High-strength corrosion-resistant easy-to-process aluminum alloy profile for photovoltaic frame and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy, and provides a high-strength corrosion-resistant easy-to-process aluminum alloy profile for a photovoltaic frame, which comprises the following components in percentage by mass: 0.70-1.25% of Si, 0.65-0.85% of Mg, 0.02-0.06% of Ti, 0.02-0.08% of Cu, 0.8-1.5% of Bi, 0.15-0.30% of Sc, less than or equal to 0.05% of Mn, less than or equal to 0.05% of Cr, less than or equal to 0.2% of Fe, less than or equal to 0.03% of Zn and the balance of Al. The invention further provides a preparation method of the aluminum alloy profile. According to the aluminum alloy profile provided by the invention, by adding Bi and Sc, the machinability of the aluminum alloy profile is remarkably improved, and the deburring procedure is simplified; meanwhile, the content of other alloy elements is adjusted, so that the mechanical property, the corrosion resistance, the conductivity and the heat conductivity of the aluminum alloy profile are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and particularly to a high-strength, corrosion-resistant and easy-to-process aluminum alloy profile for photovoltaic frames and a preparation method thereof. Background Art

[0002] Aluminum alloy frames have the characteristics of light weight, strong corrosion resistance, easy forming, high strength, easy cutting and processing, recyclability, etc. Steel frames also occupy a certain market share in photovoltaic frames. They have relatively high strength and hardness, but are relatively heavy in weight and have inferior corrosion resistance compared to aluminum alloys. Composite frames are made of multiple materials and have excellent mechanical properties and corrosion resistance, but the cost is relatively high. Therefore, generally speaking, aluminum alloy frames have better application space as photovoltaic frames.

[0003] The frame types in photovoltaic modules include the following categories: Conventional frames are the most common frame types in photovoltaic modules. Their structural design is relatively simple and they are mainly used to fix and protect photovoltaic panels; Special frames are designed according to specific application scenarios and requirements, such as frames with adjustable angles, foldable frames, etc., to meet the installation and use requirements in different environments; Roof photovoltaic power station frames are mainly used for photovoltaic modules installed on roofs. Their size and weight are relatively small to adapt to the load-bearing and installation space limitations of roofs; Ground photovoltaic power station frames are mainly used for large-scale photovoltaic power stations installed on the ground. Their size and weight are relatively large to withstand greater environmental factors such as wind pressure and snow pressure.

[0004] Photovoltaic aluminum frames need to bear the weight of solar panels and the action of environmental factors such as wind pressure and snow pressure. Therefore, they are required to have relatively high strength; By optimizing alloy components and heat treatment processes, the strength and hardness of photovoltaic aluminum frames can be improved. At the same time, photovoltaic aluminum frames are exposed to the outdoor environment for a long time and are easily affected by corrosion. Therefore, it is required that photovoltaic aluminum frames have good corrosion resistance; By adopting measures such as corrosion-resistant alloys, surface treatment technologies (such as anodic oxidation, spraying, etc.), the corrosion resistance of photovoltaic aluminum frames can be improved. In the manufacturing process of photovoltaic aluminum frames, various processing procedures such as cutting, stamping, and bending are required. Therefore, it is required that photovoltaic aluminum frames have good processability. In addition, traditional aluminum alloys are prone to burrs during the processing process and need deburring procedures; With the development of the photovoltaic industry and the progress of technology, the weight requirement for photovoltaic aluminum frames is getting higher and higher. Lightweight design can reduce the overall weight of photovoltaic modules, reduce transportation and installation costs, and improve the power generation efficiency of photovoltaic systems; As an important component in the field of renewable energy, the environmental protection performance of photovoltaic aluminum frames has also attracted much attention. Using recyclable aluminum alloy materials to manufacture photovoltaic aluminum frames can reduce environmental pollution and waste of resources.

[0005] Although 6005 aluminum alloy has relatively high strength and hardness, with the continuous increase in the size and weight of photovoltaic modules, the requirements for the strength and hardness of the frames are also getting higher and higher. In some extreme environments, such as under harsh weather conditions like strong winds and heavy snow, frames with even higher strength may be required to ensure the safe operation of photovoltaic modules. Although aluminum alloy has good corrosion resistance, in some specific environments (such as high humidity and high salt spray), its corrosion resistance may be challenged, which may lead to problems such as corrosion and rust on the photovoltaic aluminum frames during use, thus affecting their service life and performance.

[0006] In addition, with the increasing global awareness of environmental protection, the requirements for the environmental performance of photovoltaic aluminum frames are also getting higher and higher. Traditional aluminum alloy production processes may cause certain environmental pollution and energy consumption, so there is a continuous need to seek more environmentally friendly and sustainable production processes and materials. Although aluminum alloy is a recyclable material, there may be some problems during the recycling process of photovoltaic aluminum frames, such as relatively high recycling costs and complex recycling processes, which may result in low recycling rates of photovoltaic aluminum frames, thus wasting resources and causing environmental pollution. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a high-strength, corrosion-resistant and easy-to-process aluminum alloy profile for photovoltaic frames. The aluminum alloy profile provided in this application has good milling and cutting processing performance, good mechanical properties, intergranular corrosion resistance, and good electrical and thermal conductivities.

