Vacuum die casting method of high thermal conductivity aluminum alloy

Abstract

The present application relates to aluminum alloy pressure casting forming, and provides a vacuum pressure casting forming method of high-thermal-conductivity aluminum alloy. High-thermal-conductivity aluminum alloy material taking Al as a matrix is supplied into a smelting crucible of a vacuum smelting unit in a solid or liquid state, temperature regulation is performed on the high-thermal-conductivity aluminum alloy material under a vacuum environment and / or a protective atmosphere environment, so that the high-thermal-conductivity aluminum alloy material forms or remains as a high-thermal-conductivity aluminum alloy melt; the high-thermal-conductivity aluminum alloy melt reaches a preset pouring temperature higher than a liquidus temperature of the high-thermal-conductivity aluminum alloy, so as to reduce viscosity and improve filling capacity; the high-thermal-conductivity aluminum alloy melt is transferred to a pressure cylinder under the condition of reducing contact with air, is injected into a mold cavity through a pressure injection mechanism, and a pressure casting part is obtained after pressure boosting, pressure maintaining, and cooling and solidification.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy die casting technology, and more specifically, to a vacuum die casting method for high thermal conductivity aluminum alloys. In particular, it relates to a die casting method that improves the filling capacity of high thermal conductivity aluminum alloy melt and reduces oxide inclusions and gas entrapment defects by combining vacuum melting, low oxygen transfer, vacuum injection and higher pouring temperature. Background Technology

[0002] With the rapid development of artificial intelligence, big data, cloud computing, high-speed communication, and high-power electronic devices, high-performance servers, data centers, optical communication equipment, and various electronic devices are continuously evolving towards higher power density, higher integration, and miniaturization. The heat generated by these devices during operation is constantly increasing, placing higher demands on the thermal conductivity, dimensional accuracy, structural strength, and molding integrity of heat dissipation components. Heat dissipation components, such as high-speed optical modules, server heat dissipation parts, and communication equipment heat dissipation shells, typically need to achieve rapid heat conduction and diffusion within a limited space. Therefore, the thermal conductivity of the material itself and the molding capability of complex thin-walled structures become important factors affecting product performance. Among existing heat dissipation components, zinc alloys are used in some precision structural parts due to their good die-casting fluidity, dimensional accuracy, and surface quality. However, zinc alloys have a high density, and their advantages in thermal conductivity and lightweighting are relatively limited. As device power and heat dissipation requirements increase, their application in high-power heat dissipation components is somewhat restricted. In contrast, high thermal conductivity aluminum alloys have advantages such as low density, good thermal conductivity, and significant weight reduction, making them suitable for manufacturing heat dissipation structural components in high-power electronic devices and communication devices. They represent an important development direction in the fields of heat dissipation materials and die casting.

[0003] To achieve high thermal conductivity, high thermal conductivity aluminum alloys typically require reducing the content of solid solution elements in the aluminum matrix, controlling the content of elements such as Si, Mg, and Cu that may affect thermal conductivity, or using elements such as Fe, Ni, Ce, La, and Zr to form specific second phases and regulate the microstructure to reduce the scattering effect on electron conduction. While these low-silicon, low-alloy, or specific alloying designs are beneficial for improving the thermal conductivity of aluminum alloys, they often weaken the die-casting fluidity of the melt, increasing the difficulty of filling thin-walled, fine-ribbed, long-flow, or complex cavities, and easily leading to defects such as under-casting, cold shuts, localized incomplete filling, and incomplete forming of complex structures. To improve the filling ability of high thermal conductivity aluminum alloys, existing die-casting processes typically enhance melt fluidity by increasing pouring temperature, increasing mold temperature, increasing injection speed, or optimizing the gating system. Among these methods, increasing pouring temperature can reduce melt viscosity and delay premature solidification of the melt in thin-walled cavities, making it one of the effective means to improve the die-casting performance of low-silicon or low-alloy high thermal conductivity aluminum alloys. However, aluminum alloy molten metal is more prone to oxidation and gas absorption when in contact with air at higher temperatures, leading to the formation of oxide films, oxide inclusions, and gas entrapment defects. These defects can also be drawn into the casting during the injection molding process, reducing the density, thermal conductivity, mechanical properties, and service reliability of the die-casting. In traditional die-casting processes, aluminum alloy molten metal is typically melted, held, transferred, poured, and injection molded under atmospheric pressure or discontinuous low-oxygen environments. The molten metal is easily exposed to air at multiple process stages, especially under high-temperature pouring and high-speed injection conditions, further increasing the risk of oxide film breakage, entrapment, and inclusion formation. Therefore, for high thermal conductivity aluminum alloys, existing processes have long faced a technical contradiction between "increasing the pouring temperature to improve fluidity" and "inhibiting high-temperature molten metal oxidation to maintain material properties."

