Anodic oxidation dyeing method and metal piece

Abstract

The invention discloses an anodic oxidation dyeing method and a metal piece. The anodic oxidation dyeing method comprises the following steps that a workpiece is subjected to primary anodic oxidation treatment, so that a hard oxidation film is formed on the surface of the workpiece, and the hard oxidation film is provided with a plurality of first micropores; the workpiece is subjected to secondary anodic oxidation treatment, so that a dyed oxidation film is formed below the hard oxidation film, and the dyed oxidation film is provided with a plurality of second micropores; corroding the workpiece by adopting a first corrosive liquid, and applying ultrasonic waves to the workpiece to form a first microgap on the hole wall of the second micropore; and the workpiece is dyed, so that dye is adsorbed in the second micropores and the first microgaps. Therefore, the adsorption capacity of the dyeing oxidation film on the dye is not easily influenced during subsequent hole sealing, and the specific surface area can be increased, so that the adsorption capacity of the anode oxidation film on the dye is improved, and ultra-deep dyeing is further realized.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface treatment, and more particularly to an anodic oxidation dyeing method and a metal part. Background Art

[0002] In the related art, the dyeing process for aluminum alloy anodic oxide films typically includes pretreatment, anodization, activation of the porous oxide film layer, dyeing, and high-temperature sealing. Dyeing is achieved by allowing the high specific surface area of ​​the porous oxide film to adsorb dye, resulting in color. The post-dye sealing process involves high-temperature hydration, which causes the porous oxide film to expand and seal the pores. However, during the high-temperature treatment and hydration expansion process, the oxide film's ability to adsorb dye decreases. Furthermore, because the specific surface area of ​​the original oxide film comes solely from the anodization process, the amount of dye adsorbed is low, preventing the achievement of ultra-deep dyeing. Summary of the Invention

[0003] In view of this, in order to solve at least one of the above technical problems, an embodiment of the present application provides an anodizing dyeing method.

[0004] In addition, an embodiment of the present application also provides a metal part dyed by the aforementioned dyeing method.

[0005] In a first aspect, the present application provides an anodic oxidation dyeing method, the method comprising the following steps:

[0006] Performing an anodic oxidation treatment on a workpiece to form a hard oxide film on the surface of the workpiece, wherein the hard oxide film has a plurality of first micropores;

[0007] Performing a secondary anodizing treatment on the workpiece to form a dyed oxide film under the hard oxide film, wherein the dyed oxide film has a plurality of second micropores;

[0008] The workpiece is corroded by using a first corrosive liquid and ultrasonic waves are applied to the workpiece to form a first microgap on the wall of the second microhole;

[0009] The workpiece is dyed so that the dye is adsorbed in the second micropores and the first microgap.

[0010] The anodizing dyeing method of the embodiment of the present application forms a corrosion-resistant hard oxide film on the outermost layer of the workpiece surface through two anodizing processes, and forms a dyeing oxide film on the inner side of the hard oxide film, so that the adsorption capacity of the dyeing oxide film to the dye is not easily affected in subsequent sealing steps, and a first microgap is formed in the second micropores for adsorbing the dye, which can increase the specific surface area, thereby increasing the adsorption amount of the dye by the anodized film, and thus achieving ultra-deep dyeing.

[0011] In some embodiments, in the step of performing an anodizing treatment on a workpiece to form a hard oxide film on the surface of the workpiece, the temperature of the anodizing treatment is 5°C-20°C; and / or, the voltage applied to the workpiece is in the range of 30V-50V; and / or, the time range of the anodizing treatment is 5min-15min.

[0012] In this way, by adopting a reasonable temperature, voltage and time range, the generation rate, density, thickness, hardness and other characteristics of the oxide film can be adjusted, thereby forming a hard oxide film with appropriate hardness, thickness and pore size.

[0013] In certain embodiments, in the step of performing an anodizing treatment on a workpiece to form a hard oxide film on the surface of the workpiece, the electrolyte used for the anodizing treatment includes one of oxalic acid, tartaric acid or citric acid, one of phosphoric acid or phosphates, one of ethylene glycol, diethylene glycol or propylene glycol, and the balance is water, wherein the concentration range of oxalic acid, tartaric acid or citric acid is 50g / L-200g / L, the mass percentage of phosphoric acid or phosphate is 0.5%-5%, and the mass percentage of ethylene glycol, diethylene glycol or propylene glycol is 1%-5%.

[0014] In this way, a reasonable concentration of oxalic acid can provide hydrogen ions, and oxalate can act as a corrosion inhibitor. A reasonable concentration of phosphoric acid can increase the voltage of anodization and increase the pore size of the first micropores in the hard oxide film. A reasonable concentration of ethylene glycol can increase the resistance of the electrolyte, making the electric field distribution during the anodization process more uniform, thereby obtaining a hard oxide film resistant to acid corrosion.