[0008] In view of this, the present application provides a high-strength, corrosion-resistant and easy-to-process aluminum alloy profile for photovoltaic frames, which, by mass percentage, includes:

[0009] Si 0.70 - 1.25%, Mg 0.65 - 0.85%, Ti 0.02 - 0.06%, Cu 0.02 - 0.08%, Bi 0.8 - 1.5%, Sc 0.15 - 0.30%, Mn ≤ 0.05%, Cr ≤ 0.05%, Fe ≤ 0.2%, Zn ≤ 0.03%, with the balance being Al.

[0010] In some specific embodiments, the content of Si is 0.73 - 0.78%, or the content of Si is 0.95 - 1.25%.

[0011] In some specific embodiments, the content of Mg is 0.70 - 0.80%.

[0012] In some specific embodiments, the content of Bi is 0.9 - 1.2%, and / or the content of Sc is 0.18 - 0.26%.

[0013] In some specific embodiments, the content of Ti is 0.03 - 0.05%, and / or the content of Cu is 0.03 - 0.06%.

[0014] In some specific embodiments, the content of Mn is 0.02 - 0.04%, and / or the content of Cr is 0.02 - 0.04%.

[0015] In some specific embodiments, the content of Fe is ≤0.1%, and / or the content of Zn is ≤0.01%.

[0016] The present application also provides a method for preparing the aluminum alloy profile, comprising the following steps:

[0017] After proportioning according to the composition ratio, the mixed raw materials are melted and then cast to obtain an ingot;

[0018] The ingot is extruded to obtain an initial profile;

[0019] The initial profile is heat-treated to obtain an aluminum alloy profile.

[0020] In some specific embodiments, the heat treatment includes a solution treatment and an aging treatment carried out in sequence;

[0021] The temperature of the solution treatment is 500 - 550°C, the time is 1 - 5 h, and the cooling method is water cooling;

[0022] The temperature of the aging treatment is 150 - 200°C, and the time is 3 - 5 h.

[0023] In some specific embodiments, after the heat treatment, a surface treatment is further included, and the surface treatment includes the following acid sand treatment carried out in sequence:

[0024] Degreasing, water washing, pickling, water washing, alkali etching, water washing, neutralization, water washing, anodic oxidation, water washing, and sealing.

[0025] The present application provides a high-strength, corrosion-resistant, and easy-to-process aluminum alloy profile for a photovoltaic frame. By mass percentage, it includes: Si 0.70 - 1.25%, Mg 0.65 - 0.85%, Ti 0.02 - 0.06%, Cu 0.02 - 0.08%, Bi 0.8 - 1.5%, Sc 0.15 - 0.30%, Mn ≤0.05%, Cr ≤0.05%, Fe ≤0.2%, Zn ≤0.03%, and the balance is Al. By adding Bi and Sc, the aluminum alloy profile provided by the present application significantly improves the easy machinability of the aluminum alloy profile and simplifies the deburring process; at the same time, the adjustment of the contents of other alloy elements further improves the mechanical properties, corrosion resistance, electrical conductivity, and thermal conductivity of the aluminum alloy profile. Description of the Drawings

[0026] Figure 1 Metallographic photos of intergranular corrosion of the aluminum alloy profiles prepared in Example 1 and Comparative Example 1 of the present invention. Detailed implementation manners

[0027] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0028] In view of the requirements of the existing technology for the processing performance, mechanical properties and corrosion resistance of photovoltaic aluminum frames, the present application provides a high-strength, corrosion-resistant and easy-to-process aluminum alloy profile for photovoltaic frames. By adding Bi and Sc and further adjusting the contents of other alloy elements, the processing performance, mechanical properties and corrosion resistance of the aluminum alloy profile are improved. Specifically, an embodiment of the present invention discloses a high-strength, corrosion-resistant and easy-to-process aluminum alloy profile for photovoltaic frames, which includes, by mass percentage:

[0029] Si 0.70~1.25%, Mg 0.65~0.85%, Ti 0.02~0.06%, Cu 0.02~0.08%, Bi 0.8~1.5%, Sc 0.15~0.30%, Mn≤0.05%, Cr≤0.05%, Fe≤0.2%, Zn≤0.03%, with the balance being Al.

[0030] In the aluminum alloy profile provided by the present application, the content of Si is 0.70~1.25%. Specifically, the content of the Si is 0.73~0.78%, or the content of the Si is 0.95~1.25%. By way of example, the content of Si in the present application is 0.96%, 0.97%, 0.98%, 0.99%, 1.0%, 1.01%, 1.02%, 1.03%, 1.04%, 1.05%, 1.06%, 1.07%, 1.08%, 1.09%, 1.10%, 1.11%, 1.12%, 1.13%, 1.14%, 1.15%, 1.16%, 1.17%, 1.18%, 1.19%, 1.20%, 1.21%, 1.22%, 1.23%, 1.24%.

