Corrosion-resistant die-casting aluminum alloy and preparation method and anodic oxidation method thereof

Abstract

The invention discloses a corrosion-resistant die-casting aluminum alloy as well as a preparation method and an anodic oxidation method thereof. The aluminum alloy comprises the following materials: less than or equal to 0.3 wt% of Si; fe < = 1.0 wt%; cu < = 0.5 wt%; mn is 1.5 to 2.0 wt%; 0.1 to 0.3 wt% of Mg; 2.5 to 4.5 wt% of Zn; ti is 0.05 to 0.15 wt%; cr is 0.5 to 1.5 wt%; 2.5 to 3.5 wt% of Co; the total content of the impurities is less than or equal to 0.25 wt%; the tensile strength of the aluminum alloy is larger than or equal to 200 MPa, the yield strength is larger than or equal to 110 MPa, and the ductility is larger than or equal to 10% According to the invention, Cr and Co elements are introduced in a manner of adding an intermediate alloy to form a plurality of complex intermetallic compound phases with high hardness and high thermal stability, the intermetallic compound phases have extremely high thermal stability, are not easy to coarsen or dissolve into an aluminum matrix at high temperature, and can still effectively pinning grain boundaries and sub-grain boundaries in a high-temperature environment, so that the grain boundaries and sub-grain boundaries are effectively pinned, and the grain boundaries and sub-grain boundaries are effectively pinned. And grain boundary slippage and dislocation climbing are prevented, so that the softening resistance and creep resistance of the alloy are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy manufacturing technology, specifically to a corrosion-resistant die-cast aluminum alloy and its preparation and anodizing methods. Background Technology

[0002] Most gas stove covers are made of aluminum alloy. Considering the operating conditions of gas stoves, the aluminum alloy material used in the product must have high temperature characteristics. At the same time, considering the aesthetics of the product, it is required that the product be anodizable.

[0003] The shortcomings of existing technology: Currently, most aluminum alloys are still produced by forging. The disadvantage of this process is that it requires multiple processing steps, which leads to a sharp increase in the price of the finished product. In addition, the product has low stability and low high-temperature resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a corrosion-resistant die-cast aluminum alloy, its preparation method, and its anodizing method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a corrosion-resistant die-cast aluminum alloy, wherein the material composition of the aluminum alloy includes: Si≤0.3wt%; Fe≤1.0wt%; Cu≤0.5wt%; Mn1.5-2.0wt%; Mg0.1-0.3wt%; Zn2.5-4.5wt%; Ti0.05-0.15wt%; Cr0.5-1.5wt%; Co2.5-3.5wt%; the balance being Al and impurities, with a total impurity content of less than or equal to 0.25wt%; the aluminum alloy has a tensile strength ≥200MPa, a yield strength ≥110MPa, and an elongation ≥10%.

[0006] Preferably, the quantitative relationship between Co and Cr is as follows: 2.5 < Co / Cr < 4.5; The quantitative relationship between Mn, Cr, and Fe is as follows: 2.5<(Mn+Cr) / Fe<4.5; The quantitative relationship between Zn and Mg is as follows: 15 < Zn / Mg < 35.

[0007] This invention also provides a method for preparing a corrosion-resistant die-cast aluminum alloy, the method specifically comprising: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; S3. Refine the alloy melt to remove gas and impurities; S4. Die-cast the alloy melt.

[0008] Preferably, step S2 specifically includes: a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot, AlTi10, AlCr10 and AlCo5 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample.

[0009] Preferably, step S3 specifically includes: b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 .

[0010] Preferably, in step S4, the alloy melt is placed in the furnace on the side of the die-casting machine and left to stand for 20 minutes. After the temperature of the aluminum melt drops to 700°C, low-speed high-pressure die casting is performed. The temperature of the aluminum melt is 720°C, the mold temperature is 250°C, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

[0011] This invention also provides an anodizing method for corrosion-resistant die-cast aluminum alloys, the anodizing method specifically comprising: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. T3. Perform electrochemical treatment; T4. Coloring: Aluminum alloy products are colored by electrolytic coloring, with the temperature controlled at 50~65℃ and the time at 5-15min.

