Composite material, rotating shaft and middle frame

Abstract

The invention provides a composite material, a rotating shaft and a middle frame, the composite material comprises a first aluminum-based composite material, a magnesium-containing material and a second aluminum-based composite material which are sequentially stacked, and the magnesium-containing material can be pure magnesium, magnesium alloy or a magnesium-based composite material. The aluminum-based composite material can improve the mechanical property of the composite material, and the magnesium-containing material is beneficial to reducing the density of the composite material. The composite material provided by the invention integrates the advantages of good mechanical properties of an aluminum-based composite material and small density of a magnesium-containing material, and is beneficial to reducing the weight and volume of the composite material on the basis of not losing the mechanical properties. The rotating shaft prepared from the composite material is smaller in mass, and the foldable electronic equipment comprising the rotating shaft is good in operability. According to the middle frame prepared from the composite material, the thickness of the middle plate can be reduced, a larger accommodating space can be provided, and the space utilization efficiency of the electronic equipment comprising the middle frame is high.

Description

Technical Field

[0001] The present application relates to the field of terminal device hardware, and in particular, to a composite material, a hinge and a middle frame. Background Art

[0002] For example, in portable electronic devices such as mobile phones and tablet computers, the internal structural parts provide support, connection and protection for many electronic components while also occupying a certain amount of storage space. The better mechanical properties of structural parts often mean larger volume and heavier weight, which to a certain extent limits the thinness and portability of electronic devices, reduces the utilization rate of the internal space of electronic devices and the maneuverability of electronic devices.

[0003] How to reduce the weight and / or volume of a structural component without sacrificing its mechanical properties is a question worth considering. Summary of the invention

[0004] The present application provides a composite material, which includes two layers of aluminum-based composite materials, between which pure magnesium, magnesium alloy or magnesium-based composite materials are sandwiched. The aluminum-based composite material can improve the overall mechanical properties of the composite material, and the magnesium-containing material can reduce the density of the composite material to a certain extent, thereby reducing the weight of the composite material.

[0005] In a first aspect, a composite material is provided, comprising a first aluminum-based composite material, a magnesium-containing material and a second aluminum-based composite material, wherein the first aluminum-based composite material, the magnesium-containing material and the second aluminum-based composite material are stacked, the magnesium-containing material is located between the first aluminum-based composite material and the second aluminum-based composite material, and the magnesium-containing material is pure magnesium, a magnesium alloy or a magnesium-based composite material.

[0006] The reinforcing phase in aluminum-based composite materials is conducive to improving the elastic modulus, tensile strength, compressive strength and other mechanical properties of the composite materials, while the aluminum or aluminum alloy as the matrix has good plasticity and toughness. For aluminum alloys and aluminum-based composite materials of the same shape and size, the mechanical properties of aluminum-based composite materials are better. In addition, the aluminum-based composite materials are arranged on the outside of the composite materials, that is, the composite materials with better mechanical properties are used to bear the external extrusion and impact, which is conducive to making full use of the excellent mechanical properties of aluminum-based composite materials and improving the impact resistance and extrusion resistance of the composite materials.

[0007] The atomic mass of magnesium is relatively small, and adding magnesium-containing materials to composite materials is beneficial to reducing the overall density of the composite materials. For composite materials of the same volume, the composite materials containing magnesium-containing materials are lighter.

[0008] In general, the composite material provided in the present application combines the advantages of good mechanical properties of aluminum-based composite materials and low density of magnesium-containing materials, which is beneficial for reducing the weight and volume of the composite material without reducing the mechanical properties.

[0009] In combination with the first aspect, in certain implementations of the first aspect, the magnesium-containing material is a magnesium-aluminum alloy, a magnesium-zinc alloy, a magnesium-lithium alloy, or a magnesium-based composite material whose matrix is ​​a magnesium-aluminum alloy, a magnesium-zinc alloy, or a magnesium-lithium alloy.

[0010] Adding a certain amount of aluminum or zinc elements to the magnesium-containing material in contact with the aluminum-based composite material is beneficial to increasing the bonding strength between the magnesium-containing material and the aluminum-based composite material at the contact interface, that is, the magnesium-containing material and the aluminum-based composite material are not easily separated, which is beneficial to improving the structural stability of the composite material.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the mass fraction of the magnesium element in the magnesium-containing material is greater than or equal to 80%.

[0012] For magnesium alloys or magnesium-based composites, the greater the mass fraction of the magnesium element, the smaller the density of the magnesium-containing material, which is conducive to further reducing the density of the composite material.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the ratio of the volume of the magnesium-containing material to the total volume of the composite material is V, and V≥50%.

[0014] In some scenarios, the above technical solution can also be understood as: the thickness of the magnesium-containing material accounts for a proportion of the total thickness of the composite material that is greater than or equal to 50%.

[0015] The greater the proportion of magnesium-containing materials in the composite material, the smaller the proportion of the aluminum-based composite material with higher density, and the smaller the overall density of the composite material.

[0016] In combination with the first aspect, in certain implementations of the first aspect, a plurality of pores exist in the magnesium-containing material, and the diameters of the plurality of pores are one or more of the following: millimeter level, micrometer level, or nanometer level.

[0017] In some scenarios, a magnesium-containing material including a plurality of pores may also be referred to as a porous material or a honeycomb material.

[0018] Providing a plurality of pores in the structure of the magnesium-containing material is beneficial to reducing the mass of the magnesium-containing material, thereby further reducing the overall density of the composite material.

[0019] In combination with the first aspect, in certain implementations of the first aspect, the matrix of the first aluminum-based composite material and the second aluminum-based composite material is one or more of aluminum, aluminum-magnesium alloy, aluminum-zinc alloy, aluminum-manganese alloy or aluminum-lithium alloy.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the matrix of the first aluminum-based composite material and the second aluminum-based composite material is an aluminum-lithium alloy, and the density D of the aluminum-lithium alloy satisfies: 1.9 g / cm 3 ≤D≤2.4g / cm 3 .

[0021] In a possible implementation, the density D of the aluminum-lithium alloy satisfies: 2.0 g / cm 3 ≤D≤2.3g / cm 3 .

[0022] Among various aluminum alloys, aluminum-lithium alloy has a smaller density under the same level of mechanical properties. Using aluminum-lithium alloy as the matrix of aluminum-based composites is beneficial to further reduce the density of the composites and reduce the weight of the composites.

[0023] In combination with the first aspect, in certain implementations of the first aspect, the reinforcing phases of the first aluminum-based composite material and the second aluminum-based composite material are one or more of particles, fibers, or whiskers.

[0024] In a possible implementation, the reinforcement phases of the first aluminum-based composite material and the second aluminum-based composite material may be one or more of ceramic particles, ceramic fibers and carbon fibers, carbon nanotubes, graphene, graphite, diamond, and the like.

[0025] In combination with the first aspect, in certain implementations of the first aspect, the reinforcing phases of the first aluminum-based composite material and the second aluminum-based composite material are both silicon carbide particles, the proportion of the mass of the silicon carbide particles to the total mass of the first aluminum-based composite material is M1, the proportion of the mass of the silicon carbide particles to the total mass of the second aluminum-based composite material is M2, and M1 and M2 satisfy: 0.2%<M1≤60%, 0.2%<M2≤60%.

[0026] In a possible implementation, M1 and M2 satisfy: 2.0%≤M1≤20%, 2.0%≤M2≤20%.

