High-strength aluminum alloy for solar photovoltaic frame and preparation method thereof

Abstract

The application relates to the technical field of aluminum alloy materials, and discloses a high-strength aluminum alloy for a solar photovoltaic frame and a preparation method thereof; in the aluminum alloy melt, nano TiN / Ti refiner is added, meanwhile, phytic acid is added into a polyaniline skeleton in the form of doped acid, a three-dimensional network structure of -Si-O-Si- is introduced through the doping of silane, and the aluminum alloy after micro-arc oxidation is subjected to surface coating through a dip-coating method, so that the prepared aluminum alloy has fine and uniform crystal grains, the slip resistance during material deformation is improved, and the tensile strength of the aluminum alloy is improved; the phytic acid in the phosphatized polyaniline hybrid sol has 6 phosphate groups and 12 hydroxyl groups, has strong chelation capacity, can react with the hydrolyzed silane to generate -P-O-Si- bonds, makes the coating have an organic / inorganic hybrid structure, forms a smooth and dense passivation film on the surface of the aluminum alloy, can resist elastic-plastic deformation, and improves the strength, corrosion resistance and wear resistance of the aluminum alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy materials, in particular to a high-strength aluminum alloy for solar photovoltaic frames and a preparation method thereof. BACKGROUND

[0002] Photovoltaic solar aluminum alloy profiles are mainly used on photovoltaic solar panels as frames and play a supporting role. With the promotion and use of clean energy, the utilization rate of solar energy as a low-carbon renewable energy source is increasing. The solar aluminum frame profile, as one of the solar components, is in increasing demand due to its low cost and convenient use. The quality of the frame aluminum alloy directly affects the overall yield of the product and the product quality of the end customer, especially the mechanical properties of the product, which will directly affect the use function of the frame. The solar frame aluminum profile made of aluminum alloy is prone to deformation and surface scratches during use, and has insufficient corrosion resistance.

[0003] The existing market uses aluminum alloy as the raw material for the frame of the photovoltaic panel, such as 6005 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 6082 aluminum alloy, etc. However, the current focus on photovoltaic frames is on the production efficiency and size optimization of aluminum frames, and relatively little research has been done on the strength of aluminum alloys. In the prior art, the strength of aluminum alloys is generally improved by simply increasing the content of alloying elements, but this method often means deterioration of wear resistance and corrosion resistance. For example, Chinese patent CN111996423A discloses an aluminum alloy material and a method for producing a frame aluminum profile, which uses increasing the content of alloying elements Mg and Si to promote aging precipitation, but the mechanical properties are comparable to traditional 6005 alloy, and the extrusion performance and online quenching performance of the alloy are also reduced, making it difficult to achieve low-cost and high-efficiency production.

[0004] The junction of the solar photovoltaic panel and the frame is difficult to clean when there is snow accumulation or rain, and the invading rain and snow water can cause corrosion of the frame over a long period of time. The existing technology usually uses anodic oxidation to improve the corrosion resistance of the surface, but the oxide film generated by single anodic oxidation does not perform well in a humid environment, which can cause pitting corrosion of the aluminum alloy and possibly cause the photovoltaic panel frame to break, thereby affecting the service life of the photovoltaic panel. Surface treatment techniques are also used to improve the surface properties of aluminum alloys, such as using chromate technology to passivate aluminum alloys, which is simple and low in cost, but Cr is a highly toxic substance that seriously harms the human body and the environment. The present application aims to use a nano-TiN / Ti refiner to refine the aluminum alloy liquid, optimize the preparation process, and further use phytic acid and aniline as monomers to prepare a corrosion-resistant and wear-resistant hybrid sol. The aluminum alloy material obtained by dip-coating has excellent comprehensive performance and broadens its application in solar photovoltaic frames. SUMMARY

[0005] Therefore, the application aims to provide a high-strength aluminum alloy for solar photovoltaic frames and a preparation method thereof, which solves the problems of poor strength, poor corrosion resistance and short service life of the existing aluminum alloy for solar photovoltaic frames.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The high-strength aluminum alloy for solar photovoltaic frames comprises the following components in mass percentage: 0.52-0.65% of Si, 0.58-0.73% of Mg, 0.2-0.35% of Fe, 0.08-0.15% of Cu, 0.02-0.05% of Mn, 0.1-0.9% of grain refiner, and the balance of Al, with the total amount being 100%.

[0008] The preparation method of the high-strength aluminum alloy for solar photovoltaic frames is as follows.

[0009] Step (1): Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al according to mass percentage are placed in a melting furnace for melting, after complete melting, the mixed liquid is quickly analyzed, and metal elements are added to adjust the chemical composition of the target aluminum alloy, slag is removed, argon is removed, and the aluminum alloy liquid is obtained after standing for 10-25 min.