[0004] Therefore, in order to solve the technical problems of poor melt flow, difficulty in filling thin-walled and complex cavities, and the easy generation of oxide film, gas absorption, gas entrapment and oxide inclusions when increasing the pouring temperature of existing high thermal conductivity aluminum alloys during the die casting process, it is urgent to provide a new vacuum die casting method for high thermal conductivity aluminum alloys. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a vacuum die-casting method for high thermal conductivity aluminum alloys, to solve the problems of insufficient melt fluidity, difficulty in filling thin-walled and complex cavities, and the tendency to cause defects such as oxide film formation, gas absorption, gas entrapment, and oxide inclusions when increasing the pouring temperature in the existing technology. This invention improves the fluidity and filling capacity of the high thermal conductivity aluminum alloy melt by using a higher pouring temperature. Simultaneously, it uses a vacuum environment and / or a protective atmosphere to at least control the oxygen content during the temperature regulation process of the high thermal conductivity aluminum alloy material. Furthermore, it can control the oxygen content during melt transfer, injection barrel feeding, and injection filling processes, thereby reducing the risk of high-temperature melt oxidation and gas entrapment, enabling stable die-casting of high thermal conductivity aluminum alloys while maintaining good material properties.

[0006] The above objectives can be achieved through the following technical means: This invention provides a vacuum die-casting method for high thermal conductivity aluminum alloys, the method comprising the following steps: S1: Place the high thermal conductivity aluminum alloy material into the melting crucible of the vacuum melting unit in solid or liquid form; S2: In a vacuum environment and / or a protective atmosphere, the temperature of the high thermal conductivity aluminum alloy material in the melting crucible is controlled so that the high thermal conductivity aluminum alloy material is melted into a high thermal conductivity aluminum alloy melt and maintained in a molten state. S3: The high thermal conductivity aluminum alloy melt is brought to a preset pouring temperature, wherein the preset pouring temperature is higher than the liquidus temperature of the high thermal conductivity aluminum alloy. S4: Transfer the high thermal conductivity aluminum alloy melt from the vacuum melting unit to the injection cylinder of the die-casting equipment; S5: The high thermal conductivity aluminum alloy melt is injected into the mold cavity through the injection mechanism to complete the filling, and after pressurization, holding pressure and cooling solidification, a high thermal conductivity aluminum alloy die casting is obtained.

[0007] Alternatively, the composition of the high thermal conductivity aluminum alloy melt can be expressed as a percentage by mass as follows: Al-Si(a)-Fe(b)-Mg(c)-Ni(d)-Ce(e)-La(f)-Cu(g)-Zr(h), Where a, b, c, d, e, f, g, and h represent the mass percentage content of Si, Fe, Mg, Ni, Ce, La, Cu, and Zr, respectively, and satisfy the following conditions: 0≤a≤1.5, 0≤b≤2.5, 0≤c≤1.0, 0≤d≤2.0, 0≤e≤0.8, 0≤f≤5.0, 0≤g≤2.0, and 0≤h≤0.5. At least one of a, b, c, d, e, f, g, h is greater than 0, and a+b+c+d+e+f+g+h is 0.1 to 8.0, with the balance being Al and unavoidable impurities.

[0008] Alternatively, the high thermal conductivity aluminum alloy melt can be any one of the following: Al-Fe, Al-Fe-Ce, Al-Si-Fe, Al-Fe-Ni, Al-Si-Mg-Fe, or Al-La-Ni-Cu-Zr high thermal conductivity aluminum alloy melt.

[0009] Alternatively, the preset pouring temperature can be set based on the liquidus temperature of the high thermal conductivity aluminum alloy, melt flowability, mold cavity wall thickness, and filling path length.

[0010] Alternatively, the preset casting temperature can be 20 to 200°C higher than the liquidus temperature of the high thermal conductivity aluminum alloy.

[0011] Alternatively, during the temperature control process of the high thermal conductivity aluminum alloy material, as well as during the transfer, injection barrel feeding, and injection molding processes of the high thermal conductivity aluminum alloy melt, the high thermal conductivity aluminum alloy material and / or the high thermal conductivity aluminum alloy melt are kept in a closed environment that isolates them from the outside air. The closed environment is either a vacuum environment or a protective atmosphere environment, thereby reducing the contact between the high-temperature melt and the outside air and reducing the risk of oxide film, gas absorption, gas entrapment, and oxide inclusions.

[0012] Alternatively, the protective atmosphere can be argon, nitrogen, or a mixture of argon and nitrogen.

[0013] Alternatively, the absolute pressure of the vacuum environment within the vacuum melting unit can be 1 to 1000 Pa.

[0014] Alternatively, before the high thermal conductivity aluminum alloy melt is transferred to the injection barrel, the injection barrel and the mold are preheated. The preheating temperature of the injection barrel can be 100-300°C, preferably 120-250°C, and more preferably 150-200°C; the preheating temperature of the mold can be 100-350°C.

[0015] Alternatively, after the high thermal conductivity aluminum alloy melt has finished feeding into the injection barrel, the injection mechanism is activated to perform injection, thereby shortening the residence time of the high thermal conductivity aluminum alloy melt in the injection barrel and reducing melt temperature drop and oxidation. The activation timing of the injection mechanism can be determined based on the liquidus temperature of the high thermal conductivity aluminum alloy, the actual pouring temperature, the preheating temperature of the injection barrel, the melt quality, and the mold cavity structure.

[0016] Alternatively, the injection process of the injection mechanism may include a slow injection stage, a high-speed injection stage, and a pressure-increasing and holding stage.

[0017] Alternatively, the mold cavity may be a thin-walled cavity, a complex flow channel cavity, a heat dissipation structure cavity, a shell structure cavity, or any combination of two or more thereof.