[0027] A certain proportion of silicon carbide particles as a reinforcing phase of the aluminum-based composite material is beneficial to improving the elastic modulus, tensile strength and compressive strength of the aluminum-based composite material, and because the molecular weight of silicon carbide is relatively large, more silicon carbide incorporation means a greater density of the aluminum-based composite material. The doping ratio of silicon carbide provided in the technical solution is beneficial to minimizing the effect of doping on the density of the composite material while improving the mechanical properties of the aluminum-based composite material.

[0028] In combination with the first aspect, in certain implementations of the first aspect, 95% of the silicon carbide particles have a diameter less than or equal to 3 micrometers.

[0029] In combination with the first aspect, in certain implementations of the first aspect, the reinforcing phase of the first aluminum-based composite material and / or the second aluminum-based composite material is graphite and / or diamond.

[0030] The above technical solution should be understood as follows: the reinforcement phase of the first aluminum-based composite material may be graphite and / or diamond, and the reinforcement phase of the second aluminum-based composite material may also be graphite and / or diamond.

[0031] In combination with the first aspect, in certain implementations of the first aspect, a plurality of pores exist in the first aluminum-based composite material and / or the second aluminum-based composite material, and the diameters of the plurality of pores are one or more of the following: millimeter level, micrometer level, or nanometer level.

[0032] In some scenarios, an aluminum-based composite material containing a plurality of pores may also be referred to as a porous material or a honeycomb material.

[0033] Providing a plurality of pores within the structure of the aluminum-based composite material is beneficial to reducing the mass of the aluminum-based composite material, thereby further reducing the overall density of the composite material.

[0034] In combination with the first aspect, in certain implementations of the first aspect, the composite material also includes at least one layer of alloy material, and the at least one layer of alloy material is located on a side of the first aluminum-based composite material away from the magnesium-containing material, or, the at least one layer of alloy material is located on a side of the second aluminum-based composite material away from the magnesium-containing material, and the at least one layer of alloy material is an aluminum alloy or a magnesium alloy.

[0035] Aluminum alloy and magnesium alloy have good plasticity and toughness. Arranging aluminum alloy or magnesium alloy on the outside of aluminum-based composite material is conducive to improving the machinability of the composite material. In addition, the aluminum alloy located on the outside can also improve the corrosion resistance of the composite material to a certain extent.

[0036] In combination with the first aspect, in certain implementations of the first aspect, the composite material also includes at least one layer of bonding material, the bonding material is located between the first aluminum-based composite material and the magnesium-containing material and / or between the second aluminum-based composite material and the magnesium-containing material, and the bonding material is one or more of the following: solder, pure aluminum or pure zinc.

[0037] The bonding material disposed between the aluminum-based composite material and the magnesium-containing material is helpful in breaking the oxide film on the surface of the aluminum-based composite material and the magnesium-containing material during the processing of the composite material, thereby enabling the aluminum-based composite material and the magnesium-containing material to be more firmly bonded, which is helpful in improving the stability of the composite material structure.

[0038] In combination with the first aspect, in certain implementations of the first aspect, the first aluminum-based composite material and / or the second aluminum-based composite material is at least partially coated around the magnesium-containing material.

[0039] The aluminum-based composite material has strong corrosion resistance. Partially or completely covering the first aluminum-based composite material and / or the second aluminum-based composite material around the magnesium-containing material is beneficial to preventing the magnesium-containing material from being polluted or corroded by water, gas, etc. in the environment.

[0040] In a second aspect, a rotating shaft is provided, comprising: a door panel body, a rotating accessory and a rotating shaft body, wherein the rotating accessory is used to fix the door panel body and the rotating shaft body, and the door panel body is made of the composite material in the first aspect and any possible implementation thereof.

[0041] In some scenarios, the door panel body may also be called a support plate, and the rotating accessories may also be called door panel small parts or connecting parts.

[0042] The door panel body is the main component of the door panel structure. Using the composite material provided in the present application to prepare the door panel body is beneficial to reducing the weight of the door panel, and to a certain extent is also beneficial to reducing the thickness of the door panel body, reducing the volume of the door panel, and reducing the space occupied by the door panel when installed on electronic equipment.

[0043] In combination with the second aspect, in certain implementations of the second aspect, the rotating fitting is made of an amorphous alloy and / or a metal injection molding material.

[0044] Rotating parts have higher requirements on the mechanical properties of materials. Using amorphous alloys and / or metal injection molding materials with better mechanical properties to prepare rotating parts is conducive to ensuring the transmission function of the door panel structure and improving the reliability of the shaft function. In addition, preparing the rotating parts and the door panel body separately is conducive to coordinating multiple rotating parts during installation, which is conducive to improving the assembly and production efficiency of the shaft.

[0045] In combination with the second aspect, in certain implementations of the second aspect, the rotating accessory is fixedly connected to the door panel body by riveting.

[0046] In combination with the second aspect, in certain implementations of the second aspect, the thickness of the door panel body is T1, the thickness of the rotating accessory is T2, and T1 and T2 satisfy: 0.01mm<T1≤2.00mm, 0.01mm<T2≤2.00mm.

[0047] In a third aspect, a middle frame is provided, comprising: a frame and a loading plate, wherein the frame is fixedly connected to the loading plate, and the loading plate comprises a target area, and the target area is made of the composite material in the first aspect and any possible implementation thereof.

[0048] In some scenarios, the loading board may also be referred to as the middle board of the middle frame.

[0049] Compared with aluminum alloys, aluminum-based composite materials have better mechanical properties. When using aluminum-based composite materials to prepare parts, it is beneficial to reduce the thickness of the relevant area of ​​the part without reducing the overall reliability of the part. Using the composite material provided by the present application to manufacture part of the middle plate of the middle frame is beneficial to reduce the weight of the middle frame to a certain extent. In addition, the thickness of the target area prepared using the composite material of the present application can be thinner, and the target area can be used to install larger electronic components, such as batteries with larger capacity. The implementation of this technical solution is conducive to improving the space utilization inside the middle frame.

[0050] In combination with the third aspect, in certain implementations of the third aspect, the area outside the target area on the loading plate is made of one or more of the following materials: aluminum alloy, aluminum-based composite material, or the composite material in the first aspect and any possible implementations thereof.

[0051] The area outside the target area on the loading plate can contain the same aluminum element as the target area, and the target area and the area outside the target area can be fixedly connected by welding or the like. The implementation of this technical solution is conducive to improving the reliability of the connection between the target area and the area outside the target area, and is conducive to improving the structural stability of the loading plate and the middle frame.

[0052] In combination with the third aspect, in certain implementations of the third aspect, the frame is made of one or more of the following materials: pure titanium, titanium alloy, aluminum alloy, stainless steel, or amorphous alloy.

[0053] The frame portion of the middle frame is made of a material with higher strength and larger modulus, which is beneficial to improving the impact resistance and extrusion resistance of the frame. When electronic components are installed on the loading board, it is beneficial to improve the protection effect for the electronic components installed on the loading board.

[0054] In combination with the third aspect, in certain implementations of the third aspect, the area outside the target area on the loading plate and the frame are both made of aluminum alloy, and the area outside the target area on the loading plate and the frame are integrally formed.

[0055] When the area outside the target area and the frame are made of the same material, the area outside the target area and the frame on the loading plate can be made by an integrated molding process, which is beneficial to improving the production efficiency of the middle frame.

[0056] In combination with the third aspect, in certain implementations of the third aspect, the area outside the target area on the loading plate is made of an aluminum-based composite material, and the elastic modulus of the aluminum-based composite material is greater than or equal to 90 GPa.