[0010] Step (2): The grain refiner is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar, first heated to 580-650℃ at a rate of 50-80℃ / h and kept for 2-4h, then heated to 660-750℃ at a rate of 120-150℃ / h and kept for 1-3h, then cooled to 200-300℃ by strong wind, argon is removed, and the aluminum alloy substrate is obtained after standing for 20-40 min and casting.

[0011] Step (3): The aluminum alloy substrate in step (2) is polished with sandpaper, sequentially immersed in ethanol, acetone and deionized water for ultrasonic cleaning, and a pretreated aluminum alloy substrate is obtained, then the stainless steel is used as the cathode, the pretreated aluminum alloy substrate is used as the anode, and the micro-arc oxidation electrolyte is used for immersion, the micro-arc oxidation treatment is performed, the bidirectional pulse alternating current is used, the current density is 6-10A / dm 2 , the frequency is 80-120Hz, the duty cycle is 50-70%, the time is 20-40min, and the micro-arc oxidation aluminum alloy substrate is obtained.

[0012] Step (4): after polishing, polishing and cleaning the micro-arc oxidation aluminum alloy substrate obtained in step (3), first, sealing the pores in the cerium salt solution, then, placing in the phosphating polyaniline hybrid sol with a mass fraction of 0.5-4.5%, at a speed of 1-3cm / min, at 50-65℃, for 5-7 times of dip-coating, then, placing in the electric furnace, heating to 90-120℃, and keeping for 2-5h, to obtain the high-strength aluminum alloy for solar photovoltaic frame.

[0013] Further, the grain refiner is TiN / Ti refiner, and the preparation method is as follows: 100g of micron Ti powder and 8-12g of TiN particles are placed in a high-energy ball mill, and ball milling is carried out at 1500-2000r / min for 20-35min to obtain the nano TiN / Ti refiner.

[0014] Further, the melting temperature is 700-800℃.

[0015] Further, the micro-arc oxidation electrolyte in step (3) is an alkaline electrolyte, and the preparation method is as follows: sodium hydroxide, sodium silicate and sodium hexametaphosphate are dissolved in 1L of deionized water according to a mass ratio of 2:5:3, and the obtained micro-arc oxidation electrolyte is obtained after uniform stirring.

[0016] Further, the preparation method of the cerium salt solution in step (4) is as follows: cerium nitrate, hydrogen peroxide and boric acid are dissolved in 1L of deionized water according to a mass ratio of 10:15:1, and the obtained cerium salt solution is obtained after uniform stirring.

[0017] Further, the preparation method of the phosphating polyaniline hybrid sol in step (4) is as follows: under a nitrogen atmosphere, phytic acid and deionized water are added to a reaction flask, stirred and dissolved, then, aniline monomer and ammonium persulfate are added, reacted at 0-10℃ for 1-3h, sodium hydroxide is added to adjust the pH, 3-aminopropyltrimethoxysilane is added, heated to 35-50℃ and reacted for 0.5-2h, filtered, washed with deionized water until neutral, and the phosphating polyaniline hybrid sol is obtained.

[0018] Further, the mass ratio of phytic acid, deionized water, aniline monomer, ammonium persulfate and 3-aminopropyltrimethoxysilane is (2.1-2.4):(10-20):1:(2.5-2.8):(1-1.5).

[0019] Further, the pH is adjusted to 7-8.5.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The application obtains the high-strength aluminum alloy for solar photovoltaic frame by adding nano TiN / Ti refiner in aluminum alloy melt, optimizing the composition, using strong air cooling process to replace the conventional quenching process, obtaining the aluminum alloy substrate and carrying out micro-arc oxidation treatment, putting the phytic acid into the polyaniline bone in the form of doped acid, introducing the -Si-O-Si- three-dimensional inorganic network framework by the doping of silane to obtain the phosphatized polyaniline hybrid sol, using the dip-coating method to carry out the surface coating on the aluminum alloy after micro-arc oxidation, and obtaining the high-strength aluminum alloy for solar photovoltaic frame.

[0022] After the nano TiN / Ti refiner is added in the aluminum melt, a layer of TiAl3 is attached to the surface of the particles, TiN has the same face-centered cubic crystal structure as Al and can directly act as the heterogeneous nucleation core of Al to form a large number of dispersed particles, promote nucleation, refine grains, reduce segregation, accelerate the aging process and enhance the aging strengthening effect; meanwhile, the difference in wettability and thermal conductivity between TiN / Ti and the aluminum melt causes TiN / Ti to be pushed to the solid-liquid interface at the front of the dendrite growth during the solidification process, thereby inhibiting the growth of dendrites and further refining the aluminum alloy grains; the small and uniform aluminum alloy grains make the intergranular second phase small and dispersed, increase the total area of the grain boundary, improve the sliding resistance of the material during deformation, and further improve the tensile strength of the aluminum alloy.