[0031] The content of Mg is 0.65~0.85%. Specifically, the content of Mg is 0.70~0.80%. By way of example, the content of Mg in the present application is 0.66%, 0.67%, 0.68%, 0.69%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%.

[0032] The content of Ti is 0.02% - 0.06%. Specifically, the content of Ti is 0.03% - 0.05%. For example, the content of Ti in this application is 0.04%.

[0033] The content of Cu is 0.02% - 0.08%. Specifically, the content of Cu is 0.03% - 0.06%. For example, the content of Cu in this application is 0.04%, 0.05%, 0.07%.

[0034] The content of Bi is 0.8% - 1.5%. Specifically, the content of Bi is 0.9% - 1.2%. For example, the content of Bi in this application is 1.0%, 1.1%, 1.3%, 1.4%.

[0035] The content of Sc is 0.15% - 0.30%. Specifically, the content of Sc is 0.18% - 0.26%. For example, the content of Sc is 0.16%, 0.17%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.27%, 0.28%, 0.29%.

[0036] The content of Mn ≤ 0.05%. Specifically, the content of Mn is 0.02% - 0.04%. For example, the content of Mn in this application is 0.01%, 0.03%. The content of Cr ≤ 0.05%. Specifically, the content of Cr is 0.02% - 0.04%. For example, the content of Cr in this application is 0.01%, 0.03%. The content of Fe ≤ 0.2%. Specifically, the content of Fe ≤ 0.1%. Zn ≤ 0.03%. Specifically, the content of Zn ≤ 0.01%.

[0037] This application also provides a preparation method of the above aluminum alloy profile, including the following steps:

[0038] After proportioning according to the composition ratio, melt the mixed raw materials and then pour them to obtain an ingot;

[0039] Extrude the ingot to obtain an initial profile;

[0040] Heat-treat the initial profile to obtain an aluminum alloy profile.

[0041] In the preparation method of the aluminum alloy profile, the preparation method of the ingot is carried out according to the method well-known to those skilled in the art, and this application does not make special restrictions on this.

[0042] The extrusion is a conventional extrusion process for those skilled in the art, and this application does not make special restrictions on this.

[0043] After obtaining the initial profile, it is heat-treated, and the heat treatment includes solution treatment and aging treatment carried out in sequence; the temperature of the solution treatment is 500 - 550 °C, and the time is 1 - 5 h. Specifically, the temperature of the solution treatment is 520 - 530 °C, and the time is 1 - 3 h; the cooling method is water cooling; the temperature of the aging treatment is 150 - 200 °C, and the time is 3 - 5 h. Specifically, the temperature of the aging treatment is 160 - 185 °C, and the time is 3.5 - 4.5 h. The aging is carried out by air cooling. During the process of air cooling after being taken out of the furnace, the high temperature inside the furnace contacts the outside air, forming air convection, accelerating the air cooling process of the initial profile and achieving the technological purpose of air cooling the initial profile. In the traditional aging process, after the initial profile reaches the holding time, it generally needs to go through an additional 20 - minute air cooling process inside the furnace before being taken out of the furnace.

[0044] According to the present invention, after the heat treatment, surface treatment is further included, and the surface treatment includes the following acid sand treatment carried out in sequence: degreasing, water washing, pickling, water washing, alkali etching, water washing, neutralization, water washing, anodic oxidation, water washing, and sealing.

[0045] The degreasing is preferably carried out in a degreasing tank, the pickling is preferably carried out in an acid etching tank, the alkali etching is preferably carried out in an alkali washing tank, the anodic oxidation is preferably carried out in an oxidation tank, and the sealing is preferably carried out in a sealing tank. Since the acid pickling tank has poor acidity and does not play a degreasing role, if the oil stains on the aluminum alloy profile are not treated in the degreasing tank, uneven patches will appear on the surface after acid etching, greatly reducing the appearance comfort. During this process, sufficient flowing water volume must be ensured, and sufficient water washing time must be guaranteed. The aluminum alloy profile must drip dry before entering the acid pickling tank to avoid contaminating the acid pickling tank with sulfuric acid.

[0046] For the acid pickling tank, during production, fluorine reacts with aluminum to form aluminum fluoride precipitate. The aluminum fluoride precipitate in the tank solution should be removed continuously or regularly to avoid affecting the sand surface effect. Before production, the tank solution is heated. Since the fluoride ion concentration in this tank is very high, when using a stainless steel pipe for heating, the steel pipe is easily corroded. Therefore, the heating coil is set in an (underground) chemical dosing tank. When not heating, the coil should be taken out. The reaction during production is an exothermic reaction. During continuous production, the tank solution does not need to be heated separately. The operation of this process achieves zero discharge of the tank solution, and it is an excellent technological process in terms of environmental protection. After pickling, it must go through two water washings and ensure that it is washed clean. Otherwise, fluoride ions will be brought into the alkali etching tank and react with aluminum ions to form white aluminum fluoride precipitate, making the alkali etching tank extremely turbid.

