Surface treatment process of aluminum alloy profile and application of surface treatment process

Abstract

The invention discloses a surface treatment process of an aluminum alloy profile and application of the surface treatment process, and belongs to the technical field of aluminum alloy materials. The process comprises the steps that alloy elements are prepared, the rare earth element is a mixture of terbium and yttrium, and the mass ratio of Tb to Y is 0.5: (1-3); smelting, homogenizing treatment, and quenching aging after extrusion forming; the pretreatment comprises alkaline degreasing and acid pickling; a treating agent composed of organic porous particles, a silane coupling agent and a coalescing agent is used for surface treatment, and the concentration of the organic porous particles, the silane coupling agent and the coalescing agent is 20 g / L. Through the synergistic effect of rare earth microalloying and the surface treating agent, the mechanical property and corrosion resistance of the aluminum alloy are remarkably improved, the tensile strength is larger than or equal to 600 MPa, the self-corrosion current density is smaller than or equal to 1.213 microA / cm, the energy absorption value reaches 28.5-30.5 kJ, and the aluminum alloy is suitable for the fields of new energy automobile battery tray frame profiles, ocean engineering equipment, offshore wind power facilities and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy materials, and particularly relates to a surface treatment process of an aluminum alloy profile and application thereof. BACKGROUND

[0002] Al-Mg-Si aluminum alloy has been widely used in new energy vehicles, rail transit and building structures due to its excellent workability, high specific strength, corrosion resistance and weldability. Typical 6061 aluminum alloy belongs to an age hardenable alloy, and it is generally believed that Mg2Si second phases mainly composed of Mg and Si elements can be precipitated in the peak aging stage, and the alloy has good strengthening effect. On this basis, existing researches also adjust other micro-alloy components, improve processing technology and adjust heat treatment system, so as to make the grain size of the alloy and the morphology, size and distribution of the second phase reach the optimal state, form a synergistic effect and obtain good comprehensive mechanical properties.

[0003] The battery tray frame profile is an important supporting structure of the core battery module of a new energy vehicle, and is required to have high collision strength and energy absorption, and good corrosion resistance. At the same time, in order to meet the lightweight design requirement, the profile also needs to achieve the weight reduction target on the premise of ensuring the structural stability. At present, the existing technology is mostly optimized in the traditional element ratio, or the traditional T6 heat treatment process is adopted to improve the strength, but the plasticity of the material is easily reduced, and it is difficult to meet the requirements of high strength and high formability.

[0004] For example, Chinese patent application CN201610202603.9 discloses a high-strength aluminum alloy material, which comprises Al, Si, Fe, Cu, Mg, Mn, Cr, Zn, Ti, and the weight percentage of each component is as follows: Si 0.5-0.55%, Fe≤0.16%, Cu≤0.02%, Mg 0.65-0.7%, Mn 0.015-0.025%, Cr≤0.01%, Zn≤0.012%, Ti 0.017-0.025%, and the balance is Al. The application selects a specific formula to prepare a high-performance aluminum alloy material with high strength and hardness, and the material has the advantages of light weight, wear resistance, good plasticity, excellent heat dissipation, and can be used for manufacturing automobile frames, can reduce the weight of the automobile, and is widely used in the field of new energy vehicles.

[0005] For example, Chinese patent application CN201010607633.0 discloses a high-strength cast aluminum alloy for manufacturing impeller blades of axial flow fans for power stations, subways, tunnels, etc., belonging to the technical field of aluminum alloy materials, which is prepared from the following components in percentage by weight: Si: 9.0-11.0%, Cu: 0.3-0.5%, Mg: 0.3-0.4%, Mn: 0.3-0.5%, Zn: 0.2-0.35%, Fe≤0.4%, and the balance being Al. The high-strength cast aluminum alloy has a room temperature tensile strength of 320-350 MPa, an elongation of 2.5-4%, and a Brinell hardness greater than 75 under low-pressure die casting conditions.

[0006] Although these patent technologies improve the material performance to some extent, the component design mainly focuses on the strength index, and the synergistic optimization of plasticity and formability is insufficient, and it relies on traditional heat treatment process, which is difficult to meet the stringent requirements of high strength, high toughness and good processing performance of the battery tray frame profile of new energy vehicles. Therefore, it is urgent to develop an aluminum alloy material with high strength, high corrosion resistance and excellent forming performance and its preparation process to meet the dual requirements of lightweight and safety of new energy vehicles. SUMMARY

[0007] The present application provides an optimized aluminum alloy profile preparation scheme to solve the problems in the prior art. Firstly, two rare earth metal elements are added, and their ratio is accurately controlled to refine the grain, inhibit crack propagation, and improve the strength and toughness matching of the alloy. Secondly, efficient surface treatment is carried out, and the corrosion resistance and surface hardness of the profile are significantly improved through the synergistic optimization of the micro-alloying effect of rare earth elements and surface treatment process, effectively improving the service stability of the material under complex working conditions.

