Anodic oxidation coloring process of aluminum alloy wheel

Abstract

The invention discloses an anodic oxidation coloring process of an aluminum alloy wheel, which adopts an improved electrolyte formula and anodic oxidation conditions, so that the aluminum alloy wheel is remarkably improved in the aspects of corrosion resistance, wear resistance, adhesive force, weather resistance and the like. Specifically, according to the process, by optimizing the type and concentration of an additive in an electrolyte and adjusting the anodic oxidation current density and temperature, a more compact oxidation film can be formed on the surface of the aluminum alloy, and the film layer has better color consistency and adhesive force. In addition, by controlling the electrolysis temperature and time in the oxidation process, the color of the surface of the wheel is more uniform, the wheel is durable, meanwhile, the ultraviolet resistance of the wheel is improved, and the service life of the wheel is prolonged. The process has relatively high environmental protection property, and the use of harmful chemicals in a traditional method is reduced. The aluminum alloy wheel treated by the process disclosed by the invention shows relatively long-time stability and excellent performance under severe environmental conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy wheel processing, and specifically to an anodic oxidation coloring process for aluminum alloy wheels. Background Art

[0002] Aluminum alloy wheels are widely used in automobiles, motorcycles, and other means of transportation due to their light weight, high strength, excellent corrosion resistance, and good processing performance. However, during long-term use, aluminum alloy is prone to being affected by environmental factors such as corrosion, wear, and ultraviolet radiation, which will affect the service life and appearance quality of the wheels. Therefore, improving the corrosion resistance, wear resistance, weather resistance, and surface aesthetics of aluminum alloy wheels has become an important direction in material research and industrial applications.

[0003] Traditional surface treatment methods for aluminum alloy wheels mainly include spraying, painting, and anodic oxidation treatment, etc. Although spraying and painting technologies can improve the surface aesthetics and certain protection, their durability is poor, the surface coating is prone to peeling and fading, and their environmental tolerance is low. Anodic oxidation treatment is widely used in the surface treatment of aluminum alloy, which can form a hard and durable oxide film, improving the corrosion resistance, wear resistance, and adhesion of the aluminum alloy surface. However, there are still some deficiencies in the traditional anodic oxidation process in practical applications, such as the adhesion, wear resistance, and ultraviolet resistance of the oxide film need to be improved.

[0004] At present, although some research and technologies have improved the surface treatment of aluminum alloy, most processes rely on traditional anodic oxidation and spraying methods, failing to fully exploit the potential of aluminum alloy wheel surface treatment, and many processes have not been comprehensively optimized for actual environmental requirements. Therefore, developing an efficient, environmentally friendly, and excellent-performance anodic oxidation coloring process for aluminum alloy wheels has become a technical problem urgently needed to be solved in the industry. Summary of the Invention

[0005] Aiming at the above existing technical deficiencies, the purpose of the present invention is to provide an anodic oxidation coloring process for aluminum alloy wheels, enhancing the corrosion resistance and wear resistance of aluminum alloy wheels, and improving the surface gloss and weather resistance of the wheels.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] An anodic oxidation coloring process for aluminum alloy wheels includes the following steps:

[0008] a) Clean the surface of the aluminum alloy wheel to remove oil stains, dust, and oxide layers;

[0009] b) Immerse the cleaned aluminum alloy wheels in an electrolyte containing chromate, phosphate, and molybdate, and adopt an anodic oxidation process with low temperature and high current density. An inorganic colorant is added to the electrolyte;

[0010] c) During the oxidation process, control the thickness and color of the oxide film by adjusting the ion concentration, current density, and oxidation time in the electrolyte;

[0011] d) After completion of oxidation, perform post-treatment, and use low-temperature curing technology to enhance the wear resistance and adhesion of the oxide film;

[0012] e) Coat a transparent protective layer.

[0013] Preferably, the formulation of the electrolyte includes:

[0014] The chromate concentration is 5 - 15 g / L, the phosphate concentration is 2 - 8 g / L, and the molybdate concentration is 0.5 - 2 g / L.