[0057] In a possible implementation, the area outside the target area on the loading plate is made of a particle-doped aluminum-based composite material.

[0058] In a fourth aspect, a foldable electronic device is provided, comprising a first shell, a second shell and a rotating shaft in the second aspect and any possible implementation thereof, wherein the rotating shaft is connected to the first shell and the second shell respectively.

[0059] In a fifth aspect, an electronic device is provided, comprising a battery and a middle frame in the third aspect and any possible implementation thereof, wherein the battery is mounted in a target area of ​​a loading plate of the middle frame.

[0060] In the present technical solution, the battery of the electronic device is installed in an area prepared by the composite material provided in the present application. The thickness of the target area can be thinner, and accordingly, the space occupied by the battery installed in the target area can be larger, which is beneficial to improving the space utilization inside the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram of the composition structure of a composite material provided in an embodiment of the present application.

[0062] Figure 2 It is a cross-sectional schematic diagram of a composite material provided in an embodiment of the present application.

[0063] Figure 3 It is a schematic diagram of another composite material composition structure provided in an embodiment of the present application.

[0064] Figure 4 It is a flow chart of a method for preparing a composite material provided in an embodiment of the present application.

[0065] Figure 5 It is a structural schematic diagram of a foldable electronic device provided in an embodiment of the present application.

[0066] Figure 6 It is a structural schematic diagram of a middle frame of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] Embodiments of the present application are described in detail below, and examples of the embodiments of the present application are shown in the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0068] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons having ordinary skills in the technical field to which this application belongs. In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0069] Before formally introducing the embodiments of the present application, the terms that may be used in the following content are first explained.

[0070] Metal matrix composites (MMC) are generally composite materials with metal or alloy as the matrix and fibers, whiskers, particles, etc. as reinforcements. There are mainly metal matrix composites reinforced with high-performance reinforcing fibers, whiskers, particles, etc., self-reinforced composite materials in metal matrices, laminate metal matrix composites, etc. These metal matrix composites not only maintain the characteristics of the metal itself, but also have the comprehensive characteristics of composite materials. Through the optimized combination of different matrices and reinforcements, various high-performance composite materials are obtained, which have various special properties and excellent comprehensive properties. Metal matrix composites are classified according to the type of matrix material, including aluminum-based, magnesium-based, zinc-based, copper-based, intermetallic compound-based composite materials, etc.

[0071] Metal injection molding (MIM) refers to a metal processing technology. Its basic process is: first, the solid powder and the organic binder are evenly mixed, and after granulation, they are injected into the mold cavity by an injection molding machine under the heated plastic state for curing and molding, and then the binder in the molded blank is removed by chemical or thermal decomposition methods, and finally the final product is obtained by sintering and densification.

[0072] Computer numerical control (CNC) machine tools refer to the process of machining using a computer to automatically control machining tools.

[0073] Cold rolling, in metallurgical engineering, rolling, also known as rolling or calendering, refers to the process of passing a metal ingot through a pair of rollers to give it a shape by rolling. If the temperature of the metal exceeds its recrystallization temperature during rolling, then the process is called "hot rolling", otherwise it is called "cold rolling". Rolling is the most commonly used method in metal processing.

[0074] Amorphous metal, also known as metallic glass or liquid metal, refers to a metal material with disordered structure at the atomic scale. Most metal materials have a highly ordered structure, with atoms arranged periodically, showing translational symmetry, or rotational symmetry, mirror symmetry, angular symmetry, etc. Amorphous metals do not have any long-range effective structure, but have short-range and medium-range order. Methods for preparing amorphous metals include: physical vapor deposition, solid phase sintering, ion radiation and mechanical methods.

[0075] The structural parts of electronic devices, such as the middle frame of mobile phones, the hinges of folding screen devices, etc., can provide support, connection, protection and other functions for numerous electronic components in electronic devices, and therefore need to have certain mechanical properties. The mechanical properties of structural parts are generally related to one or more factors such as the shape, size, mass and constituent materials of the structural parts. The increase in size in the direction of force can improve the mechanical properties of the structural parts in the direction of force to a certain extent. However, the increase in the size of the structural parts of electronic devices often also means an increase in weight and an increase in the space occupied inside the electronic device, which often leads to a decrease in the maneuverability of the electronic device. How to reduce the weight and volume of the structural parts as much as possible without losing the mechanical properties of the structural parts is a problem worth considering.

[0076] To solve the above problems, the embodiment of the present application provides a composite material, which is a layered structure and is composed of an aluminum-based composite material and pure magnesium or a magnesium alloy or a magnesium-based composite material. The reinforcing phase in the aluminum-based composite material is conducive to improving the overall mechanical properties of the composite material, and the use of pure magnesium or a magnesium alloy or a magnesium-based composite material is conducive to reducing the volume density of the composite material without losing the mechanical properties of the composite material.

[0077] Figure 1 An exemplary composition structure of a first composite material 100 is provided, wherein the first composite material 100 is composed of three layers of stacked materials. Specifically, the first composite material 100 includes a first aluminum-based composite material 110, a magnesium-containing material 120, and a second aluminum-based composite material 130 stacked in sequence. In other words, the outer layer of the first composite material 100 is the first aluminum-based composite material 110 and the second aluminum-based composite material 130, and the magnesium-containing material 120 in the first composite material 100 is sandwiched between the first aluminum-based composite material 110 and the second aluminum-based composite material 130.

[0078] In some examples, the matrix of the first aluminum-based composite material 110 may be an aluminum alloy, such as an aluminum-magnesium alloy, an aluminum-zinc alloy, an aluminum-manganese alloy, or an aluminum-lithium alloy. As an example but not a limitation, the matrix of the first aluminum-based composite material 110 may be an aluminum-lithium alloy, and the density of the aluminum-lithium alloy may be 2.0 g / cm 3 ~2.3g / cm3 , for example 2.1 g / cm 3 or 2.2g / cm 3 wait.

[0079] In some examples, the reinforcement phase of the first aluminum-based composite material 110 may be one or more of fibers, particles or whiskers, for example, one or more of carbon fibers, glass fibers, aluminum oxide fibers, silicon carbide particles, boron carbide particles, silicon nitride particles, calcium sulfate whiskers, carbon nanotubes, graphene, graphite or diamond. For another example, a composite of the above-mentioned multiple reinforcement phases, such as graphene-coated ceramic particles. As an example and not a limitation, the reinforcement phase of the first aluminum-based composite material 110 may be silicon carbide particles, and the diameter of the silicon carbide particles may be 1 micron, 2 microns, 3 microns or 5 microns. In some examples, 90% of the silicon carbide particles have a diameter of less than 3 microns.

[0080] The proportion of the mass of the silicon carbide reinforcement phase in the total mass of the first aluminum-based composite material 110 is related to the mechanical properties of the first aluminum-based composite material 110. In some examples, the higher the amount of silicon carbide reinforcement phase incorporated, the greater the elastic modulus and the greater the tensile strength of the first aluminum-based composite material 110. Exemplarily, the value range of the incorporation ratio (mass fraction) p1 of silicon carbide can be: 0.1% ≤ p1 ≤ 60%. For example, the mass fraction of silicon carbide can be 2%, 5%, 10%, 15% or 20%, etc.

