such as salt spray, isolating the ion path between the structural part made of magnesium alloy (such as the middle frame) and the structural part made of steel (such as the rotating shaft), thereby preventing galvanic corrosion between the structural part made of magnesium alloy (such as the middle frame) and the structural part made of steel (such as the rotating shaft). In addition, compared with the current coating anti-corrosion solutions such as spraying and electrophoresis on the surface of magnesium alloy, Mylar has a better ion isolation effect, so this method has a significant inhibitory effect on galvanic corrosion.

[0062] Furthermore, in order for the composite membrane 1 to effectively isolate ions, the adhesive / Mylar composite membrane 1 must have a certain thickness. However, the composite membrane 1 should not be too thick, as this would not improve the corrosion protection and would occupy limited structural space. For example, the thickness of the adhesive / Mylar composite membrane 1 can be 0.01 mm to 0.1 mm, such as 0.01 mm, 0.05 mm, or 0.1 mm. This ensures effective ion isolation without being too thick and occupying structural space.

[0063] Furthermore, corrosion occurs at the edge of the contact area between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel, and the composite film 1 is larger than the contact area. For example, in the embodiment of the present application, the length of the composite film 1 is at least 0.02 mm larger than the length of the contact area, and the width of the composite film 1 is at least 0.02 mm larger than the width of the contact area, so that the composite film 1 completely covers the contact area, isolating the ion path between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel (such as the rotating shaft), thereby preventing galvanic corrosion between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel (such as the rotating shaft).

[0064] Second, since magnesium alloy bodies are at risk of chemical corrosion, phosphate chemical conversion films can be used to protect the magnesium alloy structures as a whole from corrosion, that is, to form a chemical conversion film on the surface of the magnesium alloy structure or on the surface of the non-contact area of ​​the magnesium alloy structure for corrosion protection. For example, the chemical conversion film is a salt anti-corrosion film, the main components of which are phosphates and metal oxides. Due to the excellent heat dissipation capacity of the salt film, the chemical conversion film can inhibit the corrosion of the magnesium alloy while ensuring the high thermal conductivity of the metal body. For example, in order to take into account both heat dissipation capacity and corrosion protection effect, the thickness of the chemical conversion film is less than or equal to 2μm.

[0065] Third, since the structural parts made of magnesium alloy (such as the middle frame) and the structural parts made of steel (such as the rotating shaft) are fixed by fasteners such as stainless steel screws, galvanic corrosion may also occur between the fasteners and the structural parts made of magnesium alloy. Therefore, in order to prevent galvanic corrosion from occurring between the fasteners and the structural parts made of magnesium alloy, in the embodiment of the present application, it can be achieved by reducing the potential difference between dissimilar metals or even cutting off the electrical connection between the fasteners and the magnesium alloy, such as using fasteners with a smaller potential difference with the magnesium alloy. For example, the fasteners are made of a material with a potential difference with magnesium that is less than a set value. This can prevent galvanic corrosion from occurring between the fasteners and the middle frame. The set value is the maximum potential difference between the two at which galvanic corrosion does not occur. It can be defined according to the specific material and is not specifically defined here. Alternatively, the electrical connection between the fasteners and the magnesium alloy can be cut off by galvanizing, electrophoretic coating, depositing a non-conductive PVD film layer 2, etc. on the surface of the fastener to achieve galvanic corrosion suppression.

[0066] Fourth, for folding devices, there is a need for electrical connection between structural parts made of magnesium alloy (such as the middle frame) and structural parts made of steel. In order to achieve electrical connection between the two without causing galvanic corrosion, electrical connection can be made in the non-direct contact area between the structural parts made of magnesium alloy (such as the middle frame) and the structural parts made of steel using shrapnel or conductive cotton 3 to ensure the electrical connection requirement between magnesium and steel.

[0067] The corrosion protection method for magnesium-containing structural parts provided in the embodiments of the present application adopts a zoned corrosion protection design. For weakly corroded areas where magnesium and steel are not in contact, a thin salt chemical conversion film is used for overall corrosion protection, thereby preserving the heat dissipation performance of the original metal material. For magnesium and steel contact areas where galvanic corrosion is severe, a film / Mylar composite film is applied to the magnesium alloy surface for directional corrosion protection. This coupling of overall and directional corrosion protection achieves high corrosion resistance when the magnesium alloy middle frame is connected to the steel shaft in folding devices, as well as excellent heat dissipation performance of the middle frame.

[0068] FIG8 is a schematic structural diagram of the middle frame and the rotating shaft provided in an embodiment of the present application; FIG9 is a schematic cross-sectional diagram of the middle frame and the rotating shaft after being connected provided in an embodiment of the present application.