[0023] The ceramic film can be grown in situ on the aluminum alloy substrate after micro-arc oxidation, has good compression resistance, and the surface coating has a flexible carbon chain that can be adjusted through its own chain or conformation change under certain stress conditions, effectively overcoming the problem that the coating is easily separated from the substrate and can withstand a large external pressure; the phytic acid in the phosphatized polyaniline hybrid sol has six phosphate groups and 12 hydroxyl groups, has strong chelating ability, and can be attached to the surface of the substrate by forming aluminum phytate with chair conformation and introducing the -Si-O-Si- three-dimensional inorganic network framework through the doping of silane. 3+ In addition, the P-OH in the phytic acid molecule reacts with the -Si-OH- generated after the hydrolysis of silane to form a -P-O-Si- bond, so that the coating has an organic / inorganic hybrid structure, the cavities on the surface of the aluminum alloy after micro-arc oxidation are effectively filled, a smooth and dense passivation film is generated on the surface of the alloy, which can resist elastic-plastic deformation and improve the strength, corrosion resistance and wear resistance of the aluminum alloy. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be specifically and detailedly described below. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the principles of the application, and these modifications and improvements should also be regarded as falling within the protection scope of the application.

[0025] The preparation method of the nano TiN / Ti refiner is as follows: 100 g of micron Ti powder and 10 g of TiN particles are placed in a high-energy ball mill, and ball milling is performed at 1800 r / min for 25 min to obtain the nano TiN / Ti refiner.

[0026] The preparation method of the micro-arc oxidation electrolyte is as follows: sodium hydroxide, sodium silicate and sodium hexametaphosphate are dissolved in 1 L of deionized water according to a mass ratio of 2:5:3, and the micro-arc oxidation electrolyte obtained after uniform stirring is obtained.

[0027] The preparation method of the cerium salt solution is as follows: cerium nitrate, hydrogen peroxide and boric acid are dissolved in 1 L of deionized water according to a mass ratio of 10:15:1, and the cerium salt solution obtained after uniform stirring is obtained.

[0028] Example 1

[0029] (1) Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al are placed in a melting furnace for melting, and the melting temperature is 750℃. After complete melting, the mixed liquid is quickly analyzed, and metal elements are added to adjust the mass ratio of Si to 0.62%, Mg to 0.68%, Fe to 0.25%, Cu to 0.12%, Mn to 0.4% and Al to 97.83%. Then, slagging, argon degassing and standing for 20 min are performed to obtain an aluminum alloy liquid.

[0030] (2) The nano TiN / Ti refiner with a mass ratio of 0.1% is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar. First, the temperature is increased to 620℃ at a rate of 65℃ / h and kept for 3h, then the temperature is increased to 700℃ at a rate of 140℃ / h and kept for 2h, and then it is cooled to 250℃ by strong wind, argon degassing and standing for 30 min, and then it is cast into a shaped aluminum alloy substrate.

[0031] Example 2

[0032] (1) Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al are placed in a melting furnace for melting, and the melting temperature is 800℃. After complete melting, the mixed liquid is quickly analyzed, and metal elements are added to adjust the mass ratio of Si to 0.52%, Mg to 0.58%, Fe to 0.2%, Cu to 0.08%, Mn to 0.05% and Al to 98.27%. Then, slagging, argon degassing and standing for 10 min are performed to obtain an aluminum alloy liquid.

[0033] (2) The nano-TiN / Ti refiner with a mass ratio of 0.3% is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar, first heated to 650°C at 80°C / h, and then heated to 750°C at 150°C / h for 1 h, and then cooled to 300°C by strong wind, argon degassing, and standing for 20 min, and then cast into a shape to obtain an aluminum alloy base material.

[0034] Example 3

[0035] (1) Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al are placed in a melting furnace for melting, the melting temperature is 700°C, after complete melting, the mixed liquid is quickly analyzed, metal elements are added to adjust the mass ratio of Si to 0.65%, Mg to 0.73%, Fe to 0.35%, Cu to 0.15%, Mn to 0.02% and Al to 97.6%, then slagging, argon degassing, and standing for 25 min to obtain an aluminum alloy liquid.

[0036] (2) The nano-TiN / Ti refiner with a mass ratio of 0.5% is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar, first heated to 580°C at 50°C / h, and then heated to 660°C at 120°C / h for 3 h, and then cooled to 200°C by strong wind, argon degassing, and standing for 40 min, and then cast into a shape to obtain an aluminum alloy base material.