[0081] The thickness or volume percentage of the first aluminum-based composite material 110 can be determined according to the design performance of the first composite material 100. For example, when the design value of the bending strength of the first composite material 100 is large, the thickness or volume percentage of the first aluminum-based composite material 110 can be appropriately increased. On the contrary, when the design value of the bending strength of the first composite material 100 is small, the thickness or volume percentage of the first aluminum-based composite material 110 can be appropriately reduced. As an example but not a limitation, the thickness of the first aluminum-based composite material 110 can be 0.3 mm to 3.0 mm, for example, 1.0 mm or 2.0 mm.

[0082] In some examples, the matrix of the second aluminum-based composite material 130 may be an aluminum alloy, such as an aluminum-magnesium alloy, an aluminum-zinc alloy, an aluminum-manganese alloy, or an aluminum-lithium alloy. As an example but not a limitation, the matrix of the second aluminum-based composite material 130 may be an aluminum-lithium alloy, and the density of the aluminum-lithium alloy is 1.9 g / cm 3 ~2.4g / cm 3 , for example 2.0g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 or 2.3g / cm 3 wait.

[0083] In some examples, the reinforcing phase of the second aluminum-based composite material 130 may be one or more of fibers, particles or whiskers, for example, one or more of carbon fibers, glass fibers, aluminum oxide fibers, silicon carbide particles, boron carbide particles, silicon nitride particles, calcium sulfate whiskers, carbon nanotubes, graphene, graphite or diamond. For another example, a composite of the above-mentioned multiple reinforcing phases, such as graphene-coated ceramic particles. As an example and not a limitation, the reinforcing phase of the second aluminum-based composite material 130 may be silicon carbide particles, and the diameter of the silicon carbide particles may be 1 micron, 2 microns, 3 microns or 5 microns. In some examples, 90% of the silicon carbide particles have a diameter of less than 3 microns.

[0084] The proportion of the mass of the silicon carbide reinforcement phase in the total mass of the second aluminum-based composite material 130 is related to the mechanical properties of the second aluminum-based composite material 130. In some examples, the higher the amount of silicon carbide reinforcement phase incorporated, the greater the elastic modulus and the greater the tensile strength of the first aluminum-based composite material 110. Exemplarily, the value range of the incorporation ratio (mass fraction) p2 of silicon carbide can be: 0.1% ≤ p2 ≤ 60%. For example, the mass fraction of silicon carbide can be 2%, 5%, 10%, 15% or 20%, etc.

[0085] The thickness or volume ratio of the second aluminum-based composite material 130 can be determined according to the design performance of the first composite material 100. For example, when the design value of the bending strength of the first composite material 100 is large, the thickness or volume ratio of the second aluminum-based composite material 130 can be appropriately increased. On the contrary, when the design value of the bending strength of the first composite material 100 is small, the thickness or volume ratio of the second aluminum-based composite material 130 can be appropriately reduced. As an example but not a limitation, the thickness of the second aluminum-based composite material 130 can be 0.3 mm to 3.0 mm, for example, 1.0 mm or 2.0 mm.

[0086] In some examples, in order to simplify the process production steps and improve the preparation efficiency of the composite material, the first aluminum-based composite material 110 and the second aluminum-based composite material 130 may be aluminum-based composite materials having the same thickness and components (matrix and reinforcement phase).

[0087] In some examples, in order to obtain aluminum-based composite materials with different properties, the components of the first aluminum-based composite material 110 and the second aluminum-based composite material 130 may be different. For example, the first aluminum-based composite material 110 may use an aluminum-lithium alloy with a lower density as a matrix, and the second aluminum-based composite material 130 may use carbon fibers with a higher tensile elastic modulus as a reinforcement phase. The present application does not limit the specific components of the first aluminum-based composite material 110 and the second aluminum-based composite material 130.

[0088] In some examples, in order to reduce the weight of the aluminum-based composite material and lower the overall density of the first composite material 100, pores may be provided in the structure of the first aluminum-based composite material 110 and / or the second aluminum-based composite material 130, that is, the first aluminum-based composite material 110 and / or the second aluminum-based composite material 130 may form a porous structure or a honeycomb structure, wherein the pores may be one or more of millimeter-scale pores, micrometer-scale pores or nanometer-scale pores, and the present application does not impose any limitation on this.

[0089] Compared with aluminum, the atomic mass of magnesium is smaller. Appropriate use of the magnesium-containing material 120 in the first composite material 100 can reduce the density of the first composite material 100 .

[0090] In some examples, the mass fraction of magnesium in the magnesium-containing material 120 is ≥ 80%, for example, 85%, 90%, 95% or 100%, etc. Exemplarily, the magnesium-containing material 120 may be pure magnesium, magnesium-zinc alloy, magnesium-lithium alloy or magnesium-aluminum alloy.

[0091] The magnesium-containing material 120 may also include one or more of the following elements: zinc, manganese, silicon, copper or nickel. For example, the elements and the mass content of each element included in the magnesium-containing material 120 may be shown in Table 1 below:

[0092] Table 1

[0093] element magnesium aluminum Zinc manganese silicon copper nickel Mass fraction (%) margin 2.5～3.5 0.60～1.40 0.20～1.00 ≤0.08 ≤0.01 ≤0.001

[0094] The thickness or volume proportion of the magnesium-containing material 120 can be determined according to the design value of the density of the first composite material 100. When the design value of the density is small, the proportion of the magnesium-containing material 120 in the first composite material 100 can be appropriately increased, or the proportion of the thickness of the magnesium-containing material 120 in the overall thickness of the first composite material 100 can be appropriately increased. On the contrary, when the design value of the density is large, the proportion of the volume of the magnesium-containing material 120 in the total volume of the first composite material 100 can be appropriately reduced, or the proportion of the thickness of the magnesium-containing material 120 in the overall thickness of the first composite material 100 can be appropriately reduced. Exemplarily, the proportion of the thickness of the magnesium-containing material 120 in the total thickness of the first composite material 100 is greater than or equal to 50%, or the proportion of the volume of the magnesium-containing material 120 in the total volume of the first composite material 100 is greater than or equal to 50%. For example, the volume content of the magnesium-containing material is r1, and r1 can be 50%, 60%, 70% or 80%, etc.

[0095] In some examples, the magnesium-containing material 120 may be a magnesium-based composite material, the matrix of which may be pure magnesium or a magnesium alloy, such as a magnesium-aluminum alloy, a magnesium-lithium alloy, or a magnesium-zinc alloy. In some examples, the reinforcing phase of the magnesium-based composite material may be one or more of fibers, particles, or whiskers, such as carbon fibers, glass fibers, aluminum oxide fibers, silicon carbide particles, boron carbide particles, silicon nitride particles, calcium sulfate whiskers, carbon nanotubes, graphene, graphite, or diamond. For another example, a composite of the above-mentioned multiple reinforcing phases, such as graphene-coated ceramic particles, etc.

[0096] In order to further reduce the weight of the magnesium-containing material 120 and reduce the density of the first composite material 100, pores can be set in the magnesium-containing material 120 so that the magnesium-containing material 120 forms a porous structure or a honeycomb structure, where the pores can be one or more of millimeter-level pores, micrometer-level pores or nanometer-level pores, and the present application does not impose any restrictions on this.

[0097] In some examples, the design value of the density of the first composite material 100 is ≤ 2.0 g / cm 3 The first aluminum-based composite material 110 and the second aluminum-based composite material 130 may both be aluminum-lithium-based composite materials, and the magnesium-containing material 120 may be pure magnesium or a magnesium alloy or a magnesium-based composite material with a mass fraction of magnesium element ≥ 80%.