[0015] Preferably, the current density is 2 A / dm 2 to 4 A / dm 2 , and the oxidation time is 20 minutes to 60 minutes.

[0016] Preferably, the inorganic colorant is a metal salt colorant, and the colorant concentration is 0.01 g / L to 0.05 g / L.

[0017] Preferably, the post-treatment step includes: after oxidation, use high-temperature water washing to remove the residual chemical substances generated during the oxidation process, and then perform low-temperature curing treatment.

[0018] Preferably, the thickness of the oxide film on the surface of the aluminum alloy wheels is 20 μm to 40 μm.

[0019] Preferably, the aluminum alloy wheels are blasted or ultrasonically cleaned to remove surface oil stains, dust, and oxide layers.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] By optimizing the composition of the electrolyte and the conditions of anodic oxidation, the process of the present invention can form a dense and strong oxide film on the surface of the aluminum alloy. This oxide film effectively isolates the erosion of the external environment on the wheels, greatly improving the corrosion resistance of the wheels. In salt spray and acid-base environment tests, there are no obvious corrosion marks on the wheel surface, and the corrosion resistance is significantly better than that of traditional anodic oxidation processes.

[0022] The aluminum alloy wheels processed by the process of the present invention show excellent wear resistance in friction and wear tests. Through the special oxide film structure, the surface hardness of the aluminum alloy wheels is significantly improved, the degree of friction and wear is significantly reduced, and the wear resistance is increased by more than 60% compared with the traditional process.

[0023] The anodizing process of the present invention effectively enhances the adhesion between the oxide film and the aluminum alloy surface, and the peeling force of the oxide film is significantly improved. Experimental data show that the adhesion of the aluminum alloy wheels processed by this process is more than 3 times that of the untreated samples, which can effectively avoid the phenomenon of the coating on the wheel surface falling off.

[0024] Through the anodizing coloring process of the present invention, the aluminum alloy wheels obtain a more uniform and smooth appearance and have excellent gloss. Compared with the traditional process, the gloss of the wheel surface processed by the process of the present invention is increased by nearly 80%, the appearance is more beautiful, and it has higher market competitiveness.

[0025] The anodized film of the present invention shows excellent stability and anti-aging ability under ultraviolet irradiation and high-temperature environment. After a long-term ultraviolet accelerated aging test, no fading, cracking and other phenomena appear on the wheel surface, and the weather resistance is greatly enhanced, which is especially suitable for long-term use in harsh environments such as high temperature and high humidity.

[0026] The process of the present invention uses an environmentally friendly electrolyte and a pollution-free treatment method, reducing the harmful substances generated during the surface treatment of traditional aluminum alloy wheels, meeting the production requirements of modern green environmental protection. Brief Description of the Drawings

[0027] Figure 1 It is a flow block diagram of the present invention. Detailed Embodiments

[0028] The present invention will be further described below with reference to the drawings.

[0029] As Figure 1 shown, an anodizing coloring process for aluminum alloy wheels, and the specific embodiments of the present invention will be described in detail below through two examples.

[0030] Example 1:

[0031] In this example, a certain type of aluminum alloy wheel is selected as the treatment object. The specific operation steps are as follows:

[0032] Surface cleaning

[0033] First, the surface of the aluminum alloy wheel is preliminarily cleaned by solvent cleaning, using degreasers and detergents to remove oil, dirt and other attachments on the wheel surface. Subsequently, it is thoroughly rinsed with deionized water to ensure that there are no impurities and residues on the wheel surface. Then, the wheel surface is further cleaned with an ultrasonic cleaning device to ensure that there are no impurities such as oil, dust, oxide layer, etc. on the wheel surface.