[0008] To achieve the above technical purposes, the technical scheme adopted by the present application is: A surface treatment process for an aluminum alloy profile, comprising the following treatment steps: (1) configuring alloy elements: according to the mass percentage of the ingredients: silicon 0.40%-0.60%, magnesium 0.80%-1.20%, iron 0.12%-0.33%, copper 0.33%-0.45%, manganese 0.10%-0.15%, chromium 0.08%-0.22%, rare earth elements 0.1%-0.30%, and the rest being aluminum and unavoidable impurities; the prepared raw materials are put into a melting furnace and melted at 720-760℃ for 30-50 minutes, and after the metal is completely melted, refining and casting are carried out to obtain a cast bar; (2) forming: homogenizing the cast bar at 480-520℃ for 6-8 hours, then extruding the homogenized cast bar to form a profile, with the extrusion temperature controlled at 490-510℃ and the extrusion speed controlled at 18-22 m / min; (3) quenching and aging treatment: water quenching the extruded profile at a cooling rate of 150℃ / min or higher to obtain a supersaturated solid solution, and then aging the profile at 170-180℃ for 4-6 hours; (4) pretreatment: sequentially performing alkaline degreasing, water washing and acid washing on the aluminum alloy profile; (5) surface treatment: immersing the aluminum alloy profile in a surface treatment agent, and treating the profile at 30-60℃ for 10-30 minutes, and then blowing cold air to dry the profile to obtain the final product.

[0009] Further, the rare earth element is a mixture of terbium (Tb) and yttrium (Y), and the mass ratio of Tb to Y is 0.5: (1-3).

[0010] Further, the solution used in the alkaline degreasing of step (4) is an aqueous solution containing 2-5% of sodium hydroxide, 3-6% of sodium carbonate and 0.1-0.3% of sodium dodecyl benzene sulfonate (the percentage is the mass percentage), and the treatment temperature is controlled at 50-60℃, and the time is 5-8 minutes; then the profile is washed with deionized water, and then is immersed in a 10-15% nitric acid solution for acid washing to remove the surface residues and promote the uniform formation of the film layer, and the acid washing time is 3-5 minutes.

[0011] Further, the surface treatment agent of step (5) is composed of organic porous particles, silane coupling agent and film forming aid, and the concentrations are: 20 g / L of organic porous particles, 20 g / L of silane coupling agent and 20 g / L of film forming aid, and the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0012] Still further, the preparation method of the organic porous particles is as follows: 1) preparation of the reaction solution: Trenesphosphonic acid (TFB) and levorotatory-trans-1,2-cyclohexanediamine (CHDA) are prepared according to the mass ratio of 1:1.05; first, TFB is dissolved in dichloromethane to prepare solution A with a concentration of 0.05 g / mL; then, CHDA is dissolved in dichloromethane with the same volume as solution A to prepare solution B; 2) Reaction: under stirring, solution B is slowly added dropwise into solution A; after the dropwise addition is completed, 1% of trifluoroacetic acid corresponding to the total mass of TFB and CHDA is added as a catalyst; then 10% of nano-silicon dioxide corresponding to the mass of the system is added, the particle size of the nano-silicon dioxide is 10-20 nm, and the reaction is continuously ultrasonically stirred at 15-35 DEG C for 12 hours; 3) Post-treatment: after the reaction is completed, the generated crystals are collected by filtration or centrifugation; the crystals are washed with a mixed solution of ethanol and dichloromethane (the volume ratio of ethanol to dichloromethane is 10:3) for multiple times to remove unreacted monomers and catalysts; finally, the washed crystals are placed in a vacuum drying oven at 60-100 DEG C and dried for 24 hours to obtain the organic porous particles.

[0013] Further, the silane coupling agent is gamma-aminopropyl triethoxysilane KH-550 or gamma-glycidyl ether propyl trimethoxysilane KH-560.

[0014] Further, the film-forming aid is polyethylene glycol or polyvinyl pyrrolidone.

