Composite material, middle frame, manufacturing method therefor and electronic device

Abstract

The present application relates to the technical field of terminals. Provided in the embodiments are a composite material, a middle frame, a manufacturing method therefor and an electronic device. The composite material comprises a casing and a first filling body, the casing defining a first accommodating channel, and the first filling body being arranged in the first accommodating channel. The first filling body is bonded to the inner wall of the first accommodating channel, the term "bonding" comprising metallurgical bonding. The casing and the first filling body can be bonded together in a metallurgical bonding mode, such that the bonding force therebetween can be increased, providing the composite material with high strength. Thus, a middle frame made of the composite material has high connection reliability.

Description

Composite material, middle frame, preparation method thereof, and electronic equipment

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 28, 2023, with application number 202311626541.0 and application name “A composite material, a middle frame, its preparation method and an electronic device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of terminal technology, and in particular to a composite material, a middle frame, a preparation method thereof, and an electronic device. Background Art

[0003] With the advancement of electronic technology, electronic devices such as mobile phones and tablets have become indispensable products in people's lives. For example, a mobile phone may include components such as a mid-frame, display, and back cover. The back cover and display are located on either side of the mid-frame and, together with the mid-frame, form the phone's internal space, which also houses the phone's internal components such as the memory card, battery, and processor.

[0004] In related technologies, the frame of the middle frame is made of stainless steel or titanium alloy, and the middle plate is made of aluminum alloy. The frame and the middle plate are connected by welding or riveting. This has a low reliability of the connection between the frame and the middle plate, affecting the overall rigidity of the middle frame.

[0005] Summary of the Invention

[0006] The present application provides a composite material, a middle frame, a method for preparing the same, and an electronic device. The outer shell and the first filler in the composite material are bonded together by metallurgical bonding, and after the middle frame is prepared using the composite material, the connection reliability of the middle frame is high.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a composite material is provided, comprising: an outer shell and a first filling body, wherein the outer shell is arranged to form a first accommodating channel; the first filling body is arranged in the first accommodating channel, and the first filling body is combined with the inner wall of the first accommodating channel, and the combination includes metallurgical bonding.

[0009] In this way, the outer shell and the first filler can be metallurgically bonded, which can increase the bonding force between the two and make the composite material have higher strength. Furthermore, after the middle frame is made of this composite material, the connection reliability of the middle frame is higher.

[0010] In one achievable manner, the shell and the first filling body are further connected via mutually engaging protrusions and grooves.

[0011] In this way, the first filler body and the outer shell can be connected via interlocking protrusions and grooves, with the bonding method being partially metallurgical and partially mechanical. This can increase the bonding force between the two, resulting in a higher strength composite material. Furthermore, when the middle frame is manufactured using this composite material, the connection reliability is high, improving the overall rigidity of the middle frame.

[0012] In one achievable manner, the protrusion is provided on the inner wall of the first accommodating channel, and the groove is provided on the outer wall of the first filling body, with interference fit between the protrusion and the groove.

[0013] In this way, the protrusions on the inner wall of the first accommodating channel can be extruded and bonded to the grooves on the outer wall of the first filling body. This bonding method can be partially metallurgical and partially mechanical, which can generate a strong bonding force between the outer shell and the first filling body, ensuring a tight connection between the two. This improves the strength of the composite material. Furthermore, when the composite material is used to manufacture the middle frame, the connection reliability is high.

[0014] In one achievable embodiment, the protrusion includes a first surface and a second surface arranged opposite to each other, the first surface and the second surface are both arranged parallel to the center line of the first accommodating channel, one end of the first surface and the second surface is connected to the inner wall of the shell, and the other ends of the first surface and the second surface intersect or are parallel.

[0015] By providing the protrusion and including the first surface and the second surface in the protrusion, the contact area between the shell and the first filler can be increased, so that a greater bonding force is generated between the shell and the first filler, thereby improving the strength of the composite material.

[0016] In one achievable manner, there are a plurality of protrusions and a plurality of grooves, and each protrusion is engaged with a groove.

[0017] In this way, by evenly arranging multiple protrusions on the inner wall of the shell, the entire shell structure can be made more stable, thereby ensuring a greater bonding force after being subsequently engaged with multiple grooves, and making the composite material have higher strength.

[0018] In one conceivable embodiment, the outer shell comprises at least one of pure titanium, a titanium alloy, stainless steel, and alloy steel. Using at least one of these materials, which have a high elastic modulus, can improve the elastic modulus and overall rigidity of the composite material. Furthermore, when the middle frame is fabricated using this composite material, connection reliability is enhanced, improving the overall rigidity of the middle frame.

[0019] In one implementation, the first filler comprises a hard aluminum alloy having a Vickers hardness greater than or equal to 120 HV. Using a high-hardness aluminum alloy for the first filler enhances the hardness of the composite material. Furthermore, when the middle frame is fabricated using this composite material, connection reliability is enhanced, improving the overall hardness of the middle frame.

[0020] In one possible implementation, the first filler comprises a decorative anodized aluminum alloy. Using this decorative anodized aluminum alloy with a high elastic modulus can improve the elastic modulus and overall rigidity of the composite material. Furthermore, when the middle frame is fabricated using this composite material, connection reliability is enhanced, improving the overall rigidity of the middle frame.

[0021] In one achievable embodiment, the first filler comprises a first aluminum-based composite material, which includes pure aluminum or an aluminum alloy and at least one of the following: silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond. Using an aluminum-based composite material with a high elastic modulus for the first filler can improve the elastic modulus and overall rigidity of the composite material. Furthermore, when the middle frame is fabricated using this composite material, connection reliability is improved, enhancing the overall rigidity of the middle frame.

[0022] In one achievable manner, the mass percentage of silicon carbide in the first aluminum-based composite material is less than 65%.

[0023] In this way, by increasing the content of silicon carbide in the first aluminum-based composite material, the content of silicon carbide added to the aluminum alloy can be made more appropriate, thereby improving the elastic modulus and bending resistance of the first aluminum-based composite material.

[0024] In one achievable manner, the silicon carbide in the first aluminum-based composite material includes submicron-sized first silicon carbide particles and micron-sized first silicon carbide particles;

[0025] The mass percentage of the submicron-sized first silicon carbide particles in the first aluminum-based composite material is 0-20%, and the mass percentage of the micron-sized first silicon carbide particles in the first aluminum-based composite material is 5%-40%.

[0026] Specifically, the D50 in the cumulative particle size distribution of the submicron-sized first silicon carbide particles is 0.3 μm-1.0 μm, the D50 in the cumulative particle size distribution of the micron-sized silicon carbide particles is 3 μm-20 μm, and the D50 in the cumulative particle size distribution of the aluminum alloy is less than or equal to 20 μm.

[0027] In this way, by controlling the content of submicron-sized first silicon carbide particles and micron-sized first silicon carbide particles in the first aluminum-based composite material, the content of silicon carbide added to the aluminum alloy can be made more appropriate, thereby improving the elastic modulus and bending resistance of the first aluminum-based composite material.

[0028] In one feasible embodiment, the composite material also includes a second filling body, a second accommodating channel is provided in the first filling body, and the center line of the second accommodating channel is parallel to the center line of the first accommodating channel; the second filling body is provided in the second accommodating channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding.

[0029] The first and second filler bodies can be metallurgically bonded to each other, increasing the bonding strength between them and resulting in a composite material with higher strength. Furthermore, using the composite material comprising the first and second filler bodies and the outer shell to form a midframe can enhance the midframe's overall bending resistance, drop resistance, and overall strength.

[0030] In one achievable manner, the second filler body includes a second aluminum-based composite material, and the mass percentage of silicon carbide in the second aluminum-based composite material is less than 65%.

[0031] In this way, by increasing the content of silicon carbide in the second aluminum-based composite material, the content of silicon carbide added to the aluminum alloy can be made more appropriate, thereby improving the elastic modulus and bending resistance of the second aluminum-based composite material.

[0032] In one achievable manner, the silicon carbide in the second aluminum-based composite material includes submicron-sized second silicon carbide particles and micron-sized second silicon carbide particles;

[0033] The submicron-sized second silicon carbide particles comprise 0-10% by mass of the second aluminum-based composite material, while the micron-sized second silicon carbide particles comprise 15-50% by mass of the second aluminum-based composite material. The cumulative particle size distribution of the submicron-sized second silicon carbide particles has a D50 of 0.5-1.0 microns, while the cumulative particle size distribution of the micron-sized second silicon carbide particles has a D50 of 3-20 microns.

[0034] By controlling the content of submicron-sized second silicon carbide particles and micron-sized second silicon carbide particles in the second aluminum-based composite material, the content of silicon carbide added to the aluminum alloy can be made more appropriate, thereby improving the elastic modulus and bending resistance of the second aluminum-based composite material.

[0035] In one achievable manner, the elastic modulus of the first filling body is greater than or equal to 85 GPa, and the elastic modulus of the second filling body is greater than or equal to 110 GPa.

[0036] In a feasible manner, the elongation of the first filling body is greater than 3%, and the elongation of the second filling body is greater than 0.2%.

[0037] The first filler provided in the embodiments of the present application has a high elastic modulus, which can improve the overall rigidity of the composite material and the rigidity of the resulting middle frame. Furthermore, the first filler has a high elongation, indicating a strong plastic deformation capability. This can enhance the processing versatility of the composite material and the processing versatility of the resulting middle frame.