[0098] In order to improve the bonding strength between two adjacent layers of different materials in the first composite material 100, during the preparation of the first composite material 100, a layer of bonding material can be set between the first aluminum-based composite material 110 and the magnesium-containing material 120 and between the second aluminum-based composite material 130 and the magnesium-containing material 120. During the processing, the bonding material can break the oxide film on the surface of the first aluminum-based composite material 110, the magnesium-containing material 120 and the second aluminum-based composite material 130, so that the first aluminum-based composite material 110 and the magnesium-containing material 120 are more firmly bonded, and the magnesium-containing material 120 and the second aluminum-based composite material 130 are more firmly bonded, thereby improving the structural stability of the first composite material 100.

[0099] The aforementioned bonding material may be materials of different compositions and properties according to different preparation processes of the first composite material 100. In some examples, the thickness of the bonding material may be less than or equal to 50 microns, such as 30 microns, 20 microns, or 10 microns.

[0100] In some examples, the first composite material 100 is prepared by a rolling process. In this case, the bonding material between the first aluminum-based composite material 110 and the magnesium-containing material 120 and / or between the second aluminum-based composite material 130 and the magnesium-containing material 120 can be pure aluminum or pure zinc, such as a pure aluminum sheet or a pure zinc sheet with a thickness of less than 30 microns.

[0101] In some examples, welding is used to connect the first aluminum-based composite material 110 and the magnesium-containing material 120, and the magnesium-containing material 120 and the second aluminum-based composite material 130 in the first composite material 100. Before welding, a layer of brazing filler metal may be provided between the first aluminum-based composite material 110 and the magnesium-containing material 120, and / or between the magnesium-containing material 120 and the second aluminum-based composite material 130, that is, in this case, the aforementioned bonding material may be a brazing filler metal.

[0102] Exemplarily, the solder may be one or more of an aluminum-based solder, a silver-based solder, a copper-based solder, a nickel-based solder, a tin-based solder, a lead-based solder, a zinc-based solder, and the like.

[0103] In the case where the brazing material is disposed between the first aluminum-based composite material 110 and the magnesium-containing material 120, the melting point of the brazing material may be lower than the melting points of the first aluminum-based composite material 110 and the magnesium-containing material 120. In the case where the brazing material is disposed between the second aluminum-based composite material 130 and the magnesium-containing material 120, the melting point of the brazing material may be lower than the melting points of the second aluminum-based composite material 130 and the magnesium-containing material 120. Exemplarily, the melting point of the brazing material may be less than or equal to 700°C, such as 650°C, 600°C, 550°C, or 450°C, etc.

[0104] Since the corrosion resistance of the aluminum-based composite material is better than that of the aforementioned magnesium-containing material, in order to improve the corrosion resistance of the first composite material 100 as a whole, in some examples, part or all of the first aluminum-based composite material 110 and / or the second aluminum-based composite material 120 located outside the first composite material 100 can be coated on the outside of the magnesium-containing material 120, that is, forming a Figure 2 The structure shown enables the periphery of the first composite material 100 to be covered with the aluminum-based composite material.

[0105] Figure 2 The figure shown can be regarded as a cross-sectional surface obtained by cutting the first composite material 100 along the stacking direction of the multi-layer material. The periphery of the first composite material 100 can also be provided with a coating material 140, which is coated on the outside of the magnesium-containing material 120 to prevent the gas, moisture, etc. in the environment from polluting and corroding the magnesium-containing material 120, thereby improving the stability of the first composite material 100.

[0106] In some examples, the cladding material 140 may be obtained by extending the surrounding portions of the first aluminum-based composite material 110 in a direction close to the second aluminum-based composite material 130 , and one end of the cladding material 140 close to the second aluminum-based composite material 130 may be connected to the second aluminum-based composite material 130 .

[0107] In some examples, the cladding material 140 may be obtained by extending the surrounding portions of the second aluminum-based composite material 130 in a direction close to the first aluminum-based composite material 110 , and one end of the cladding material 140 close to the first aluminum-based composite material 110 may be connected to the first aluminum-based composite material 110 .

[0108] In some examples, the cladding material 140 can be obtained by extending the surrounding portions of the first aluminum-based composite material 110 and the surrounding portions of the second aluminum-based composite material 130 in directions approaching each other, that is, the portion of the cladding material 140 close to the first aluminum-based composite material 110 is extended from the first aluminum-based composite material 110, and the portion close to the second aluminum-based composite material 130 is extended from the second aluminum-based composite material 130.

[0109] The coating material 140 may also be coated around the magnesium-containing material 120 in other ways, which is not limited in the present application.

[0110] In some examples, the aluminum-based composite material in the first composite material 100 may also be a titanium-based composite material, a magnesium-based composite material, or an iron-based composite material.

[0111] Figure 3 The composition structure of a second composite material 200 provided in an embodiment of the present application is shown. The second composite material 200 is similar to the aforementioned first composite material 100 and also has a layered structure. The second composite material 200 includes the first aluminum-based composite material 110, the magnesium-containing material 120, and the second aluminum-based composite material 130 of the first composite material 100. The properties such as the composition and relative position relationship of these three materials are basically consistent with the relevant description in the aforementioned first composite material 100. For details, please refer to the relevant content in the aforementioned first composite material 100. For the sake of brevity, it will not be repeated here.

[0112] Different from the first composite material 100, at least one layer of alloy material may be stacked on the outer side of the second composite material 200, or in other words, at least one layer of alloy material may be stacked on the side of the first aluminum-based composite material 110 away from the magnesium-containing material 120 and / or the side of the second aluminum-based composite material 130 away from the magnesium-containing material 130 in the second composite material 200. The alloy material may be an aluminum alloy (e.g., aluminum-magnesium alloy, aluminum-zinc alloy, aluminum-manganese alloy, or aluminum-lithium alloy, etc.) or a magnesium alloy (e.g., magnesium-aluminum alloy, magnesium-lithium alloy, or magnesium-zinc alloy, etc.).

[0113] Aluminum alloy and magnesium alloy have good plasticity and toughness. Arranging aluminum alloy or magnesium alloy on the outside of aluminum-based composite material is conducive to improving the machinability of the composite material. In addition, the aluminum alloy located on the outside can also improve the corrosion resistance of the composite material to a certain extent.

[0114] For example, Figure 3 The second composite material 200 shown has a first alloy material 210 stacked on a side of the first aluminum-based composite material 110 away from the magnesium-containing material 120, and a second alloy material 220 stacked on a side of the second aluminum-based composite material 130 away from the magnesium-containing material 120. The first alloy material 210 may be an aluminum alloy, and the second alloy material 220 may be a magnesium alloy.

[0115] It should be understood that more layers of alloy materials may be stacked on the outer side of the second composite material 200, such as 4 layers, 5 layers, 6 layers, etc. These alloy materials may be aluminum alloys or magnesium alloys, and the present application does not impose any limitation on this.

[0116] Figure 4 The figure shows a method for preparing a first composite material 100 provided in an embodiment of the present application. An aluminum-based composite material and a magnesium-containing material are prepared separately, and the first composite material 100 can be formed by laminating multiple layers of materials.

[0117] S101, preparing a first aluminum-based composite material and a second aluminum-based composite material.

[0118] According to the different reinforcement phases in aluminum-based composite materials, different processes can be used to prepare aluminum-based composite materials. Commonly used aluminum-based composite material preparation processes include powder metallurgy, pressure infiltration, reaction self-generation, high-energy and high-speed consolidation, spray deposition and ball milling.