[0018] Alternatively, the composition of the high thermal conductivity aluminum alloy melt, by mass percentage, is selected from any one of the following three options: The first type consists of 0.8%–1.2% Fe, with the balance being Al and unavoidable impurities; The second type consists of Fe 1.5%–1.9%, Ni 0.8%–1.2%, with the balance being Al and unavoidable impurities; The third type consists of 0.6%–0.9% Fe and 0.6%–0.9% Ni, with the balance being Al and unavoidable impurities.

[0019] According to the above technical solution, the vacuum die-casting method for high thermal conductivity aluminum alloy provided by the present invention has the following advantages compared with the prior art: 1) By bringing the high thermal conductivity aluminum alloy melt to a preset pouring temperature higher than its liquidus temperature, the present invention can reduce the melt viscosity and improve the melt's filling ability in thin-walled, long-flow or complex cavities, thereby improving the problem of insufficient die casting fluidity of high thermal conductivity aluminum alloys caused by low silicon, low alloying or specific composition design.

[0020] 2) The present invention establishes a vacuum environment and / or a protective atmosphere environment at least during the temperature control process of high thermal conductivity aluminum alloy materials, and can further establish a closed environment that isolates the outside air during melt transfer, injection barrel feeding and injection filling processes. The closed environment is either a vacuum environment or a protective atmosphere environment.

[0021] 3) This invention combines a higher pouring temperature with a low-oxygen molding environment to improve melt fluidity while inhibiting high-temperature oxidation, thereby alleviating the technical contradiction in the existing high thermal conductivity aluminum alloy die casting process of being unable to simultaneously achieve "improving fluidity" and "reducing oxidation defects".

[0022] 4) This invention is beneficial to improving the molding integrity, density, thermal conductivity and service reliability of high thermal conductivity aluminum alloy die castings, and is applicable to the manufacture of high thermal conductivity aluminum alloy die castings such as thin-walled structures, complex flow channel structures, heat dissipation structures or shell structures.

[0023] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process state of vacuum die casting of high thermal conductivity aluminum alloy according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a heat dissipation housing assembly for an optical module prepared by vacuum die casting according to an embodiment of the present invention; Figure 3 A comparison chart of the electrical conductivity of aluminum alloys with different compositions; Figure 4 A comparison chart of the thermal conductivity of aluminum alloys with different compositions; Figure 5 This is a flow chart of a vacuum die-casting method for high thermal conductivity aluminum alloy according to an embodiment of the present invention.

[0026] The reference numerals in the attached figures are: 10. First heat dissipation housing component; 20. Second heat dissipation housing component. Detailed Implementation

[0027] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for ease of description of one or more embodiments.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] This invention can be modified and has various embodiments, with specific embodiments illustrated in the accompanying drawings. However, this invention is not limited to this particular implementation and all modifications, equivalents, and substitutions falling within the spirit and technical scope of this invention are to be understood as included.

[0030] Ordinal terms such as first, second, etc., may be used to describe various constituent elements, but the constituent elements are not limited to these terms. These terms are used only to distinguish one constituent element from another. For example, without departing from the scope of the claims of this invention, a second constituent element may be named a first constituent element, and similarly, a first constituent element may be named a second constituent element. The term "and / or" refers to any one or any combination of the listed items.

[0031] It should be understood that when referring to a constituent element being "connected" or "in contact" with other constituent elements, this includes not only cases where it is directly connected or in contact with other constituent elements, but also cases where other constituent elements exist between them. Conversely, when referring to a constituent element being "directly connected" or "directly in contact" with other constituent elements, it should be understood that no other constituent elements exist between them.

[0032] To address the aforementioned problems in existing technologies regarding insufficient melt fluidity, difficulty in filling thin-walled and complex cavities during high thermal conductivity aluminum alloy die casting, and the potential for defects such as oxide film formation, gas absorption, gas entrapment, and oxide inclusions when increasing the pouring temperature, this invention proposes a vacuum die casting method for high thermal conductivity aluminum alloys. This invention improves the fluidity and filling capacity of the high thermal conductivity aluminum alloy melt by using a higher pouring temperature. Simultaneously, it achieves low-oxygen control at least during the temperature regulation process of the high thermal conductivity aluminum alloy material through a vacuum environment and / or a protective atmosphere. Furthermore, it can further control the low-oxygen process during melt transfer, injection barrel feeding, and injection filling, thereby reducing the risk of high-temperature melt oxidation and gas entrapment. This allows high thermal conductivity aluminum alloys to achieve stable die casting while maintaining good material properties.

[0033] In this invention, the "high thermal conductivity aluminum alloy material" refers to the aluminum alloy material used to form a high thermal conductivity aluminum alloy melt, which can be supplied to the melting crucible of the vacuum melting unit in solid or liquid form. Solid high thermal conductivity aluminum alloy material may include room temperature aluminum alloy ingots, aluminum alloy bars, preheated aluminum alloy ingots, or preheated aluminum alloy bars; liquid high thermal conductivity aluminum alloy material may include pre-melted high-temperature aluminum alloy melt that has been transported to the melting crucible.

[0034] The term "high thermal conductivity aluminum alloy" as used in this invention refers to an aluminum alloy material with Al as the matrix, suitable for die casting into heat dissipation components, and is not limited to an aluminum alloy with a specific composition. Unless otherwise stated, the content of each alloying element mentioned in this invention refers to a percentage by mass.