[0038] Furthermore, the second filler has a relatively high elastic modulus, which is higher than that of the first filler. Composite materials produced using the first and second fillers also have a relatively high elastic modulus, thereby enhancing the overall rigidity of the composite material. Furthermore, the second filler has a relatively high elongation, resulting in composite materials with enhanced plastic deformation and a high degree of processing versatility.

[0039] In a second aspect, the present invention also provides a method for preparing a composite material, the method comprising:

[0040] A shell is prepared, and the shell is arranged to form a first accommodating channel. A first filling body is prepared and installed in the first accommodating channel, and the first filling body is combined with the inner wall of the first accommodating channel, and the combination includes metallurgical combination.

[0041] In this way, the prepared shell and the first filler can be metallurgically bonded, which can increase the bonding force between the two and make the composite material have higher strength. Furthermore, after the middle frame is prepared using this composite material, the connection reliability is higher.

[0042] In one achievable manner, the first filling body is installed in the first accommodating channel, including: extruding the outer shell and the first filling body, wherein the outer shell and the first filling body are connected via mutually engaging protrusions and grooves so that the outer shell and the first filling body have an interference fit.

[0043] In this way, by extruding the first filler and the outer shell, they can be connected via interlocking protrusions and grooves, which can be partially metallurgical and partially mechanical. This can increase the bonding force between the two, resulting in a higher strength composite material. Furthermore, when the middle frame is manufactured using this composite material, the connection reliability is high, improving the overall rigidity of the middle frame.

[0044] In one practicable manner, extruding the outer shell and the first filling body includes: performing isostatic pressing on the outer shell and the first filling body.

[0045] By performing isostatic pressing on the shell and the first filling body, the prepared composite material can have excellent performance and a short production cycle.

[0046] In one achievable manner, the shell and the first filling body are subjected to isostatic pressing, which includes: extruding according to a predetermined extrusion ratio, and heating the shell and the first filling body while extruding.

[0047] By extruding according to a predetermined extrusion ratio and heating the outer shell and first filler simultaneously, the outer shell and first filler are fully bonded, ensuring the resulting composite material has high strength. Furthermore, when this composite material is used to form a middle frame, the connection reliability is high, improving the overall rigidity of the middle frame.

[0048] In one feasible embodiment, preparing the shell includes: providing a first rod body, forming a first accommodating channel in the first rod body, and the center line of the first accommodating channel is parallel to the center line of the first rod body; forming a protrusion on the inner wall of the first accommodating channel, and the protrusion extends in a direction parallel to the center line of the first rod body.

[0049] Preparing the first filling body includes providing a second rod and forming a groove on an outer wall of the second rod, the groove extending parallel to a centerline of the second rod. Installing the first filling body in the first receiving channel also includes inserting the second rod into the first receiving channel parallel to the centerline of the first rod, with the protrusion engaging the groove.

[0050] By providing protrusions on the inner wall of the first accommodating channel and grooves on the outer wall of the first filling body, the first filling body and the outer shell can be bonded partially by metallurgy and partially by mechanical bonding, which can increase the bonding strength between the two and ensure a tight connection between them. This improves the strength of the composite material. Furthermore, when the composite material is used to manufacture the middle frame, the connection reliability is higher.

[0051] In one achievable manner, preparing the first filling body further includes: forming a second accommodating channel on the first filling body, wherein a center line of the second accommodating channel is parallel to a center line of the first accommodating channel.

[0052] The method further includes: preparing a second filling body, installing the second filling body in the second receiving channel, and bonding the second filling body to the second receiving channel, wherein the bonding includes metallurgical bonding.

[0053] By preparing a second filler and installing it within the second accommodating channel, the first and second fillers can be metallurgically bonded, increasing the bonding strength between them and resulting in a composite material with higher strength. Furthermore, using this composite material, including the first and second fillers and the outer shell, to form the middle frame improves its overall bending resistance, drop resistance, and strength.

[0054] In a third aspect, an embodiment of the present application further provides a middle frame, which is made of the composite material of the first aspect. The middle frame includes a frame and a middle plate, which is connected to the frame and is configured to be arranged inside the electronic device; the frame includes a shell, and the middle plate includes a first filling body.

[0055] The frame portion of the middle frame includes an outer shell, and the middle plate portion includes a first filler. On the one hand, the first filler can be made of a first aluminum-based composite material, an anodized aluminum alloy or a hard aluminum alloy, which has a high elastic modulus and high hardness, thereby improving the bending resistance and overall drop resistance of the entire middle frame, thereby improving the strength of the entire middle frame. On the other hand, the corresponding thickness of the middle plate can be thinned, and the battery area where the battery is set in the middle frame can be thinned to accommodate larger capacity batteries, thereby contributing more battery capacity. On the other hand, the frame and the middle plate in the middle frame are integrally formed, and the connection reliability is high, which improves the overall rigidity of the middle frame.

[0056] In one feasible embodiment, the composite material also includes a second filling body, a second accommodating channel is provided in the first filling body, and the center line of the second accommodating channel is parallel to the center line of the first accommodating channel; the second filling body is provided in the second accommodating channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding.

[0057] The middle plate includes a battery area and a non-battery area. The battery area includes a second filling body, and the non-battery area includes a first filling body.

[0058] The battery area of ​​the midplane includes a second filler, while the non-battery area includes a first filler. The elastic modulus of the second aluminum-based composite material corresponding to the second filler is higher than the elastic modulus of the first aluminum-based composite material corresponding to the first filler. This provides more reliable protection for the battery and enhances the user experience.

[0059] Fourthly, an embodiment of the present application further provides a middle frame, which is made of the composite material of the first aspect. The middle frame includes a frame and a back cover. The frame is connected to the back cover, and the back cover is configured to be located on the back of the electronic device; the frame includes an outer shell, and the back cover includes a first filling body.

[0060] The frame portion of the middle frame includes an outer shell, and the back cover portion includes a first filling body. On the one hand, the first filling body can be made of a first aluminum-based composite material, anodized aluminum alloy or hard aluminum alloy, which has a high elastic modulus and high hardness, thereby improving the bending resistance and overall drop resistance of the entire middle frame, thereby improving the strength of the entire middle frame. On the other hand, the corresponding thickness of the back cover can be thinned, and the battery area where the battery is set in the middle frame can be thinned to accommodate larger capacity batteries, thereby contributing more battery capacity. On the other hand, the frame and back cover in the middle frame are integrally formed, with high connection reliability, which improves the overall rigidity of the middle frame.

[0061] In one feasible embodiment, the composite material also includes a second filling body, a second accommodating channel is provided in the first filling body, and the center line of the second accommodating channel is parallel to the center line of the first accommodating channel; the second filling body is provided in the second accommodating channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding.

[0062] The back cover includes a battery area and a non-battery area, the battery area includes a second filler, and the non-battery area includes a first filler. At least a portion of the outer surface of the back cover is provided with a decorative layer made of anodized aluminum alloy.

[0063] The battery area of ​​the back cover includes a second filler, while the non-battery area includes a first filler. The elastic modulus of the second aluminum-based composite material corresponding to the second filler is higher than the elastic modulus of the first aluminum-based composite material corresponding to the first filler. This provides more reliable protection for the battery and enhances the user experience.

[0064] At the same time, at least part of the outer surface of the back cover is provided with a decorative layer, which not only has a good decorative effect, but also will not be easily damaged and has good integrity. It can prevent the metal material inside the middle frame from oxidizing, thereby achieving effective protection for the metal material inside the middle frame.

[0065] In a fifth aspect, embodiments of the present application further provide a method for preparing a middle frame, comprising: preparing a composite material using the method for preparing a composite material described in the second aspect; cutting the composite material along a square perpendicular to the centerline of the first accommodating channel to form a plate; and cutting the plate so that the outer shell forms the border of the middle frame, and the first filler forms the middle plate of the middle frame.

[0066] In a sixth aspect, embodiments of the present application further provide a method for preparing a middle frame, the method comprising: preparing a composite material using the method for preparing a composite material described in the second aspect; cutting the composite material along a square perpendicular to the centerline of the first accommodating channel to form a plate; and cutting the plate so that the outer shell forms the frame of the middle frame, and the first filler forms the back cover of the middle frame.

[0067] In one achievable manner, the plate is cut so that the shell forms the frame of the middle frame, and the first filling body forms the back cover of the middle frame, and further comprises: anodizing at least a portion of the outer surface of the back cover to obtain a decorative layer.