[0015] In certain embodiments, in the step of performing a secondary anodizing treatment on the workpiece to form a dyed oxide film under the hard oxide film, the temperature of the secondary anodizing treatment is 20°C-30°C; and / or, the voltage applied to the workpiece is in the range of 15V-25V; and / or, the time range of the secondary anodizing treatment is 30min-60min.

[0016] In this way, by changing the parameters during the anodizing treatment, a dye oxide film capable of adsorbing dyes is formed under the hard oxide film, thereby increasing the stability of the surface structure of the workpiece.

[0017] In some embodiments, in the step of performing a secondary anodizing treatment on the workpiece to form a dyed oxide film under the hard oxide film, the electrolyte used for the secondary anodizing treatment includes water, sulfuric acid, and one of oxalic acid, citric acid, or tartaric acid, wherein the concentration of sulfuric acid is 50g / L-200g / L, the concentration of oxalic acid, citric acid, or tartaric acid is 5g / L-50g / L, and the balance is water.

[0018] In this way, sulfuric acid can provide the hydrogen ions required for anodic oxidation, and a reasonable concentration of oxalic acid can improve the corrosion resistance of the oxide film and obtain second micropores with a suitable pore size.

[0019] In some embodiments, the first etching solution comprises at least one weak acid and at least one quaternary ammonium compound, wherein the concentration of the weak acid is 0.2 g / L-1 g / L, the concentration range of the quaternary ammonium compound is 0.05 g / L-0.5 g / L, the etching temperature ranges from 8° C. to 15° C.; and / or the frequency of the ultrasonic wave is 96 kHz to 144 kHz; and / or the etching time ranges from 5 min to 15 min.

[0020] Thus, within this power range, the ultrasonic wave can effectively improve the uniformity of the lateral dimensions of the second micro-gap, thereby not easily damaging the dyed oxide film and enhancing the stability of the dyed oxide film. In addition, the appropriate acid concentration can balance the generation of H + The corrosion rate is further adjusted by adjusting the rate of the anodic oxide film and the rate of dissolving the anodic oxide film to generate Al3+, which is beneficial to controlling the size of the first microgap and the uniformity of its distribution.

[0021] In certain embodiments, after the step of performing a secondary anodizing treatment on the workpiece, and before the step of corroding the surface of the workpiece with a first corrosive solution and applying ultrasound to the workpiece, the anodizing dyeing method includes:

[0022] The surface structure of the workpiece is roughened to form a dense oxide film with second micro-gaps under the dyed oxide layer.

[0023] In this way, a dense oxide film having second micro-gaps is formed under the dyed oxide layer, thereby increasing the surface roughness of the dense oxide film.

[0024] In some embodiments, roughening the surface structure of the workpiece includes: etching the dense oxide film with a second etching solution,

[0025] The second etching solution includes one of water, boric acid or borate and one of polyethylene glycol 200, propylene glycol or glycerol, wherein the concentration range of boric acid or borate is 10g / L-100g / L, the mass percentage range of polyethylene glycol 200, propylene glycol or glycerol is 0.1%-1%, and the balance is water. In the step of roughening the surface structure of the workpiece, the roughening treatment temperature range is 4°C-6°C; and / or, the roughening voltage applied to the workpiece is in the range of 300V-500V; and / or, the roughening treatment time range is 300s-900s.

[0026] In this way, boric acid or borate provides an electrolyte and forms aluminum borate crystals, increasing dye adsorption. Polyethylene glycol 200, propylene glycol, or glycerol acts as a corrosion inhibitor, while also improving the uniformity of the electric field and promoting a uniform distribution of the second microgaps. A high voltage roughening voltage achieves electrical breakdown and guides H+ ions. Within a reasonable roughening temperature and time range, the distribution of the second microgaps is uniform, with an appropriate range and size, achieving the desired roughening effect.

[0027] In certain embodiments, dyeing the workpiece so that the dye is adsorbed in the second micropores and the first microgap comprises:

[0028] The workpiece is dyed in the first stage, the second stage and the third stage with dyes of increasing concentrations.

[0029] Wherein, during the first stage of dyeing, the dyeing temperature range is 36°C-54°C, the dyeing time is 2 min-3 min, and the dye concentration is 0.8 g / L-1.2 g / L; and / or,

[0030] During the second stage of dyeing, the dyeing temperature is 36° C.-54° C., the dyeing time is 2.4 min-3.6 min, and the dye concentration is 2.4 g / L-3.6 g / L; and / or,

[0031] During the third stage of dyeing, the dyeing temperature is 20° C.-30° C., the dyeing time is 8 min-12 min, and the dye concentration is 4 g / L-6 g / L.