[0035] In this invention, "temperature control" refers to at least one of the following: heating and melting, temperature rise, temperature holding, and composition homogenization treatment, based on the initial state of the high thermal conductivity aluminum alloy material. When the high thermal conductivity aluminum alloy material is supplied in solid form, the temperature control includes at least heating and melting; when the high thermal conductivity aluminum alloy material is supplied in liquid form, the temperature control includes at least one of temperature rise, temperature holding, and composition homogenization treatment, to maintain it as a high thermal conductivity aluminum alloy melt.

[0036] In this invention, the "vacuum environment" is not limited to absolute vacuum, but may include a low-pressure environment, a low-oxygen environment, or a reduced-pressure environment formed by vacuuming; the "protective atmosphere" may be argon, nitrogen, or a mixture of argon and nitrogen. The vacuum environment and / or protective atmosphere environment at least act on the temperature control process of the high thermal conductivity aluminum alloy material, and may further act on the melt transfer, injection barrel feeding, and injection filling processes.

[0037] In this invention, the "preset pouring temperature" can be set according to the liquidus temperature of the high thermal conductivity aluminum alloy, the fluidity of the melt, the wall thickness of the mold cavity, the length of the filling path, and the complexity of the die casting structure. The purpose is to reduce the viscosity of the high thermal conductivity aluminum alloy melt and improve the melt filling capacity.

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] To illustrate the vacuum die-casting method for high thermal conductivity aluminum alloys provided by this invention, Figure 5 A flow chart of a vacuum die-casting method for high thermal conductivity aluminum alloys according to an embodiment of the present invention is shown.

[0040] like Figure 5 As shown, the high thermal conductivity aluminum alloy vacuum die casting method provided in this embodiment includes the following steps: S1: Place the high thermal conductivity aluminum alloy material into the melting crucible of the vacuum melting unit in solid or liquid form; S2: In a vacuum environment and / or a protective atmosphere, the temperature of the high thermal conductivity aluminum alloy material in the melting crucible is controlled so that the high thermal conductivity aluminum alloy material is melted into a high thermal conductivity aluminum alloy melt and maintained in a molten state. S3: The high thermal conductivity aluminum alloy melt is brought to a preset pouring temperature, wherein the preset pouring temperature is higher than the liquidus temperature of the high thermal conductivity aluminum alloy. S4: Transfer the high thermal conductivity aluminum alloy melt from the vacuum melting unit to the injection cylinder of the die-casting equipment; S5: The high thermal conductivity aluminum alloy melt is injected into the mold cavity through the injection mechanism to complete the filling, and after pressurization, holding pressure and cooling solidification, a high thermal conductivity aluminum alloy die casting is obtained.

[0041] In embodiments of the present invention, a vacuum environment and / or a protective atmosphere environment act at least on the temperature control process of the high thermal conductivity aluminum alloy material, and may further act on the melt transfer, injection barrel feeding and injection molding process, so as to reduce the formation of oxide film, gas absorption, gas entrapment and oxide inclusions of the high thermal conductivity aluminum alloy melt during the temperature control, transfer and injection molding process.

[0042] In some embodiments, from the time the high thermal conductivity aluminum alloy material is formed or maintained as a high thermal conductivity aluminum alloy melt through temperature control until the high thermal conductivity aluminum alloy melt completes the injection molding, the high thermal conductivity aluminum alloy melt is continuously or quasi-continuously in a vacuum environment, a protective atmosphere environment, or a closed environment isolated from the outside air.

[0043] To achieve the vacuum die-casting method for high thermal conductivity aluminum alloys of the present invention, it is possible to use methods such as... Figure 1 The vacuum melting unit, cold chamber injection unit, mold forming unit, and vacuum environment and / or protective atmosphere environment control system shown are used in conjunction to achieve this.

[0044] exist Figure 1 In the illustrated embodiment, the vacuum melting unit receives high thermal conductivity aluminum alloy material supplied in solid or liquid form and regulates the temperature of the high thermal conductivity aluminum alloy material in a vacuum environment and / or protective atmosphere. The vacuum melting unit may include a melting chamber, a melting crucible, and a heating device. The cold chamber injection unit may include an injection barrel and an injection punch for receiving the high thermal conductivity aluminum alloy melt transferred from the vacuum melting unit and injecting the high thermal conductivity aluminum alloy melt into the mold cavity. The mold forming unit may include a mold, a cavity, and an ingate for forming a high thermal conductivity aluminum alloy die casting. The vacuum environment and / or protective atmosphere environment control system may be connected to one or more of the vacuum melting unit, the cold chamber injection unit, and the mold forming unit for evacuating, introducing protective gas, or controlling the low-oxygen environment in the corresponding areas.

[0045] It should be noted that, Figure 1The structures shown are only used to illustrate the process state of the high thermal conductivity aluminum alloy melt during melting, transfer, injection, and molding in this invention, and are not intended to limit the specific structure, relative position, or connection method of the vacuum melting unit, cold chamber injection unit, mold forming unit, and vacuum environment and / or protective atmosphere environment control system. Any system capable of controlling the vacuum and / or protective atmosphere during the temperature control process of the high thermal conductivity aluminum alloy material and during the transfer and injection molding processes of the high thermal conductivity aluminum alloy melt can be applied to this invention.