[0047] The alkali washing treatment time is about 2 minutes; after the pickling treatment, there is a layer of sticky substance on the surface of the aluminum alloy profile, which is removed by alkali washing. The neutralization is to neutralize the alkali solution remaining in the alkali washing process. The neutralization solution is preferably H2SO4. When the free sulfuric acid concentration is low, concentrated sulfuric acid is added. For every 245kg of concentrated sulfuric acid added, the free sulfuric acid concentration increases by 1g / L. The concentration of H2SO4 in the neutralization tank is 150~220g / L, and the neutralization time is 1~5min. The sealing is a green liquid compounded by metal nickel salt, complexing agent, buffer, dispersant, etc. Adjustment of the pH value of the bath liquid: when the pH value is high, exceeding 5.8, you can slowly and evenly add an appropriate amount of glacial acetic acid to lower the pH value to the normal range. When the pH value of the bath liquid is lower than 5.3, you can dilute an appropriate amount of WF-16-A with pure water and then add it evenly to increase the pH value. If the pH value is low, you can add a small amount of ammonia water in combination with WF-16-A to adjust it. When there are many impurities in the bath liquid and the sealing effect is poor, you need to clean the bath and update part of the bath liquid for treatment.

[0048] The water washing in each step is preferably performed twice. The degreasing includes H2SO4 with a concentration of 150-220 g / L, and specifically, the content of H2SO4 is 160-200 g / L. The pickling reagent includes NH4HF2, and specifically, the concentration of NH4HF2 is 35-45 g / L, and more specifically, the concentration of NH4HF2 is 38-42 g / L. The alkaline etching includes NaOH and Al 3+ Specifically, the concentration of NaOH is 30~60g / L, Al 3+ The concentration of NaOH is ≤65g / L. More specifically, the concentration of NaOH is 40~50g / L. 3+ The concentration of ≤45g / L. The anodic oxidation includes H2SO4 and Al 3+ Specifically, the concentration of H2SO4 is 150-170 g / L, specifically, the concentration of H2SO4 is 160 g / L; Al 3+ The concentration is ≤18g / L, specifically, Al 3+ The concentration of Ni is 15-17 g / L. 2+ , its concentration is 0.8~1.3g / L, specifically, Ni 2+ The concentration is 0.9~1.0g / L and its pH is 5.3~5.8.

[0049] The acid sand treatment makes the surface of the aluminum alloy profile more uniform and delicate, and enhances the corrosion resistance and aesthetics.

[0050] The machinability of the aluminum alloy profile provided by this application is significantly improved, enabling burr-free production during the processing of aluminum alloy frames. This not only simplifies the deburring process but also reduces the labor and time costs during production; the burr-free production process ensures the product quality of the photovoltaic aluminum frame, effectively avoiding problems such as scratches and deformation that may occur in the traditional deburring process, thus improving the overall quality and reliability of the product; the machinability of the aluminum alloy profile also indirectly promotes environmental protection and sustainable development. Burr-free production reduces the generation of waste materials and waste gases, reducing environmental pollution. At the same time, through optimized design and production processes, the utilization rate of the aluminum alloy profile can be further increased, reducing resource waste. The aluminum alloy profile provided by this application effectively improves the hardness of the alloy by precisely adjusting the contents of elements such as Si and Mg and adding elements such as Mn, Cr, Cu, Bi, and Sc. The aluminum alloy profile shows higher strength when resisting external forces, is not easily deformed or damaged, and its tensile strength has been significantly improved, which means that under the same load conditions, the aluminum alloy profile provided by this application can better withstand the tensile force and is not easily broken or fail.

[0051] Furthermore, the aluminum alloy profile provided by this application optimizes its thermal conductivity by adjusting the alloy composition. In a hotter use environment such as a desert, the aluminum alloy profile can transfer heat more effectively, reducing the internal stress of the material caused by temperature changes, thereby improving its stability and durability; the specially added Sc element and the optimized alloy composition enable the alloy profile to have higher thermal deformation resistance under high-temperature conditions; this ensures that the photovoltaic aluminum frame can still maintain good shape and dimensional stability under extreme climate conditions, thus ensuring the safety and performance of the photovoltaic module.

[0052] By optimizing the alloy composition and adding the Sc element, the oxidation resistance of the aluminum alloy profile provided by this application has also been significantly improved, enabling the photovoltaic aluminum frame to better resist oxidation corrosion during long-term use and extending its service life.

[0053] The aluminum alloy profile provided by this application can be applied to the frame of photovoltaic modules and has a broader application prospect in the field of photovoltaic aluminum frames. In addition to traditional rooftop and ground photovoltaic power stations, it can also be considered for application in other photovoltaic products with higher requirements for frame quality, such as solar street lights and solar chargers.