[0015] The aluminum alloy profile obtained by the surface treatment process of the aluminum alloy profile mainly applied to a new energy automobile battery tray frame profile has excellent corrosion resistance, coating adhesion and long-term stability, can effectively cope with the challenges of thermal expansion, vibration impact and electrolyte corrosion of the battery system under complex working conditions, and can also be applied in the preparation of marine engineering equipment and offshore wind power facilities.

[0016] Advantages: (1) Optimize alloying elements: the present application creatively selects terbium (Tb) and yttrium (Y) for composite addition. Tb element has extremely high chemical activity, can form high melting point compounds with impurity elements such as H and O in the melt, play a role in deep purification of the melt, and reduce pores and inclusions in the ingot. Y element can significantly inhibit recrystallization and grain growth due to its strong surface activity, and strongly refine the grains. With the cooperation of the two, Tb removes the obstacles for the effective play of Y, and Y fully plays its role in fine grain strengthening and stabilizing grain boundaries, producing a "1+1>2" synergistic effect, so that the alloy matrix obtains finer and more uniform equiaxed crystal structure, the grain boundary is cleaner, and the intrinsic strength, toughness and intergranular corrosion resistance of the matrix are significantly improved. (2) Optimizing surface treatment process: using organic porous particles, silane coupling agent and film forming additives to form a surface treatment agent, wherein the prepared organic porous particles have high specific surface area and abundant microporous structure, and the nanoscale regular channels thereof act as a "nanoreactor" and a "physical barrier" during the film forming process. On the one hand, the silane hydrolysis product is adsorbed and fixed, and the crosslinking density is enhanced; on the other hand, the penetration path of the corrosion medium is prolonged. The silane coupling agent forms a Si-O-Si three-dimensional network after hydrolysis, which constitutes the skeleton structure of the film and is firmly combined with the matrix through Si-O-Al bonds. The film forming additive acts as a "bridge" and a "regulator", which improves the dispersibility of the organic porous particles in the solution through hydrogen bonding and other interactions, and promotes the effective fusion of the organic particles and the silane network, ensuring the formation of a dense, uniform and defect-free composite film layer. When the three components are used at the same concentration, the molecular forces of the three phases at the interface reach the best balance, and they can jointly build a dense, firm and excellent organic-inorganic hybrid protective film with excellent hydrophobicity and barrier effect. If the concentration is too low (such as 10 g / L), the film layer coverage is insufficient, and the protective performance is reduced; if the concentration is too high (such as 30 g / L), the intermolecular steric hindrance may increase, and even the local aggregation of organic particles may occur, which destroys the continuity and density of the film layer, and reduces its adhesion and protective effect.

[0017] (3) In summary, through the synergistic optimization of alloy design and surface treatment process, the unification of material lightweight, high strength and high corrosion resistance is realized, and a systematic solution is provided for the reliability of structural materials in extreme service environments. The aluminum alloy profile prepared by the present application exhibits excellent overall performance: tensile strength ≥ 600 MPa, peak load ≥ 390 kN; after surface treatment, the corrosion resistance is effectively improved. In addition to being applied to new energy vehicle battery tray frame profiles, it can also be applied to rail transit vehicle structural parts, marine engineering equipment supports and aerospace lightweight corrosion-resistant parts, etc. fields, to meet the long-term safe service requirements in complex environments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 SEM image of the organic porous particles of the present application; Figure 2 Size diagram of the test transverse and longitudinal tensile specimens of the present application; Figure 3 Size diagram (a) of the thin-walled beam section and physical diagram (b) of the extruded workpiece of the crushing test of the present application; Figure 4 Macroscopic crushing morphology and partial enlarged view of the test pieces of Examples 1-3, wherein (a-b) are the macroscopic crushing morphology and partial enlarged view of Example 1, (c-d) are the macroscopic crushing morphology and partial enlarged view of Example 2, and (e-f) are the macroscopic crushing morphology and partial enlarged view of Example 3; Figure 5The macroscopic crush morphology of the comparative example is shown in the enlarged view. DETAILED DESCRIPTION

[0019] The technical solutions of the present application are further described below in combination with specific examples, but are not limited thereto.