[0046] exist Figure 5 In the illustrated embodiment, in S1, the high thermal conductivity aluminum alloy material can be fed into the melting crucible in either solid or liquid form. The solid high thermal conductivity aluminum alloy material can be fed directly into the melting crucible, or it can be transported into the melting crucible after preheating; the liquid high thermal conductivity aluminum alloy material can be transported into the melting crucible by pumping, metering furnace supply, gravity casting, pressure conveying, or other melt supply methods.

[0047] In S2, the temperature of the high thermal conductivity aluminum alloy material in the melting crucible is controlled under vacuum and / or protective atmosphere. When the high thermal conductivity aluminum alloy material is supplied in solid form, it is heated and melted by a heating device, and subjected to heating, holding, and composition homogenization treatments as needed. When the high thermal conductivity aluminum alloy material is supplied in liquid form, it is heated and / or held by a heating device, and subjected to composition homogenization treatments as needed, so that the high thermal conductivity aluminum alloy material is maintained as a high thermal conductivity aluminum alloy melt.

[0048] In step S3, the high thermal conductivity aluminum alloy melt is brought to a preset pouring temperature. This preset pouring temperature is higher than the liquidus temperature of the high thermal conductivity aluminum alloy and is configured to reduce the viscosity of the melt and improve its filling capacity. In some embodiments, the preset pouring temperature is set based on the liquidus temperature of the high thermal conductivity aluminum alloy, melt flowability, mold cavity wall thickness, and filling path length. The preset pouring temperature can be 20–200°C higher than the liquidus temperature of the high thermal conductivity aluminum alloy. By bringing the melt to the preset pouring temperature, the viscosity of the high thermal conductivity aluminum alloy melt can be reduced, premature solidification of the melt in thin-walled cavities, long-flow cavities, or complex cavities can be delayed, thereby improving the filling capacity.

[0049] In step S4, the high thermal conductivity aluminum alloy molten material is transferred from the vacuum melting unit to the injection barrel under conditions that minimize the contact between the molten material and air. Specifically, a vacuum environment and / or a protective atmosphere environment can be established in the vacuum melting unit, the molten material transfer path, and / or the injection barrel to reduce the contact between the high thermal conductivity aluminum alloy molten material and air during the transfer process from the vacuum melting unit to the injection barrel.

[0050] In step S5, the high thermal conductivity aluminum alloy molten material is injected into the mold cavity through an injection mechanism to complete the filling process. The molten material is then pressurized, held under pressure, and cooled to solidify, resulting in a high thermal conductivity aluminum alloy die casting. The die casting can be an aluminum alloy structural component with heat dissipation requirements, such as a thin-walled structural component, a heat dissipation structural component, a shell structural component, a structural component with a thermally conductive contact surface, or a structural component with complex cavity features.

[0051] In the above process, a higher preset pouring temperature is used to improve the fluidity and filling capacity of the high thermal conductivity aluminum alloy melt; a vacuum environment and / or a protective atmosphere environment are used to reduce oxide film formation, gas absorption, gas entrapment, and oxide inclusions in the high-temperature melt during temperature control, transfer, injection barrel feeding, and injection filling processes. Therefore, this invention can improve the die-casting capability of high thermal conductivity aluminum alloys while reducing the adverse effects of high-temperature oxidation on the thermal conductivity, density, and molding integrity of the die-cast parts.

[0052] To illustrate the effects of this invention in detail, specific embodiments are provided below. Unless otherwise specified, the raw materials used in the embodiments of this invention for preparing high thermal conductivity aluminum alloys are all commercially available industrial-grade raw materials.

[0053] Example 1

[0054] This embodiment provides a vacuum die-casting method for Al-Fe and Al-Fe-Ni high thermal conductivity aluminum alloys, mainly to illustrate the representative compositions of Al-Fe and Al-Fe-Ni high thermal conductivity aluminum alloys and the vacuum die-casting process applicable to the above compositions. The high thermal conductivity aluminum alloy in this embodiment uses Al as the matrix and contains Fe or Fe and Ni. The amount of Fe and Ni added can be adjusted according to the target thermal conductivity, melt flowability, microstructure, and die-cast part structure. This embodiment specifically lists three representative nominal compositions: Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni, but the high thermal conductivity aluminum alloys applicable to this invention are not limited to these three nominal compositions.

[0055] In this article, Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni are alloy composition codes expressed according to nominal composition, and the content of each element is a mass percentage. In actual batching and smelting processes, the actual content of each element may fluctuate around the corresponding nominal content, with the balance being Al and unavoidable impurities.

[0056] In a first preferred embodiment, the high thermal conductivity aluminum alloy is an Al-Fe based high thermal conductivity aluminum alloy, comprising 0.8% to 1.2% Fe by mass percentage, with the balance being Al and unavoidable impurities. Further, the nominal Fe content can be 1.0%, meaning the high thermal conductivity aluminum alloy can be Al-1Fe.

[0057] In this composition system, Ni is not actively added as an alloying element, but trace amounts of Ni and other impurity elements inevitably introduced during the raw materials or smelting process cannot be excluded.

[0058] In a second preferred embodiment, the high thermal conductivity aluminum alloy is an Al-Fe-Ni based high thermal conductivity aluminum alloy, comprising, by mass percentage, 1.5%–1.9% Fe, 0.8%–1.2% Ni, with the balance being Al and unavoidable impurities. Further, the nominal Fe content can be 1.7%, and the nominal Ni content can be 1.0%, meaning the high thermal conductivity aluminum alloy can be Al-1.7Fe-1Ni.

