Brass-aluminum brass composite material and its cold composite preparation method and application

Abstract

This application provides a brass-aluminum-brass composite material, its preparation method, and its application. The preparation method includes: performing solid-solid cold composite rolling on brass, aluminum, and copper to obtain a first intermediate composite material, wherein the thickness ratio of brass, aluminum, and copper is 1:(1~8):1, the solid-solid cold composite rolling is a single-pass rolling process with a single-pass reduction rate of 50%~70%; followed by diffusion annealing treatment at a temperature of 350~480℃ for 2~10 minutes; and finally, cold rolling to obtain a composite material of the target thickness. The 50%-70% reduction deformation breaks down the surface oxide film between the two metal layers; the diffusion annealing process controls the formation of an intermetallic compound layer at the junction of the two metal layers, improving the bonding strength between the metal layers. This composite material has high interlayer bonding strength, improved thermal conductivity, lower density, and good electrical conductivity compared to brass.

Description

Technical Field

[0001] This application relates to the field of metal composite material processing, and in particular to a brass-aluminum-brass composite material and its preparation method and application in cold bonding. Background Technology

[0002] As a key structural component of LED packaging, the light-emitting diode (LED) bracket must possess characteristics such as conductivity, thermal conductivity, mechanical support, and lightweight.

[0003] Traditional LED brackets are mostly made of single-metal materials such as brass (e.g., C2680). Single-metal brass has a high density (about 8.9 g / cm³), which makes the overall weight of LED bracket products large, which is not conducive to the requirement of lightweighting. In addition, single-metal brass LED brackets have poor heat dissipation performance.

[0004] Therefore, there is an urgent need for a lightweight material that can meet the requirements of LED heat dissipation, conductivity, and mechanical properties. Summary of the Invention

[0005] This application provides a brass-aluminum-brass composite material and its preparation method and application for cold bonding, in order to meet the requirements of lightweight, heat dissipation, electrical conductivity and mechanical properties of LED brackets.

[0006] In a first aspect, this application provides a method for preparing a cold composite material of brass and aluminum, the method comprising the following steps:

[0007] First brass, aluminum and second brass are subjected to solid-solid cold composite rolling to obtain a first intermediate composite material. The solid-solid cold composite rolling is a single-pass rolling, the single-pass rolling reduction rate is 50%~70%, and the thickness ratio of the first brass, the aluminum and the second brass is 1:(1~8):1.

[0008] The first intermediate composite material is subjected to diffusion annealing to obtain the second intermediate composite material. The diffusion annealing temperature is 350~480℃ and the diffusion annealing time is 2~10min.

[0009] The second intermediate composite material is cold-rolled to obtain a brass-aluminum-brass composite material of the target thickness.

[0010] Furthermore, the aluminum material is selected from one of the following: 1-series aluminum alloys, 3-series aluminum alloys, 5-series aluminum alloys, and 8-series aluminum alloys;

[0011] And / or, the mass fraction of copper in the first brass and the second brass is greater than 58%.

[0012] Furthermore, the rolling speed of the solid-cold composite rolling is 1-3 m / min.

[0013] Furthermore, the cold rolling process includes roughing and finishing rolling;

[0014] The total reduction rate of the roughing process is 50%~75%, the single-pass reduction rate is 15%~25%, the pre-rolling tension and post-rolling tension are 300~600Kg, the rolling speed is 10-40m / min, and the surface roughness Ra of the work roll is 0.4~1.2µm.

[0015] The total reduction rate of the finishing rolling process is 50%~75%, the single-pass reduction rate is 15%~25%, the pre-rolling tension and post-rolling tension are 200~400Kg, the rolling speed is controlled at 10-40m / min, and the surface roughness Ra of the work rolls is 0.2~0.8µm.

[0016] Furthermore, the preparation method further includes:

[0017] After the rough rolling process, intermediate annealing is performed at a temperature of 350~450℃ for a time of 5~12 minutes.

[0018] After the finishing rolling process, the finished product is annealed at a temperature of 350~450℃ for a time of 5~12 minutes.

[0019] Furthermore, prior to the solid-solid cold composite rolling, the surfaces of the first brass and the second brass include a pure copper layer of 200-1000 nm.

[0020] Furthermore, prior to the solid-solid cold composite rolling, the preparation method further includes:

[0021] The surfaces of the brass and the aluminum are roughened using an online roughening machine.

[0022] In a second aspect, this application provides a brass-aluminum-brass composite material, wherein the brass-aluminum-brass composite material is prepared by any of the preparation methods described in the first aspect, and the thickness ratio of the brass layer, the aluminum layer and the brass layer in the brass-aluminum-brass composite material is 1:(1~8):1.