[0020] Example 1 A surface treatment process of an aluminum alloy profile includes the following steps: (1) configuring alloy elements: ingredients in percentage by mass: silicon 0.4%, magnesium 0.8%, iron 0.12%, copper 0.33%, manganese 0.1%, chromium 0.08%, rare earth elements 0.1%, and the rest being aluminum and unavoidable impurities; the prepared raw materials are put into a smelting furnace, and smelting is performed at 720-760℃ for 30 minutes; after the metal is completely melted, refining and casting are performed to obtain a cast rod; (2) forming: the cast rod is homogenized at 480-520℃ for 6 hours, and then the homogenized cast rod is extruded to form a profile, with the extrusion temperature being controlled at 490-510℃ and the extrusion speed being 18 m / min; (3) quenching and aging treatment: the extruded profile is water-quenched, with the cooling rate being controlled at more than 150℃ / min to obtain a supersaturated solid solution; then, aging treatment is performed at 170-180℃ for 4 hours; (4) pretreatment: the aluminum alloy profile is sequentially subjected to alkaline degreasing, water washing and pickling; (5) surface treatment: the aluminum alloy profile is immersed in a surface treatment agent, and treated at 30-60℃ for 10 minutes; after the treatment, cold air is used for drying to obtain a final product of aluminum alloy.

[0021] The rare earth elements are a mixture of terbium (Tb) and yttrium (Y), and the mass ratio of Tb to Y is 0.5:3.

[0022] In step (4), the solution for alkaline degreasing is an aqueous solution containing 2% of sodium hydroxide, 3% of sodium carbonate and 0.1% of sodium dodecyl benzene sulfonate (the percentages are mass percentages), and the treatment temperature is controlled at 50-60℃, and the time is 5-8 minutes; then, the profile is washed with deionized water, and then is subjected to pickling in a nitric acid solution with a mass concentration of 10-15% to remove surface residues and promote the uniform formation of a film layer, and the pickling time is 3-5 minutes.

[0023] In step (5), the surface treatment agent is composed of organic porous particles, silane coupling agent and film-forming aid, and the concentrations are: 20 g / L of organic porous particles, 20 g / L of silane coupling agent and 20 g / L of film-forming aid, and the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0024] The preparation method of the organic porous particles is: 1) reaction solution preparation: uniformly distribute the trimesic aldehyde TFB and the levorotatory-trans-1,2-cyclohexanediamine CHDA according to the mass ratio of 1:1.05; first, dissolve the TFB in a proper amount of dichloromethane to prepare a solution A with a concentration of 0.05 g / mL; then, dissolve the CHDA in the dichloromethane with the same volume as the solution A to prepare a solution B; 2) reaction: under stirring, slowly drop the solution B into the solution A; after the dropping is completed, add 1% of the total mass of TFB and CHDA of trifluoroacetic acid as a catalyst; then, add 10% of the mass of the system of nano-silicon dioxide, the particle size of which is 10-20 nm, and continuously ultrasonically stir the reaction at 15-35℃ for 12 hours; 3) post-treatment: after the reaction is completed, collect the generated crystals by filtration or centrifugation; wash the crystals with a mixed solution of ethanol and dichloromethane (the volume ratio of ethanol to dichloromethane is 10:3) for multiple times to remove the unreacted monomers and catalysts; finally, dry the washed crystals in a vacuum drying oven at 60-100℃ for 24 hours to obtain the organic porous particles.

[0025] The organic porous particles are characterized by using a scanning electron microscope SU 4800 of Japan Hitachi Company, and the sample is tested after being subjected to a gold spraying treatment. The micrograph is shown in Figure 1 As can be clearly observed, the particles have a regular flower-like three-dimensional morphology, the average particle size is about 200 nm, and the surface has a rich microporous structure.

[0026] The silane coupling agent is γ-aminopropyl triethoxysilane KH-550.

[0027] The film-forming aid is polyethylene glycol.

[0028] Example 2 A surface treatment process of an aluminum alloy profile includes the following treatment steps: (1) configuring alloy elements: uniformly distribute the alloy elements according to the mass percentage: silicon 0.40%, magnesium 1.10%, iron 0.22%, copper 0.40%, manganese 0.12%, chromium 0.15%, rare earth elements 0.20%, and the rest is aluminum and unavoidable impurities; put the prepared raw materials into a smelting furnace, smelt at 720℃-760℃ for 50 minutes, and after the metal is completely melted, perform refining and casting to obtain a cast rod; (2) forming: uniformly treat the cast rod at 480℃-520℃ for 7 hours, then perform extrusion forming on the uniformly treated cast rod, control the extrusion temperature to be 490℃-510℃, and control the extrusion speed to be 19 m / min to obtain a profile with a required shape; (3) quenching and aging treatment: quenching the extruded profile by water cooling, the cooling rate is controlled above 150℃ / min to obtain supersaturated solid solution; then aging treatment is carried out at 170-180℃ for 5 hours; (4) pretreatment: the aluminum alloy profile is sequentially subjected to alkaline degreasing, water washing and acid pickling; (5) surface treatment: the aluminum alloy profile is immersed in a surface treatment agent, treated at 30-60℃ for 20 minutes, after completion, cold air is blown to dry, and the final product aluminum alloy is obtained.