[0037] Example 4

[0038] (1) Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al are placed in a melting furnace for melting, the melting temperature is 720°C, after complete melting, the mixed liquid is quickly analyzed, metal elements are added to adjust the mass ratio of Si to 0.6%, Mg to 0.7%, Fe to 0.3%, Cu to 0.1%, Mn to 0.05% and Al to 97.55%, then slagging, argon degassing, and standing for 15 min to obtain an aluminum alloy liquid.

[0039] (2) The nano-TiN / Ti refiner with a mass ratio of 0.7% is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar, first heated to 600°C at 70°C / h, and then heated to 700°C at 135°C / h for 2 h, and then cooled to 280°C by strong wind, argon degassing, and standing for 35 min, and then cast into a shape to obtain an aluminum alloy base material.

[0040] Example 5

[0041] (1) Put Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al into a smelting furnace for melting, the melting temperature is 760℃, after complete melting, take the mixed liquid for rapid analysis, add metal elements to adjust to 0.65% of Si, 0.65% of Mg, 0.3% of Fe, 0.15% of Cu, 0.03% of Mn and 97.32% of Al by mass fraction, then perform slagging, argon degassing, and stand for 25 min to obtain an aluminum alloy liquid.

[0042] (2) Wrap 0.9% of nano TiN / Ti refiner by mass fraction with aluminum foil and press into the aluminum alloy liquid in step (1) with bell jar, first heat to 620℃ at 60℃ / h and keep for 4h, then heat to 750℃ at 150℃ / h and keep for 3h, then cool to 300℃ with strong wind, argon degassing, stand for 40 min, and cast into shape to obtain an aluminum alloy base material.

[0043] Comparative Example 1

[0044] Put Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al into a smelting furnace for melting, the melting temperature is 750℃, after complete melting, take the mixed liquid for rapid analysis, add metal elements to adjust to 0.62% of Si, 0.68% of Mg, 0.25% of Fe, 0.12% of Cu, 0.4% of Mn and 97.83% of Al by mass fraction, then perform slagging, argon degassing, and stand for 20 min to obtain an aluminum alloy liquid, first heat to 620℃ at 65℃ / h and keep for 3h, then heat to 700℃ at 140℃ / h and keep for 2h, then cool to 250℃ with strong wind, argon degassing, stand for 30 min, and cast into shape to obtain an aluminum alloy base material.

[0045] Average grain size test: the aluminum alloy base materials prepared in Examples 1-5 and Comparative Example 1 were analyzed for grain size using Photoshop 7.0 and Image-Pro Plus 6.0 image analysis software.

[0046] Tensile strength test: the test was performed in accordance with GB / T228.1-2010, the prepared aluminum alloy base material was cut into dumbbell-shaped samples, and the tensile property test was performed using an electronic tensile testing machine, the test temperature was 25℃, the tensile speed was 5mm / min, and the average value of three measurements was taken.

[0047] Table 1 Particle size and strength test

[0048]

[0049]

[0050] From the test results of the above table, with the increase of the content of nano TiN / Ti refiner, the average grain size of the aluminum alloy substrate gradually decreases, the size in Example 4 is 210.56 μm, while in Comparative Example 1, no nano TiN / Ti refiner is added, the grain size is 410.32 μm, and the refining effect is obvious; This is because on the one hand, after adding nano TiN / Ti refiner in aluminum melt, a layer of TiAl3 refining grain will be attached to the surface of the particle, TiN has the same face-centered cubic crystal structure as Al, which can directly act as a heterogeneous nucleation core for Al, forming a large number of dispersed particles, promoting nucleation, refining grains, reducing segregation, accelerating aging process and enhancing aging strengthening effect; On the other hand, the difference in wettability and thermal conductivity between TiN / Ti and aluminum melt leads to its migration to the solid-liquid interface at the front of the dendrite growth during solidification, inhibiting the growth of dendrites and further refining the aluminum alloy grains.

[0051] The tensile strength of the aluminum alloy in the example after adding nano TiN / Ti refiner is obviously improved compared with Comparative Example 1, among which it reaches 207.24 MPa in Example 4, because nano TiN / Ti refiner can make the grain of aluminum alloy small and uniform, make the intergranular second phase small and dispersed, increase the total area of grain boundary, and improve the sliding resistance of the material during deformation, thereby improving the tensile strength of the aluminum alloy.