[0023] Furthermore, an intermetallic compound layer of 200-500 nm is included between the brass layer and the aluminum layer.

[0024] Secondly, this application provides an LED bracket, which is prepared by the brass-aluminum-brass composite material described in the second aspect.

[0025] This application provides a brass-aluminum-brass composite material, its cold-bonding preparation method, and its application. The preparation method improves the interlayer bonding strength by using a 50%-70% compression deformation; it also enhances the interlayer bonding strength by controlling the diffusion annealing process to form an intermetallic compound layer of appropriate thickness at the junction of the two metal layers. The resulting brass-aluminum-brass composite material, with a brass thickness ratio of 1:(1~8):1, exhibits tensile strength, hardness, and other properties close to those of single-metal brass. The composite material demonstrates high interlayer bonding strength and no delamination. Compared to single brass, the composite material exhibits improved thermal conductivity, lower density, and good electrical conductivity. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 A flowchart illustrating a method for preparing a brass-aluminum-brass composite material provided in this application;

[0028] Figure 2 This is a cross-sectional SEM image of the brass-aluminum-brass composite material from Example 1.

[0029] Figure 3 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material of Example 1;

[0030] Figure 4 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material in Example 2;

[0031] Figure 5 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material of Example 3.

[0032] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] To reduce the cost of LED bracket materials without compromising their electrical conductivity, thermal conductivity, and mechanical properties, this application uses a brass-aluminum-brass composite material instead of a single metal. Aluminum has a much lower density than copper; using a copper-aluminum-copper composite material as a single metal reduces the weight of the LED bracket. Aluminum has better thermal conductivity than copper, making the copper-aluminum-copper composite material more beneficial for the thermal conductivity of the LED bracket material. The electrical conductivity of 5-series aluminum is slightly higher than that of brass; therefore, the electrical conductivity of the brass-aluminum-brass composite material is slightly higher than that of brass alone.

[0035] Figure 1 A flowchart of a method for preparing a brass-aluminum-brass composite material provided in this application is shown below. Figure 1 As shown, the preparation method includes the following steps:

[0036] S1. The first brass, aluminum and second brass are subjected to solid-solid cold composite rolling to obtain the first intermediate composite material. The solid-solid cold composite rolling is a single-pass rolling with a single-pass rolling reduction rate of 50%~70%. The thickness ratio of the first brass, aluminum and second brass is 1:(1~8):1.

[0037] It should be noted that in this application, the first and second are only used to distinguish the brass on both sides of the aluminum, and the two types of brass can be the same type.

[0038] S2. The first intermediate composite material is subjected to diffusion annealing to obtain the second intermediate composite material. The diffusion annealing temperature is 350~480℃ and the diffusion annealing time is 2~10min.

[0039] S3. The second intermediate composite material is cold-rolled to obtain a brass-aluminum-brass composite material of the target thickness.

[0040] In step S1, since brass and aluminum are dissimilar metals, both metals have a certain oxide layer on their surfaces, resulting in low interlayer bonding strength. Solid-solid cold composite rolling, with a single-pass reduction of 50% to 70%, can crush the oxide film on the interlayer surfaces of the two metals, exposing fresh metal at the interlayer interface and allowing them to come into close contact, thereby achieving good interfacial bonding and improving the interlayer bonding strength.

[0041] To improve the mechanical, electrical, and thermal conductivity of brass-aluminum-brass composites, the thickness ratio of the three layers (brass, aluminum, and brass) is controlled within the range of 1:(1~8):1. Examples include 1:1:1, 1:3:1, 1:5:1, 1:6:1, 1:8:1, or any combination of two of these ratios. Controlling the thickness ratio within this range allows the composite material to achieve tensile strength, hardness, and thermal conductivity close to those of brass, while also possessing excellent thermal and electrical conductivity.

[0042] After cold composite rolling in step S1, the metal interface forms a certain mechanical and physical bond, but there will still be some physical defects such as voids in the interface. If these defects are not eliminated, they will continue to crack along the defects in the subsequent rough rolling and finish rolling, resulting in failure of delamination composite.

[0043] Therefore, in step S2, a diffusion annealing process is used to treat the composite material. Diffusion annealing provides activation energy, causing dissimilar metal atoms to diffuse outward along the interface, forming layered copper-aluminum compounds between the metals, gradually eliminating physical defects at the interface. Diffusion annealing after composite formation reduces material hardness and work hardening, providing a plastic basis for further thinning and rolling.