[0068] In the seventh aspect, an embodiment of the present application further provides an electronic device, which includes a display screen, a battery, and a middle frame as described in the third aspect, or a middle frame as described in the fourth aspect, wherein the display screen and the battery are arranged on the middle frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG1 is a schematic structural diagram of a middle frame provided in an embodiment of the present application;

[0070] FIG2 is a schematic diagram of a scenario in which a mobile phone is bent and deformed, provided by an embodiment of the present application;

[0071] FIG3 is a first structural diagram of an electronic device provided in an embodiment of the present application;

[0072] FIG4 is a first structural diagram of a middle frame provided in an embodiment of the present application;

[0073] FIG5 is a second structural diagram of the middle frame provided in an embodiment of the present application;

[0074] FIG6 is a third structural diagram of the middle frame provided in an embodiment of the present application;

[0075] FIG7 is a second structural diagram of an electronic device provided in an embodiment of the present application;

[0076] FIG8 is a fourth structural diagram of the middle frame provided in an embodiment of the present application;

[0077] FIG9 is a fifth structural diagram of a middle frame provided in an embodiment of the present application;

[0078] FIG10 is a schematic diagram of the structure of a composite material in an embodiment of the present application;

[0079] FIG11 is a schematic structural diagram of a housing provided in an embodiment of the present application;

[0080] FIG12 is a schematic structural diagram of a first surface and a second surface of a protrusion provided in an embodiment of the present application;

[0081] FIG13 is a first structural diagram of a protrusion provided in an embodiment of the present application;

[0082] FIG14 is a second structural schematic diagram of a protrusion provided in an embodiment of the present application;

[0083] FIG15 is a third structural diagram of a protrusion provided in an embodiment of the present application;

[0084] FIG16 is a schematic structural diagram of a second filling body provided in an embodiment of the present application;

[0085] FIG17 is a schematic diagram of a first process for preparing a composite material according to an embodiment of the present application;

[0086] FIG18 is a second flow chart of the method for preparing a composite material in an embodiment of the present application. DETAILED DESCRIPTION

[0087] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Among them, in the description of the present application, unless otherwise specified, " / " indicates that the objects associated before and after are in an "or" relationship. For example, A / B can represent A or B; "and / or" in the present application is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple. In addition, in order to facilitate a clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish identical or similar items with basically the same functions and effects.

[0088] Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit differences. At the same time, in some embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or design. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0089] For ease of understanding, some examples of concepts related to the embodiments of this application are provided for reference as follows:

[0090] Metal matrix composite (MMC) is a composite material with metal or alloy as the matrix and fibers, whiskers and particles as reinforcement.

[0091] Metal-matrix composites (MMCs) retain the inherent properties of metals while possessing the combined characteristics of composite materials. By optimizing the combination of different matrices and reinforcements, various high-performance composites are created, exhibiting a variety of specialized properties and excellent overall performance. MMCs can be categorized by the type of matrix material, including aluminum-based, magnesium-based, zinc-based, copper-based, and intermetallic compound-based composites.

[0092] D50: The particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 50%.

[0093] In the related art, as shown in Figure 1 , the frame 11 of the middle frame 10 is made of stainless steel or titanium alloy, and the middle plate 12 is made of aluminum alloy. Alternatively, the frame 11 of the middle frame 10 is made of aluminum alloy, and the middle plate 12 is made of aluminum alloy doped with silicon carbide (SiC) particles. The frame 11 and middle plate 12 are connected by welding or riveting. On the one hand, the frame and middle plate need to be pre-processed separately and then connected by external force or thermal connection. The connection between the two is mechanical, with low connection reliability, which affects the overall rigidity of the middle frame. For foldable phones, this will squeeze the display and folding axis, increasing the failure rate between the display and folding axis. On the other hand, aluminum alloy has a low elastic modulus, and the silicon carbide particle-doped aluminum alloy has a low silicon carbide content, so its elastic modulus is also low. As a result, the frame 11 and middle plate 12 are prone to bending, causing the entire phone to bend and deform in a three-point bending scenario, as shown in Figure 2. Furthermore, the low elastic modulus of the middle plate 12 prevents the battery area within the middle plate 12 from being thinned and contributing more battery capacity. This reduces the user experience.

[0094] To solve the above technical problems, referring to FIG3 , an embodiment of the present application provides an electronic device 300 , which includes a display screen 31 , a middle frame 32 , printed circuit boards (PCBs) 33 , a battery 34 and a back cover 35 .

[0095] The display screen 31 and back cover 35 are mounted on opposite sides of the middle frame 32. The interior of the middle frame 32 is the internal space of the electronic device 300, which can accommodate the PCB 33 and battery 34 of the electronic device 300. In some examples, the internal space can also accommodate internal components of the electronic device 300, such as a SIM card, memory card, speaker, and receiver.

[0096] It should be noted that, in other embodiments, the electronic device 300 may not include the display screen 31 , but may include components without a display function, such as a top cover.

[0097] The electronic device may include but is not limited to a mobile phone, a tablet computer, a laptop computer, an ultra-mobile personal computer (UMPC), a netbook, a personal digital assistant (PDA), a wearable device, an artificial intelligence (AI) device, and the like.

[0098] The present embodiment further provides a middle frame. Referring to FIG4 , the middle frame 32 may include a middle plate 36 and a frame 37. The middle plate 36 is connected to the frame 37 and is configured to be disposed within the interior of the electronic device. The middle plate 36 is positioned within the frame 37 and is integrally formed with the frame 37. The middle plate 36 is used to support the display screen and internal components of the electronic device, providing support for the internal components, thereby preventing the display screen from collapsing and protecting the internal components.

[0099] In some examples, Figure 5 is a schematic diagram of the structure of the middle frame 32 shown in Figure 3, cut along the AA direction, under one embodiment. Referring to Figure 5 , the middle frame 32 includes an edge portion 321, a center portion 322, and a connecting portion 323. The edge portion 321, the center portion 322, and the connecting portion 323 are integrally formed. Specifically, the center portion 322 is located inside the edge portion 321, and the connecting portion 323 is connected between the edge portion 321 and the center portion 322. The edge portion 321 and the connecting portion 323 form a frame 37, and the center portion 322 forms the middle plate 36.

[0100] It should be noted that the integral molding of the edge portion 321 , the center portion 322 and the connecting portion 323 means that the edge portion 321 , the center portion 322 and the connecting portion 323 are formed together through a processing technology, rather than being assembled by riveting or welding after each processing is completed.

[0101] In some embodiments, the edge portion 321 forms a frame 37, and the center portion 322 and the connecting portion 323 form a middle plate 36. FIG5 is only an example of a middle frame, and the embodiment of the present application does not limit the specific structure of the middle frame.

[0102] In some embodiments of the present application, referring to FIG6 , the middle plate 36 includes a battery area 361 and a non-battery area 362 . The battery area 361 is used to carry the battery, and the non-battery area 362 is used to carry internal components of the electronic device, such as a SIM card, a memory card, a speaker, and a receiver.

[0103] The electronic device 300 provided in the embodiment of the present application is not limited to the structure shown in FIG3 . The electronic device 300 may not have a separate back cover, but may be positioned within the middle frame. Referring to FIG7 , the electronic device 300 may include a display 31, a PCB 33, a battery 34, and a middle frame 32. The display 31 and middle frame 32 are mounted on opposite sides of the electronic device 300.

[0104] The middle frame 32 includes a frame 37 and a back cover 38. The frame 37 and back cover 38 are integrally connected, and the back cover 38 is configured to be located on the back of the phone. The interior space of the middle frame 32 can accommodate the PCB board 33 and battery 34 of the electronic device 300. Similarly, the interior space can also accommodate internal components of the electronic device 300, such as the SIM card, memory card, speaker, and receiver.

[0105] In some embodiments of the present application, referring to FIG8 , the back cover 38 includes a battery area 361 and a non-battery area 362. Similarly, the battery area 361 is used to hold the battery, and the non-battery area 362 is used to hold internal components of the electronic device, such as a SIM card, memory card, speaker, and receiver.

[0106] In one implementation, as shown in FIG9 , the surface of the back cover 38 facing away from the display screen can form a decorative layer 67 for the middle frame 32. Specifically, the decorative layer 67 can be provided on the entire outer surface of the back cover 38, or even on a portion of the outer surface. The decorative layer 67 can be made of a decorative anodized aluminum alloy. Because low-alloy aluminum alloys in decorative anodized aluminum alloys have excellent decorative effects, the outer surface of the back cover 38 has a high-quality decorative effect. This ensures that the middle frame 32 has a high-quality appearance. It should be noted that the appearance of a decorative anodized aluminum alloy refers to the oxide film formed after anodizing the aluminum alloy without becoming dull or numb and being easily corroded by hand sweat, etc. This way, the decorative layer 67 not only has a good decorative effect but is also resistant to damage and has good integrity. It can prevent oxidation of the metal material inside the middle frame 32, effectively protecting the metal material inside the middle frame 32.

[0107] It should be noted that the structures of the above-mentioned electronic device and the middle frame are merely exemplary descriptions, and the embodiments of the present application do not specifically limit the corresponding structures of the electronic device and the middle frame.

[0108] The embodiment of the present application also provides a composite material, which can be used to prepare the middle frame in the above embodiment. Referring to Figure 10, the composite material includes: an outer shell 90 and a first filling body 91. The structure of the outer shell 90 can be a hollow columnar structure, for example, a hollow cylindrical structure and a hollow prismatic structure. The outer shell 90 is arranged to form a first accommodating channel 92, and the structure of the first accommodating channel 92 can also be a columnar structure, for example, a cylindrical structure and a prismatic structure. The outer shell 90 can include at least one of pure titanium, titanium alloy, stainless steel and alloy steel, that is, it can be made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel.

[0109] Alternatively, the first filler body 91 may be a columnar structure, such as a hollow cylindrical structure or a hollow prismatic structure. The first filler body 91 may be disposed within the first accommodating channel 92 and bonded to the inner wall of the first accommodating channel 92, wherein the bonding may include metallurgical bonding. Thus, the metallurgical bonding between the first filler body 91 and the outer shell 90 can be achieved, thereby enhancing the composite material's processing properties, improving the connection reliability between the first filler body 91 and the outer shell 90, and improving the overall rigidity of the composite material.

[0110] In some embodiments, the first filling body 91 may include a first aluminum-based material, or a decorative anodized aluminum alloy, or a hard aluminum alloy, that is, it may be made of a first aluminum-based material, or a decorative anodized aluminum alloy, or a hard aluminum alloy.