[0052] Example 6

[0053] (1) Under nitrogen atmosphere, 55 g of phytic acid and 400 g of deionized water were added to a reaction flask, stirred and dissolved, then 25 g of aniline monomer and 65 g of ammonium persulfate were added, and the reaction was carried out at 5°C for 2 h, then sodium hydroxide was added to adjust the pH to 7.5, 32.5 g of 3-aminopropyltrimethoxysilane was added, the temperature was raised to 45°C and the reaction was carried out for 1 h, then filtered and washed with deionized water until neutral to obtain a phosphatized polyaniline hybrid sol.

[0054] (2) The aluminum alloy substrate (prepared by Example 4) was polished with sandpaper, and then sequentially immersed in ethanol, acetone and deionized water for ultrasonic cleaning to obtain a pretreated aluminum alloy substrate. Then, a stainless steel was used as the cathode, and the pretreated aluminum alloy substrate was used as the anode, and then the micro-arc oxidation treatment was carried out by immersing the substrate in a micro-arc oxidation electrolyte. A two-way pulse alternating current was used with a current density of 8 A / dm 2 , a frequency of 100 Hz, a duty cycle of 60%, and a time of 30 min to obtain a micro-arc oxidized aluminum alloy substrate.

[0055] (3) After polishing, polishing and cleaning the micro-arc oxidation aluminum alloy substrate, it is first placed in a cerium salt solution for sealing, then placed in a 0.5% by mass phosphonated polyaniline hybrid sol for dip-coating at a speed of 2 cm / min at 55°C, repeated for 6 times, then placed in an electric furnace, heated to 110°C for 4h, to obtain a high-strength aluminum alloy for solar photovoltaic frame.

[0056] Example 7

[0057] (1) Under a nitrogen atmosphere, 84g of phytic acid and 400g of deionized water are added to a reaction flask, stirred and dissolved, then 40g of aniline monomer and 100g of ammonium persulfate are added, reacted at 10°C for 1h, sodium hydroxide is added to adjust the pH to 7, 40g of 3-aminopropyltrimethoxysilane is added, heated to 50°C for 0.5h, filtered, washed with deionized water until neutral, to obtain a phosphonated polyaniline hybrid sol.

[0058] (2) The aluminum alloy substrate (prepared by Example 4) is polished with sandpaper, sequentially placed in ethanol, acetone, deionized water for ultrasonic cleaning, to obtain a pretreated aluminum alloy substrate, then a stainless steel is used as a cathode, the pretreated aluminum alloy substrate is used as an anode, immersed in a micro-arc oxidation electrolyte, treated by micro-arc oxidation, a bidirectional pulse alternating current is used, the current density is 10A / dm 2 , the frequency is 120Hz, the duty cycle is 70%, the time is 20min, to obtain a micro-arc oxidation aluminum alloy substrate.

[0059] (3) After polishing, polishing and cleaning the micro-arc oxidation aluminum alloy substrate, it is first placed in a cerium salt solution for sealing, then placed in a 1.5% by mass phosphonated polyaniline hybrid sol for dip-coating at a speed of 3 cm / min at 65°C, repeated for 5 times, then placed in an electric furnace, heated to 120°C for 2h, to obtain a high-strength aluminum alloy for solar photovoltaic frame.

[0060] Example 8

[0061] (1) Under a nitrogen atmosphere, 48g of phytic acid and 400g of deionized water are added to a reaction flask, stirred and dissolved, then 20g of aniline monomer and 56g of ammonium persulfate are added, reacted at 0°C for 3h, sodium hydroxide is added to adjust the pH to 8.5, 30g of 3-aminopropyltrimethoxysilane is added, heated to 35°C for 2h, filtered, washed with deionized water until neutral, to obtain a phosphonated polyaniline hybrid sol.

[0062] (2) The aluminum alloy substrate (prepared by Example 4) was polished with sandpaper, sequentially placed in ethanol, acetone, deionized water for ultrasonic cleaning, to obtain a pretreated aluminum alloy substrate, then a stainless steel was used as a cathode, the pretreated aluminum alloy substrate was used as an anode, immersed in a micro-arc oxidation electrolyte, and micro-arc oxidation treatment was performed, a bidirectional pulse alternating current was used, the current density was 6 A / dm 2 , the frequency was 80 Hz, the duty cycle was 50%, and the time was 40 min, to obtain a micro-arc oxidation aluminum alloy substrate.

[0063] (3) After polishing, polishing and cleaning the micro-arc oxidation aluminum alloy substrate, it was first placed in a cerium salt solution for sealing, then placed in a phosphonated polyaniline hybrid sol with a mass fraction of 2.5%, immersed and pulled at a speed of 1 cm / min at 50°C, repeated 7 times, then placed in an electric furnace, heated to 90°C for 5 h, to obtain a high-strength aluminum alloy for solar photovoltaic frames.