[0044] The diffusion annealing temperature is 350–480°C. For example, 350°C, 380°C, 410°C, 450°C, 480°C, or any combination thereof. Because copper (Cu) and aluminum (Al) are face-centered cubic (FCC) metals, their atomic diffusion ability increases with increasing temperature. Below 350°C, the atomic diffusion rate is too low, making it difficult to form an effective interfacial bonding layer, potentially leading to insufficient interfacial bonding strength. Above 480°C, the atomic diffusion rate is too fast, resulting in excessive formation of intermetallic compounds (IMCs), such as brittle phases like CuAl2 and Cu9Al4, which reduce the toughness and bonding strength of the interface. Within the 350–480°C range, Cu and Al atoms diffuse moderately at the interface, forming a thin and uniform diffusion layer. This diffusion layer enhances the metallurgical bonding of the interface while avoiding a thick and brittle intermetallic compound layer, thus improving the intermetallic bonding force.

[0045] The diffusion annealing time is 2–10 minutes. For example, 2 min, 4 min, 6 min, 8 min, 10 min, or any combination of these ranges. If the diffusion time is less than 2 minutes, diffusion is insufficient, and the interfacial bonding strength may be weak, making it difficult to form a stable metallurgical bond. If the diffusion time exceeds 10 minutes, the excessive diffusion time may lead to an excessively thick intermetallic compound (IMC) layer (such as CuAl2, Cu9Al4), and these brittle phases will reduce the plasticity and fatigue properties of the interface. Therefore, annealing for 2–10 minutes can form a thin and uniform diffusion layer, enhancing the metallurgical bonding of the copper-aluminum interface, while avoiding the excessive formation of brittle phases.

[0046] Furthermore, this solution uses brass instead of pure copper. During diffusion annealing of pure copper (Cu) and aluminum (Al), the interface primarily forms binary intermetallic compounds such as CuAl2, Cu9Al4, and CuAl. Brass contains zinc; for example, H65 brass has a zinc content greater than 30%. Zinc participates in the interfacial reaction, leading to a more complex IMC layer composition. Therefore, the diffusion annealing time is controlled within the range of 4–8 minutes to control the Zn diffusion depth and IMC layer thickness, preventing Zn from forming complex phases. The process window for pure copper and aluminum composites is wider.

[0047] After step S2, the obtained second intermediate composite material is cold-rolled to reduce the thickness of the composite material and obtain the desired target thickness. The cold rolling process can be carried out by a single set of rolling passes, followed by annealing to obtain the composite material of the target thickness, or by two rolling passes: rough rolling first, intermediate annealing, and then finish rolling, followed by product annealing to obtain the composite material of the target thickness.

[0048] The above preparation method improves the bonding strength between metal layers by using a 50%-70% reduction deformation. Furthermore, controlled diffusion annealing forms an intermetallic compound layer of appropriate thickness at the junction of the two metal layers, further enhancing the bonding strength. The resulting brass-aluminum-brass composite material, with a brass-aluminum thickness ratio of 1:(1~8):1, exhibits tensile strength, hardness, and other properties close to those of single-metal brass. The composite material demonstrates high interlayer bonding strength and exhibits no delamination. Compared to single brass, the composite material shows improved thermal conductivity, lower density, and good electrical conductivity.

[0049] In some embodiments, the aluminum material is selected from one of the 1-series, 3-series, 5-series, and 8-series aluminum alloys. The 5-series aluminum alloy 5083 is representative, as its thermal and electrical conductivity are higher than that of brass C2680 (H65 / H66). Therefore, the composite material exhibits superior thermal and electrical conductivity compared to single-metal brass. Furthermore, aluminum alloys have a lower density than brass, thus the composite material offers a weight reduction effect compared to single-metal materials.

[0050] In some embodiments, the mass fraction of copper in the first brass and the second brass is greater than 58%. The first brass and the second brass may be selected from one of the brasses H58, H59, H60, H62, H62.5, H63, H65, H66, H68, H70, H80, H85, H90, H95, and H96 in GB / T 5231-2022, respectively.

[0051] In some embodiments, the rolling speed of the solid-solid cold composite rolling is 1-3 m / min. For example, 1 m / min, 2 m / min, 3 m / min, or any combination thereof. A rolling speed of 1-3 m / min can effectively control the temperature of the material, helping to prevent the metal from heating up too quickly during rolling, thereby ensuring the uniformity and adhesion of the composite layer.

[0052] In some embodiments, the cold rolling process includes roughing and finishing rolling.

[0053] The total reduction rate of roughing is 50%~75%, the single-pass reduction rate is 15%~25%, the pre-rolling tension and post-rolling tension are 300~600Kg, the rolling speed is 10-40m / min, and the surface roughness Ra of the work rolls is 0.4~1.2µm.