[0059] In a third preferred embodiment, the high thermal conductivity aluminum alloy is an Al-Fe-Ni based high thermal conductivity aluminum alloy, comprising, by mass percentage, 0.6%–0.9% Fe and 0.6%–0.9% Ni, with the balance being Al and unavoidable impurities. Further, the nominal content of both Fe and Ni can be 0.75%, meaning the high thermal conductivity aluminum alloy can be Al-0.75Fe-0.75Ni.

[0060] To further illustrate the electrical and thermal conductivity of the aforementioned representative alloys, electrical and thermal conductivity tests were conducted on aluminum alloys with different compositions, including Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni. The test results are shown below. Figure 3 and Figure 4 As shown.

[0061] Depend on Figure 3 The results show that the electrical conductivities of Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni are 30.23 MS / m, 28.56 MS / m, and 31.12 MS / m, respectively, all of which are not lower than 28.56 MS / m. Among them, the electrical conductivity of Al-0.75Fe-0.75Ni reaches 31.12 MS / m. The above test results indicate that the three representative components listed in this embodiment can maintain good electronic conductivity while introducing Fe and / or Ni elements.

[0062] Depend on Figure 4The results show that the thermal conductivity of Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni are 207.0 W / (m·K), 196.2 W / (m·K), and 212.8 W / (m·K), respectively, all exceeding 196 W / (m·K). Among them, Al-0.75Fe-0.75Ni achieves a thermal conductivity of 212.8 W / (m·K). These test results demonstrate that the three representative components listed in this embodiment all possess good thermal conductivity and are suitable for preparing high thermal conductivity aluminum alloy die-castings with heat dissipation requirements.

[0063] Any of the high thermal conductivity aluminum alloy materials among Al-1Fe, Al-1.7Fe-1Ni and Al-0.75Fe-0.75Ni can be fed into the melting crucible of the vacuum melting unit in solid or liquid form using the aforementioned feeding method.

[0064] When the high thermal conductivity aluminum alloy material is supplied in solid form, the solid alloy material prepared according to the corresponding nominal composition can be placed directly into the melting crucible, or it can be transported into the melting crucible after preheating; when the high thermal conductivity aluminum alloy material is supplied in liquid form, the high thermal conductivity aluminum alloy melt can be transported into the melting crucible by pumping, quantitative furnace supply, gravity casting, pressure conveying or other melt supply methods.

[0065] Temperature control is performed on the high thermal conductivity aluminum alloy material in a melting crucible under vacuum and / or protective atmosphere conditions. When the high thermal conductivity aluminum alloy material is supplied in solid form, the temperature control includes heating and melting it, and performing heating, holding, and composition homogenization treatments as needed; when the high thermal conductivity aluminum alloy material is supplied in liquid form, the temperature control includes at least one of heating, holding, and composition homogenization treatments to maintain it as a high thermal conductivity aluminum alloy melt.

[0066] In some embodiments, the absolute pressure of the vacuum environment within the vacuum melting unit can be 1–1000 Pa. In other embodiments, argon, nitrogen, or a mixture of argon and nitrogen can be introduced after evacuation to create a protective atmosphere within the vacuum melting unit.

[0067] After temperature control of the high thermal conductivity aluminum alloy material, the obtained or maintained high thermal conductivity aluminum alloy melt reaches a preset pouring temperature. The preset pouring temperature can be set according to the liquidus temperature of the corresponding high thermal conductivity aluminum alloy, melt flowability, die casting wall thickness, mold cavity structure, and filling path length. For example, the preset pouring temperature can be 20–200°C higher than the liquidus temperature of the corresponding high thermal conductivity aluminum alloy.

[0068] Because the content of elements such as Si and Mg, which improve die-casting fluidity, is relatively low or not added as major alloying elements in the aforementioned Al-Fe and Al-Fe-Ni high thermal conductivity aluminum alloys, the die-casting fluidity of the high thermal conductivity aluminum alloy melt may be lower than that of conventional high-silicon die-casting aluminum alloys. By bringing the high thermal conductivity aluminum alloy melt to a preset pouring temperature higher than its liquidus temperature, the melt viscosity can be reduced, and the filling ability of the melt in thin-walled cavities, long-flow cavities, or complex cavities can be improved.

[0069] Before transferring the high thermal conductivity aluminum alloy molten material, the injection barrel and mold can be preheated. The preheating temperature of the injection barrel can be 100–300°C, preferably 120–250°C. In this embodiment, the preheating temperature of the injection barrel can be 150–200°C. The preheating temperature of the mold can be 100–350°C, which can be determined based on the wall thickness of the die-cast part to be formed, the filling path length, the cavity structure, and the fluidity of the corresponding high thermal conductivity aluminum alloy molten material.

[0070] At the same time, the injection barrel and / or mold cavity can be evacuated to reduce the gas content in the injection barrel and mold cavity.

[0071] Subsequently, under conditions that minimize the contact between the high thermal conductivity aluminum alloy molten material and the outside air, the corresponding high thermal conductivity aluminum alloy molten material is transferred from the vacuum melting unit to the injection barrel. The molten material transfer process can be carried out in at least one of the following environments: a vacuum environment, a protective atmosphere environment, or a closed environment isolated from the outside air, in order to reduce the formation of oxide film and gas absorption during the transfer process.