[0119] In some examples, the matrix of the first aluminum-based composite material 110 and the second aluminum-based composite material 130 are both aluminum-zinc alloys, and the reinforcement phase of the first aluminum-based composite material 110 and the second aluminum-based composite material 130 are both silicon carbide particles. Table 2 exemplarily provides a composition of an aluminum-zinc alloy.

[0120] Table 2

[0121]

[0122] The first aluminum-based composite material 110 is obtained by adding silicon carbide particles of a certain mass fraction (for example, 5%) and a certain size (for example, a particle diameter of less than 3 microns) into the base material aluminum-zinc alloy, mixing the two evenly, sintering them into shape, and mechanically processing (for example, cutting) them to obtain a plate-shaped or sheet-shaped composite material with a certain thickness (for example, 1.2 mm).

[0123] The preparation method of the second aluminum-based composite material 130 is similar to that of the first aluminum-based composite material 110 , and can also be prepared through a process flow of mixing, sintering, and machining, which will not be described here for brevity.

[0124] S102, preparing a magnesium-containing material.

[0125] In the case where the magnesium-containing material is a magnesium alloy, its preparation method may include one or more of the following: gravity casting, low pressure casting, die casting, semi-solid casting, extrusion, forging and rolling.

[0126] In some examples, magnesium alloys can be prepared by cold rolling forming process, where a configured metal ingot containing multiple metal elements is rolled by rollers to form a Figure 1 , Figure 2 or Figure 3 The magnesium-containing material 120 shown is in a plate or sheet shape with a certain thickness.

[0127] In the case where the magnesium-containing material is a magnesium-based composite material, its preparation method may be one or more of the following: stirring casting, liquid infiltration, powder metallurgy, spray deposition, and the like.

[0128] In some examples, the matrix of the magnesium-containing material 120 is a magnesium-aluminum alloy, and the reinforcing phase of the magnesium-containing material 120 is alumina fiber. The process of preparing the magnesium-containing material 120 by powder metallurgy is roughly as follows: the prefabricated aluminum-magnesium alloy and alumina fiber are uniformly mixed, vacuum degassing, consolidation forming, and then pressure processing is performed to form a composite material with the desired shape, size and performance.

[0129] S103, preparing a first composite material.

[0130] In some examples, the first composite material is formed by rolling, and the first aluminum-based composite material 110, the magnesium-containing material 120, and the second aluminum-based composite material 130 prepared in S101 and S102 are stacked in sequence and put into a rolling mill for rolling, so as to form Figure 1 A first composite material 100 is shown.

[0131] As an example but not a limitation, in order to improve the firmness of the bonding between the first aluminum-based composite material 110 and the magnesium-containing material 120 and the firmness of the bonding between the second aluminum-based composite material 130 and the magnesium-containing material 120, a layer of pure aluminum sheet or pure zinc sheet with a thickness of less than or equal to 50 microns can be respectively provided between the first aluminum-based composite material 110 and the magnesium-containing material 120 and / or between the second aluminum-based composite material 130 and the magnesium-containing material 120. During the pressing process, the pure aluminum sheet or pure zinc sheet can break the oxide film on the surface of the first aluminum-based composite material 110, the magnesium-containing material 120 and the second aluminum-based composite material 130, so that the first aluminum-based composite material 110 and the magnesium-containing material 120 are more firmly bonded, and the magnesium-containing material 120 and the second aluminum-based composite material 130 are more firmly bonded.

[0132] In some examples, the first aluminum-based composite material 110 and the magnesium-containing material 120 and / or the second aluminum-based composite material 130 and the magnesium-containing material 120 may be connected by welding. The first aluminum-based composite material 110 and the magnesium-containing material 120, and the second aluminum-based composite material 130 and the magnesium-containing material 120 may be welded in sequence to obtain a composite material such as Figure 1 A first composite material 100 is shown.

[0133] As an example but not limitation, in order to improve the bonding strength between the first aluminum-based composite material 110 and the magnesium-containing material 120 and the bonding strength between the second aluminum-based composite material 130 and the magnesium-containing material 120, a layer of solder with a thickness less than or equal to 50 microns can be provided between the first aluminum-based composite material 110 and the magnesium-containing material 120 and / or between the second aluminum-based composite material 130 and the magnesium-containing material 120. During the welding process, the solder helps to break down the oxide film on the surface of the aluminum-based composite material and the magnesium-containing material, thereby making the bonding between the first aluminum-based composite material 110 and the magnesium-containing material 120 more firmly, and the bonding between the magnesium-containing material 120 and the second aluminum-based composite material 130 more firmly.

[0134] Exemplarily, the solder may be one or more of an aluminum-based solder, a silver-based solder, a copper-based solder, a nickel-based solder, a tin-based solder, a lead-based solder, a zinc-based solder, and the like.

[0135] In the case where the brazing material is disposed between the first aluminum-based composite material 110 and the magnesium-containing material 120, the melting point of the brazing material may be lower than the melting points of the first aluminum-based composite material 110 and the magnesium-containing material 120. In the case where the brazing material is disposed between the second aluminum-based composite material 130 and the magnesium-containing material 120, the melting point of the brazing material may be lower than the melting points of the second aluminum-based composite material 130 and the magnesium-containing material 120. Exemplarily, the melting point of the brazing material may be less than or equal to 700°C, such as 650°C, 600°C, 550°C, or 450°C, etc.

[0136] It should be noted that the preparation of the magnesium-containing material 120 may also be performed before the preparation of the first aluminum-based composite material 110 and the second aluminum-based composite material 130 , that is, S102 may also be performed before S101 .

[0137] The preparation method of the aforementioned second composite material 200 is similar to the preparation method of the aforementioned first composite material 100. The alloy material and the aluminum-based composite material containing magnesium in the second composite material 200 can be stacked in sequence, and then rolled to obtain the second composite material 200. The detailed preparation method can refer to the relevant description of the first composite material 100 in the previous text, which will not be expanded here.

[0138] The first composite material 100 and the second composite material 200 have the advantages of good mechanical properties, low density, and good plasticity, and can be widely used to manufacture various structural parts of different electronic devices, such as: the middle frame of a mobile phone or tablet computer, the shaft, hinge, door panel, etc. of a foldable electronic device. The structural parts made of the first composite material 100 and / or the second composite material 200 have good mechanical properties and are also light in weight and small in volume.

[0139] The following takes the application of the first composite material 100 on the hinge of a foldable screen mobile phone and on the middle frame of an electronic device as an example to illustrate the specific application method of the composite material provided in the present application. It should be understood that the composite material provided in the present application can also be used to make other more structural parts, and the embodiments of the present application do not limit this.

[0140] like Figure 5 The figure shows a schematic diagram of the structure of a first electronic device 300 provided in an embodiment of the present application. The first electronic device 300 is a foldable electronic device. The first electronic device 300 may include a first housing 310, a second housing 320, a first display screen 330, a second display screen 340 and a hinge 350. Both sides of the hinge 350 are fixedly connected to the first housing 310 and the second housing 320, respectively. The first display screen 330 and the second display screen 340 are respectively carried on the first housing 310 and the second housing 320. The first display screen 330 and the second display screen 340 may be two different screens separated from each other, or the first display screen 330 and the second display screen 340 may be two different areas of the same screen.