[0054] By applying a high reduction rate, the material's grains are stretched and reorganized, resulting in smaller grains and thus increased metal strength. Therefore, a higher reduction rate (50%–75%) helps refine the grains and improve the material's strength and hardness. In step 3, the material surface no longer has an oxide layer, so an excessively high single-pass reduction rate is unnecessary. An excessively high single-pass reduction rate can lead to significant material deformation, easily causing cracks or surface defects. Therefore, a single-pass reduction rate of 15%–25% helps achieve sufficient plastic deformation without damaging the material.

[0055] The purpose of tension is to maintain the tension balance of the material during the rolling process. The range of front tension and back tension is 300~600kg, which helps to tighten the metal strip during rolling, reduce warping or bending caused by plastic deformation of the metal, reduce uneven stretching or uneven thickness, and ensure uniform thickness of the entire sheet or strip.

[0056] Roll surface roughness (Ra) refers to the microscopic unevenness of the roll surface, which has a significant impact on the surface quality of metal strip. Maintaining a roll surface roughness of 0.4~1.2µm can make the surface of the rolled material smoother, especially in subsequent finishing rolling processes with high precision requirements.

[0057] The total reduction rate of the finishing rolling process is 50%~75%, the single-pass reduction rate is 15%~25%, the pre-rolling tension and post-rolling tension are 200~400Kg, the rolling speed is controlled at 10-40m / min, and the surface roughness Ra of the work rolls is 0.2~0.8µm.

[0058] The purpose of finish rolling is to further reduce the thickness of the material, improve surface quality and precision, and enhance the mechanical properties of the final product. Since the material surface has already undergone preliminary rough rolling, meticulous finish rolling can further eliminate residual deformation and surface defects. In this scheme, the rolling parameters for finish rolling can be the same as for rough rolling, but the surface roughness of the work rolls in finish rolling is lower, with Ra ranging from 0.2 to 0.8 µm. For example, 0.2 µm, 0.4 µm, 0.6 µm, 0.8 µm, or any combination of two of these values. Lower surface roughness reduces friction between the rolls and the metal strip, resulting in a smoother, scratch-free metal surface.

[0059] In some embodiments, the preparation method further includes:

[0060] After rough rolling, intermediate annealing is performed at a temperature of 350~450℃, for example, 350℃, 380℃, 420℃, 450℃, or any combination thereof. The intermediate annealing time is 5~12min, for example, 5 min, 8 min, 10 min, 12 min, or any combination thereof.

[0061] The purpose of intermediate annealing after rough rolling is to eliminate the work hardening and internal stress accumulated during rough rolling, so as to facilitate subsequent finish rolling.

[0062] After finishing rolling, the finished product is annealed at a temperature of 350~450℃, for example, 350℃, 380℃, 420℃, 450℃, or any combination thereof. The annealing time is 5~12 minutes, for example, 5 minutes, 8 minutes, 10 minutes, 12 minutes, or any combination thereof.

[0063] After precision rolling, the product has achieved the target dimensions and surface accuracy, but the metal will still have residual stress and a certain degree of work hardening. Therefore, finished product annealing is required to stabilize the microstructure and properties.

[0064] The zinc in the brass used in this scheme has a certain inhibitory effect on the formation of copper-aluminum compounds, and its bonding strength is not as good as that of pure copper and aluminum alloys. Therefore, in some embodiments, a layer of pure copper is attached to the surface of the brass before solid-solid cold composite rolling, and the brass surface includes a pure copper layer of 200-1000 nm. For example, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, or any combination of the above.

[0065] The pure copper layer acts as a barrier, effectively preventing direct reaction between zinc and aluminum in brass, thus avoiding the formation of complex IMC layers. The interface between pure copper and aluminum facilitates the formation of a more stable IMC layer. The pure copper layer provides stronger interfacial bonding between brass and aluminum alloys, thereby enhancing the overall mechanical properties of the composite material.

[0066] There are no restrictions on the methods used to apply a layer of pure copper to the surface of brass; electroplating, spraying, or hot-dip galvanizing are all acceptable.

[0067] In some embodiments, prior to the solid-solid cold composite rolling, the preparation method further includes:

[0068] The surfaces of brass and aluminum are roughened using an online roughening machine.

[0069] An online dry texturing machine is used to texturize each single-layer metal, mechanically removing the surface oxide layer and increasing surface roughness. Simultaneously after online texturing, a solid-solid cold composite process is performed using a single-pass 60%–70% reduction deformation on a four-high rolling mill. This effectively improves the bonding strength between metal layers, forming a strong physical bond between them.