[0054] To further understand the present invention, the following examples are used to illustrate in detail the high-strength, corrosion-resistant, and easy-to-process aluminum alloy profile for photovoltaic frames and its preparation method provided by the present invention. The protection scope of the present invention is not limited by the following examples.

[0055] Example 1

[0056] A high-strength, corrosion-resistant and easy-to-process aluminum alloy profile, the composition of which is shown in Table 1:

[0057] Mix the pure aluminum ingot and the master alloy of other raw materials according to the composition ratio in Table 1, then melt and pour to obtain an aluminum alloy ingot;

[0058] Perform solution treatment on the initial profile obtained by extruding the ingot, and then perform aging treatment after water cooling; among them, the solution treatment temperature is 530 °C and the time is 1 h, and the aging treatment temperature is 185 °C and the time is 4.5 h;

[0059] Perform acid sand treatment on the profile after aging treatment to obtain an aluminum alloy profile;

[0060] Among them, the specific process of acid sand treatment is: degreasing → water washing → water washing → acid etching → water washing → water washing → alkali etching → water washing → water washing → neutralization → water washing → water washing → anodic oxidation → hot water washing → water washing → sealing → water washing → water washing; the process parameters involved in the above steps are shown in Table 2;

[0061] Perform machining on the aluminum alloy profile to obtain an aluminum frame profile for photovoltaic use.

[0062] Table 1 Composition data table of the aluminum alloy profile in this embodiment (wt%)

[0063]

[0064] Table 2 Parameter data table of acid sand treatment in this embodiment

[0065]

[0066] Comparative Example 1

[0067] The preparation method is the same as that of Example 1, the difference is that: the composition of the aluminum alloy profile is adjusted, as shown in Table 3;

[0068] Table 3 Composition data table of the aluminum alloy profile in this comparative example (wt%)

[0069]

[0070] Perform performance testing on the aluminum alloy profiles of the above examples and comparative examples, including the following aspects:

[0071] 1. High-speed milling and drilling tests

[0072] (1) High-speed milling (milling speed 200 m / min, high-cobalt high-speed steel tool)

[0073] For the chips formed by high-speed milling of two aluminum alloy profiles, it can be observed that: the chips of the aluminum alloy profile prepared in Example 1 are relatively fine, with an average particle size of about 1 mm; the average particle size of the chips of the aluminum alloy profile prepared in Comparative Example 1 is 2 - 3 mm, slightly larger than that in Example 1. From the scanning electron microscope photos of the machined surface, it can be seen that: the milling surface of the aluminum alloy profile prepared in Comparative Example 1 shows obvious scratches and is uneven, while the surface of the aluminum alloy profile prepared in Example 1 is relatively smooth and flat. In summary, comparing the two alloys, the milling effect of the aluminum alloy profile prepared in Example 1 is the best.

[0074] (2)High-speed drilling

[0075] In actual production, the working environment of drilling is most likely to cause the phenomenon of tool entanglement. Therefore, drilling tests were carried out and the drill chips were collected to evaluate the drilling performance of the alloys. It can be observed from the drill chips of the two alloys that: the drill chips of the aluminum alloy profile prepared in Example 1 are in powder form and there is no tool entanglement phenomenon, while the drill chips of the aluminum alloy profile prepared in Comparative Example 1 are long and complete and completely wound together with almost no chip breaking; therefore, the drilling effect of the aluminum alloy profile prepared in Example 1 is the best, and the drilling performance of the aluminum alloy profile prepared in Comparative Example 1 is poor.

[0076] 2. Ordinary milling and drilling tests

[0077] (1)Low-speed milling (milling speed 30 m / min, ordinary milling cutter)

[0078] In order to study the chip breaking mechanism of the alloys, ordinary cutting tests of the alloys were also carried out. It can be observed from the chip morphology formed by ordinary milling of the two alloy profiles that: the chips of the aluminum alloy profile prepared in Example 1 are curled into needle shapes and are relatively small in size, while the chips of the aluminum alloy profile prepared in Comparative Example 1 are in the shape of sheets with a size of 3 mm × 3 mm. From the scanning electron microscope photos of the machined surface, it can be seen that: the surface of the aluminum alloy profile prepared in Example 1 is relatively smooth, while the surface of the aluminum alloy profile prepared in Comparative Example 1 has neat and deep tool marks.

[0079] (2)Ordinary drilling

[0080] The phenomenon of tool entanglement in the drilling of the two alloy profiles is not serious. It can be observed from the drilling shape that: the drill chips of the alloy profile prepared in Example 1 are relatively small, while the drill chips of the alloy profile prepared in Comparative Example 1 are thick and irregular in shape.