[0111] In some embodiments of the present application, the first aluminum-based composite material may include pure aluminum or an aluminum alloy, and at least one of the following: silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

[0112] In some embodiments of the present application, the mass percentage of silicon carbide in the first aluminum-based composite material is less than 65%.

[0113] The silicon carbide includes submicron-sized first silicon carbide particles and micron-sized first silicon carbide particles. The mass percentage of the submicron-sized first silicon carbide particles in the first aluminum-based composite material is 0-20%, and the mass percentage of the micron-sized first silicon carbide particles in the first aluminum-based composite material is 5%-40%.

[0114] In one implementation, the mass percentage of the submicron-sized first silicon carbide particles in the first aluminum-based composite material is 0-10%, and the mass percentage of the micron-sized first silicon carbide particles in the first aluminum-based composite material is 5%-25%.

[0115] Among them, the D50 in the cumulative particle size distribution of the first submicron silicon carbide particles is 0.3 microns to 1.0 microns, the D50 in the cumulative particle size distribution of the micron-sized silicon carbide particles is 3 microns to 20 microns, and the D50 in the cumulative particle size distribution of the aluminum alloy in the first aluminum-based composite material is less than or equal to 20 microns.

[0116] In other embodiments of the present application, the first submicron silicon carbide particles may comprise 0-10% by weight of the first aluminum-based composite material, and the first micron-sized silicon carbide particles may comprise 8-25% by weight of the first aluminum-based composite material. The cumulative particle size distribution of the first submicron silicon carbide particles may have a D50 of 0.5-1.0 μm, and the cumulative particle size distribution of the micron-sized silicon carbide particles may have a D50 of 3-20 μm.

[0117] Thus, the first filler can be made of a first aluminum-based composite material. By controlling the proportion of the submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles in the first aluminum-based composite material, the silicon carbide content added to the aluminum alloy can be adjusted to a more appropriate level, thereby improving the elastic modulus and bending resistance of the first aluminum-based composite material.

[0118] Furthermore, the first filler can be made of a decorative anodized aluminum alloy or a hard aluminum alloy. The decorative aluminum alloy can be used in the aluminum alloy system used in electronic device housings, including 5-series aluminum alloys, 6-series aluminum alloys, and 7-series aluminum alloys with an aluminum content greater than 88%. The hard aluminum alloy has a Vickers hardness greater than 150 HV. The decorative anodized aluminum alloy has a higher elastic modulus, while the hard aluminum alloy has a higher strength, thereby improving the elastic modulus and bending resistance of the first filler.

[0119] In some embodiments, the shell 90 and the first filling body 91 are further connected via mutually engaged protrusions and grooves.

[0120] It should be noted that the embodiments of the present application do not limit the specific locations of the protrusions and grooves. For example, the inner wall of the outer shell 90 may be provided with a protrusion, and the outer wall of the first filling body 91 may be provided with a groove. For another example, the inner wall of the outer shell 90 may be provided with a groove, and the outer wall of the first filling body 91 may be provided with a protrusion.

[0121] Based on the above, on one hand, the composite material obtained by combining the first filler and the outer shell is used to prepare the middle frame, which can improve the bending resistance, overall drop resistance and strength of the entire middle frame.

[0122] On the other hand, the first filling body and the outer shell can be connected by mutually interlocking protrusions and grooves, and the bonding method between the two can be partial metallurgical bonding and partial mechanical bonding. Of course, the first filling body and the outer shell can also be fully metallurgical bonding. In this way, the bonding force between the two can be increased, so that the composite material has higher strength. Furthermore, after the middle frame is prepared using this composite material, the connection reliability is higher, and the frame and middle plate / back cover of the middle frame are an integrated molding structure, which improves the overall rigidity of the middle frame.

[0123] At the same time, the thickness of the middle plate in the middle frame provided by this application can reach 0.15mm, which can reduce the thickness of the battery area in the middle frame where the battery is installed, and can accommodate larger capacity batteries, thereby contributing more battery capacity and improving the user experience.

[0124] It should be noted that the above-mentioned composite material includes but is not limited to being used for preparing the middle frame, and can also be used for preparing other devices in electronic devices, which is not specifically limited in this application.

[0125] In some embodiments of the present application, the elastic modulus of the first filler is greater than or equal to 85 GPa, and the elongation of the first filler is greater than 3%.

[0126] Thus, the first filler provided in the embodiments of the present application has a high elastic modulus, which can improve the overall rigidity of the composite material and the rigidity of the middle frame. Furthermore, the first filler has a high elongation, that is, a strong plastic deformation capability. This can enhance the processing versatility of the composite material and the processing versatility of the middle frame.

[0127] In some embodiments of the present application, referring to Figure 11 , the protrusion 101 may be provided on the inner wall of the first accommodating channel 92. Continuing to refer to Figure 10 , the groove 102 may be provided on the outer wall of the first filling body 91, and the protrusion 101 and the groove 102 may be interference fit.

[0128] In one implementation, the groove 102 may be provided on the inner wall of the first accommodating channel 92 , and the protrusion 101 may be provided on the outer wall of the first filling body 91 , with an interference fit between the protrusion 101 and the groove 102 .

[0129] In this way, the protrusion 101 on the inner wall of the first accommodating channel 92 can be extruded and bonded to the groove 102 on the outer wall of the first filling body 91. The bonding method between the two can be partially metallurgical and partially mechanical, which can generate a strong bonding force between the shell 90 and the first filling body 91, and the two can be tightly bonded, thereby improving the strength of the composite material.

[0130] In some embodiments of the present application, referring to FIG. 12 , the protrusion 101 includes a first surface 1011 and a second surface 1012 arranged opposite to each other, the first surface 1011 and the second surface 1012 are both arranged parallel to the center line of the first accommodating channel 92, one end of the first surface 1011 and the second surface 1012 are connected to the inner wall of the outer shell 90, and the other ends of the first surface 1011 and the second surface 1012 intersect or are parallel.

[0131] In some examples, the structure of the protrusion 101 may be an angled structure. Continuing to refer to FIG12 , the structure of the protrusion 101 may be a tooth-shaped structure, where the first surface 1011 and one end of the second surface 1012 of the protrusion 101 intersect.

[0132] In some examples, the structure of the protrusion 101 can be an arc structure or an angle structure. The protrusion 101 can also include a third surface 1013 , which intersects with the first surface 1011 and the second surface 1012 .

[0133] Illustratively, the structure of the protrusion 101 may be a prismatic structure. Referring to FIG. 13 , the third surface 1013 of the protrusion 101 intersects with one end of the first surface 1011 and the second surface 1012 to form an angle.

[0134] 14 , the first surface 1011 of the protrusion 101 is parallel to one end of the second surface 1012 , and the third surface 1013 forms an angle with the first surface 1011 and the second surface 1012 .

[0135] 15 , the first surface 1011 of the protrusion 101 is parallel to one end of the second surface 1012 , and the third surface 1013 is an arc surface and forms an angle with the first surface 1011 and the second surface 1012 .

[0136] The protrusion 101 may be in the shape of teeth, columns or other irregular shapes. The groove 102 may be a complementary structure corresponding to the protrusion 101, which will not be described in detail here. It should be noted that the embodiment of the present application does not specifically limit the implementation form of the protrusion 101 and the groove 102.

[0137] In this way, the embodiment of the present application can increase the contact area between the shell 90 and the first filling body 91 by setting the protrusion 101 and including the first surface 1011 and the second surface 1012 in the protrusion 101, so that a greater bonding force is generated between the shell 90 and the first filling body 91, thereby improving the strength of the composite material.

[0138] In some embodiments of the present application, there are multiple protrusions 101 and grooves 102 , and each protrusion 101 is engaged with one groove 102 .

[0139] There can be multiple protrusions 101, which are arranged on the inner wall of the housing 90, and each protrusion 101 is engaged with a groove 102. In addition, the multiple protrusions 101 can have the same structure or different structures. The multiple grooves 102 can have the same structure or different structures.

[0140] Thus, by providing a plurality of protrusions 101 and grooves 102, each protrusion 101 including a first surface 1011 and a second surface 1012, the contact area between the outer shell 90 and the first filling body 91 can be increased. At the same time, each protrusion 101 is engaged with a groove 102, which can generate a greater bonding force between the outer shell 90 and the first filling body 91, thereby improving the strength of the composite material.

[0141] In some embodiments of the present application, the plurality of protrusions 101 may be uniformly arranged on the inner wall of the housing 90. For example, the plurality of protrusions 101 may be uniformly arranged along the centerline of the first accommodating channel 92 and / or uniformly arranged along a direction perpendicular to the centerline of the first accommodating channel 92.

[0142] In this way, by evenly arranging multiple protrusions 101 on the inner wall of the shell 90, the structure of the entire shell 90 can be made more stable, thereby ensuring a greater bonding force after being subsequently engaged with the multiple grooves 102, and making the composite material have higher strength.

[0143] In some embodiments of the present application, referring to FIG16 , the composite material further includes a second filling body 93. A second accommodating channel 94 is provided in the first filling body 91. The centerline of the second accommodating channel 94 is parallel to the centerline of the first accommodating channel 92. The second accommodating channel 94 can have a columnar structure, such as a cylindrical structure or a prismatic structure.

[0144] In addition, the second filling body 93 may also be a columnar structure, such as a hollow cylindrical structure or a hollow prism structure. The second filling body 93 may be disposed in the second accommodating channel 94 and combined with the first filling body 91, wherein the combination includes metallurgical bonding.