[0070] To ensure that the shape and dimensions of the finished product meet the requirements, the composite material needs to undergo tension straightening treatment at a linear speed of 5~10m / min. After tension straightening, the plate shape is flat.

[0071] The target thickness of the prepared composite material ranges from 0.05 to 1.5 mm, with a dimensional tolerance controllable to ±0.003 mm, and the width ranges from 0.8 to 1000 mm, with a dimensional tolerance controllable to ±0.1 mm.

[0072] This application also provides a brass-aluminum-brass composite material, which is prepared by any of the above preparation methods, wherein the thickness ratio of the brass layer, the aluminum layer and the brass layer in the brass-aluminum-brass composite material is 1:(1~8):1.

[0073] Composite materials within this thickness range exhibit superior electrical and thermal conductivity and lower density while ensuring that the mechanical properties of the composite material are close to those of brass.

[0074] In some embodiments, the brass-aluminum-brass composite material includes a 200-500 nm intermetallic compound layer between the brass layer and the aluminum layer. The intermetallic compound layer is less than 500 nm to prevent brittleness at the interface between the two layers; the intermetallic compound layer is greater than 200 nm to ensure interlayer bonding and prevent interface delamination or separation. Therefore, the 200-500 nm intermetallic compound layer provides sufficient bonding strength without being too thick and increasing brittleness.

[0075] This application also provides an LED bracket, which is prepared by the above-mentioned brass-aluminum-brass composite material.

[0076] Compared to pure copper brackets, LED brackets are cheaper in terms of material cost, and their mechanical properties are close to those of brass, while exhibiting better electrical and thermal conductivity and lower density.

[0077] The present invention will be further described below through specific embodiments.

[0078] Example 1

[0079] In this embodiment 1, the materials selected are 5083 aluminum alloy and C2680 brass alloy. 5083 aluminum alloy has high thermal and electrical conductivity, and also has a certain strength, and its material cost is lower than that of brass. C2680 brass is a copper-zinc alloy, and currently, C2680 is the brass material used for LED brackets.

[0080] The thickness ratio of the raw materials for the copper-aluminum-copper composite material is C2680:5083:C2680=1:1:1. The copper alloy raw material specifications are selected as 0.6mm×180mm×Coil; the aluminum alloy raw material specifications are also 0.6mm×180mm×Coil; and the final rolled target thickness is 0.18mm×75mm×Coil.

[0081] First, the surfaces of the copper and aluminum alloy raw materials need to be brushed to ensure cleanliness. Then, the interface layer of the copper-aluminum-copper three-layer structure is dry-polished and roughened using an online roughening machine. After roughening, the copper, aluminum, and copper layers are fed into a four-roll cold composite rolling mill in a sandwich structure for composite rolling. The single-pass composite reduction rate is 65%, and the thickness of the three metal layers after rolling is 0.67mm ± 0.05mm. The composite rolling speed is 3m / min.

[0082] After composite rolling, diffusion annealing is required using a continuous annealing furnace under inert gas protection. The annealing temperature is set at 480℃, and the furnace time is 5 minutes. The surface of the diffusion-annealed material needs to be brushed at a speed of 3 m / min to ensure surface cleanliness. The material is then trimmed, reducing the composite width from 180 mm to 170 mm. It is then rolled on a 20-roll mill (surface roughness 0.2-0.8 μm) with a tension of 220-420 kg before and after rolling. The thicknesses after each pass are 0.430 mm, 0.305 mm, 0.230 mm, and 0.180 mm, for a total of four passes. After reaching the finished thickness, the material is brushed to remove rolling oil stains. Finally, the material undergoes finished product annealing in a continuous furnace under inert gas protection at 420℃ for 5 minutes.

[0083] To ensure proper form, the material is tension-leveled after annealing at a speed of 3 m / min. After tension leveling, the composite material undergoes edge trimming, followed by cleaning and packaging. The finished product measures 0.18 mm × 75 mm × Coil.

[0084] Example 2

[0085] In Example 2, the materials used are the same as in Example 1. The thickness ratio of the brass-aluminum-brass composite material is C2680:5083:C2680=1:4:1. The specifications of the copper alloy raw material are 0.3mm×180mm×Coil; the specifications of the aluminum alloy raw material are 1.2mm×180mm×Coil; and the final rolling target thickness is 0.15mm×75mm×Coil.