[0034] Anodizing

[0035] The cleaned aluminum alloy wheels are immersed in an electrolyte containing chromate, phosphate and molybdate. The electrolyte ratio is: chromate concentration is 10g / L, phosphate concentration is 4g / L, and molybdate concentration is 1g / L. The temperature of the electrolytic cell is controlled between 5℃ and 15℃, and the current density is set to 3A / dm 2 , the oxidation time is 40 minutes. During the anodizing process, the control of current density, electrolyte concentration and oxidation time is very critical, which can effectively adjust the thickness and color of the oxide film.

[0036] Use of inorganic colorants

[0037] During the electrolysis process, a certain concentration of inorganic colorant is added, and metal salt colorants such as titanium salts or iron salts are used, and the concentration is controlled at 0.02g / L to 0.05g / L. The inorganic colorant combines with the oxide film on the surface of the aluminum alloy during the electrolysis process, thereby forming a uniform coloring effect on the oxide film. The coloring effect is manifested as a metallic gray color on the wheel surface, with uniform color and consistent depth.

[0038] Post-processing steps

[0039] After anodizing and coloring, the aluminum alloy wheel is immediately removed and cleaned with deionized water to remove any chemicals that may remain on the surface. Next, a low-temperature curing treatment is carried out, with the curing temperature controlled between 80°C and 120°C for 30 minutes. This step helps to enhance the wear resistance and adhesion of the oxide film and increase the service life of the wheel.

[0040] Embodiment 2:

[0041] In the second embodiment, the same aluminum alloy wheel is used as the test object, but some changes are made in the process flow to further improve the adhesion and wear resistance of the oxide film. The specific operation steps are as follows:

[0042] Surface cleaning

[0043] In this embodiment, the surface of the aluminum alloy wheel is treated by sandblasting. Finer abrasive materials (such as aluminum alloy sand grains) are used in the sandblaster, and the surface of the wheel is evenly polished by high-speed spraying to remove the oxide layer and impurities on the wheel surface. At the same time, the surface roughness is increased, providing a better basis for the adhesion of the oxide film.

[0044] Anodic oxidation treatment

[0045] The cleaned aluminum alloy wheel is placed in an anodic oxidation tank. The electrolyte ratio uses a mixed solution of chromate, phosphate, and molybdate. The chromate concentration is 8 g / L, the phosphate concentration is 5 g / L, and the molybdate concentration is 1.5 g / L. The electrolysis temperature is controlled between 10°C and 12°C, and the current density is 4 A / dm 2 , and the oxidation time is 45 minutes.

[0046] Addition of inorganic colorant

[0047] During the electrolysis process, a titanium salt is added as an inorganic colorant, and the titanium salt concentration is controlled at 0.03 g / L. Since the titanium salt can react with the surface of the aluminum alloy during electrolysis to form a black oxide film with metallic luster, the aesthetics and wear resistance of the wheel are enhanced.

[0048] Post-treatment steps

[0049] After the oxidation treatment is completed, water washing is immediately carried out to remove the chemical substances remaining on the surface. Subsequently, the high-temperature water washing method is used to remove the chemical residues during the oxidation process, and finally, low-temperature curing treatment is carried out. The curing temperature is 90°C and the time is 40 minutes. Through this process, the density of the oxide film can be increased, further enhancing the corrosion resistance, wear resistance, and adhesion of the film layer.

[0050] Performance test experiment

[0051] The anodic oxidation coloring process of the aluminum alloy wheel adopted in the present invention has been experimentally verified to have remarkable corrosion resistance, wear resistance, and excellent surface adhesion. To ensure the effectiveness of the process and the service performance of the wheel, a number of tests and comparative experiments have been carried out. The following are the specific test contents and experimental parameters.

[0052] 1. Corrosion resistance test

[0053] Purpose: To verify the corrosion resistance of aluminum alloy wheels in a salt spray environment.

[0054] Experimental steps:

[0055] The aluminum alloy wheel samples are divided into two groups: the first group is the samples treated by the process of the present invention, and the second group is the original aluminum alloy wheel samples without anodic oxidation treatment.

[0056] Put all the samples into the salt spray chamber, set the salt spray test environment, control the temperature of the salt spray chamber at 35°C, and the salt spray concentration is 5% sodium chloride solution.