[0081] Analyzing the above milling and drilling results, the specific reasons are as follows:

[0082] Adjustments to the basic elements (Si, Mg, Mn, Cr, Cu) have an impact on the physical and chemical properties of aluminum alloy profiles. However, these adjustments are made to meet specific mechanical or corrosion resistance requirements, rather than directly targeting machinability. The addition of bismuth (Bi) and scandium (Sc) has specific effects on the properties of aluminum alloy profiles. As a metal with low melting point and low hardness, bismuth (Bi) may play a role in lubricating and reducing friction during cutting, reducing the resistance and temperature during cutting, thereby improving machinability and reducing the generation of burrs. Scandium (Sc) can affect the microstructure of the material, significantly improving the strength and thermal stability of aluminum alloy profiles, and also having an impact on the deformation and fracture behavior of the profiles during cutting, thus indirectly affecting machinability.

[0083] 3. Mechanical Properties

[0084] The tensile strength, yield strength, and elongation of the aluminum alloy profile prepared in Comparative Example 1 are 274 MPa, 243 MPa, and 11.3% respectively. The tensile strength, yield strength, and elongation of the aluminum alloy profile prepared in Example 1 are 296 MPa, 274 MPa, and 11.9% respectively. Compared with the aluminum alloy profile prepared in Comparative Example 1, the tensile strength, yield strength, and elongation of the aluminum alloy profile prepared in Example 1 are increased by 8.0%, 12.8%, and 5.3% respectively, with a relatively obvious improvement.

[0085] For the analysis of the above mechanical properties, the specific reasons are as follows:

[0086] ① Alloy element adjustment

[0087] Adjustment of the content of silicon (Si) and magnesium (Mg): The content range of Si in the aluminum alloy profile prepared in Example 1 is adjusted to 0.70 - 1.25%, compared with 0.60 - 0.90% of the aluminum alloy profile prepared in Comparative Example 1. This adjustment helps to optimize the crystal structure of the aluminum alloy profile and improve mechanical properties. The content of Mg in the aluminum alloy profile prepared in Example 1 also increases, with a range of 0.65 - 0.85%, while that in Comparative Example 1 is 0.40 - 0.60%. As a basic strengthening element in aluminum alloy profiles, the increase in its content helps to improve the strength and hardness of aluminum alloy profiles.

[0088] Minor adjustment of manganese (Mn), chromium (Cr), and copper (Cu): The content of Mn, Cr, and Cu in the aluminum alloy profile prepared in Example 1 is lower or slightly adjusted compared with that in the aluminum alloy profile prepared in Comparative Example 1. This adjustment helps to reduce the adverse effects of impurity elements on the mechanical properties of aluminum alloy profiles while maintaining the stability and corrosion resistance of aluminum alloy profiles.

[0089] ② Special added elements

[0090] Addition of Bismuth (Bi): 0.8% - 1.5% of Bi was specially added to the aluminum alloy profiles prepared in Example 1. Bi can act as a modifier in the aluminum alloy profiles to refine the grains, reduce casting defects, and thus improve the mechanical properties and processing performance of the aluminum alloy profiles.

[0091] Addition of Scandium (Sc): Sc is a rare earth element. Adding a small amount of Sc to the aluminum alloy profiles can form compounds such as Al3Sc. These compounds have high thermal stability and high hardness, and can effectively improve the strength and heat resistance of the aluminum alloy profiles.

[0092] ③ Comprehensive effect

[0093] Grain refinement: The addition of elements such as Bi and Sc helps to refine the grains of the alloy, increase the quantity and quality of grain boundaries, and thus enhance the mechanical properties and toughness of the aluminum alloy profiles.

[0094] Solid solution strengthening: Elements such as Mg, Si, and Cu form solid solutions in the aluminum alloy, and the strength of the aluminum alloy profiles is improved through solid solution strengthening.

[0095] Precipitation strengthening: During the heat treatment process, certain elements in the alloy form precipitation phases. These precipitation phases play a role in hindering the dislocation slip process, thereby improving the strength of the aluminum alloy profiles.

[0096] 4. Intergranular corrosion

[0097] (1) Data

[0098] The aluminum alloy profiles prepared in Example 1 and Comparative Example 1 were tested for intergranular corrosion, and the results are shown in Table 4;

[0099] Table 4 Data table of intergranular corrosion results of aluminum alloy profiles prepared in examples and comparative examples

[0100]

[0101] Note: The intergranular corrosion was carried out according to the evaluation method for intergranular corrosion sensitivity of aluminum alloys GB / T 7998 - 2023, that is, the specimens were pretreated according to the above standard requirements, immersed in the test solution at an experimental temperature of 30°C for 6 h with stirring; the test method used was the corrosion depth method, the water conductivity was 18.25 μS / cm, the test temperature was 30°C, and the test time was 6 h. The instruments used in this process included: LC - WB_4 + magnetic constant temperature water bath YONZ - CS - SB - 018 & XSR205DU analytical balance YONZ - CS - SB - 016 & BX53M metallurgical microscope.