[0086] The process of brushing, roughening, and rolling the copper and aluminum raw materials is the same as in Example 1. The size after composite rolling is 0.540mm ± 0.05mm, the single-pass composite reduction rate is 70%, and the composite rolling speed is 3m / min. The diffusion annealing temperature is set at 480℃, the furnace time is 5min, and inert gas protection is used. The brushing and trimming operations are the same as in Example 1. Rough rolling is performed on 20 rolls (surface roughness is 0.4~1.2µm), with pre-rolling and post-rolling tensions of 300~600 Kg. The dimensions of each pass are 0.420mm, 0.340mm, and 0.280mm, for a total of 3 passes, with a total rolling reduction rate of 45%~50%. The intermediate annealing temperature is 450℃, the intermediate annealing time is 5min, and the trimming and cleaning are the same as in Example 1.

[0087] The product was then finished using a 20-roll mill (surface roughness 0.2~0.8µm). The pre- and post-roll tensions were 200~400Kg, and the dimensions for each pass were 0.220mm, 0.175mm, and 0.150mm, for a total of 3 passes, with a total rolling reduction of 45%~50%. After rolling, the edges were trimmed and cleaned, followed by finished product annealing under inert gas protection at a heating temperature of 420℃ for 5 minutes. Subsequent cleaning, straightening, trimming, and packaging were the same as in Example 1, resulting in a finished product with dimensions of 0.15mm×75mm×Coil.

[0088] Example 3

[0089] In Example 3, the materials are the same as in Example 1. The thickness ratio of the brass-aluminum-brass composite material is C2680:5083:C2680=1:8:1. The specifications of the copper alloy raw material are 0.3mm×180mm×Coil; the specifications of the aluminum alloy raw material are 2.4mm×180mm×Coil; and the final rolling target thickness is 0.15mm×75mm×Coil.

[0090] The process of brushing, texturing, and rolling the copper and aluminum raw materials together is the same as in Example 1. The size after composite rolling is 1.350mm ± 0.05mm, the single-pass composite reduction rate is 55%, and the composite rolling speed is 3m / min. The diffusion annealing temperature is set at 480℃, the furnace time is 5min, and inert gas protection is used. The brushing and trimming operations are the same as in Example 1. Rough rolling is performed on 20-roll mills (surface roughness 0.4~1.2µm), with pre-roll and post-roll tensions of 300~600 Kg. The dimensions for each pass are 1.030mm, 0.810mm, 0.650mm, 0.530mm, and 0.440mm, for a total of 5 passes. Continuous annealing is performed in between at 420℃ for 8 minutes. Finish rolling is then performed again on 20-roll mills (surface roughness 0.2~0.8µm), with pre-roll and post-roll tensions of 200~400 Kg. The dimensions for each pass are 0.340mm, 0.270mm, 0.220mm, 0.180mm, and 0.150mm, for a total of 5 passes. After rolling, the edges are trimmed and cleaned, and the finished product is annealed under inert gas protection. The heating temperature is set to 350℃ and the furnace time is 5 minutes. Subsequent cleaning, straightening, trimming, and packaging are the same as in Example 1, resulting in a finished product with specifications of 0.15mm×75mm×Coil.

[0091] Example 4

[0092] The preparation method of this embodiment is basically the same as that of Example 1, except that the single-pass rolling reduction rate of the solid-solid cold composite is 50%.

[0093] Example 5

[0094] The preparation method in this embodiment is basically the same as that in Example 1, except that the rolling speed of the solid-solid cold composite rolling is 1 m / min.

[0095] Example 6

[0096] The preparation method in this embodiment is basically the same as that in Example 1, except that the diffusion annealing temperature is 350°C.

[0097] Example 7

[0098] The preparation method in this embodiment is basically the same as that in Example 1, except that the diffusion annealing temperature is 410°C.

[0099] Example 8

[0100] The preparation method in this embodiment is basically the same as that in Example 1, except that the diffusion annealing time is 10 min.

[0101] Example 9

[0102] The preparation method in this embodiment is basically the same as that in Example 1, except that the diffusion annealing time is 2 minutes.

[0103] Example 10

[0104] The preparation method in this embodiment is basically the same as that in Example 1, except that the surface of the brass raw material includes a layer of 1000nm pure copper.

[0105] Example 11

[0106] The preparation method of this embodiment is basically the same as that of Example 1, except that the surface of the brass raw material includes a layer of 200nm pure copper.

[0107] Comparative Example 1

[0108] The preparation method of this comparative example is basically the same as that of Example 1, except that the thickness ratio of brass:aluminum:brass is 1:0.5:1 before lamination.

[0109] Comparative Example 2

[0110] The preparation method of this comparative example is basically the same as that of Example 1, except that the thickness ratio of brass:aluminum:brass is 1:10:1 before lamination.