[0064] Example 9

[0065] (1) Under a nitrogen atmosphere, 33.8 g of phytic acid and 230 g of deionized water were added to a reaction flask, stirred and dissolved, then 15 g of aniline monomer and 39.3 g of ammonium persulfate were added, reacted at 5°C for 3 h, sodium hydroxide was added to adjust the pH to 8, 18 g of 3-aminopropyltrimethoxysilane was added, heated to 40°C for 1.5 h, filtered, and washed with deionized water until neutral, to obtain a phosphonated polyaniline hybrid sol.

[0066] (2) The aluminum alloy substrate (prepared by Example 4) was polished with sandpaper, sequentially placed in ethanol, acetone, deionized water for ultrasonic cleaning, to obtain a pretreated aluminum alloy substrate, then a stainless steel was used as a cathode, the pretreated aluminum alloy substrate was used as an anode, immersed in a micro-arc oxidation electrolyte, and micro-arc oxidation treatment was performed, a bidirectional pulse alternating current was used, the current density was 9 A / dm 2 , the frequency was 100 Hz, the duty cycle was 65%, and the time was 35 min, to obtain a micro-arc oxidation aluminum alloy substrate.

[0067] (3) After polishing, polishing and cleaning the micro-arc oxidation aluminum alloy substrate, it was first placed in a cerium salt solution for sealing, then placed in a phosphonated polyaniline hybrid sol with a mass fraction of 3.5%, immersed and pulled at a speed of 2 cm / min at 60°C, repeated 6 times, then placed in an electric furnace, heated to 110°C for 3 h, to obtain a high-strength aluminum alloy for solar photovoltaic frames.

[0068] Example 10

[0069] (1) 22.5 g of phytic acid and 160 g of deionized water were added to a reaction flask under a nitrogen atmosphere, and after stirring and dissolving, 10 g of aniline monomer and 26 g of ammonium persulfate were added, and the reaction was carried out at 0°C for 3 h. Then, sodium hydroxide was added to adjust the pH to 8.5, and 13 g of 3-aminopropyltrimethoxysilane was added, and the temperature was raised to 45°C for 2 h. Filtration and washing with deionized water until neutralization were performed to obtain a phosphatized polyaniline hybrid sol.

[0070] (2) The aluminum alloy substrate (prepared by Example 4) was polished with sandpaper, and sequentially ultrasonically cleaned in ethanol, acetone, and deionized water to obtain a pretreated aluminum alloy substrate. Then, the pretreated aluminum alloy substrate was used as an anode, and a stainless steel was used as a cathode, and immersed in a micro-arc oxidation electrolyte to perform micro-arc oxidation treatment. A two-way pulse alternating current was used, with a current density of 10 A / dm 2 , a frequency of 120 Hz, a duty cycle of 50%, and a time of 40 min to obtain a micro-arc oxidation aluminum alloy substrate.

[0071] (3) After polishing, polishing, and cleaning of the micro-arc oxidation aluminum alloy substrate, it was first placed in a cerium salt solution for sealing, and then placed in a 4.5% by mass phosphatized polyaniline hybrid sol, and immersed and pulled at a speed of 3 cm / min at 65°C for 5 times. Then, it was placed in an electric furnace and heated to 100°C for 5 h to obtain a high-strength aluminum alloy for a solar photovoltaic frame.

[0072] Comparative Example 2

[0073] (1) The aluminum alloy substrate (prepared by Example 4) was polished with sandpaper, and sequentially ultrasonically cleaned in ethanol, acetone, and deionized water to obtain a pretreated aluminum alloy substrate. Then, the pretreated aluminum alloy substrate was used as an anode, and a stainless steel was used as a cathode, and immersed in a micro-arc oxidation electrolyte to perform micro-arc oxidation treatment. A two-way pulse alternating current was used, with a current density of 8 A / dm 2 , a frequency of 100 Hz, a duty cycle of 60%, and a time of 30 min to obtain a micro-arc oxidation aluminum alloy substrate.

[0074] (2) After polishing, polishing, and cleaning of the micro-arc oxidation aluminum alloy substrate, it was first placed in a cerium salt solution for sealing, and then placed in a 0.5% by mass phytic acid solution, and immersed and pulled at a speed of 2 cm / min at 55°C for 6 times. Then, it was placed in an electric furnace and heated to 110°C for 4 h to obtain an aluminum alloy for a solar photovoltaic frame.