[0141] The rotating shaft 350 may include a first door panel 351A, a second door panel 351B, a keel 352, and other components. The first door panel 351A and the second door panel 351B are respectively located on both sides of the keel 352, and the first door panel 351A and the second door panel 351B are respectively used to support the first display screen 330 and the second display screen 340. In some scenarios, the keel 352 may also be referred to as the rotating shaft body 352.

[0142] In some examples, the first door panel 351A includes a first support plate 353A and a plurality of first connectors 354A, and the second door panel 351B includes a second support plate 353B and a plurality of second connectors 354B. The plurality of first connectors 354A are disposed on a side of the first door panel 351A close to the keel 352, and are respectively fixedly connected to the first support plate 353A and the keel 352, so that the first door panel 351A and the keel 352 are relatively fixed. The plurality of second connectors 354B are disposed on a side of the second door panel 351B close to the keel 352, and are respectively fixedly connected to the second support plate 353B and the keel 352, so that the second door panel 351B and the keel 352 are relatively fixed.

[0143] The first support plate 353A may also be referred to as the main body of the first door panel 351A or the door panel body of the first door panel 351A, and the first support plate 353A may be used to support the aforementioned first display screen 330. The plurality of first connecting members 354A may also be referred to as the small part of the first door panel 351A or the rotating part of the first door panel 351A. The second support plate 353B may also be referred to as the main body of the second door panel 351B or the door panel body of the second door panel 351B, and the second support plate 353B may be used to support the aforementioned second display screen 340. The plurality of second connecting members 354B may also be referred to as the small part of the second door panel 351B or the rotating part of the second door panel 351B.

[0144] In some examples, part or all of the first door panel 351A and the second door panel 351B may be made of the composite material provided in the present application (eg, the first composite material 100 ).

[0145] Exemplarily, the first support plate 353A of the first door panel 351A and the second support plate 353B of the second door panel 351B can be made of the aforementioned first composite material 100. The plurality of first connectors 354A of the first door panel 351A and the plurality of second connectors 354B of the second door panel 351B can be made of a material with higher strength, such as amorphous metal, amorphous alloy or high-strength metal injection molding material.

[0146] In some examples, the thickness h1 of the first support plate 353A, the thickness h2 of the second support plate 353B, the thickness h3 of the first connector 354A, and the thickness h4 of the second connector 354B all satisfy: 0.01 mm ≤ h ≤ 2 mm. For example, h1, h2, h3, and h4 can be 0.50 mm, 1.0 mm, 1.5 mm, and 2.0 mm, respectively.

[0147] Dividing the door panel into independent support panels and connecting parts, and using different materials to prepare the support panels and connecting parts respectively, is conducive to making different parts of the door panel have different properties, and is conducive to reducing the total weight of the door panel on the basis of ensuring the mechanical properties of the door panel. In addition, the two parts of the door panel can be prepared separately according to different processes, which is conducive to achieving compatibility with existing door panel production methods, production equipment, and production processes, and improving the production efficiency of the door panel.

[0148] Each of the multiple connectors of the door panel is generally provided with a connection hole or a track groove, and the axial direction of these connection holes or track grooves can be parallel to the axial direction of the rotating shaft 350, and the multiple connection holes or track grooves on different connectors need to be coaxial. The multiple connectors in the door panel are prepared separately and mounted on the support plate, which is conducive to ensuring that the connection holes or track grooves on the multiple connectors are coaxial.

[0149] Also exemplarily, the first support plate 353A and the plurality of first connecting members 354A of the first door panel 351A may both be composed of the aforementioned first composite material 100, but the components of the first composite material 100 constituting the first support plate 353A and the components of the first composite material 100 constituting the plurality of first connecting members 354A may be different. For example, the content of the magnesium-containing material in the first composite material 100 constituting the first support plate 353A is higher, and the content of the magnesium-containing material in the first composite material 100 constituting the first connecting member 354A is lower. Similarly, the second support plate 353B and the plurality of second connecting members 354B of the second door panel 351B may also be composed of the first composite material 100 with different components.

[0150] In some examples, a plurality of first through holes may be provided at the connection position between the first support plate 353A of the first door panel 351A and the plurality of first connectors 354A, and correspondingly, a plurality of second through holes may also be provided on the first connector 354A, and the first support plate 353A and the first connector 354A may be fixedly connected through the first through holes and the second through holes. Exemplarily, the first support plate 353A and the first connector 354A are fixedly connected through the first through holes and the second through holes by riveting. In addition, the first support plate 353A and the first connector 354A may also be fixedly connected by other means such as gluing or welding.

[0151] In the actual production process of the door panel, the support plate and the connecting parts of the door panel can be manufactured separately, and then the support plate and the connecting parts are assembled by riveting or the like and undergo appropriate post-processing steps to obtain a complete door panel structure.

[0152] The yield strength of the door panel made of the composite material provided in the embodiment of the present application is at a comparable level to that of the door panel made of aluminum alloy, but the weight can be reduced by about 20% and the elastic modulus can be increased by 20% to 40%.

[0153] like Figure 6 The middle frame 400 of a second electronic device provided in an embodiment of the present application is shown. The middle frame 400 may include a frame 410 and a middle plate 420. The frame 410 is arranged on the periphery of the middle plate 420. The frame 410 and the middle plate 420 are fixedly connected.

[0154] The plate-shaped or sheet-shaped middle plate 420 can be regarded as a mounting platform for multiple electronic components (e.g., camera, battery, motherboard, etc.) in the second electronic device. The middle plate 420 can also be called a loading plate 420 of the middle frame 400. In some examples, one or more openings can be provided on the middle plate 420, and one or more recesses can also be provided on the middle plate 420. The electronic components in the second electronic device can be embedded in the openings or recesses on the middle plate 420, thereby achieving relative fixation with the middle plate 420.

[0155] Different areas of the middle plate 420 are equipped with different electronic components. For the sake of convenience, the middle plate 420 is divided into the following areas: Figure 6 The three areas shown are the first area 421, the second area 422 and the third area 423. The first area 421 can be used to install electronic components such as the camera and chip of the second electronic device, the third area 423 can be used to install electronic components such as the fingerprint recognition module and the vibration motor of the second electronic device, and the second area 422 can be used to accommodate electronic components such as the battery of the second electronic device. The second area 422 can also be called the battery compartment area, and the first area 421 and the third area 423 can also be called the non-battery compartment area.

[0156] In some examples, the entire middle plate 420 is made of the composite material (the first composite material 100 or the second composite material 200) provided in the embodiments of the present application, and the openings or recesses on the middle plate 420 can be obtained by machining the composite material.

[0157] In some examples, the second region 422 of the middle plate 420 can be made of a composite material provided by an embodiment of the present application. In this case, the first region 421 and the third region 423 of the middle plate 420 can be made of an aluminum alloy or an aluminum-based composite material. Exemplarily, the first region 421 and the third region 423 can be made of one or more of the following aluminum alloys: aluminum-magnesium alloy, aluminum-zinc alloy, aluminum-manganese alloy, and aluminum-lithium alloy. Also exemplarily, the matrix of the aluminum-based composite material for preparing the first region 421 and the third region 423 can be one or more of the following: aluminum-magnesium alloy, aluminum-zinc alloy, aluminum-manganese alloy, or aluminum-lithium alloy; the reinforcing phase of the aluminum-based composite material for preparing the first region 421 and the third region 423 can be one or more of the following: fibers, particles, or whiskers, etc.