[0012] Preferably, step T2 specifically includes: t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:1. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process, and then perform high-pressure spray cleaning. t3. Place it in a neutralization tank to form a porous oxide film; t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid is used, with a volume ratio of sulfuric acid to phosphoric acid of 1:1.

[0013] Preferably, step T3 specifically includes: u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, phosphoric acid, and chromic acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath liquid so that an oxide film is formed on the surface of the aluminum alloy product. The thickness of the oxide film is 10-25μm. u3. The aluminum alloy uses a special anodizing power supply waveform with a frequency of 10kHz and a pulse waveform.

[0014] Preferably, in step u2, the voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention relates to a corrosion-resistant die-cast aluminum alloy, its preparation method, and its anodizing method. Cr and Co elements are introduced by adding them to an intermediate alloy, forming various complex intermetallic compound phases with high hardness and high thermal stability. These phases exhibit extremely high thermal stability, resisting coarsening or dissolution into the aluminum matrix at high temperatures. Even under high-temperature conditions, these particles effectively pin grain boundaries and subgrain boundaries, preventing grain boundary slip and dislocation climb, thereby significantly improving the alloy's resistance to softening and creep. Furthermore, by controlling the element ratios and combining them with appropriate die-casting process design, the die-casting and anodizing properties of the aluminum alloy furnace hood product are achieved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the microstructure of the present invention; Figure 2 DSC curves of materials for this invention Figure 3 The high-pressure die-casting anodized product of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are 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.

[0019] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integrated connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0021] Example 1 Please see Figure 1-3 As shown, the present invention provides a corrosion-resistant die-cast aluminum alloy technical solution: the material composition of the aluminum alloy includes: Si 0.25wt%; Fe 0.7wt%; Cu 0.3wt%; Mn 1.8wt%; Mg 0.18wt%; Zn 3.0wt%; Ti 0.12wt%; Cr 0.9wt%; Co 3.2wt%; the balance is Al and impurities, the total impurity content is less than or equal to 0.25wt%; the quantitative relationship between Co and Cr is Co / Cr = 3.5; the quantitative relationship between Mn, Cr and Fe is (Mn+Cr) / Fe = 3.8; the quantitative relationship between Zn and Mg is 16.6.

[0022] The solid-liquid phase range of the material tested using DSC equipment is 633-684℃, representing a melting point of 633℃; this meets the high-temperature requirement of 610℃ in practical applications.

[0023] Through the synergistic reaction of Co, Cr, and Mn elements in high-temperature molten aluminum, a more complex dispersed phase is generated. In the Al-Co-Cr ternary system, a stable ternary intermetallic compound phase is formed, whose composition is usually close to (Al,Co,Cr) or a specific ternary phase, such as... During precipitation, Co and Cr atoms can substitute for each other and enter the same lattice position in the same crystal structure. Co and Cr atoms are "locked" in the composite phase, which significantly reduces their diffusion rate in the aluminum matrix. The coarsening process depends on the long-distance diffusion of solute atoms in the matrix. The reduced diffusion rate means that the kinetics of coarsening of precipitated phase particles are greatly slowed down. These ternary compounds usually have higher melting points and hardness than binary compounds. They can maintain their shape and strength at high temperatures, thus ensuring the high-temperature resistance of the product.

[0024] This invention also provides a method for preparing a corrosion-resistant die-cast aluminum alloy, specifically comprising: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours to ensure temperature uniformity inside the smelting furnace. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot, AlTi10, AlCr10 and AlCo5 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample; S3. Refine the alloy melt to remove gas and impurities; b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 ; S4. Die casting the alloy melt: Place the alloy melt into the furnace on the side of the die casting machine and let it stand for 20 minutes. After the temperature of the aluminum melt drops to 700℃, perform low-speed high-pressure die casting. The temperature of the aluminum melt is 720℃, the mold temperature is 250℃, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