[0075] Comparative Example 3

[0076] The aluminum alloy substrate (prepared from Example 4) was polished with sandpaper, ultrasonically cleaned in ethanol, acetone, and deionized water in sequence to obtain a pretreated aluminum alloy substrate, then immersed in a micro-arc oxidation electrolyte with stainless steel as the cathode and the pretreated aluminum alloy substrate as the anode, and subjected to micro-arc oxidation treatment using a bidirectional pulse alternating current with a current density of 8 A / dm 2 , a frequency of 100 Hz, a duty cycle of 60%, and a time of 30 min to obtain a micro-arc oxidized aluminum alloy substrate.

[0077] Tensile strength test: The prepared aluminum alloy substrate was cut into dumbbell-shaped samples according to GB / T 228.1-2010, and the tensile properties were tested using an electronic tensile testing machine at a temperature of 25°C and a tensile speed of 5 mm / min. The test was repeated three times and the average value was taken.

[0078] Hardness test: The hardness of the sample was tested using a micro Vickers hardness tester according to GB / T 16865-2023. The indenter was a diamond pyramid with a 136° included angle, and the load was 0.49 N. The sample was loaded for 15 s and then unloaded uniformly. Five points were randomly selected on the surface of each sample for measurement, and the average value was taken as the final result.

[0079] Table 2 Strength and hardness test

[0080] Tensile strength (MPa) Hardness (HV) Example 4 207.24 240.1 Example 6 220.35 325.5 Example 7 228.12 364.6 Example 8 235.06 380.2 Example 9 241.12 392.8 Example 10 243.28 395.3 Comparative Example 2 215.48 277.2 Comparative Example 3 212.56 256.4

[0081] As can be seen from the test results in the above table, the strength and hardness of the aluminum alloy gradually increase with the increase of the mass fraction of phosphated polyaniline hybrid sol. The tensile strength of Example 10 is 243.28 MPa, and the hardness is 395.3 HV, which has good mechanical properties. This is because, on the one hand, the ceramic film can be grown in situ on the aluminum alloy substrate by micro-arc oxidation, which has good compression resistance. The surface coating has a flexible carbon chain that can adjust itself under certain stress conditions by changing the chain length or conformation, effectively overcoming the problem of easy separation of the coating from the substrate, and can withstand a large external pressure. On the other hand, phytic acid in the phosphated polyaniline hybrid sol has 6 phosphate groups and 12 hydroxyl groups, which have strong chelating ability. Al 3+ The aluminum phytate with chair conformation generated by the combination of phytic acid and Al can be attached to the surface of the substrate, and the introduction of -Si-O-Si- three-dimensional inorganic network skeleton through the doping of silane, in addition, the P-OH in the phytic acid molecule will react with -Si-OH- generated after the hydrolysis of silane to form -P-O-Si- bond, so that the coating has organic / inorganic hybrid structure, and the holes on the surface of the aluminum alloy after micro-arc oxidation are effectively filled, generating a smooth and dense passivation film on the surface of the alloy, which can resist elastic-plastic deformation and improve the strength of the aluminum alloy.

[0082] The aluminum alloy in Comparative Example 2 is treated by micro-arc oxidation and impregnated with a phytic acid coating, which can form a chelate with the aluminum alloy, but the effect is limited; Comparative Example 3 is only treated by micro-arc oxidation without further surface treatment, and the mechanical properties of the aluminum alloy are poor.

[0083] Wear resistance test: a multifunctional friction tester is used for friction and wear experiment, and the friction pair is a GCr15 steel ball with a diameter of 5 mm. The experimental conditions are set as follows: ambient temperature 25℃, normal load 3N, reciprocating friction frequency 5Hz, stroke 10mm, friction time 8min, after the experiment, the abrasive debris on the surface of each sample is cleaned, then immersed in anhydrous ethanol for ultrasonic cleaning and dried, the mass of each sample after friction and wear is weighed by an electronic balance, and the weight loss is calculated.

[0084] Corrosion resistance test: tested according to GB / T1771-1991, the spray chamber temperature is 35℃, the sodium chloride concentration is 60g / L, and the pH is 7, and whether bubbling and rusting occurs after 168h is observed;

[0085] Table 3 wear and corrosion resistance test

[0086]

[0087]

[0088] The presence of a proper amount of polyaniline can transfer the electrons generated during the corrosion process of the alloy, passivate the alloy, and thus improve the corrosion resistance of the composite coating; the phosphonated polyaniline hybrid sol synthesized by the dopant has an imine salt structure in the doped state and is in an intermediate oxidation-reduction state, has good conductivity and strong oxidation-reduction capacity, and exhibits good corrosion resistance and wear resistance.

[0089] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application.