[0057] Carry out the salt spray test for 48 hours and regularly check the surface of the samples.

[0058] After the test is completed, take out the samples, conduct visual inspection, record the corrosion situation on the surface of the samples, and measure the corrosion area with an electronic measuring instrument.

[0059] Comparison of experimental results:

[0060] Samples treated by the process of the present invention: After 48 hours of salt spray exposure, no obvious corrosion marks appeared on the surface and the oxide film remained intact.

[0061] Untreated aluminum alloy wheels: After 24 hours of salt spray exposure, slight corrosion spots appeared, and the corrosion area reached 5% - 10% after 48 hours.

[0062] Result analysis: The aluminum alloy wheels treated by the process of the present invention showed significant corrosion resistance in the salt spray test. Compared with untreated aluminum alloy wheels, the corrosion resistance was improved by more than 60%.

[0063] 2. Wear resistance test

[0064] Purpose: To evaluate the wear resistance of the oxide film on the surface of aluminum alloy wheels.

[0065] Experimental steps:

[0066] Select two groups of aluminum alloy wheel samples: The first group is the aluminum alloy wheels treated by the process of the present invention, and the second group is the aluminum alloy wheels without anodic oxidation treatment.

[0067] Use a friction and wear testing machine to conduct wear tests on each group of samples. The friction medium is standard abrasive paper (grain size: P600), and a vertical load of 2N is applied under the test conditions.

[0068] During the test, each group of samples is subjected to friction and wear at a speed of 120 rpm for 1000 cycles.

[0069] After the test is completed, measure the wear area on the surface of each sample, observe the wear situation with an electron microscope, and record the wear depth.

[0070] Comparison of experimental results:

[0071] Samples treated by the process of the present invention: The wear depth is about 0.02 mm, and the wear area is about 1.5 cm 2 .

[0072] Untreated aluminum alloy wheels: The wear depth is about 0.08 mm, and the wear area is about 4.5 cm2 .

[0073] Result analysis: The aluminum alloy wheels processed by the process of the present invention exhibit remarkable wear resistance. The wear depth and wear area are reduced by 75% and 67% respectively compared with the untreated samples, which proves that this process effectively enhances the wear resistance of the wheel surface.

[0074] 3. Adhesion test

[0075] Purpose: To evaluate the adhesion of the anodic oxidation film.

[0076] Experimental procedure:

[0077] Select aluminum alloy wheel samples and use the peel test method to determine the adhesion of the oxidation film.

[0078] After anodizing the surface of the aluminum alloy wheels, use a standard adhesion test tool for peel testing. During the test, use a tensiometer to measure the maximum force required for peeling.

[0079] During the test, gradually increase the peeling force and record the value of the maximum adhesion force during the peeling process, and measure the adhesion force of each sample respectively.

[0080] During the test, also select aluminum alloy wheels without anodizing treatment as control samples.

[0081] Comparison of experimental results:

[0082] Samples processed by the process of the present invention: The maximum adhesion force is 15 N / cm 2 , and there is no sign of peeling of the oxidation film.

[0083] Untreated aluminum alloy wheels: The maximum adhesion force is 5 N / cm 2 , and there is slight peeling of the oxidation film.

[0084] Result analysis: The process of the present invention enhances the adhesion of the oxidation film through anodizing and post-treatment steps. The maximum adhesion force is increased by 200%, making the oxidation film on the surface of the aluminum alloy wheels more stable and more durable.

[0085] 4. Glossiness test

[0086] Purpose: To evaluate the glossiness and appearance effect of the surface of aluminum alloy wheels after anodizing.

[0087] Experimental procedure:

[0088] Select two groups of samples: The first group is the aluminum alloy wheels processed by the process of the present invention, and the second group is the untreated aluminum alloy wheels.

[0089] Use a glossiness meter to measure the glossiness of the sample surface. The instrument uses an incident angle of 60° to test the surface glossiness value.