[0025] This invention also provides a method for anodizing corrosion-resistant die-cast aluminum alloys, specifically including: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:1. The grease will undergo a hydrolysis reaction to produce glycerol and higher fatty acids, which is beneficial to the subsequent coloring and gloss. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process. The purpose is to provide a smooth and uniform surface for anodizing. Then, perform high-pressure spray cleaning. t3. Place it in the neutralization tank to form a porous oxide film, reduce the residual impurities on the surface of the aluminum alloy product, provide a good foundation for subsequent coloring, and improve the corrosion resistance, wear resistance and insulation performance of the aluminum alloy. t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid with a volume ratio of 1:1 is used to further remove the grayish-brown or grayish-black ash adhering to the product surface after alkaline washing, prevent contamination of the anodizing bath solution, and ensure that the product can obtain a uniform and clean anodized film. T3. Perform electrochemical treatment; u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, phosphoric acid, and chromic acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath, so that an oxide film can be formed on the surface of the aluminum alloy product. The oxide film thickness is 10-25μm. The voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K; Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4; u3. The aluminum alloy uses a special anodizing power supply waveform with a frequency of 10kHz and a pulse waveform. T4. Coloring: Aluminum alloy products are colored by electrolytic coloring, with the temperature controlled at 50~65℃ and the time at 5-15min.

[0026] Therefore, the aluminum alloy material prepared through the above process achieves a tensile strength of 230 MPa, a yield strength of 120 MPa, and an elongation of 12%. After color anodizing, the product has a bright surface color, such as... Figure 3 After being heated at 600℃ for 2 hours, the product did not deform and met the application requirements.

[0027] Example 2 This invention provides a corrosion-resistant die-cast aluminum alloy technical solution: the material composition of the aluminum alloy includes: Si 0.15wt%; Fe 0.75wt%; Cu 0.35wt%; Mn 1.7wt%; Mg 0.15wt%; Zn 3.5wt%; Ti 0.1wt%; Cr 0.8wt%; Co 3.5wt%; the balance is Al and impurities, the total impurity content is less than or equal to 0.25wt%; the quantitative relationship between Co and Cr is Co / Cr = 4.3; the quantitative relationship between Mn, Cr and Fe is (Mn+Cr) / Fe = 3.3; the quantitative relationship between Zn and Mg is 23.3.

[0028] The solid-liquid phase range of the material tested using DSC equipment is 633-684℃, representing a melting point of 633℃; this meets the high-temperature requirement of 610℃ in practical applications.

[0029] Through the synergistic reaction of Co, Cr, and Mn elements in high-temperature molten aluminum, a more complex dispersed phase is generated. In the Al-Co-Cr ternary system, a stable ternary intermetallic compound phase is formed, whose composition is usually close to (Al,Co,Cr) or a specific ternary phase, such as... During precipitation, Co and Cr atoms can substitute for each other and enter the same lattice position in the same crystal structure. Co and Cr atoms are "locked" in the composite phase, which significantly reduces their diffusion rate in the aluminum matrix. The coarsening process depends on the long-distance diffusion of solute atoms in the matrix. The reduced diffusion rate means that the kinetics of coarsening of precipitated phase particles are greatly slowed down. These ternary compounds usually have higher melting points and hardness than binary compounds. They can maintain their shape and strength at high temperatures, thus ensuring the high-temperature resistance of the product.

[0030] This invention also provides a method for preparing a corrosion-resistant die-cast aluminum alloy, specifically comprising: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours to ensure temperature uniformity inside the smelting furnace. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot, AlTi10, AlCr10 and AlCo5 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample; S3. Refine the alloy melt to remove gas and impurities; b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 ; S4. Die casting the alloy melt: Place the alloy melt into the furnace on the side of the die casting machine and let it stand for 20 minutes. After the temperature of the aluminum melt drops to 700℃, perform low-speed high-pressure die casting. The temperature of the aluminum melt is 720℃, the mold temperature is 250℃, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