[0111] Comparative Example 3

[0112] The preparation method of this comparative example is basically the same as that of Example 1, except that the single-pass rolling reduction rate of the solid-cold composite is 40%.

[0113] Comparative Example 4

[0114] The preparation method of this comparative example is basically the same as that of Example 1, except that the diffusion annealing time is 15 minutes.

[0115] Comparative Example 5

[0116] The preparation method of this comparative example is basically the same as that of Example 1, except that the diffusion annealing temperature is 530℃.

[0117] Comparative Example 6

[0118] The preparation method of this comparative example is basically the same as that of Example 1, except that the diffusion annealing temperature is 300°C.

[0119] Comparative Example 7

[0120] The preparation method of this comparative example is basically the same as that of Example 1, except that the annealing temperature of the finished product is 250°C.

[0121] Comparative Example 8

[0122] The preparation method of this comparative example is basically the same as that of Example 1, except that the annealing temperature of the finished product is 550°C.

[0123] Test Example 1

[0124] Surface hardness testing: Using the Vickers hardness test method, a diamond pyramidal indenter (136° angle) was pressed into the material surface under a load of 50g and held for 10 seconds to form an indentation. The hardness value was then calculated by measuring the diagonal length of the indentation. Surface hardness was measured at different locations on both sides of the roll material. Detailed test results for each embodiment and comparative example are shown in Tables 1-4. Table 4 presents the summary data, with the values ​​obtained by averaging the hardness of each surface of each tested sample.

[0125] Yield strength test: The composite materials of each embodiment or comparative example were tested using a tensile testing machine. The sample was placed in a fixture, and the tensile force was gradually increased to stretch the sample, and its stress and strain were measured. The stress corresponding to the yield point in the stress-strain curve is the yield strength. Multiple samples were measured for each embodiment and comparative example. Detailed test results are shown in Tables 1-4. Table 4 is a summary data, with the yield strength of each tested sample averaged to obtain the values ​​in the table.

[0126] Tensile strength test: The stress value corresponding to the point of maximum tension during testing on a tensile testing machine is the tensile strength. Detailed test results for each embodiment and comparative example are shown in Tables 1-4. Table 4 presents the summary data, obtained by averaging the tensile strength of each tested sample.

[0127] Elongation test: When tested on a tensile testing machine, the ratio of the change in length of the sample before and after stretching to the original length is the elongation. Detailed test results for each embodiment and comparative example are shown in Tables 1-4. Table 4 is a summary of the data, obtained by averaging the elongation of each tested sample.

[0128] Bond strength test: The peel strength test method in GB / T32468-2025 was used to detect whether delamination occurred after peeling. Detailed test results for each example and comparative example are shown in Table 4.

[0129] IMC layer thickness range test: The samples of each embodiment and comparative example were subjected to cross-sectional SEM test. The shaded and blurred area at the junction of the two phases in the cross-sectional SEM image is the IMC layer. The thickness range of the IMC layer can be determined from the image. Figure 2 This is a cross-sectional SEM image of the brass-aluminum-brass composite material from Example 1. Figure 2The MC layer thickness ranged from 212 to 313 nm. Test results for other embodiments and comparative examples are detailed in Table 4.

[0130] Figure 3 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material of Example 1. The high-magnification photograph shows that Example 1 formed a brass-aluminum-brass sandwich structure composite material. The distance (L) in the high-magnification photograph represents the thickness of each layer at each test location.

[0131] Table 1 shows the surface hardness and mechanical properties of the finished product of copper-aluminum-copper (thickness ratio 1:1:1) in Example 1.

[0132]

[0133] Figure 4 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material of Example 2. The high-magnification photograph shows that Example 2 formed a brass-aluminum-brass sandwich structure composite material. The distance (L) in the high-magnification photograph represents the thickness of each layer at each test location.

[0134] Table 2 shows the surface hardness and mechanical properties of the finished product (copper-aluminum-copper, thickness ratio 1:4:1) from Example 2.

[0135]

[0136] Figure 5 This is a high-magnification photograph of the cross-section of the brass-aluminum-brass composite material in Example 3. The high-magnification photograph shows that a brass-aluminum-brass sandwich structure has been formed. The distance (L) in the high-magnification photograph represents the thickness of each layer at each test location.

[0137] Table 3 shows the surface hardness and mechanical properties of the finished product of copper-aluminum-copper (thickness ratio 1:8:1) in Example 3.