[0145] In some embodiments of the present application, the second filler 93 may include a second aluminum-based material, i.e., be made of a second aluminum-based material. The second aluminum-based composite material includes pure aluminum or an aluminum alloy, and at least one of the following: silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite, and diamond.

[0146] In some embodiments of the present application, the mass percentage of silicon carbide in the second aluminum-based composite material is less than 65%.

[0147] The silicon carbide includes submicron-sized second silicon carbide particles and micron-sized second silicon carbide particles. The submicron-sized second silicon carbide particles account for 0-10% by mass of the second aluminum-based composite material, and the micron-sized second silicon carbide particles account for 15%-50% by mass of the second aluminum-based composite material.

[0148] Among them, D50 in the cumulative particle size distribution of the second submicron silicon carbide particles is 0.5 microns to 1.0 microns, D50 in the cumulative particle size distribution of the second micron-sized silicon carbide particles is 3 microns to 20 microns, and D50 in the cumulative particle size distribution of the aluminum alloy in the second aluminum-based composite material is less than or equal to 20 microns.

[0149] Thus, the second filler can be made of a second aluminum-based composite material. By controlling the content of the submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles in the second aluminum-based composite material, the silicon carbide content added to the aluminum alloy can be more optimal, thereby improving the elastic modulus and bending resistance of the second aluminum-based composite material.

[0150] Based on the above, on the one hand, after the composite material including the first filler, the second filler and the shell is used to prepare the middle frame, the bending resistance, overall drop resistance and strength of the entire middle frame can be improved.

[0151] On the other hand, after being bonded, the first and second filler bodies can be connected to the outer shell through interlocking protrusions and grooves. The bonding between the two is partially metallurgical and partially mechanical. Of course, the bonding between the two can also be entirely metallurgical. In this way, the bonding force between the two can be increased, so that the composite material has higher strength. Furthermore, after using this composite material to prepare the middle frame, the connection reliability is higher.

[0152] In some embodiments of the present application, the elastic modulus of the second filler is greater than or equal to 110 GPa, and the elongation of the second filler is greater than 0.2%. The second filler has a higher elastic modulus, and the elastic modulus of the second filler is higher than the elastic modulus of the first filler. The composite material made by adopting the first filler and the second filler also has a higher elastic modulus, which can improve the rigidity of the composite material as a whole. At the same time, the second filler has a higher elongation. In this way, the composite material made by adopting the first filler and the second filler has a stronger plastic deformation ability and a higher processing diversity.

[0153] In some embodiments of the present application, the decorative anodized aluminum alloy includes 6013 aluminum alloy, 3003 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy and 7003 aluminum alloy, wherein the aluminum content in the decorative anodized aluminum alloy is greater than 90%.

[0154] In some embodiments of the present application, the aluminum alloys in the first aluminum-based composite material and the second aluminum-based composite material include 7055 aluminum alloy, 2024 aluminum alloy, 7034 aluminum alloy, 5052 aluminum alloy, and 5083 aluminum alloy.

[0155] The first aluminum-based composite material and the second aluminum-based composite material may include fiber-doped particles, wherein the fiber-doped particles include carbon fiber-doped particles. The fiber-doped particles may have a diameter of less than 200 nm.

[0156] The present application also provides a method for preparing a composite material, which is used to prepare the composite material in the above embodiment. Referring to FIG. 17 , the method includes:

[0157] S1701. Prepare a shell, which is configured to form a first accommodating channel.

[0158] In some embodiments of the present application, referring to FIG. 18 , during the process of preparing the housing, a first rod 1801 may be provided, and a first accommodating channel may be formed in the first rod 1801, with the centerline of the first accommodating channel being parallel to the centerline of the first rod 1801. Furthermore, a protrusion 1803 may be formed on the inner wall of the first accommodating channel, extending in a direction parallel to the centerline of the first rod.

[0159] In some embodiments, the shell can be made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel. Specifically, at least one of pure titanium, titanium alloy, stainless steel and alloy steel can be extruded into a hollow cylindrical rod through melting. Among them, the titanium alloy can be TC4 titanium alloy, and the alloy steel can be 316L stainless steel. The cylindrical rod can be the first rod 1801, and the hollow structure in the cylindrical rod forms a first accommodating channel, and the center line of the hollow structure is parallel to the center line of the entire cylindrical rod. In addition, a protrusion can be provided on the inner wall of the hollow cylindrical rod, and the protrusion extends in a direction parallel to the center line of the entire cylindrical rod. It should be noted that the specific structure and implementation form of the protrusion are similar to the protrusion introduced in the above-mentioned composite material, and will not be repeated here.

[0160] S1702, prepare a first filling body.

[0161] In some embodiments of the present application, referring to FIG. 18 , during the preparation of the first filling body, a second rod 1802 may be provided, and a groove 1804 may be formed on the outer wall of the second rod 1802 , extending in a direction parallel to the center line of the second rod 1802 .

[0162] In some embodiments, second rod 1802 can be made of the first aluminum-based composite material, or a decorative anodized aluminum alloy, or a hard aluminum alloy. Specifically, the first aluminum-based composite material, or the decorative anodized aluminum alloy, or the hard aluminum alloy can be milled or turned into a cylindrical rod with a diameter of 20 mm to 500 mm, which serves as second rod 1802. Furthermore, a groove 1804 can be provided on the outer wall of second rod 1802, extending parallel to the centerline of second rod 1802. It should be noted that the specific structure and implementation of the groove are similar to those described in the composite material above and will not be further described here.

[0163] In some embodiments of the present application, the preparation method of the first aluminum-based composite material includes:

[0164] The submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are pretreated and surface modified. Specifically, the submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are pretreated by pickling, sensitization, and activation, and surface modified by electroless copper plating or nickel plating.

[0165] Next, the treated submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are mixed to obtain a first reinforcement material. The submicron-sized first silicon carbide particles may comprise 0-20% by weight of the first aluminum-based composite material, and the micron-sized first silicon carbide particles may comprise 5-40% by weight of the first aluminum-based composite material.

[0166] In one achievable manner, the mass percentage of the submicron-sized first silicon carbide particles in the first aluminum-based composite material may be 0-10%, and the mass percentage of the micron-sized first silicon carbide particles in the first aluminum-based composite material may be 5%-25%.

[0167] In another achievable embodiment, the mass percentage of the first micron-sized silicon carbide particles in the first aluminum-based composite material may be 8% to 25%. The cumulative particle size distribution of the submicron-sized first silicon carbide particles has a D50 of 0.3 to 1.0 microns, and the cumulative particle size distribution of the micron-sized silicon carbide particles has a D50 of 3 to 20 microns.

[0168] The aluminum alloy powder and the first reinforcement powder are uniformly mixed in a ball mill to obtain a first aluminum-based composite material. The first aluminum-based composite material should be free of segregation and agglomeration.

[0169] The first aluminum-based composite material is cold pressed in a hydraulic press to form a first cold-pressed blank, wherein the aluminum alloy has a cumulative particle size distribution of D50 less than or equal to 20 microns, a cold pressing pressure of 3 MPa to 15 MPa, and a holding time of 5 to 45 minutes.

[0170] The first cold-pressed blank is then placed in a hot-pressing mold, using 0.3-1mm thick graphite paper as a lubricant to facilitate demolding. Hot-pressing and sintering are then performed in a hot-pressing furnace using a metal wire, such as molybdenum wire, as a resistance heating wire to produce the first filled body. The temperature is 580-620°C, the pressure is 5-30 MPa, and the holding time is 10-60 minutes.

[0171] S1703. Install the first filling body in the first accommodating channel, and combine the first filling body with the inner wall of the first accommodating channel, wherein the combination includes metallurgical bonding.

[0172] In some embodiments of the present application, during the process of installing the first filling body in the first accommodating channel, the outer shell and the first filling body can be squeezed, and the outer shell and the first filling body are connected by mutually embedded protrusions and grooves, so that the outer shell and the first filling body have an interference fit.

[0173] Specifically, during the process of extruding the shell and the first filling body, the shell and the first filling body may be subjected to isostatic pressing. For example, the shell and the first filling body may be extruded according to a predetermined extrusion ratio and heated during the extrusion.

[0174] In some embodiments of the present application, during the process of installing the first filling body in the first accommodating channel, the second rod 1802 can be inserted into the first accommodating channel in a direction parallel to the center line of the first rod 1801, and the protrusion 1803 can be embedded in the groove 1804.

[0175] In some embodiments, the second rod 1802 may be placed inside the first rod 1801 , so that the first rod 1801 and the second rod 1802 form an interference fit.

[0176] Specifically, the first rod and the second rod can be placed together and bonded by cold isostatic pressing or hot isostatic pressing to bond the first rod to the second rod. For example, a press-formed titanium alloy and a press-formed first aluminum-based composite material can be cold isostatically pressed to bond the first rod to the second rod. For another example, a press-formed titanium alloy and a press-formed decorative anodized aluminum alloy can be hot isostatically pressed to bond the first rod to the second rod.

[0177] In some embodiments, the first filler and the outer shell can be placed in an extruder and extruded at a predetermined ratio to form a composite material that is partially metallurgically bonded and partially mechanically bonded. The predetermined extrusion ratio is 5:20. It should be noted that the outer shell and the first filler can be extruded by hot extrusion, or other extrusion methods are also possible, and are not specifically limited herein.