[0031] This invention also provides a method for anodizing corrosion-resistant die-cast aluminum alloys, specifically including: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:1. The grease will undergo a hydrolysis reaction to produce glycerol and higher fatty acids, which is beneficial to the subsequent coloring and gloss. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process. The purpose is to provide a smooth and uniform surface for anodizing. Then, perform high-pressure spray cleaning. t3. Place it in the neutralization tank to form a porous oxide film, reduce the residual impurities on the surface of the aluminum alloy product, provide a good foundation for subsequent coloring, and improve the corrosion resistance, wear resistance and insulation performance of the aluminum alloy. t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid with a volume ratio of 1:1 is used to further remove the grayish-brown or grayish-black ash adhering to the product surface after alkaline washing, prevent contamination of the anodizing bath solution, and ensure that the product can obtain a uniform and clean anodized film. T3. Perform electrochemical treatment; u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, phosphoric acid, and chromic acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath, so that an oxide film can be formed on the surface of the aluminum alloy product. The oxide film thickness is 10-25μm. The voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K; Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4; u3. The aluminum alloy uses a special anodizing power supply waveform with a frequency of 10kHz and a pulse waveform. T4. Coloring: Aluminum alloy products are colored by electrolytic coloring, with the temperature controlled at 50~65℃ and the time at 5-15min.

[0032] Therefore, the aluminum alloy material prepared by the above process has a tensile strength of 225 MPa, a yield strength of 115 MPa, and an elongation of 11.3%.

[0033] Example 3 This invention provides a corrosion-resistant die-cast aluminum alloy technical solution: the material composition of the aluminum alloy includes: Si 0.12wt%; Fe 0.85wt%; Cu 0.25wt%; Mn 1.6wt%; Mg 0.25wt%; Zn 3.8wt%; Ti 0.13wt%; Cr 0.95wt%; Co 2.8wt%; the balance is Al and impurities, the total impurity content is less than or equal to 0.25wt%; the quantitative relationship between Co and Cr is Co / Cr = 2.9; the quantitative relationship between Mn, Cr and Fe is (Mn+Cr) / Fe = 3.0; the quantitative relationship between Zn and Mg is 15.2.

[0034] The solid-liquid phase range of the material tested using DSC equipment is 633-684℃, representing a melting point of 633℃; this meets the high-temperature requirement of 610℃ in practical applications.

[0035] Through the synergistic reaction of Co, Cr, and Mn elements in high-temperature molten aluminum, a more complex dispersed phase is generated. In the Al-Co-Cr ternary system, a stable ternary intermetallic compound phase is formed, whose composition is usually close to (Al,Co,Cr) or a specific ternary phase, such as... During precipitation, Co and Cr atoms can substitute for each other and enter the same lattice position in the same crystal structure. Co and Cr atoms are "locked" in the composite phase, which significantly reduces their diffusion rate in the aluminum matrix. The coarsening process depends on the long-distance diffusion of solute atoms in the matrix. The reduced diffusion rate means that the kinetics of coarsening of precipitated phase particles are greatly slowed down. These ternary compounds usually have higher melting points and hardness than binary compounds. They can maintain their shape and strength at high temperatures, thus ensuring the high-temperature resistance of the product.

[0036] This invention also provides a method for preparing a corrosion-resistant die-cast aluminum alloy, specifically comprising: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours to ensure temperature uniformity inside the smelting furnace. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot, AlTi10, AlCr10 and AlCo5 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample; S3. Refine the alloy melt to remove gas and impurities; b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 ; S4. Die casting the alloy melt: Place the alloy melt into the furnace on the side of the die casting machine and let it stand for 20 minutes. After the temperature of the aluminum melt drops to 700℃, perform low-speed high-pressure die casting. The temperature of the aluminum melt is 720℃, the mold temperature is 250℃, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

[0037] This invention also provides a method for anodizing corrosion-resistant die-cast aluminum alloys, specifically including: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:1. The grease will undergo a hydrolysis reaction to produce glycerol and higher fatty acids, which is beneficial to the subsequent coloring and gloss. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process. The purpose is to provide a smooth and uniform surface for anodizing. Then, perform high-pressure spray cleaning. t3. Place it in the neutralization tank to form a porous oxide film, reduce the residual impurities on the surface of the aluminum alloy product, provide a good foundation for subsequent coloring, and improve the corrosion resistance, wear resistance and insulation performance of the aluminum alloy. t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid with a volume ratio of 1:1 is used to further remove the grayish-brown or grayish-black ash adhering to the product surface after alkaline washing, prevent contamination of the anodizing bath solution, and ensure that the product can obtain a uniform and clean anodized film. T3. Perform electrochemical treatment; u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, phosphoric acid, and chromic acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath, so that an oxide film can be formed on the surface of the aluminum alloy product. The oxide film thickness is 10-25μm. The voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K; Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4; u3. The aluminum alloy uses a special anodizing power supply waveform with a frequency of 10kHz and a pulse waveform. T4. Coloring: Aluminum alloy products are colored by electrolytic coloring, with the temperature controlled at 50~65℃ and the time at 5-15min.