[0029] The rare earth element is a mixture of terbium Tb and yttrium Y, wherein the mass ratio of Tb to Y is 0.5:2.

[0030] The solution for alkaline degreasing is an aqueous solution containing 3% sodium hydroxide, 5% sodium carbonate and 0.2% sodium dodecyl benzene sulfonate (the percentage is mass percentage), the treatment temperature is controlled at 50-60℃, and the time is 5-8 minutes; then the profile is washed with deionized water, and then enters a 10%-15% nitric acid solution for acid pickling to remove surface residues and promote uniform film formation, and the acid pickling time is 3-5 minutes.

[0031] The surface treatment agent is composed of organic porous particles, silane coupling agent and film forming aid, and the concentration is: organic porous particles 20 g / L, silane coupling agent 20 g / L, film forming aid 20 g / L, and the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0032] The preparation method of the organic porous particles is: 1) preparation of reaction solution: trifromal TFB and levorotatory-trans-1,2-cyclohexanediamine CHDA are dosed according to the mass ratio of 1:1.05; first, TFB is dissolved in an appropriate amount of dichloromethane to prepare solution A with a concentration of 0.05 g / mL; then, CHDA is dissolved in dichloromethane with the same volume as solution A to prepare solution B; 2) reaction: under stirring, solution B is slowly added to solution A; after the addition is completed, 1% of TFB and CHDA in total mass of trifluoroacetic acid is added as a catalyst; then 10% of nano-silicon dioxide in system mass is added, the particle size of nano-silicon dioxide is 10-20 nm, and the reaction is continuously stirred under ultrasonic at 15-35℃ for 12 hours; 3) post-treatment: after the reaction is completed, the generated crystals are collected by filtration or centrifugation; the crystals are washed with a mixed solution of ethanol and dichloromethane (the volume ratio of ethanol to dichloromethane is 10:3) for multiple times to remove unreacted monomers and catalysts; finally, the washed crystals are placed in a vacuum drying oven at 60-100℃ for drying for 24 hours to obtain organic porous particles.

[0033] The silane coupling agent is γ-glycidoxypropyltrimethoxysilane KH-560.

[0034] The film forming aid is polyvinylpyrrolidone.

[0035] Example 3 A surface treatment process of an aluminum alloy profile, comprising the following treatment steps: (1) configuring alloy elements: ingredients according to mass percentage: silicon 0.60%, magnesium 1.20%, iron 0.33%, copper 0.45%, manganese 0.15%, chromium 0.22%, rare earth elements 0.30%, and the rest is aluminum and unavoidable impurities; put the prepared raw materials into a smelting furnace, smelt at 720-760℃ for 50 minutes, and after the metal is completely melted, carry out refining and casting to obtain a cast rod; (2) forming: homogenize the cast rod at 480-520℃ for 8 hours, then extrude the homogenized cast rod to form a profile, control the extrusion temperature to be 490-510℃, and the extrusion speed to be 22 m / min, to obtain a profile with a desired shape; (3) quenching and aging treatment: quench the extruded profile by water cooling at a cooling rate of above 150℃ / min to obtain a supersaturated solid solution; then age at 170-180℃ for 6 hours; (4) pretreatment: sequentially carry out alkaline degreasing, water washing and pickling on the aluminum alloy profile; (5) surface treatment: immerse the aluminum alloy profile in a surface treatment agent, treat at 30-60℃ for 30 minutes, after completion, dry with cold air, to obtain a final product aluminum alloy.

[0036] The rare earth elements are a mixture of terbium Tb and yttrium Y, and the mass ratio of Tb to Y is 0.5:1.

[0037] The solution for alkaline degreasing in step (4) is an aqueous solution containing 5% sodium hydroxide, 6% sodium carbonate and 0.3% sodium dodecyl benzene sulfonate (the percentage is mass percentage), the treatment temperature is controlled at 50-60℃, and the time is 5-8 minutes; then wash thoroughly with deionized water, and then enter a 10-15% nitric acid solution for pickling, to remove surface residues and promote the uniform formation of the film layer, and the pickling time is 3-5 minutes.