[0178] In some embodiments of the present application, the extruded shell and the first filler can also be prepared into a cuboid structure, and subjected to solution treatment and aging treatment to obtain a composite material with a cuboid structure. Specifically, the extruded shell and the first filler are prepared into a cuboid structure, solution treated at 450°C-480°C for 1h-4h, then quenched with cold water, and then the quenched material is artificially aged at 120°C-150°C for 2h-18h. The corresponding length of the cuboid structure is 170mm-200mm, and the width is 60mm-85mm.

[0179] Based on the above, the composite material obtained by using at least one of pure titanium, titanium alloy, stainless steel, and alloy steel together with the first aluminum-based composite material can also have a high elastic modulus. In addition, at least one of pure titanium, titanium alloy, stainless steel, and alloy steel can be combined with the first aluminum-based composite material through mutually interlocking protrusions and grooves. The materials are combined in a partial metallurgical bond and a partial mechanical bond. The bonding force between the two is relatively large, resulting in a high strength of the composite material. Furthermore, after the composite material is used to make the middle frame, the overall rigidity and connection reliability of the middle frame are improved.

[0180] In some embodiments of the present application, in S1701, the process of preparing the first filling body further includes forming a second accommodating channel on the first filling body, wherein the centerline of the second accommodating channel is parallel to the centerline of the first accommodating channel. Specifically, during the process of forming the second rod body, a hollow cylindrical structure may be provided in the second rod body, i.e., the hollow structure forms the second accommodating channel. The centerline of the second accommodating channel is parallel to the centerline of the first accommodating channel.

[0181] In addition, before extruding the shell and the first filling body, the method further includes: preparing a second filling body, installing the second filling body in the second accommodating channel, and combining the second filling body with the second accommodating channel, wherein the combination includes metallurgical bonding.

[0182] In some embodiments, referring to FIG18 , a third rod 1805 may be provided. The third rod 1805 is made of the second aluminum-based composite material. Specifically, the second aluminum-based composite material may be milled or turned into a cylindrical rod. The cylindrical rod serves as the third rod 1805 .

[0183] Simultaneously, while the second filler body is being installed within the second receiving channel, the third rod 1805 can be placed within the hollow cylindrical structure of the second rod 1802 and bonded to the second receiving channel. This bonding includes metallurgical bonding, such that the third rod 1805 forms an interference fit with the second rod 1802. Specifically, the third rod 1805 and the second rod 1802 can be placed in an extruder and extruded at a predetermined ratio to form a composite material. The predetermined extrusion ratio is 5:20.

[0184] In some embodiments of the present application, the preparation method of the second aluminum-based composite material includes:

[0185] The submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles are pretreated and surface modified. Specifically, the submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles are pretreated by pickling, sensitization, and activation, and surface modified by electroless copper plating or nickel plating.

[0186] Next, the treated submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles are mixed to obtain a second reinforcement material, wherein the submicron-sized second silicon carbide particles account for 0-10% by weight of the second aluminum-based composite material, and the micron-sized second silicon carbide particles account for 15-50% by weight of the second aluminum-based composite material.

[0187] The aluminum alloy powder and the second reinforcement powder are uniformly mixed in a ball mill to obtain a second aluminum-based composite material. The second aluminum-based composite material should be free of segregation and agglomeration.

[0188] In some embodiments of the present application, the second aluminum-based composite material is cold-pressed in a hydraulic press to form a second cold-pressed blank, wherein the cold-pressing pressure is 3 MPa-15 MPa and the holding time is 5 min-45 min.

[0189] The second cold-pressed blank is then placed in a hot-pressing mold, using 0.3-1mm thick graphite paper as a lubricant to facilitate demolding. Hot-pressing and sintering are then performed in a hot-pressing furnace using a metal wire, such as molybdenum wire, as a resistance heating element to produce the second filled body. The temperature is 580-620°C, the pressure is 5-30 MPa, and the holding time is 10-60 minutes.

[0190] In this way, the elastic modulus of the titanium alloy, alloy steel, first aluminum-based composite material, and second aluminum-based composite material is relatively high, and the resulting composite material can also have a relatively high elastic modulus. In addition, the first aluminum-based composite material bonded to the second aluminum-based composite material can be combined with at least one of pure titanium, titanium alloy, stainless steel, and alloy steel through mutually interlocking protrusions and grooves. The material bonding method is partial metallurgical bonding and partial mechanical bonding. The bonding force between the two is relatively large, which makes the composite material have higher strength. Furthermore, after the composite material is used to prepare the middle frame, the overall rigidity and connection reliability of the middle frame are improved.

[0191] The present application also provides a method for preparing a middle frame, wherein the middle frame is made from the composite material described above. The frame includes an outer shell, and the middle plate includes a first filler. The method for preparing the middle frame may include: cutting the composite material along a square perpendicular to the centerline of the first accommodating channel to form a plate. Next, cutting the plate so that the outer shell forms the frame of the middle frame, and the first filler forms the middle plate of the middle frame.

[0192] In some embodiments of the present application, the height of the middle plate is 0.15 mm.

[0193] For example, the rectangular composite material obtained above can be cut into blanks with a height of 7 mm to 15 mm to form a plate body. This plate body is then processed using a computer numerical control (CNC) machine tool to form a middle frame. The frame portion of the middle frame includes the outer shell, and the middle plate portion includes the first filler.

[0194] In an embodiment of the present application, the frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and the middle plate portion is made of a first aluminum-based composite material, or a decorative anodized aluminum alloy, or a hard aluminum alloy. On the one hand, the first aluminum-based composite material, the decorative anodized aluminum alloy or the hard aluminum alloy has a high elastic modulus and a high hardness, which improves the bending resistance and overall fall resistance of the entire middle plate, thereby improving the strength of the entire middle frame. On the other hand, the corresponding thickness of the middle plate can be 0.15mm, and the battery area where the battery is set in the middle frame is thinned, so that larger capacity batteries can be placed, thereby contributing more battery capacity. On the other hand, the frame and the middle plate in the middle frame are integrally formed, and the connection reliability is high, which improves the overall rigidity of the middle frame.

[0195] In some embodiments of the present application, the elastic modulus of the second filler is greater than that of the first filler. Continuing with Figure 6 , the battery area 361 of the midplane can be made of the second filler, while the non-battery area 362 is made of the first filler. This can significantly improve the midplane's battery area's resistance to bending and overall drop deformation, thereby enhancing the reliability of battery protection.

[0196] The present application also provides a method for preparing a middle frame, wherein the middle frame is made from the composite material described above. The middle frame includes a frame and a back cover, wherein the frame is connected to the back cover, and the back cover is configured to be positioned on the back of the mobile phone. The frame includes an outer shell, and the back cover includes a first filler. A decorative layer is provided on at least a portion of the outer surface of the back cover, and the decorative layer is made of a decorative anodized aluminum alloy.

[0197] The specific method for preparing the middle frame may include: cutting the composite material along a square perpendicular to the centerline of the first accommodating channel to form a plate body. Next, cutting the plate body so that the outer shell forms the frame of the middle frame, and the first filler forms the back cover of the middle frame. During the process of forming the back cover, at least a portion of the outer surface of the back cover may be anodized to form a decorative layer. The decorative layer comprises a decorative anodized aluminum alloy.

[0198] In some embodiments of the present application, the height of the back cover is 0.6 mm.

[0199] For example, the rectangular composite material obtained above can be cut into blanks with a height of 7mm-15mm to form a plate body. This plate body is then CNC machined to form a middle frame. The frame portion of the middle frame includes the outer shell, and the back cover portion includes the first filler.

[0200] In an embodiment of the present application, the frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and the back cover portion is made of a first aluminum-based composite material, or a decorative anodized aluminum alloy, or a hard aluminum alloy. On the one hand, the first aluminum-based composite material, the decorative anodized aluminum alloy or the hard aluminum alloy has a high elastic modulus and a high hardness, which improves the bending resistance and overall drop resistance of the entire middle plate, thereby improving the strength of the entire middle frame. On the other hand, the corresponding thickness of the back cover can be 0.6mm, and the battery area where the battery is set in the middle frame is thinned, so that larger capacity batteries can be placed, thereby contributing more battery capacity. On the other hand, the frame and the back cover in the middle frame are integrally formed, and the connection reliability is high, which improves the overall rigidity of the middle frame.

[0201] In some embodiments of the present application, referring to FIG8 , the battery area 361 in the back cover includes a second filler, and the non-battery area 362 includes a first filler. By using the second filler to form the battery area in the back cover, the bending resistance and overall drop resistance of the battery area can be significantly improved. This can improve the reliability of battery protection. At the same time, at least part of the outer surface of the back cover is provided with a decorative layer made of a decorative anodized aluminum alloy to enhance the appearance of the middle frame. In turn, this improves the user experience.

[0202] The composite material and a middle frame prepared based on the composite material are introduced below through specific examples. The composite material prepared in the examples is used to prepare a middle frame, and the performance of the middle frame is tested.

[0203] In some embodiments of the present application, the steps of preparing the first filling body and the second filling body are as follows:

[0204] The submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are pretreated and surface-modified. The treated submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are then mixed to produce a first reinforcement material. The submicron-sized first silicon carbide particles may comprise 2% by weight of the first aluminum-based composite material, and the micron-sized first silicon carbide particles may comprise 18% by weight of the first aluminum-based composite material.

[0205] The 7055 aluminum alloy powder and the first reinforcement powder are uniformly mixed in a ball mill to obtain a first aluminum-based composite material.