[0090] During the test, multiple different positions on the surface of the sample are measured at multiple points to ensure the accuracy of the data.

[0091] Comparison of experimental results:

[0092] The sample processed by the process of the present invention: The glossiness is 80 GU (gloss unit), and the surface presents a metallic luster, which is uniform.

[0093] The untreated aluminum alloy wheel: The glossiness is 45 GU, and the surface presents a matte effect with a lower glossiness.

[0094] Result analysis: Through the anodic oxidation treatment of the process of the present invention, the surface glossiness of the aluminum alloy wheel is significantly improved, and the glossiness is increased by about 78%, making the appearance of the wheel more visually attractive.

[0095] 5. Weather resistance test

[0096] Purpose: To evaluate the ultraviolet resistance and high-temperature resistance of the oxide film on the surface of the aluminum alloy wheel.

[0097] Experimental steps:

[0098] Put the processed aluminum alloy wheel sample into an ultraviolet accelerated aging chamber to simulate the environment of the wheel being exposed to sunlight for a long time.

[0099] Set the ultraviolet intensity to 1.5 W / m 2 , the test temperature is 65 °C, and conduct continuous ultraviolet irradiation for 240 hours.

[0100] Take out the sample every 48 hours, observe and record the surface changes until the end of the 240-hour test.

[0101] Comparison of experimental results:

[0102] The sample processed by the process of the present invention: After ultraviolet irradiation, there is no obvious fading or cracking on the surface, and the oxide film remains intact.

[0103] The untreated aluminum alloy wheel: After 48 hours of ultraviolet irradiation, slight fading appears on the surface, and fine cracks appear after 120 hours.

[0104] Result analysis: Through the ultraviolet accelerated aging test, the aluminum alloy wheel processed by the process of the present invention shows stronger weather resistance, better surface stability after ultraviolet irradiation, and higher ultraviolet resistance and high-temperature resistance.

[0105] Summary:

[0106] Through the above various performance test experiments and combined with the comparative data, it can be confirmed that the anodic oxidation coloring process of the present invention significantly improves the corrosion resistance, wear resistance, adhesion, gloss and weather resistance of aluminum alloy wheels, and shows more excellent performance compared with untreated aluminum alloy wheels. The experimental results fully prove the effectiveness and application prospects of the process of the present invention.

Claims

1. An anodic oxidation coloring process for aluminum alloy wheels, characterized in that, It includes the following steps: a) Surface cleaning of the aluminum alloy wheel to remove oil stains, dust and oxide layer; b) Immerse the cleaned aluminum alloy wheel in an electrolyte containing chromate, phosphate and molybdate, and adopt an anodic oxidation process with low temperature and high current density. An inorganic colorant is added to the electrolyte; c) During the oxidation process, control the thickness and color of the oxide film by adjusting the ion concentration, current density and oxidation time in the electrolyte; d) After the oxidation is completed, perform post-treatment and use low-temperature curing technology to enhance the wear resistance and adhesion of the oxide film; e) Coat a transparent protective layer.

2. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The proportion of the electrolyte includes: The chromate concentration is 5-15 g / L, the phosphate concentration is 2-8 g / L, and the molybdate concentration is 0.5-2 g / L.

3. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The current density is 2 A / dm 2 to 4 A / dm 2 , and the oxidation time is from 20 minutes to 60 minutes.

4. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The inorganic colorant is a metal salt colorant, and the concentration of the colorant is 0.01 g / L to 0.05 g / L.

5. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The post-treatment steps include: after oxidation, use high-temperature water washing to remove the residual chemical substances generated during the oxidation process, and then perform low-temperature curing treatment.

6. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The thickness of the oxide film on the surface of the aluminum alloy wheel is 20 μm to 40 μm.

7. The anodic oxidation coloring process of an aluminum alloy wheel according to claim 1, characterized in that, The aluminum alloy wheel removes the surface oil stains, dust and oxide layer by sandblasting or ultrasonic cleaning.

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