[0032] In this way, using dyes with increasing concentrations for staged dyeing can reduce the congestion during the dye diffusion process, avoid the clogging of the upper micropores when high-concentration dyes are directly used, and affect the adsorption of the dye at the bottom of the dyeing oxide film. At the same time, it can also make the adsorption of the dye in the second micropores more uniform and sufficient.

[0033] In certain embodiments, after dyeing the workpiece so that the dye is adsorbed in the second micropores and the first microgaps, the anodic oxidation dyeing method includes:

[0034] Use color fixing agent to fix the workpiece.

[0035] The color fixing agent includes an agglomeration inducing agent, an acid-base balancing agent, a first corrosion inhibitor and water, and the mass percentages of the agglomeration inducing agent, the acid-base balancing agent, the first corrosion inhibitor and the water are (0.2%-5%): (0.2%-2%): (0.5%-5%): the balance;

[0036] Among them, the agglomeration inducing agent includes one or more combinations of cocamidopropyl betaine, sodium lauryl polyether sulfate, polyquaternium salt, hexadecyltrimethylammonium chloride and dodecyldimethylbenzylmethylammonium chloride; the acid-base balancer includes one or more combinations of weak acid substances such as nicotinic acid, salicylic acid, tartaric acid, tannic acid, and ascorbic acid; the first corrosion inhibitor includes one or more combinations of nitrate, benzotriazole, and thiourea; the fixing time ranges from 2 min to 10 min, and the fixing temperature ranges from 60°C to 90°C.

[0037] This fixative treatment reduces the diffusion rate of dyes during the high-temperature sealing process, minimizing discoloration after sealing and paving the way for the next step of ultra-deep color sealing. Furthermore, the fixative is fluorine-free, contributing to environmental benefits.

[0038] In certain embodiments, after the step of fixing the workpiece with a fixing agent, the anodizing dyeing method includes:

[0039] The workpiece is sealed with a sealing agent to close the first micropores in the hard oxide film.

[0040] The sealing agent includes a hydration reaction accelerator, an acid-base stabilizer, a surface ash suppressant and a second corrosion inhibitor, wherein the mass percentages of the hydration reaction accelerator, the acid-base stabilizer, the surface ash suppressant and the second corrosion inhibitor are (0.1%-5%): (0.01%-0.5%): (0.5%-2%): (0.01%-0.05%), and the balance is a solvent;

[0041] Among them, the hydration reaction promoter includes at least one amine organic matter, the acid-base stabilizer includes acetate, the surface dust inhibitor includes at least one organic ester compound, the second corrosion inhibitor includes one or more of benzotriazole, thiourea, phosphine carboxylic acid, sulfonated lignin, carboxyhydroxy cellulose, and octadecylamine, the sealing time ranges from 90min to 120min, and the sealing temperature ranges from 90℃ to 95℃.

[0042] By sealing the first micropores in the hard oxide film, the effects of high-temperature hydration on the second micropores are reduced. This prevents the dye adsorption capacity and amount of the dye in the dyed oxide film from decreasing, thereby increasing the depth and stability of the color and improving the stability of the dyed oxide film. The sealant is a nickel-free formula, enabling nickel-free sealing, eliminating the effects of nickel ions that can cause color deviation in the oxide layer after sealing, improving the dyeing effect while maintaining the physical and chemical properties of both the hard and dyed oxide films.

[0043] In the second aspect, the present application provides a metal part, which includes a substrate and a hard oxide film and a dyed oxide film stacked on the surface of the substrate, the hard oxide film is located on the outer layer of the dyed oxide film away from the substrate, the hard oxide film has a plurality of first micropores, the dyed oxide film has a plurality of second micropores, the pore walls of the second micropores are formed with second microgaps, and the second micropores are used to adsorb dyes.

[0044] In this way, the first microgap, the second microgap, and the second micropore can all adsorb dyes, thereby increasing the specific surface area and the amount of dye adsorbed, thereby helping to achieve ultra-deep dyeing of the anodized film and enriching and expanding the appearance color of the metal parts.

[0045] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0047] Figure 1 is a flow chart of the anodic oxidation dyeing method according to an embodiment of the present application;

[0048] Figure 2 is a schematic diagram of the surface structure of a metal part according to an embodiment of the present invention;

[0049] Figure 3 Schematic diagram of the structure of the hard oxide film and the dyed oxide film according to the embodiment of the present application;

[0050] Figure 4 is a schematic diagram of the enlarged structure of the second micropore and the first microgap in an embodiment of the present application;

[0051] Figure 5 is an enlarged structural schematic diagram of a dense oxide film according to an embodiment of the present application;

[0052] Figure 6 The present invention is another embodiment of the anodic oxidation dyeing method of the flow chart.