[0206] The submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles are pretreated and surface-modified. The treated submicron-sized second silicon carbide particles and the micron-sized second silicon carbide particles are then mixed to produce a second reinforcement material. The submicron-sized second silicon carbide particles comprise 5% by weight of the second aluminum-based composite material, while the micron-sized second silicon carbide particles comprise 40% by weight of the second aluminum-based composite material.

[0207] The 7055 aluminum alloy powder and the second reinforcement powder are uniformly mixed in a ball mill to obtain a second aluminum-based composite material.

[0208] The first aluminum-based composite material and the second aluminum-based composite material are respectively cold-pressed in a hydraulic press to form a cold-pressed green body, wherein the cold-pressing pressure is 10 MPa and the holding time is 30 minutes.

[0209] The two cold-pressed blanks are then placed in hot-pressing molds, lubricated with 0.6mm thick graphite paper to facilitate demolding. Hot-pressing and sintering are then performed in a hot-pressing furnace using a metal wire, such as molybdenum wire, as a resistance heating element to produce the first and second filling bodies. The temperature is 590°C, the pressure is 25 MPa, and the holding time is 40 minutes.

[0210] The steps for preparing the composite material are as follows:

[0211] A hollow cylindrical structure is provided in the first filling body, and the first filling body is surrounded to form a second accommodating channel.

[0212] A second filler body is installed in the second receiving channel. The second filler body has a diameter of 300 mm. Specifically, the second filler body is placed inside the first filler body and then placed in an extruder. The first and second filler bodies are combined according to a predetermined extrusion ratio. The combined first and second filler bodies have a diameter of 350 mm.

[0213] The outer shell is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and is configured to enclose a first accommodating channel.

[0214] The first filling body and the second filling body are installed in the first accommodating channel, and the shell and the first filling body are connected through mutually embedded protrusions and grooves.

[0215] The outer shell and the first filler are extruded according to a predetermined extrusion ratio to obtain a composite material having a rectangular parallelepiped structure, wherein the composite material has a length of 175 mm and a width of 74 mm.

[0216] The composite material of the rectangular structure was solution treated at 450°C for 2 hours and then quenched with cold water. The quenched material was then artificially aged at 140°C for 16 hours to obtain a composite material for preparing the middle frame.

[0217] The steps for preparing the middle frame are as follows:

[0218] The composite material obtained above is cut into 10mm-high blanks to form a plate body. This plate body is then CNC machined to form a middle frame. The frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel, and alloy steel, while the middle plate portion is made of the first aluminum-based composite material.

[0219] The middle plate portion may include a battery area and a non-battery area. The battery area is made of the second aluminum-based composite material, and the non-battery area is made of the first aluminum-based composite material.

[0220] Alternatively, the frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and the back cover portion is made of the first aluminum-based composite material.

[0221] The back cover may include a battery area and a non-battery area. The battery area is made of the second aluminum-based composite material, and the non-battery area is made of the first aluminum-based composite material.

[0222] As mentioned above, the elastic modulus of the first aluminum-based composite material is 101 GPa, and the elongation is 6.1%. The elastic modulus of the second aluminum-based composite material is 145 GPa, and the elongation is 1.7%.

[0223] In some other embodiments of the present application, the steps of preparing the first filling body are as follows:

[0224] The submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are pretreated and surface-modified. The treated submicron-sized first silicon carbide particles and the micron-sized first silicon carbide particles are then mixed to produce a first reinforcement material. The submicron-sized first silicon carbide particles may comprise 5% by weight of the first aluminum-based composite material, and the micron-sized first silicon carbide particles may comprise 21% by weight of the first aluminum-based composite material.

[0225] The 7034 aluminum alloy powder and the first reinforcement powder are uniformly mixed in a ball mill to obtain a first aluminum-based composite material.

[0226] The first aluminum-based composite material is cold-pressed in a hydraulic press to form a cold-pressed embryonic body, wherein the cold-pressing pressure is 9 MPa and the holding time is 40 minutes.

[0227] The cold-pressed green body is then placed in a hot-pressing mold, lubricated with 0.5 mm thick graphite paper to facilitate demolding. Hot-pressing and sintering are then performed in a hot-pressing furnace using a metal wire, such as molybdenum wire, as a resistance heating element to produce the first filling body. The temperature is 580°C, the pressure is 30 MPa, and the holding time is 60 minutes.

[0228] The steps for preparing the composite material are as follows:

[0229] The outer shell is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and is configured to enclose a first accommodating channel.

[0230] The first filling body (with a diameter of 400 mm) is installed in the first accommodating channel, and the outer shell and the first filling body are connected through mutually embedded protrusions and grooves.

[0231] The outer shell and the first filler are extruded according to a predetermined extrusion ratio to obtain a composite material having a rectangular parallelepiped structure, wherein the composite material has a length of 190 mm and a width of 80 mm.

[0232] The composite material of the rectangular structure was solution treated at 450°C for 4 hours and then quenched with cold water. The quenched material was then artificially aged at 150°C for 15 hours to obtain a composite material for preparing the middle frame.

[0233] The steps for preparing the middle frame are as follows:

[0234] The composite material obtained above is cut into 10mm-high blanks to form a plate body. This plate body is then CNC machined to form a middle frame. The frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel, and alloy steel, while the middle plate portion is made of the first aluminum-based composite material.

[0235] Alternatively, the frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and the back cover portion is made of the first aluminum-based composite material.

[0236] As mentioned above, the elastic modulus of the first aluminum-based composite material is 102 GPa, and the elongation is 5.5%.

[0237] In some embodiments of the present application, the steps of preparing the composite material are as follows:

[0238] The first filling body is prepared using a decorative anodized aluminum alloy.

[0239] The outer shell is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and is configured to enclose the first accommodating channel. The titanium alloy may be TC4 titanium alloy, the alloy steel may be 316L alloy steel, and the decorative anodized aluminum alloy may be 6013 anodized aluminum alloy.

[0240] The first filling body is installed in the first accommodating channel, and the outer shell and the first filling body are connected through mutually embedded protrusions and grooves.

[0241] The outer shell and the first filling body are extruded according to a predetermined extrusion ratio to obtain a composite material with a rectangular parallelepiped structure.

[0242] The steps for preparing the middle frame are as follows:

[0243] The composite material obtained above is cut into 10mm-high blanks to form panels. These panels are then CNC-machined to form the middle frame. The frame is made of at least one of pure titanium, titanium alloy, stainless steel, and alloy steel, while the middle panel is made of a decorative anodized aluminum alloy.

[0244] Alternatively, the frame portion of the middle frame is made of at least one of pure titanium, titanium alloy, stainless steel and alloy steel, and the back cover portion is made of decorative anodized aluminum alloy.

[0245] It should be noted that the outer surface of at least part of the back cover in the above-mentioned middle frame may be provided with a decorative layer made of decorative anodized aluminum alloy, which will not be described in detail here.

[0246] Based on the above embodiments, the elastic modulus of the first aluminum-based composite material provided by the present application is greater than or equal to 85GPa, and the elastic modulus of the second aluminum-based composite material is greater than or equal to 110GPa. On the one hand, the high-modulus first aluminum-based composite material, or the first aluminum-based composite material and the second aluminum-based composite material can be applied to the entire middle plate or back cover to improve the elastic modulus of the entire middle frame, thereby improving the thermal conductivity and rigidity of the entire middle frame. On the other hand, the battery area in the present application can adopt a high-modulus second aluminum-based composite material to improve the reliability of protecting the battery. In addition, the thickness of the middle plate or back cover can be reduced to 0.15mm, which can increase a certain amount of battery capacity. On the other hand, the middle plate or back cover is connected to the frame through mutually interlocking protrusions and grooves, which saves costs while having a high connection reliability. At the same time, some areas of the back cover can also be provided with a decorative layer, which is more ornamental. In addition, the user experience is enhanced.

[0247] An embodiment of the present application provides a middle frame, which is made of the above-mentioned composite material. The middle frame includes a frame and a middle plate. The middle plate is connected to the frame and is configured to be set inside the electronic device; the frame includes a shell, and the middle plate includes a first filling body.

[0248] Specifically, the middle plate includes a battery area and a non-battery area. The battery area includes the second filling body, and the non-battery area includes the first filling body.

[0249] An embodiment of the present application provides a middle frame, which is made of the composite material described above. The middle frame includes a frame and a back cover. The frame is connected to the back cover, and the back cover is configured to be located on the back of the electronic device; the frame includes a shell, and the back cover includes a first filling body.

[0250] Specifically, the back cover includes a battery area and a non-battery area, the battery area includes a second filler, and the non-battery area includes a first filler. At least a portion of the outer surface of the back cover is provided with a decorative layer made of a decorative anodized aluminum alloy.

[0251] An embodiment of the present application provides an electronic device, which includes a display screen, a battery, and the middle frame as described above, wherein the display screen and the battery are arranged on the middle frame.

[0252] The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present application.

[0253] In some embodiments, multiple embodiments of the present application may be combined and the combined embodiments may be implemented. Optionally, some operations in the processes of the various method embodiments may be optionally combined, and / or the order of some operations may be optionally changed. Furthermore, the execution order between the steps of each process is merely exemplary and does not constitute a limitation on the execution order between the steps. Other execution orders may also be used between the steps. This is not intended to indicate that the execution order is the only order in which these operations may be performed.

[0254] Those skilled in the art will appreciate various ways to reorder the operations described in the embodiments of the present application. In addition, it should be noted that the process details involved in a certain embodiment of the present application are also applicable to other embodiments in a similar manner, or different embodiments can be used in combination.