[0038] Therefore, the aluminum alloy material prepared by the above process has a tensile strength of 210 MPa, a yield strength of 113 MPa, and an elongation of 10.6%.

[0039] Comparative Example 1 Another aluminum alloy technical solution is provided: the material composition of the aluminum alloy includes: Si 0.23wt%; Fe 0.75wt%; Cu 0.25wt%; Mn 1.8wt%; Mg 0.28wt%; Zn 3.1wt%; Ti 0.12wt%; the balance is Al and impurities.

[0040] A method for preparing an aluminum alloy is provided, specifically including: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours to ensure temperature uniformity inside the smelting furnace. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot and AlTi10 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample; S3. Refine the alloy melt to remove gas and impurities; b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 ; S4. Die casting the alloy melt: Place the alloy melt into the furnace on the side of the die casting machine and let it stand for 20 minutes. After the temperature of the aluminum melt drops to 700℃, perform low-speed high-pressure die casting. The temperature of the aluminum melt is 720℃, the mold temperature is 250℃, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

[0041] A method for anodizing aluminum alloys is provided, specifically including: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:1. The grease will undergo a hydrolysis reaction to produce glycerol and higher fatty acids, which is beneficial to the subsequent coloring and gloss. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process. The purpose is to provide a smooth and uniform surface for anodizing. Then, perform high-pressure spray cleaning. t3. Place it in the neutralization tank to form a porous oxide film, reduce the residual impurities on the surface of the aluminum alloy product, provide a good foundation for subsequent coloring, and improve the corrosion resistance, wear resistance and insulation performance of the aluminum alloy. t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid with a volume ratio of 1:1 is used to further remove the grayish-brown or grayish-black ash adhering to the product surface after alkaline washing, prevent contamination of the anodizing bath solution, and ensure that the product can obtain a uniform and clean anodized film. T3. Perform electrochemical treatment; u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, and phosphoric acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath, so that an oxide film can be formed on the surface of the aluminum alloy product. The oxide film thickness is 10-25μm. The voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K; Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4.

[0042] T4. Coloring: Coloring aluminum alloy products by electrolytic coloring.

[0043] Therefore, the aluminum alloy material prepared by the above process has a tensile strength of 180 MPa, a yield strength of 100 MPa, an elongation of 10.2%, and a solidus point of 608℃.

[0044] In summary, through Examples 1, 2, 3 and Comparative Example 1, compared with aluminum alloy materials containing Cr and Co, the solid-liquid phase temperature is reduced and the high-temperature resistance is reduced.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A corrosion-resistant die-cast aluminum alloy, characterized in that: The aluminum alloy comprises: Si ≤ 0.3 wt%; Fe ≤ 1.0 wt%; Cu ≤ 0.5 wt%; Mn 1.5-2.0 wt%; Mg 0.1-0.3 wt%; Zn 2.5-4.5 wt%; Ti 0.05-0.15 wt%; Cr 0.5-1.5 wt%; Co 2.5-3.5 wt%; the balance being Al and impurities, with a total impurity content of less than or equal to 0.25 wt%. The aluminum alloy has a tensile strength ≥ 200 MPa, a yield strength ≥ 110 MPa, and an elongation ≥ 10%.

2. The corrosion-resistant die-cast aluminum alloy according to claim 1, characterized in that: The quantitative relationship between Co and Cr is as follows: 2.5 < Co / Cr < 4.5; The quantitative relationship between Mn, Cr, and Fe is as follows: 2.5<(Mn+Cr) / Fe<4.5; The quantitative relationship between Zn and Mg is as follows: 15 < Zn / Mg < 35.

3. The method for preparing a corrosion-resistant die-cast aluminum alloy according to any one of claims 1-2, characterized in that: The preparation method specifically includes: S1. Prepare raw materials according to the proportions; S2. Prepare an alloy melt; S3. Refine the alloy melt to remove gas and impurities; S4. Die-cast the alloy melt.