[0158] In some examples, the elastic modulus of the aluminum-based composite material used to prepare the first region 421 and the third region 423 is greater than or equal to 90 GPa, for example, 95 GPa or 100 GPa, etc. In some examples, the elongation at break of the aluminum-based composite material used to prepare the first region 421 and the third region 423 is greater than or equal to 5%, for example, 6% or 6.5%, etc.

[0159] For the middle plate 420 composed of different materials, the frame 410 of the middle frame 400 can be made of one or more of the following materials: aluminum alloy, pure titanium, titanium alloy, stainless steel or amorphous alloy.

[0160] In some examples, the first region 421 and the third region 423 of the frame 410 and the middle plate 420 are both made of aluminum alloy. In this case, the frame 410, the first region 421 and the third region 423 of the middle plate 420 can be obtained by CNC processing using the same piece of aluminum alloy material, that is, in this case, the frame 410, the first region 421 and the third region 423 can be formed as one piece.

[0161] In some examples, the frame 410, the first area 421 and the third area 423 of the middle plate 420, and the second area 422 of the middle plate 420 are prepared separately. In this case, the second area 422 and the first area 421, the second area 422 and the third area 423, the second area 422 and the frame 410, the first area 421 and the frame 410, and the third area 423 and the frame 410 can be connected by one or more of the following connection methods: welding, riveting, and screw connection, etc.

[0162] The second electronic device may further include a display screen and a battery, wherein the display screen is fixed on the middle frame 400 , and the battery is accommodated in the second area 422 of the middle frame 400 .

[0163] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0164] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A composite material, characterized in that: include: a first aluminum-based composite material, a magnesium-containing material, and a second aluminum-based composite material, The first aluminum-based composite material, the magnesium-containing material and the second aluminum-based composite material are stacked, the magnesium-containing material is located between the first aluminum-based composite material and the second aluminum-based composite material, and the magnesium-containing material is pure magnesium, a magnesium alloy or a magnesium-based composite material.

2. The composite material according to claim 1, characterized in that The magnesium-containing material is a magnesium-aluminum alloy, a magnesium-zinc alloy, a magnesium-lithium alloy, or a magnesium-based composite material whose matrix is ​​a magnesium-aluminum alloy, a magnesium-zinc alloy, or a magnesium-lithium alloy.

3. The composite material according to claim 1 or 2, characterized in that: The mass fraction of magnesium in the magnesium-containing material is greater than or equal to 80%.

4. The composite material according to any one of claims 1 to 3, characterized in that The volume of the magnesium-containing material accounts for a proportion of the total volume of the composite material, V, which is ≥ 50%.

5. The composite material according to any one of claims 1 to 4, characterized in that There are a plurality of pores in the magnesium-containing material, and the diameters of the plurality of pores are one or more of the following: millimeter level, micrometer level or nanometer level.

6. The composite material according to any one of claims 1 to 4, characterized in that The matrix of the first aluminum-based composite material and the second aluminum-based composite material is one or more of aluminum, aluminum-magnesium alloy, aluminum-zinc alloy, aluminum-manganese alloy or aluminum-lithium alloy.

7. The composite material according to claim 5, characterized in that The matrix of the first aluminum-based composite material and the second aluminum-based composite material is an aluminum-lithium alloy, and the density D of the aluminum-lithium alloy satisfies: 1.9g / cm 3 ≤D≤2.4g / cm 3 。 8. The composite material according to any one of claims 1 to 6, characterized in that The reinforcement phases of the first aluminum-based composite material and the second aluminum-based composite material are one or more of particles, fibers or whiskers.

9. The composite material according to claim 8, characterized in that The reinforcing phases of the first aluminum-based composite material and the second aluminum-based composite material are both silicon carbide particles, the mass of the silicon carbide particles accounts for a proportion of the total mass of the first aluminum-based composite material is M1, the mass of the silicon carbide particles accounts for a proportion of the total mass of the second aluminum-based composite material is M2, and M1 and M2 satisfy: 0.2%<M1≤60%, 0.2%<M2≤60%.

10. The composite material according to claim 9, characterized in that 95% of the silicon carbide particles have a diameter less than or equal to 3 micrometers.

11. The composite material according to any one of claims 7 to 10, characterized in that The reinforcement phase of the first aluminum-based composite material and / or the second aluminum-based composite material is graphite and / or diamond.

12. The composite material according to any one of claims 1 to 11, characterized in that There are a plurality of pores in the first aluminum-based composite material and / or the second aluminum-based composite material, and the diameters of the plurality of pores are one or more of the following: millimeter level, micrometer level or nanometer level.

13. The composite material according to any one of claims 1 to 12, characterized in that The composite material also includes at least one layer of alloy material, which is located on a side of the first aluminum-based composite material away from the magnesium-containing material, or the at least one layer of alloy material is located on a side of the second aluminum-based composite material away from the magnesium-containing material, and the at least one layer of alloy material is an aluminum alloy or a magnesium alloy.

14. The composite material according to any one of claims 1 to 13, characterized in that The composite material also includes at least one layer of bonding material, which is located between the first aluminum-based composite material and the magnesium-containing material and / or between the second aluminum-based composite material and the magnesium-containing material, and the bonding material is one or more of the following: solder, pure aluminum or pure zinc.

15. The composite material according to any one of claims 1 to 14, characterized in that The first aluminum-based composite material and / or the second aluminum-based composite material at least partially covers the magnesium-containing material.

16. A rotating shaft, characterized in that: include: A door panel body, a rotating accessory and a rotating shaft body, wherein the rotating accessory is used to fixedly connect the door panel body and the rotating shaft body, and the door panel body is made of the composite material described in any one of claims 1 to 15.

17. The rotating shaft according to claim 16, characterized in that: The rotating fitting is made of amorphous alloy and / or metal injection molding material.

18. The rotating shaft according to claim 17, characterized in that: The rotating accessory is fixedly connected to the door panel body by riveting.

19. The rotating shaft according to any one of claims 16 to 18, characterized in that: The thickness of the door panel body is T1, and the thickness of the rotating accessory is T2. T1 and T2 satisfy: 0.01mm<T1≤2.00mm, 0.01mm<T2≤2.00mm.

20. A middle frame, characterized in that: The invention comprises: a frame and a loading plate, wherein the frame is fixedly connected to the loading plate, the loading plate comprises a target area, and the target area is made of the composite material according to any one of claims 1 to 15.

21. The middle frame according to claim 20, characterized in that: The area outside the target area on the loading plate is made of one or more of the following materials: an aluminum alloy, an aluminum-based composite material, or the composite material according to any one of claims 1 to 15.

22. The middle frame according to claim 20 or 21, characterized in that: The frame is made of one or more of the following materials: pure titanium, titanium alloy, aluminum alloy, stainless steel or amorphous alloy.

23. The middle frame according to claim 22, characterized in that: The area outside the target area on the loading plate and the frame are both made of aluminum alloy, and the area outside the target area on the loading plate and the frame are integrally formed.

24. The middle frame according to claim 21, characterized in that: The area outside the target area on the loading plate is made of an aluminum-based composite material, and the elastic modulus of the aluminum-based composite material is greater than or equal to 90 GPa.

25. A foldable electronic device, characterized in that: include: A first shell, a second shell and a rotating shaft as claimed in any one of claims 16 to 19, wherein the rotating shaft is connected to the first shell and the second shell respectively.

26. An electronic device, characterized in that: include: A battery and the middle frame according to any one of claims 20 to 24, wherein the battery is mounted in a target area of ​​a loading plate of the middle frame.

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