[0038] The surface treatment agent in step (5) is composed of organic porous particles, silane coupling agent and film forming aid, and the concentration is: organic porous particles 20 g / L, silane coupling agent 20 g / L, and film forming aid 20 g / L, and the mixed solvent of water and ethanol is used as the solvent, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0039] The preparation method of the organic porous particles is: 1) Preparation of reaction solution: uniformly-3, 3', 5, 5'-tetramethyl-1, 1'-biphenyl-4, 4'-dicarboxylic acid (TFB) and L-trans-1, 2-cyclohexanediamine (CHDA) are prepared according to the mass ratio of 1:1.05; first, TFB is dissolved in dichloromethane to prepare solution A with a concentration of 0.05 g / mL; then, CHDA is dissolved in dichloromethane with the same volume as solution A to prepare solution B; 2) Reaction: under stirring, solution B is slowly added to solution A; after the addition is completed, 1% of the total mass of TFB and CHDA of trifluoroacetic acid is added as a catalyst; then, 10% of the mass of the system of nano-silicon dioxide is added, the particle size of the nano-silicon dioxide is 10-20 nm, and the ultrasonic stirring reaction is continued at 15-35℃ for 12 hours; 3) Post-treatment: after the reaction is completed, the generated crystals are collected by filtration or centrifugation; the crystals are washed with a mixed solution of ethanol and dichloromethane (the volume ratio of ethanol to dichloromethane is 10:3) for multiple times to remove unreacted monomers and catalysts; finally, the washed crystals are placed in a vacuum drying oven at 60-100℃ for drying for 24 hours to obtain organic porous particles.

[0040] The silane coupling agent is γ-aminopropyl triethoxysilane KH-550.

[0041] The film-forming aid is polyethylene glycol.

[0042] Comparative Example 1 This comparative example is the same as Example 1 in terms of raw materials and process methods except that no Tb element is added in the alloy composition. That is: A surface treatment process for an aluminum alloy profile, comprising the following treatment steps: (1) Preparation of alloy elements: according to the mass percentage, the prepared raw materials are put into a melting furnace, and melted at 720-760℃ for 30 minutes; after the metal is completely melted, refining and casting are carried out to obtain a cast rod; The rare earth element is yttrium Y.

[0043] Comparative Example 2 This comparative example is the same as Example 1 in terms of raw materials and process methods except that no yttrium Y element is added in the alloy composition. That is: A surface treatment process for an aluminum alloy profile, comprising the following treatment steps: (1) Configuration of alloy elements: ingredients according to mass percentage: silicon 0.4%, magnesium 0.8%, iron 0.12%, copper 0.33%, manganese 0.1%, chromium 0.08%, rare earth elements 0.1%, and the rest being aluminum and unavoidable impurities; the prepared raw materials are put into a smelting furnace, smelted at 720-760°C for 30 minutes, and after the metal is completely melted, refined, and cast to obtain a cast rod; The rare earth element is terbium (Tb).

[0044] Comparative Example 3 In this comparative example, except that no organic porous particles, silane coupling agent, and film-forming aid are used in the surface treatment agent, the rest of the ingredients and processes are the same as in Example 1. That is: In step (5), the surface treatment agent is a mixed solution of water and ethanol, and the volume ratio of water to ethanol in the mixed solution is 10:1.

[0045] Comparative Example 4 In this comparative example, except that no organic porous particles are used in the surface treatment agent, the rest of the ingredients and processes are the same as in Example 1. That is: In step (5), the surface treatment agent is composed of a silane coupling agent and a film-forming aid, and the concentrations are: 20 g / L of silane coupling agent and 20 g / L of film-forming aid. The solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0046] Comparative Example 5 In this comparative example, except that no silane coupling agent is used in the surface treatment agent, the rest of the ingredients and processes are the same as in Example 1. That is: In step (5), the surface treatment agent is composed of organic porous particles and a film-forming aid, and the concentrations are: 20 g / L of organic porous particles and 20 g / L of film-forming aid. The solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0047] Comparative Example 6 In this comparative example, except that no film-forming aid is used in the surface treatment agent, the rest of the ingredients and processes are the same as in Example 1. That is: In step (5), the surface treatment agent is composed of organic porous particles and a silane coupling agent, and the concentrations are: 20 g / L of organic porous particles and 20 g / L of silane coupling agent. The solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0048] Comparative Example 7 In this comparative example, except that the concentrations of the raw materials are reduced in the surface treatment agent, the rest of the raw materials and process steps are the same as in Example 1. That is: The surface treatment agent of step (5) is composed of organic porous particles, silane coupling agent and film forming aid, and the concentration is: organic porous particles 10 g / L, silane coupling agent 10 g / L, film forming aid 10 g / L, and the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0049] Comparative Example 8 In this comparative example, the concentration of each raw material in the surface treatment agent is increased, and the remaining raw materials and process steps are the same as in Example 1. That is: The surface treatment agent of step (5) is composed of organic porous particles, silane coupling agent and film forming aid, and the concentration is: organic porous particles 10 g / L, silane coupling agent 10 g / L, film forming aid 10 g / L, and the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol in the mixed solvent is 10:1.