[0102] (2) Pictures

[0103] After grinding and polishing the specimens of the aluminum alloy profiles prepared in Example 1 and Comparative Example 1 after corrosion, and then conducting metallographic inspection, the results are as Figure 1 shown, and the following observation results are obtained:

[0104] Aluminum alloy profile prepared in Comparative Example 1 (right figure): The corrosion of the aluminum alloy profile prepared in Comparative Example 1 is very obvious under the metallographic microscope. It can be clearly seen that the grain boundary region of the aluminum alloy profile has suffered relatively severe erosion, forming obvious corrosion gullies and corrosion pits; these corrosion characteristics indicate that in the corrosion environment, the grain boundaries of the aluminum alloy profile prepared in Comparative Example 1 have become the preferential channels for corrosion, resulting in the occurrence of intergranular corrosion.

[0105] Aluminum alloy profile prepared in Example 1 (left figure): Almost no obvious corrosion traces can be seen on the metallographic photograph of the aluminum alloy profile prepared in Example 1; the grains and grain boundaries of the aluminum alloy profile remain relatively intact, without obvious corrosion gullies or corrosion pits; this indicates that under the same corrosion conditions, the aluminum alloy profile prepared in Example 1 has significantly better corrosion resistance than the original aluminum alloy profile prepared in Comparative Example 1 and can effectively resist intergranular corrosion and other forms of corrosion.

[0106] Through the metallographic inspection of the specimens of the aluminum alloy profiles prepared in Example 1 and Comparative Example 1 after corrosion, the significant difference in corrosion resistance between the two can be intuitively seen; due to its unique composition and microstructure, the aluminum alloy profile prepared in Example 1 exhibits higher intergranular corrosion resistance.

[0107] (3) Cause analysis

[0108] Aluminum alloy profile prepared in Comparative Example 1: The aluminum alloy profile prepared in Comparative Example 1 shows a relatively deep corrosion depth (43.86 μm) and a relatively high corrosion level (level 3) in the intergranular corrosion test; this is because some elements (such as Cu, Fe, etc.) in the alloy segregate along the grain boundaries during the heat treatment process, forming microcells for electrochemical corrosion, resulting in the occurrence of intergranular corrosion; in addition, the microstructure of the alloy (such as grain size, grain boundary characteristics, etc.) also affects the sensitivity to intergranular corrosion.

[0109] Aluminum alloy profile prepared in Example 1: The aluminum alloy profile prepared in Example 1 shows general corrosion in the intergranular corrosion test and has no clear corrosion level; this indicates that the intergranular corrosion resistance of the aluminum alloy profile prepared in Example 1 has been significantly improved, and the addition of Bi plays a key role. The Bi element improves the corrosion resistance by affecting the microstructure of the alloy (such as refining grains, reducing grain boundary defects, etc.). In addition, the addition of Bi also changes the distribution and state of other elements in the aluminum alloy profile, thereby reducing the tendency of intergranular corrosion.

[0110] 5. Conductivity and thermal conductivity tests

[0111] (1)Data

[0112] The aluminum alloy profiles prepared in Example 1 and the aluminum alloy profiles prepared in Comparative Example 1 were tested for electrical conductivity and thermal conductivity. The results are shown in Table 5:

[0113] Table 5 Data table of electrical conductivity and thermal conductivity of aluminum alloy profiles prepared in Example 1 and Comparative Example 1

[0114]

[0115] As can be seen from Table 5, the thermal conductivity and electrical conductivity of the aluminum alloy profiles prepared in Comparative Example 1 are 27.8 ms / m and 166.3 W / (m·K) respectively, and the thermal conductivity and electrical conductivity of the aluminum alloy profiles prepared in Example 1 are 31.5 ms / m and 189.5 W / (m·K) respectively; compared with the aluminum alloy profiles prepared in Comparative Example 1, the thermal conductivity and electrical conductivity of the aluminum alloy profiles prepared in Example 1 increased by 13.3% and 14.0% respectively.

[0116] (2)Cause analysis

[0117] ① Optimization of alloy composition

[0118] Adjustment of the contents of silicon (Si) and magnesium (Mg): The contents of Si and Mg in the aluminum alloy profiles prepared in Example 1 were adjusted compared with those in the aluminum alloy profiles prepared in Comparative Example 1. This adjustment helps to optimize the microstructure of the alloy, reduce impurities and defects, and thus improve the thermal conductivity and electrical conductivity;

[0119] Reduction of impurity elements: The contents of impurity elements such as Mn, Cr, Fe, Ti, and Cu in the aluminum alloy profiles prepared in Example 1 were lower than those in the aluminum alloy profiles prepared in Comparative Example 1. These impurity elements will reduce the thermal conductivity and electrical conductivity of the aluminum alloy profiles. Therefore, their reduction helps to improve the above properties;

[0120] ② Influence of specially added elements

[0121] Addition of bismuth (Bi): Bi can be used as an effective grain refiner in aluminum alloy profiles, which can refine the grains and reduce the defects at the grain boundaries, thus improving the thermal conductivity and electrical conductivity;

[0122] Addition of scandium (Sc): Sc is a rare earth element. It can form stable compounds in aluminum alloy profiles, such as Al3Sc. These compounds have high thermal stability and high electrical conductivity. The addition of Sc not only improves the strength of the aluminum alloy profiles, but also helps to improve the thermal conductivity and electrical conductivity;

[0123] ③ Improvement of microstructure

[0124] The aluminum alloy profile prepared in Example 1 has improved the microstructure of the alloy by optimizing the alloy composition and adding special elements. The refinement of grains, the reduction of defects, and the formation of stable compounds all contribute to improving the thermal conductivity and electrical conductivity of the aluminum alloy profile.