Claims

1. A method for preparing a high-strength aluminum alloy for a solar photovoltaic frame, characterized by, The aluminum alloy comprises the following components in mass percentage: 0.52-0.65% of Si, 0.58-0.73% of Mg, 0.2-0.35% of Fe, 0.08-0.15% of Cu, 0.02-0.05% of Mn, 0.1-0.9% of grain refiner, and the balance of Al, with the total amount being 100%. The preparation method of the high-strength aluminum alloy for solar photovoltaic frames is as follows: Step (1): Al-Si alloy, metal Mg, metal Fe, metal Cu, metal Mn and metal Al are placed in a melting furnace for melting, after complete melting, the mixed liquid is quickly analyzed, and metal elements are added to adjust the chemical composition of the target aluminum alloy, slag is removed, argon is removed, and the aluminum alloy liquid is obtained after being placed for 10-25 min; Step (2): The grain refiner is wrapped with aluminum foil and pressed into the aluminum alloy liquid in step (1) by bell jar, first heated to 580-650 DEG C at a rate of 50-80 DEG C / h, then heated to 660-750 DEG C at a rate of 120-150 DEG C / h for 1-3 h, and then cooled to 200-300 DEG C by strong wind, argon is removed, and the aluminum alloy substrate is obtained after being placed for 20-40 min and casting; Step (3): The aluminum alloy substrate in step (2) is polished with sandpaper, sequentially ultrasonically cleaned in ethanol, acetone and deionized water to obtain a pretreated aluminum alloy substrate, and then immersed in a micro-arc oxidation electrolyte with the pretreated aluminum alloy substrate as an anode and stainless steel as a cathode, and subjected to micro-arc oxidation treatment by using a bidirectional pulse alternating current with a current density of 6-10 A / dm 2 , a frequency of 80-120 Hz, a duty cycle of 50-70%, and a time of 20-40 min to obtain a micro-arc oxidation aluminum alloy substrate; Step (4): After the micro-arc oxidation aluminum alloy substrate obtained in step (3) is polished, polished and cleaned, it is first placed in a cerium salt solution for sealing, then placed in a phosphated polyaniline hybrid sol with a mass fraction of 0.5-4.5%, immersed and pulled at a speed of 1-3 cm / min at 50-65 DEG C, repeated 5-7 times, then placed in an electric furnace and heated to 90-120 DEG C for 2-5 h, to obtain a high-strength aluminum alloy for solar photovoltaic frames; The grain refiner is TiN / Ti refiner; The preparation method of the phosphated polyaniline hybrid sol in step (4) is as follows: under a nitrogen atmosphere, phytic acid and deionized water are added to a reaction flask, stirred and dissolved, then aniline monomer and ammonium persulfate are added, reacted at 0-10 DEG C for 1-3 h, the pH is adjusted by adding sodium hydroxide, 3-aminopropyltrimethoxysilane is added, heated to 35-50 DEG C and reacted for 0.5-2 h, filtered and washed with deionized water until neutral to obtain the phosphated polyaniline hybrid sol; The mass ratio of phytic acid, deionized water, aniline monomer, ammonium persulfate and 3-aminopropyltrimethoxysilane is (2.1-2.4):(10-20):1:(2.5-2.8):(1-1.5).

2. The method for preparing high-strength aluminum alloy for solar photovoltaic frames according to claim 1, characterized in that, The preparation method of the grain refiner is as follows: 100 g of micron Ti powder and 8-12 g of TiN particles are placed in a high-energy ball mill and ball milled at 1500-2000 r / min for 20-35 min to obtain a nano TiN / Ti refiner.

3. The method for preparing high-strength aluminum alloy for solar photovoltaic frames according to claim 1, characterized in that, The melting temperature is 700-800 DEG C.

4. The method for preparing high-strength aluminum alloy for solar photovoltaic frames according to claim 1, characterized in that, The micro-arc oxidation electrolyte in step (3) is an alkaline electrolyte, and the preparation method is as follows: sodium hydroxide, sodium silicate and sodium hexametaphosphate are dissolved in 1 L of deionized water according to a mass ratio of 2:5:3, and the obtained micro-arc oxidation electrolyte is stirred uniformly.

5. The method for preparing high-strength aluminum alloy for solar photovoltaic frames according to claim 1, characterized in that, The preparation method of the cerium salt solution in the step (4) is that cerium nitrate, hydrogen peroxide and boric acid are dissolved in 1 L deionized water according to a mass ratio of 10:15:1, and the cerium salt solution obtained after uniform stirring is obtained.

6. The method of producing a high-strength aluminum alloy for a solar photovoltaic frame according to claim 1, characterized in that, The pH is adjusted to 7-8.

5.

7. A high-strength aluminum alloy for a solar photovoltaic frame, characterized by comprising, in mass %, The preparation method of any one of claims 1-6.

Images