[0050] Performance Test The aluminum alloy materials obtained in Examples 1-3 and Comparative Examples 1-8 were subjected to performance tests, and the test indexes and methods are as follows: Hardness Test: The hardness test of the aluminum alloy profile was carried out on a HVS-1000 type Vickers hardness tester, the test loading force was 9.800 N, and the time lasted for 15 s. The sample size was 10 mm x 10 mm. In order to obtain the accurate hardness value of the sample, 5 hardness values of each sample were selected, and the final result was the average of the 5 values.

[0051] Mechanical Property Test: The room temperature tensile test was carried out by YNS300 microcomputer control electro-hydraulic servo universal testing machine according to GB / T228.1, and the tensile speed was 3 mm / min until fracture. The tensile sample size is as shown in Figure 2 Each treated sample was subjected to 3 times of tensile test, and the result was the average value.

[0052] Crushing Test: The quasi-static axial crushing test of the aluminum alloy profile was carried out on a WAW-1000FC hydraulic testing machine, and the cross-sectional size diagram and actual size diagram of the crushing sample are as shown in Figure 3 (unit: mm). The changes of load and displacement were recorded in real time by computer. The control compression speed was 20 mm / min, and the control deformation displacement amount was 200 mm during the test process.

[0053] Electrochemical Performance Test: The electrochemical experiment was carried out by using CH1760 type electrochemical workstation, through three electrode system, saturated calomel as reference electrode, carbon rod as auxiliary electrode, and aluminum alloy sample as working electrode. The corrosion solution was 3.5% NaCl solution, and the test temperature was room temperature.

[0054] Table 1 Performance test results From Table 1, it can be seen that the tensile strength, hardness, self-corrosion potential and current density of Examples 1-3 are better than those of the comparative examples, indicating that the optimized process significantly improves the mechanical and corrosion resistance of the material. The peak load and energy absorption value also increase with the improvement of performance, among which Example 3 reaches the maximum energy absorption of 30.5 kJ, which is about 15.1% higher than that of Comparative Example 8, showing better energy absorption capacity and better safety. From the macro crushing deformation result graph (4-5), it can be seen that the samples of Examples and comparative examples all have "symmetrical" folding deformation, and in the two adjacent sides, one side is deformed inward, and the other side is deformed outward. Careful observation shows that the Example 1 sample does not show macroscopic cracking at the position of the reinforcing rib. However, the comparative sample shows obvious cracks at the same position, indicating that its deformation resistance is weak.

[0055] In the comparative examples, by adjusting the composition of alloying elements and surface treatment agents, the changes in various performance indicators can be observed. Comparative Examples 1 and 2 remove terbium and yttrium in rare earth elements, respectively, resulting in a significant decrease in tensile strength, hardness and corrosion resistance, indicating that these two elements have a synergistic effect on improving the comprehensive performance of the material. Comparative Examples 3 to 6 verify the importance of each component in the surface treatment agent: the absence of organic porous particles, silane coupling agent and film-forming aids will weaken the mechanical properties and corrosion resistance of the material to varying degrees. Especially when these additives are not used at all, the self-corrosion current density increases sharply, indicating that the corrosion resistance is greatly reduced.

[0056] In addition, Comparative Examples 7 and 8 further explore the effect of concentration changes on performance. Reducing the concentration of each component in the surface treatment agent can still improve some performance, but the effect is not as significant as the examples; while increasing the concentration brings some improvement, it does not achieve a breakthrough, and even may affect the uniformity of the film layer due to too high concentration. This result shows that reasonable control of the concentration of the surface treatment agent is one of the key factors to ensure performance optimization.

[0057] In summary, the process parameters and formula design used in the examples are precisely controlled, which can achieve the best balance in terms of tensile strength, hardness, corrosion resistance and energy absorption capacity, etc. This not only provides reliable protection for the practical application of aluminum alloy profiles, but also points the way for future research, i.e. under the premise of maintaining process stability, more functional components can be introduced or the existing system can be optimized to further tap the potential.

[0058] It should be noted that the above-mentioned embodiments only illustrate some but not all of the preferred ways for implementing the present application. Obviously, based on the above-mentioned embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work should belong to the protection scope of the present application.