[0072] After the high thermal conductivity aluminum alloy molten material enters the injection barrel, it is injected into the mold cavity through the injection punch. The injection process can include a slow injection stage, a high-speed injection stage, and a pressure-increasing and holding stage. The slow injection stage is used to propel the molten material steadily into the runner; the high-speed injection stage is used to rapidly fill the mold cavity; and the pressure-increasing and holding stage is used to improve the density of the die casting. The high-speed injection speed, pressure, and holding time can be set according to the die casting wall thickness, filling path length, mold cavity structure, and the composition of the high thermal conductivity aluminum alloy used.

[0073] The three representative high thermal conductivity aluminum alloy compositions described above can all be prepared using the vacuum die casting method described in this embodiment. By using a higher preset pouring temperature to improve the fluidity of the high thermal conductivity aluminum alloy melt, and by using a vacuum environment and / or a protective atmosphere to reduce the risks of oxidation, gas absorption, gas entrapment, and oxidation inclusions during temperature control, transfer, injection barrel feeding, and injection filling processes, the high thermal conductivity aluminum alloy die castings are improved in terms of molding integrity, density, and thermal conductivity.

[0074] It should be noted that the Al-1Fe, Al-1.7Fe-1Ni, and Al-0.75Fe-0.75Ni listed in this embodiment are preferred representative compositions, and not an exhaustive list of the composition range of the high thermal conductivity aluminum alloy of the present invention. The content of Fe and Ni can be adjusted within the range defined in the claims according to the target thermal conductivity, melt flowability, microstructure, and die-casting structure; the method of the present invention can also be used for other Al-Fe systems, Al-Fe-Ni systems, and other high thermal conductivity aluminum alloy systems that meet the corresponding composition ranges.

[0075] Example 2

[0076] This embodiment provides a vacuum die-casting method for heat dissipation housing components for optical modules made of high thermal conductivity aluminum alloy.

[0077] like Figure 2 As shown, the method of this embodiment can be used to fabricate a first heat dissipation housing component 10 and a second heat dissipation housing component 20. The first heat dissipation housing component 10 and the second heat dissipation housing component 20 may have a thin-walled structure, a housing structure, a mounting and positioning structure, a thermally conductive contact surface, a local groove, a stepped structure, a rib structure, or a combination thereof. The first heat dissipation housing component 10 and the second heat dissipation housing component 20 can serve as components of a heat dissipation housing assembly for an optical module, or as heat dissipation structural components in other electronic devices, communication devices, or high-power devices.

[0078] The high thermal conductivity aluminum alloy used in this embodiment can be Al-1Fe, Al-1.7Fe-1Ni, or Al-0.75Fe-0.75Ni as described in Example 1, or it can be an Al-Si-Mg-Fe, Al-Fe-Ce, Al-Si-Fe, or Al-La-Ni-Cu-Zr series high thermal conductivity aluminum alloy. In specific implementation, the appropriate high thermal conductivity aluminum alloy composition can be selected according to the thermal conductivity, structural strength, wall thickness, and filling path of the heat dissipation shell component for the optical module. The specific compositions mentioned above are used to illustrate that the method of the present invention is applicable to different high thermal conductivity aluminum alloy systems, and do not indicate that the improvement of the present invention is limited to a specific alloy composition.

[0079] The high thermal conductivity aluminum alloy material used in this embodiment can be fed into the melting crucible of the vacuum melting unit in solid or liquid form according to any of the aforementioned feeding methods, and the temperature is controlled in a vacuum environment and / or protective atmosphere to form or maintain it as a high thermal conductivity aluminum alloy melt. Subsequently, according to the structural characteristics of the heat dissipation shell component, the high thermal conductivity aluminum alloy melt is brought to a preset pouring temperature. For heat dissipation shell components with thin walls, long flow paths, grooves, steps, or locally complex structures, a higher preset pouring temperature can be used to increase the flow distance of the melt in the mold cavity and the integrity of the filling.

[0080] Before injection, the injection barrel can be preheated to 150–200°C, and the mold preheated to 100–350°C according to the structure and wall thickness of the heat dissipation shell component. A vacuum environment is established for the injection barrel and / or mold cavity using a vacuum environment and / or protective atmosphere environment control system. Subsequently, under conditions that minimize the contact between the melt and air, the high thermal conductivity aluminum alloy melt is transferred to the injection barrel, and the melt is injected into the mold cavity through the inner gate using the injection punch. After the melt fills the mold cavity, it is pressurized, held under pressure, and cooled to solidify. The mold is then opened to obtain the first heat dissipation shell component 10 and / or the second heat dissipation shell component 20.

[0081] In this embodiment, since the heat sink housing component typically has thin walls, a long filling path, and locally complex structures, if ordinary atmospheric pressure melting and transfer methods are used, oxide films, gas absorption, gas entrapment, and oxide inclusions are easily generated after increasing the casting temperature. By employing the vacuum melting, low-oxygen transfer, vacuum injection, and higher casting temperature synergistic control of the present invention, the melt filling capacity can be improved while reducing the risk of high-temperature oxidation, thereby improving the molding integrity, thermal conductivity, and service reliability of the heat sink housing component.

[0082] In other alternative embodiments, the high thermal conductivity aluminum alloy can also be an Al-1.5Fe, Al-2Fe-0.3Ce, Al-0.75Si-0.75Fe, Al-0.4Si-0.6Mg-0.25Fe, or Al-La-Ni-Cu-Zr series aluminum alloy. The other composition systems described above can also be prepared using the vacuum die-casting method of this invention.