[0138]

[0139] Table 4. Preparation process parameters for each embodiment and comparative example

[0140]

[0141] Table 5. Mechanical property test results of each embodiment and comparative example

[0142]

[0143] Based on the data in Tables 4 and 5, it can be seen that the composite materials of Comparative Example 1 (three-layer thickness ratio of 1:0.5:1) and Comparative Example 2 (three-layer thickness ratio of 1:10:1) have worse average surface hardness and yield strength compared to the examples. In Comparative Example 3, the single-pass reduction rate during cold rolling was 40%, resulting in lower bonding strength and product delamination. In Comparative Example 4, the diffusion annealing time was greater than 10 minutes, specifically 15 minutes. Compared to the examples, the IMC layer thickness was slightly increased, but the average surface hardness and yield strength decreased. In Comparative Example 5, the diffusion annealing temperature was increased to 530°C. Compared to the examples, the IMC layer thickness was slightly increased, but the average surface hardness and yield strength decreased.

[0144] Test Example 2

[0145] Heat dissipation performance (thermal conductivity) test: At room temperature of 25℃, the sample is made into a small disc (thickness of 3mm). The sample is uniformly irradiated with short laser pulses to raise its temperature. The temperature rise process is continuously measured with an infrared detector. The thermal diffusivity of the material can be calculated based on the temperature change over time. Then, the thermal conductivity can be calculated based on the specific heat capacity and density.

[0146] Conductivity test: At room temperature (25°C), a probe is used to contact the surface of the columnar material, a constant current is passed through it, the voltage across the material is measured, the resistance is calculated, and then converted into conductivity.

[0147] Table 6. Other performance test results for each embodiment and comparative example

[0148]

[0149] Based on the data in Table 6 above, the electrical conductivity of the composite materials in each embodiment is comparable to that of C2680 brass alloy (15-22 MS / m), and the thermal conductivity is also comparable to that of C2680 brass alloy (70-150 W·m). -1 ·K -1 The thermal conductivity is comparable to that of brass. Therefore, the above-mentioned brass-aluminum-brass composite material can replace brass in the manufacture of LED brackets, which can reduce raw material costs and maintain comparable electrical and thermal conductivity while being lightweight.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cold composite material of brass and aluminum, characterized in that, The preparation method includes the following steps: A first intermediate composite material is obtained by solid-solid cold composite rolling of a first brass, an aluminum material, and a second brass. The solid-solid cold composite rolling is a single-pass rolling process with a reduction rate of 50% to 70%. The thickness ratio of the first brass, the aluminum material, and the second brass is 1:(1~8):

1. The aluminum material is selected from one of 1-series, 3-series, 5-series, and 8-series aluminum alloys. The mass fraction of copper in the first and second brass is greater than 58%. The first intermediate composite material is subjected to diffusion annealing to obtain the second intermediate composite material. The diffusion annealing temperature is 350~480℃ and the diffusion annealing time is 2~5min. The second intermediate composite material is cold-rolled to obtain a brass-aluminum-brass composite material of the target thickness, wherein the brass-aluminum-brass composite material includes an intermetallic compound layer of 200-500 nm between the brass layer and the aluminum layer.

2. The preparation method according to claim 1, characterized in that, The rolling speed of the solid-solid cold composite rolling is 1-3 m / min.

3. The preparation method according to claim 1 or 2, characterized in that, The cold rolling process includes roughing and finishing rolling; The total reduction rate of the roughing process is 50%~75%, the single-pass reduction rate is 15%~25%, and the surface roughness Ra of the work roll is 0.4~1.2µm; The total reduction rate of the finishing mill is 50%~75%, the single-pass reduction rate is 15%~25%, and the surface roughness Ra of the work rolls is 0.2~0.8µm.

4. The preparation method according to claim 3, characterized in that, The preparation method further includes: After rough rolling, intermediate annealing is performed at a temperature of 350~450℃. After the finishing rolling, the finished product is annealed at a temperature of 350~450℃.

5. The preparation method according to claim 1 or 2, characterized in that, Prior to the solid-solid cold composite rolling process, the surfaces of the first brass and the second brass comprise a 200-1000 nm pure copper layer.

6. The preparation method according to claim 1 or 2, characterized in that, Prior to the solid-solid cold composite rolling, the preparation method further includes: The surfaces of the first brass, the second brass, and the aluminum material are roughened using an online roughening machine.

7. A brass-aluminum-brass composite material, characterized in that, The brass-aluminum-brass composite material is prepared by the preparation method according to any one of claims 1-6, wherein the thickness ratio of the brass layer, the aluminum layer and the brass layer in the brass-aluminum-brass composite material is 1:(1~8):1; An intermetallic compound layer of 200-500 nm is included between the brass layer and the aluminum layer.

8. An LED bracket, characterized in that, The LED bracket is prepared using the brass-aluminum-brass composite material described in claim 7.

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