Claims

1. A surface treatment process for an aluminum alloy profile, characterized in that, The process comprises the following steps: (1) configuring alloy elements: ingredients in mass percentage: silicon 0.4%-0.6%, magnesium 0.8%-1.2%, iron 0.12%-0.33%, copper 0.33%-0.45%, manganese 0.1%-0.15%, chromium 0.08%-0.22%, rare earth elements 0.1%-0.3%, and the rest being aluminum and inevitable impurities; the prepared raw materials are put into a smelting furnace, smelted at 720-760℃ for 30-50 minutes, and after the metal is completely melted, refined and cast to obtain a cast rod; (2) forming: the cast rod is homogenized at 480-520℃ for 6-8 hours, and then the homogenized cast rod is extruded to control the extrusion temperature at 490-510℃ and the extrusion speed at 18-22 m / min to obtain a profile of the desired shape; (3) quenching and aging treatment: the extruded profile is water-quenched to control the cooling rate at above 150℃ / min to obtain a supersaturated solid solution; and then aged at 170-180℃ for 4-6 hours; (4) pretreatment: the aluminum alloy profile is sequentially subjected to alkaline degreasing, water washing and pickling; (5) surface treatment: the aluminum alloy profile is immersed in a surface treatment agent, treated at 30-60℃ for 10-30 minutes, and after completion, dried by cold air to obtain the final product of aluminum alloy.

2. The surface treatment process for an aluminum alloy extrusion of claim 1 wherein, The rare earth elements are a mixture of terbium Tb and yttrium Y, and the mass ratio of Tb to Y is 0.5: (1-3).

3. The surface treatment process for aluminum alloy shapes according to claim 1, characterized by, The solution for alkaline degreasing in step (4) is an aqueous solution containing 2%-5% of sodium hydroxide, 3%-6% of sodium carbonate and 0.1%-0.3% of sodium dodecyl benzene sulfonate, and the treatment temperature is controlled at 50-60℃, and the time is 5-8 minutes; then it is washed with deionized water, and then enters a 10%-15% nitric acid solution for pickling to remove surface residues and promote the uniform formation of the film layer, and the pickling time is 3-5 minutes.

4. The surface treatment process for aluminum alloy shapes according to claim 1, characterized by, The surface treatment agent in step (5) is composed of organic porous particles, silane coupling agent and film-forming additives, and the concentrations are: organic porous particles 20 g / L, silane coupling agent 20 g / L, and film-forming additives 20 g / L, and the solvent is a mixed solvent of water and ethanol with a volume ratio of 10:

1.

5. The surface treatment process for an aluminum alloy extrusion of claim 4 wherein, The preparation method of the organic porous particles is as follows: 1) preparation of reaction solution: trifromal TFB and levorotatory-trans-1,2-cyclohexanediamine CHDA are prepared according to the mass ratio of 1:1.05; first, TFB is dissolved in an appropriate amount of dichloromethane to prepare solution A with a concentration of 0.05 g / mL; then, CHDA is dissolved in dichloromethane with the same volume as solution A to prepare solution B; 2) reaction: under stirring, solution B is slowly added to solution A; after the addition is completed, 1% of trifluoroacetic acid corresponding to the total mass of TFB and CHDA is added as a catalyst; then 10% of nano-silicon dioxide is added to the system, and the reaction is continuously ultrasonically stirred at 15-35℃ for 12 hours; 3) Post-processing: after the reaction is completed, the generated crystals are collected by filtration or centrifugation; the crystals are washed with a mixed solution of ethanol and dichloromethane for multiple times to remove unreacted monomers and catalysts, and finally, the washed crystals are placed in a vacuum drying oven at 60-100℃ for drying for 24 hours to obtain the organic porous particles.

6. The surface treatment process for an aluminum alloy extrusion of claim 4 wherein, The silane coupling agent is γ-aminopropyl triethoxysilane KH-550 or γ-glycidyl ether propyl trimethoxysilane KH-560.

7. The surface treatment process for aluminum alloy shapes according to claim 4, characterized by, The film-forming aid is polyethylene glycol or polyvinyl pyrrolidone.

8. An aluminum alloy profile obtained by a surface treatment process of the aluminum alloy profile according to any one of claims 1-7.

9. Use of the aluminum alloy profile according to claim 8 in preparation of a new energy vehicle battery tray frame profile.

10. Use of the aluminum alloy profile according to claim 8 in preparation of marine engineering equipment and offshore wind power facilities.

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