[0069] As shown in Figures 8 and 9 , the magnesium-containing structural member provided in the embodiments of the present application is, for example, a middle frame 13 made of a magnesium alloy. The middle frame 13, as a component of the aforementioned first shell 11 or second shell 12, includes a middle frame body 14 and a first swing arm 15 connected to or integrally formed with the middle frame body 14. The middle frame 13 is connected to the rotating shaft via the first swing arm 15, thereby rotating relative to the rotating shaft. The steel structural member provided in the embodiments of the application is, for example, a rotating shaft 21 made of steel. The rotating shaft 21, as a component of the aforementioned folding hinge, includes a rotating shaft body 22 and a second swing arm 23 connected to or integrally formed with the rotating shaft body 22.

[0070] For example, in the embodiment of the present application, in the X direction (or the length direction), two first swing arms 15 are provided on one side of the middle frame 13, and the two first swing arms 15 are provided at both ends of the middle frame 13, for example. In the X direction (or the length direction), two second swing arms 23 are provided on both sides of the rotating shaft 21, for example. The two second swing arms 23 are provided at both ends of the rotating shaft 21, respectively. The structures and shapes of the middle frame 13, the rotating shaft 21, and the first and second swing arms 15, 23 are exemplary. The embodiment of the present application is intended to illustrate the principle of corrosion prevention between the middle frame and the rotating shaft, and is not intended to limit the structures of the middle frame, the rotating shaft, and the swing arms. The embodiment of the present application can be applied to corrosion prevention between middle frames and rotating shafts of various structures.

[0071] As shown in Figure 9, when the middle frame 13 is connected to the rotating shaft 21, the first swing arm 15 and the second swing arm 23 can be connected and fixed by fasteners 5 such as screws, thereby achieving the connection between the middle frame 13 and the rotating shaft 21. Of course, the first swing arm 15 and the second swing arm 23 are not limited to being fixed by fasteners such as screws, and can also be fixed by glue or other methods, such as snap-fitting.

[0072] As shown in FIG9 , to prevent galvanic corrosion between the middle frame 13 and the rotating shaft 21, in this embodiment of the present application, a composite film 1 composed of adhesive film and Mylar is applied to the contact area between the middle frame 13 and the rotating shaft 21, specifically between the first swing arm 15 and the second swing arm 23. The adhesive film is applied to the magnesium alloy component on one side, while the Mylar component contacts the steel component on the other. This is because if applied to a steel component, the galvanic corrosion protection effect is weakened and the magnesium alloy component is exposed to the risk of chemical corrosion. The adhesive film / Mylar composite film 1, with the adhesive film side attached to the magnesium alloy surface, seals the magnesium alloy component, effectively blocking the ingress of corrosive media such as salt spray and interrupting the ion path between the magnesium alloy component (e.g., the middle frame) and the steel component (e.g., the rotating shaft), thereby preventing galvanic corrosion between the magnesium alloy component (e.g., the middle frame) and the steel component (e.g., the rotating shaft). In addition, compared with the current coating anti-corrosion solutions such as spraying and electrophoresis on the surface of magnesium alloys, Mylar has better ion isolation effect, so this method has a significant inhibitory effect on galvanic corrosion.

[0073] Furthermore, in order for the composite membrane 1 to effectively isolate ions, the adhesive / Mylar composite membrane 1 must have a certain thickness. However, the composite membrane 1 should not be too thick, as this would not improve the corrosion protection and would occupy limited structural space. For example, the thickness of the adhesive / Mylar composite membrane 1 can be 0.01 mm to 0.1 mm, such as 0.01 mm, 0.05 mm, or 0.1 mm. This ensures effective ion isolation without being too thick and occupying structural space.

[0074] Furthermore, corrosion occurs at the edge of the contact area between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel, and the composite film 1 is larger than the contact area. For example, in the embodiment of the present application, the length of the composite film 1 is at least 0.02 mm larger than the length of the contact area, and the width of the composite film 1 is at least 0.02 mm larger than the width of the contact area, so that the composite film 1 completely covers the contact area, isolating the ion path between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel (such as the rotating shaft), thereby preventing galvanic corrosion between the structural member made of magnesium alloy (such as the middle frame) and the structural member made of steel (such as the rotating shaft).

[0075] Please refer to Figure 9 again. To achieve corrosion protection for the middle frame 13 made of magnesium alloy, in this embodiment of the present application, a chemical conversion film is formed on the surface of the middle frame 13 or on the surface of the middle frame body 14. Exemplarily, the chemical conversion film is a salt-based anti-corrosion film, the main components of which are phosphates and metal oxides. Due to the excellent heat dissipation capability of the salt film, the chemical conversion film can inhibit corrosion of the magnesium alloy while ensuring the high thermal conductivity of the metal body. Exemplarily, to achieve a balanced heat dissipation capability and corrosion protection, the thickness of the chemical conversion film is less than or equal to 2μm.