[0255] Furthermore, some steps in the method embodiments may be equivalently replaced with other possible steps. Alternatively, some steps in the method embodiments may be optional and may be deleted in certain usage scenarios. Alternatively, other possible steps may be added to the method embodiments.

[0256] Furthermore, the various method embodiments may be implemented separately or in combination.

[0257] The above content is only a specific embodiment of this application, but the scope of protection of this application is not limited to this. Any changes or replacements within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A composite material, characterized in that: include: A shell, wherein the shell is configured to enclose a first accommodating passage; a first filling body; The first filling body is disposed in the first accommodating channel, and the first filling body is combined with the inner wall of the first accommodating channel, and the combination includes metallurgical bonding.

2. The composite material according to claim 1, characterized in that The shell and the first filling body are also connected via mutually engaging protrusions and grooves.

3. The composite material according to claim 2, characterized in that The protrusion is arranged on the inner wall of the first accommodating channel, and the groove is arranged on the outer wall of the first filling body; the protrusion and the groove are interference fit.

4. The composite material according to claim 3, characterized in that The protrusion includes a first surface and a second surface arranged opposite to each other, the first surface and the second surface are both arranged parallel to the center line of the first accommodating channel, one end of the first surface and the second surface are connected to the inner wall of the shell, and the other end of the first surface and the second surface intersect or are parallel.

5. The composite material according to any one of claims 2 to 4, characterized in that: There are multiple protrusions and multiple grooves, and each protrusion is engaged with one groove.

6. The composite material according to any one of claims 1 to 5, characterized in that: The shell includes at least one of pure titanium, titanium alloy, stainless steel and alloy steel.

7. The composite material according to any one of claims 1 to 6, characterized in that: The first filling body includes a hard aluminum alloy, and the Vickers hardness of the hard aluminum alloy is greater than or equal to 120 HV.

8. The composite material according to any one of claims 1 to 6, characterized in that: The first filler body comprises a decoratively anodized aluminum alloy.

9. The composite material according to any one of claims 1 to 6, characterized in that: The first filler body includes a first aluminum-based composite material, which includes pure aluminum or an aluminum alloy, and at least one of the following: silicon carbide, aluminum oxide, boron carbide, titanium diboride, graphene, carbon nanotubes, graphite and diamond.

10. The composite material according to claim 9, characterized in that The mass percentage of silicon carbide in the first aluminum-based composite material is less than 65%.

11. The composite material according to claim 10, characterized in that The silicon carbide in the first aluminum-based composite material includes submicron-sized first silicon carbide particles and micron-sized first silicon carbide particles; The mass percentage of the submicron-sized first silicon carbide particles in the first aluminum-based composite material is 0-20%, and the mass percentage of the micron-sized first silicon carbide particles in the first aluminum-based composite material is 5%-40%.

12. The composite material according to claim 11, characterized in that The D50 in the cumulative particle size distribution of the submicron first silicon carbide particles is 0.3 microns to 1.0 microns, the D50 in the cumulative particle size distribution of the micron silicon carbide particles is 3 microns to 20 microns, and the D50 in the cumulative particle size distribution of the aluminum alloy is less than or equal to 20 microns.

13. The composite material according to any one of claims 1 to 12, characterized in that: The composite material also includes a second filling body, a second containing channel is arranged in the first filling body, and the center line of the second containing channel is parallel to the center line of the first containing channel; the second filling body is arranged in the second containing channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding.

14. The composite material according to claim 13, characterized in that The second filler body includes a second aluminum-based composite material, and the mass percentage of silicon carbide in the second aluminum-based composite material is less than 65%.

15. The composite material according to claim 14, characterized in that The silicon carbide in the second aluminum-based composite material includes submicron-sized second silicon carbide particles and micron-sized second silicon carbide particles; The mass percentage of the submicron-sized second silicon carbide particles in the second aluminum-based composite material is 0-10%, and the mass percentage of the micron-sized second silicon carbide particles in the second aluminum-based composite material is 15%-50%.

16. The composite material according to claim 15, characterized in that The D50 of the cumulative particle size distribution of the submicron-sized second silicon carbide particles is 0.5 micrometers to 1.0 micrometers, and the D50 of the cumulative particle size distribution of the micron-sized second silicon carbide particles is 3 micrometers to 20 micrometers.

17. The composite material according to any one of claims 13 to 16, characterized in that: The elastic modulus of the first filling body is greater than or equal to 85 GPa, and the elastic modulus of the second filling body is greater than or equal to 110 GPa.

18. The composite material according to any one of claims 13 to 17, characterized in that: The elongation of the first filling body is greater than 3%, and the elongation of the second filling body is greater than 0.2%.

19. A method for preparing a composite material, characterized in that: The method comprises: Prepare a shell, wherein the shell is configured to enclose a first accommodating channel; preparing a first filling body; The first filling body is installed in the first containing channel, and the first filling body is combined with the inner wall of the first containing channel, and the combination includes metallurgical bonding.

20. The preparation method according to claim 19, characterized in that: The step of installing the first filling body in the first accommodating channel comprises: The outer shell and the first filling body are extruded, and the outer shell and the first filling body are connected via mutually engaging protrusions and grooves, so that the outer shell and the first filling body are interference-fitted.

21. The preparation method according to claim 20, characterized in that: The extruding of the outer shell and the first filling body comprises: The shell and the first filling body are subjected to isostatic pressing.

22. The preparation method according to claim 21, characterized in that: The isostatic pressing of the shell and the first filling body comprises: The extrusion is performed at a predetermined extrusion ratio, and the outer shell and the first filling body are heated while being extruded.

23. The preparation method according to any one of claims 19 to 22, characterized in that: The preparation of the shell comprises: Providing a first rod body, forming a first accommodating channel in the first rod body, wherein a center line of the first accommodating channel is parallel to a center line of the first rod body; A protrusion is formed on the inner wall of the first accommodating channel, and the protrusion extends in a direction parallel to the center line of the first rod body.

24. The preparation method according to any one of claims 19 to 23, characterized in that: The preparation of the first filling body comprises: Providing a second rod body, forming a groove on an outer wall of the second rod body, the groove extending in a direction parallel to a center line of the second rod body; The step of installing the first filling body in the first accommodating channel further includes: inserting the second rod into the first accommodating channel along a direction parallel to the center line of the first rod, and embedding the protrusion into the groove.

25. The preparation method according to any one of claims 19 to 24, characterized in that: The preparing the first filling body further comprises: A second accommodating channel is formed on the first filling body, wherein a center line of the second accommodating channel is parallel to a center line of the first accommodating channel; The method further comprises: A second filling body is prepared, the second filling body is installed in the second receiving channel, and the second filling body is combined with the second receiving channel, wherein the combination includes metallurgical bonding.

26. A middle frame, said middle frame being made of the composite material according to any one of claims 1 to 18, characterized in that: The middle frame includes a frame and a middle plate, the middle plate is connected to the frame, and the middle plate is configured to be arranged inside the electronic device; the frame includes the housing, and the middle plate includes the first filling body.

27. The middle frame according to claim 26, characterized in that: The composite material further includes a second filling body, a second containing channel is provided in the first filling body, and a center line of the second containing channel is parallel to a center line of the first containing channel; the second filling body is provided in the second containing channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding; The middle plate includes a battery area and a non-battery area, the battery area includes the second filler, and the non-battery area includes the first filler.

28. A middle frame, said middle frame being made of the composite material according to any one of claims 1 to 18, characterized in that: The middle frame includes a frame and a back cover, the frame is connected to the back cover, and the back cover is configured to be located on the back of the electronic device; the frame includes the shell, and the back cover includes a first filling body.

29. The middle frame according to claim 28, characterized in that: The composite material further includes a second filling body, the first filling body is provided with a second containing channel, and the center line of the second containing channel is parallel to the center line of the first containing channel; the second filling body is provided in the second containing channel, and the second filling body is combined with the first filling body, and the combination includes metallurgical bonding; The back cover includes a battery area and a non-battery area, the battery area includes the second filling body, and the non-battery area includes the first filling body.

30. The middle frame according to claim 28 or 29, characterized in that: At least part of the outer surface of the rear cover is provided with a decorative layer, and the decorative layer is made of anodized aluminum alloy.

31. A method for preparing a middle frame, characterized in that: The method comprises: A composite material is prepared by the method for preparing a composite material according to any one of claims 19 to 25; Cutting the composite material along a square perpendicular to the center line of the first accommodating channel to form a plate body; The plate body is cut so that the outer shell forms a frame of the middle frame, and the first filling body forms a middle plate of the middle frame.

32. A method for preparing a middle frame, characterized in that: The method comprises: A composite material is prepared by the method for preparing a composite material according to any one of claims 19 to 25; Cutting the composite material along a square perpendicular to the center line of the first accommodating channel to form a plate body; The plate body is cut so that the outer shell forms a frame of the middle frame, and the first filling body forms a back cover of the middle frame.

33. The method according to claim 32, characterized in that The plate body is cut so that the outer shell forms a frame of the middle frame, and the first filling body forms a back cover of the middle frame, and further includes: At least a portion of the outer surface of the back cover is anodized to obtain a decorative layer.

34. An electronic device, characterized in that: The electronic device comprises a display screen, a battery and a middle frame as described in claim 26 or claim 27, or a middle frame as described in any one of claims 28 to 30, wherein the display screen and the battery are arranged on the middle frame.

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