[0083] In contrast, when high thermal conductivity aluminum alloy die castings are prepared using ordinary atmospheric pressure melting and transfer methods, the high thermal conductivity aluminum alloy melt is easily exposed to air during melting, holding, transfer, and pouring. If the pouring temperature is further increased to improve filling capacity, the rate of oxide film formation in the melt increases. The oxide film is prone to breakage and entrapment into the casting during transfer and injection, forming oxide inclusions or air entrapment defects, which in turn affect the density, thermal conductivity, and molding integrity of the die casting.

[0084] In contrast, the present invention simultaneously controls the temperature regulation process of high thermal conductivity aluminum alloy materials by using a vacuum environment and / or a protective atmosphere environment to achieve low oxygen control. It can further control the low oxygen control of the melt transfer, injection barrel feeding and injection filling processes. Combined with a higher preset pouring temperature, it is beneficial to improve the fluidity and melt cleanliness of high thermal conductivity aluminum alloys at the same time, thereby improving the overall quality of high thermal conductivity aluminum alloy die castings.

[0085] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A vacuum die-casting method for high thermal conductivity aluminum alloys, characterized in that, Includes the following steps: S1: Place the high thermal conductivity aluminum alloy material into the melting crucible of the vacuum melting unit in solid or liquid form; S2: In a vacuum environment and / or a protective atmosphere, the temperature of the high thermal conductivity aluminum alloy material in the melting crucible is controlled so that the high thermal conductivity aluminum alloy material is melted into a high thermal conductivity aluminum alloy melt and maintained in a molten state. S3: The high thermal conductivity aluminum alloy melt is brought to a preset pouring temperature, wherein the preset pouring temperature is higher than the liquidus temperature of the high thermal conductivity aluminum alloy. S4: Transfer the high thermal conductivity aluminum alloy melt from the vacuum melting unit to the injection cylinder of the die-casting equipment; S5: The high thermal conductivity aluminum alloy melt is injected into the mold cavity through the injection mechanism to complete the filling, and after pressurization, holding pressure and cooling solidification, a high thermal conductivity aluminum alloy die casting is obtained.

2. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The composition of the high thermal conductivity aluminum alloy melt, expressed as a mass percentage, is as follows: Al-Si(a)-Fe(b)-Mg(c)-Ni(d)-Ce(e)-La(f)-Cu(g)-Zr(h), Where a, b, c, d, e, f, g, and h represent the mass percentage content of Si, Fe, Mg, Ni, Ce, La, Cu, and Zr, respectively, and satisfy the following conditions: 0≤a≤1.5, 0≤b≤2.5, 0≤c≤1.0, 0≤d≤2.0, 0≤e≤0.8, 0≤f≤5.0, 0≤g≤2.0, and 0≤h≤0.

5. At least one of a, b, c, d, e, f, g, h is greater than 0, and a+b+c+d+e+f+g+h is 0.1 to 8.0, with the balance being Al and unavoidable impurities.

3. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 2, characterized in that, The high thermal conductivity aluminum alloy melt is any one of the following: Al-Fe system, Al-Fe-Ce system, Al-Si-Fe system, Al-Fe-Ni system, Al-Si-Mg-Fe system, or Al-La-Ni-Cu-Zr system high thermal conductivity aluminum alloy melt.

4. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The preset pouring temperature is set based on the liquidus temperature of the high thermal conductivity aluminum alloy, the melt flowability, the mold cavity wall thickness, and the filling path length.

5. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The preset casting temperature is 20 to 200°C higher than the liquidus temperature of the high thermal conductivity aluminum alloy.

6. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, During the temperature control process of the high thermal conductivity aluminum alloy material, as well as the transfer, injection barrel feeding and injection molding processes of the high thermal conductivity aluminum alloy melt, the high thermal conductivity aluminum alloy material and / or the high thermal conductivity aluminum alloy melt are kept in a closed environment that isolates them from the outside air. The closed environment is either a vacuum environment or a protective atmosphere environment.

7. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The protective atmosphere is argon, nitrogen, or a mixture of argon and nitrogen.

8. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The absolute pressure of the vacuum environment within the vacuum melting unit is 1–1000 Pa.

9. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, Before the high thermal conductivity aluminum alloy melt is transferred to the injection barrel, the injection barrel and the mold are preheated, wherein the preheating temperature of the injection barrel is 100-300℃ and the preheating temperature of the mold is 100-350℃.

10. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The injection process of the injection mechanism includes a slow injection stage, a high-speed injection stage, and a pressure increase and holding stage.

11. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 1, characterized in that, The mold cavity is a thin-walled cavity, a complex flow channel cavity, a heat dissipation structure cavity, a shell structure cavity, or any combination of two or more of them.

12. The vacuum die-casting method for high thermal conductivity aluminum alloy according to claim 2, characterized in that, The composition of the high thermal conductivity aluminum alloy melt, by mass percentage, is selected from any one of the following three options: The first type consists of 0.8%–1.2% Fe, with the balance being Al and unavoidable impurities; The second type consists of Fe 1.5%–1.9%, Ni 0.8%–1.2%, with the balance being Al and unavoidable impurities; The third type consists of 0.6%–0.9% Fe and 0.6%–0.9% Ni, with the balance being Al and unavoidable impurities.

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