[0076] It should be understood that, to enhance the corrosion protection effect, in the embodiment of the present application, other auxiliary coatings may be formed on the contact area between the middle frame 13 and the rotating shaft 21 or on the surface of the middle frame 13 to achieve even better corrosion protection. Furthermore, the corrosion protection principles of the present application are not limited to corrosion protection between magnesium alloys and steel, but can also be applied to corrosion protection between other dissimilar metals.

[0077] In order to verify the anti-corrosion method or the anti-corrosion effect of the magnesium-containing component according to the embodiment of the present application, the following experiments were conducted:

[0078] Example:

[0079] The first swing arm of the electronic device's magnesium alloy middle frame is connected to the second swing arm of the hinge with screws. The magnesium alloy middle frame is coated with a chemical conversion coating approximately 1μm thick, primarily composed of calcium phosphate and manganese oxide. A film / Mylar composite is applied to the sidewalls of the magnesium alloy middle frame, where the middle frame contacts the hinge arm. The total thickness of the composite film is 0.03mm.

[0080] Comparative Example:

[0081] The two swing arms of the electronic device's middle frame are connected to the hinge swing arms with screws. The magnesium alloy surface is fully coated with a polymer electrophoretic coating approximately 15μm thick.

[0082] The electronic devices in the examples and comparative examples were then placed in a salt spray environment for corrosion resistance testing and temperature rise testing. The test results are shown in Table 1.

[0083] Table 1

[0084] In summary, the anti-corrosion method of the embodiments of the present application or the electronic device containing magnesium components can achieve good anti-corrosion effects and excellent heat dissipation performance.

[0085] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A corrosion prevention method, characterized in that: Applied to the contact surface between the first structural member and the second structural member, the anti-corrosion method comprises: attaching a composite film to the contact surface of the first structural member and the second structural member, wherein the composite film comprises an adhesive film and Mylar.

2. The anti-corrosion method according to claim 1, characterized in that: The thickness of the composite film is 0.01 mm to 0.1 mm.

3. The anti-corrosion method according to claim 1, characterized in that: The length of the composite film is at least 0.02 mm greater than the length of the contact surface, and the width of the composite film is at least 0.02 mm greater than the width of the contact surface.

4. The anti-corrosion method according to any one of claims 1 to 3, characterized in that: The first structural member is a magnesium-containing structural member, the second structural member is a steel structural member, the adhesive film in the composite film is attached to the first structural member, and the Mylar in the composite film faces the second structural member.

5. The anti-corrosion method according to claim 4, characterized in that: A chemical conversion film is formed on the surface of the first structural member.

6. The anti-corrosion method according to claim 5, characterized in that: The thickness of the chemical conversion film is less than or equal to 2 μm.

7. The anti-corrosion method according to claim 5, characterized in that: The components of the chemical conversion film include phosphate and metal oxide.

8. A magnesium-containing component, characterized in that: include: A middle frame, the middle frame comprising a body and a first swing arm connected to the body, the middle frame being made of magnesium alloy; A rotating shaft, the rotating shaft comprising a body and a second swing arm connected to the body, the rotating shaft being made of steel; The middle frame is connected and fixed to the rotating shaft via the first swing arm and the second swing arm; A composite film is attached to the contact surface between the first swing arm and the second swing arm, wherein the composite film comprises an adhesive film and Mylar, wherein the adhesive film in the composite film is attached to the surface of the first swing arm, and the Mylar in the composite film faces the second swing arm.

9. The magnesium-containing component according to claim 8, characterized in that The thickness of the composite film is 0.01 mm to 0.1 mm.

10. The magnesium-containing component according to claim 8, characterized in that The length of the composite film is at least 0.02 mm greater than the length of the contact surface, and the width of the composite film is at least 0.02 mm greater than the width of the contact surface.

11. The magnesium-containing component according to any one of claims 8 to 10, characterized in that: A chemical conversion film is formed on the surface of the middle frame or the middle frame body.

12. The magnesium-containing component according to claim 11, characterized in that The thickness of the chemical conversion film is less than or equal to 2 μm.

13. The magnesium-containing component according to claim 11, characterized in that The components of the chemical conversion film include phosphate and metal oxide.

14. The magnesium-containing component according to any one of claims 8 to 10, characterized in that: An anti-corrosion coating is formed on the surface of the first swing arm, and the composite film is attached to the anti-corrosion coating.

15. The magnesium-containing component according to any one of claims 8 to 10, characterized in that: The first swing arm and the second swing arm are connected and fixed by fasteners, glue dispensing or snapping.

16. The magnesium-containing component according to claim 15, characterized in that The fastener is made of a material having a potential difference with magnesium that is less than a set value.

17. The magnesium-containing component according to claim 15, characterized in that An anti-corrosion coating is formed on the surface of the fastener by electrophoresis or physical vapor deposition.

18. An electronic device, characterized in that: The magnesium-containing component comprises any one of claims 10-17.

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