[0125] ④Combined effect

[0126] The optimization of the alloy composition, the influence of the specially added elements, and the improvement of the microstructure act together, making the aluminum alloy profile prepared in Example 1 have a significant improvement in thermal conductivity and electrical conductivity compared with the aluminum alloy profile prepared in Comparative Example 1.

[0127] Example 2

[0128] The preparation method is the same as that in Example 1, except that: the composition of the aluminum alloy profile is adjusted, as shown in Table 6 specifically;

[0129] Table 6 Composition data table of the aluminum alloy profile in this example (wt%)

[0130]

[0131] Example 3

[0132] The preparation method is the same as that in Example 1, except that: the composition of the aluminum alloy profile is adjusted, as shown in Table 7 specifically;

[0133] Table 7 Composition data table of the aluminum alloy profile in this example (wt%)

[0134]

[0135] Example 4

[0136] The preparation method is the same as that in Example 1, except that: the composition of the aluminum alloy profile is adjusted, as shown in Table 8 specifically;

[0137] Table 8 Composition data table of the aluminum alloy profile in this example

[0138]

[0139] Example 5

[0140] The preparation method is the same as that in Example 1, except that: the composition of the aluminum alloy profile is adjusted, as shown in Table 9 specifically;

[0141] Table 9 Composition data table of the aluminum alloy profile in this example (wt%)

[0142]

[0143] Example 6

[0144] The preparation method is the same as that of Example 1, except that the composition of the aluminum alloy profile is adjusted, as shown in Table 10 specifically;

[0145] Table 10 Composition data table of the aluminum alloy profile in this example (wt%)

[0146]

[0147] The mechanical properties, intergranular corrosion, electrical conductivity, and thermal conductivity of the aluminum alloy profiles in the above examples were tested, and the results are shown in Table 11:

[0148] Table 11 Performance data table of the aluminum alloy profiles prepared in the examples

[0149]

[0150] Note: General corrosion in the above table indicates that there are no obvious corrosion marks; "——" in the corrosion level indicates that since there are no obvious corrosion marks, the corrosion level is lower than the lowest corrosion grade.

[0151] The descriptions of the above examples are only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0152] The above descriptions of the disclosed embodiments enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-strength, corrosion-resistant and easily machined aluminum alloy profile for a photovoltaic frame, characterized in that, In terms of mass percentage, it includes: Si 0.70~1.25%, Mg 0.65~0.85%, Ti 0.02~0.06%, Cu 0.02~0.08%, Bi 0.8~1.5%, Sc0.15~0.30%, Mn≤0.05%, Cr≤0.05%, Fe≤0.2%, Zn≤0.03%, Al balance.

2. The aluminum alloy profile according to claim 1, wherein The Si content is 0.73-0.78%, or the Si content is 0.95-1.25%.

3. The aluminum alloy profile according to claim 1, characterized in that, The Mg content is 0.70-0.80%.

4. The aluminum alloy profile according to claim 1, wherein, The Bi content is 0.9-1.2%, and / or the Sc content is 0.18-0.26%.

5. The aluminum alloy profile according to claim 1, characterized in that, The Ti content is 0.03-0.05%, and / or the Cu content is 0.03-0.06%.

6. The aluminum alloy profile according to claim 1, wherein, The Mn content is 0.02-0.04%, and / or the Cr content is 0.02-0.04%.

7. The aluminum alloy profile according to claim 1, wherein The Fe content is ≤0.1%, and / or the Zn content is ≤0.01%.

8. The method for preparing the aluminum alloy profile according to any one of claims 1 to 7, comprising the following steps: After mixing the ingredients according to the composition ratio, the mixed raw materials are melted and then poured to obtain an ingot; Extruding the ingot to obtain an initial profile; The initial profile is heat treated to obtain an aluminum alloy profile.

9. The preparation method according to claim 8, characterized in that, The heat treatment includes solution treatment and aging treatment performed sequentially; The temperature of the solution treatment is 500-550°C, the time is 1-5h, and the cooling method is water cooling; The aging treatment is carried out at a temperature of 150-200° C. and for a time of 3-5 hours.

10. The preparation method according to claim 9, characterized in that, The heat treatment also includes surface treatment, which includes the following acid sand treatments performed in sequence: Degreasing, water washing, pickling, water washing, alkali etching, water washing, neutralization, water washing, anodizing, water washing, and sealing.

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