4. The method for preparing a corrosion-resistant die-cast aluminum alloy according to claim 3, characterized in that: Step S2 specifically includes: a1. Set the temperature of the smelting furnace to 400℃ and preheat for 3 hours. a2. After the smelting furnace is preheated, set the heating temperature to 800℃; a3. Put A00 into the melting furnace to melt it. After it is completely melted, take a TP sample to confirm the material composition. a4. Add AlFe20, AlMn20, Cu, magnesium ingot, zinc ingot, AlTi10, AlCr10 and AlCo5 master alloy in sequence, stir evenly to obtain alloy melt, and confirm the material composition with TP sample.

5. The method for preparing a corrosion-resistant die-cast aluminum alloy according to claim 3, characterized in that: Step S3 specifically includes: b1. Argon gas is introduced into the alloy melt as a protective gas at a rate of 0.15-6 L / min. b2. Add RJ-01 refining agent, set the refining time to 20-25 minutes, and the amount of refining agent added is 0.3% of the alloy melt mass. After refining, the density of the aluminum liquid is greater than 2.68 g / cm³. 3 .

6. The method for preparing a corrosion-resistant die-cast aluminum alloy according to claim 3, characterized in that: In step S4, the alloy melt is placed in the furnace on the side of the die-casting machine and left to stand for 20 minutes. After the temperature of the aluminum melt drops to 700°C, low-speed high-pressure die casting is performed. The temperature of the aluminum melt is 720°C, the mold temperature is 250°C, the vacuum degree is -0.09MPa, the casting pressure is 90MPa, and the speed is 0.1m / s.

7. The anodizing method for a corrosion-resistant die-cast aluminum alloy according to claim 3, characterized in that: The anodizing method specifically includes: T1. Cut and deburr the die-cast aluminum alloy blanks to separate the aluminum alloy products from the slag bag and gate. T2. Perform chemical pretreatment, which includes degreasing, water washing, alkaline washing, second water washing, ash removal, and water washing. T3. Perform electrochemical treatment; T4. Coloring: Aluminum alloy products are colored by electrolytic coloring, with the temperature controlled at 50~65℃ and the time at 5-15min.

8. The anodizing method for a corrosion-resistant die-cast aluminum alloy according to claim 7, characterized in that: Step T2 specifically includes: t1. Place the aluminum alloy product in a degreasing tank and pickle it with an acidic degreasing agent for 5 minutes, then rinse it with distilled water. The acidic degreasing agent is a mixed solution of sulfuric acid, phosphoric acid and nitric acid, with a volume ratio of sulfuric acid, phosphoric acid and nitric acid of 2:3:

1. t2. Place it in an alkaline tank to remove the oil stains that were not removed in the degreasing tank and the marks left during the die casting process, and then perform high-pressure spray cleaning. t3. Place it in a neutralization tank to form a porous oxide film; t4. Ash removal: A mixed solution of sulfuric acid and phosphoric acid is used, with a volume ratio of sulfuric acid to phosphoric acid of 1:

1.

9. The anodizing method for a corrosion-resistant die-cast aluminum alloy according to claim 7, characterized in that: Step T3 specifically includes: u1. Electrochemical polishing is performed using an acidic solution, which is one or a mixture of fluoroboric acid, sulfuric acid, phosphoric acid, and chromic acid, and the solution temperature is 20℃. u2. Use an ice machine to control the temperature of the oxidation bath liquid so that an oxide film is formed on the surface of the aluminum alloy product. The thickness of the oxide film is 10-25μm. u3. The aluminum alloy uses a special anodizing power supply waveform with a frequency of 10kHz and a pulse waveform.

10. The anodizing method for a corrosion-resistant die-cast aluminum alloy according to claim 9, characterized in that: In step u3, the voltage is set to 80-100V and the current is set to 3A / dm. 2 The time was set to 30 minutes, and the oxide film thickness formula was: Oxide film thickness ≈ current density × time × K Wherein, the oxide film thickness is in μm, the current density is in A / dm², the time is in min, and k is a coefficient ranging from 0.3 to 0.4.

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