[0053] Description of reference numerals:

[0054] 1000-metal part, 100-workpiece, 10-hard oxide film, 11-first micropore, 20-dyed oxide film, 21-second micropore, 22-first microgap, 30-dense oxide film, 31-second microgap, 40-substrate. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] See also Figure 1 、 Figure 4 and Figure 5 The anodic oxidation dyeing method according to the embodiment of the present application comprises the following steps:

[0057] Step S10 , performing an anodic oxidation treatment on a workpiece 100 to form a hard oxide film 10 on the surface of the workpiece 100 , wherein the hard oxide film 10 has a plurality of first micropores 11 ;

[0058] Step S20 , performing a secondary anodizing treatment on the workpiece 100 to form a dyed oxide film 20 under the hard oxide film 10 , wherein the dyed oxide film 20 has a plurality of second micropores 21 ;

[0059] Step S30, corroding the workpiece 100 with a first corrosive solution and applying ultrasonic waves to the workpiece 100 to form a first microgap 22 on the wall of the second microhole 21;

[0060] In step S40 , the workpiece 100 is dyed so that the second micropores 21 and the first microgap 22 are adsorbed with dye.

[0061] The anodizing dyeing method of the embodiment of the present application forms a corrosion-resistant hard oxide film 10 on the outermost layer of the surface of the workpiece 100 through two anodizing operations, and forms a dyeing oxide film 20 on the inner side of the hard oxide film 10, so that the adsorption capacity of the dyeing oxide film 20 to the dye is not easily affected in subsequent sealing steps, and a first micro-gap 22 is formed in the second micropore 21 for adsorbing the dye, which can increase the specific surface area, thereby increasing the adsorption amount of the dye by the anodized film, and thus achieving ultra-deep dyeing.

[0062] Specifically, the workpiece 100 is an aluminum or aluminum alloy workpiece 100, and the workpiece 100 includes a substrate 40. In step S10, the workpiece 100 is placed in an electrolyte, and a certain voltage is applied to perform an anodic oxidation treatment with the substrate 40 as an anode to form a porous hard oxide film 10 on the surface of the workpiece 100.

[0063] In step S20, the workpiece 100, having the hard oxide film 10 formed thereon, is placed in another electrolyte solution and a certain voltage is applied to perform a secondary anodizing treatment. The electrolyte composition, applied voltage, and anodizing treatment duration used in step S20 are all different from those used in step S10. Therefore, after the secondary anodizing treatment, a dyed oxide film 20, which is different from the hard oxide film 10, is formed on the surface of the workpiece 100.

[0064] Combine Figures 3-5 The hard oxide film 10 can be located at the outermost layer of the surface of the workpiece 100. The dyed oxide film 20 is formed below the hard oxide film 10, which means that the dyed oxide film 20 is located on the side of the hard oxide film 10 facing the substrate 40 and is stacked with the hard oxide film 10. The hard oxide film 10 has greater hardness and better corrosion resistance than the dyed oxide film 20.

[0065] Along the thickness direction of the hard oxide film 10 and the dyed oxide film 20, the first micropores 11 can penetrate the hard oxide film 10, and the second micropores 21 can penetrate the dyed oxide film 20, with at least a portion of the first micropores 11 and the second micropores 21 being connected. This allows the dye to penetrate into the second micropores 21 and the second microgap 31 beneath the hard oxide film 10.

[0066] In step S30, the first etching solution is a weak acid solution, which slightly corrodes the pore wall of the second micropore 21. The mechanism of the corrosion effect may be that the Al 3+ Dissociation and / or ionization of weak acid molecules to produce hydrogen ions (H + ), H + The walls of the second micropores 21 are slightly dissolved, thereby etching a plurality of first micro-gaps 22 on the walls of the second micropores 21. Since the hard oxide film 10 has good corrosion resistance and is almost unaffected by the first etching solution, the first micropores 11 on the hard oxide film 10 can maintain relatively smooth walls in step S30.

[0067] In the process of the first etching liquid etching the wall of the second micro-hole 21, applying ultrasonic waves to the workpiece 100 can cause microscopic movement of the first etching liquid through high-frequency vibration, thereby promoting the flow and penetration of the first etching liquid and changing the hydrogen ion (H + ) diffusion direction, and further regulate the distribution state and size of the first micro-gap 22, to obtain a microstructure with an appropriate distribution range and relatively uniform size. Specifically, the direction of the ultrasonic wave is perpendicular to the depth direction of the second micro-pore 21.

[0068] The first microgaps 22 can extend in a tree-like pattern along the radial direction of the second micropores 21 (perpendicular to the depth of the second micropores 21). Along the radial direction of the second micropores 21, the intervals between the first microgaps 22 are smaller than the center-to-center distance between two adjacent second micropores 21. Along the depth direction of the second micropores 21, the width of each of the first microgaps 22 is much smaller than the thickness of the dyed oxide film 20, and the corrosion area is primarily concentrated on the surface of the dyed oxide film 20. This keeps the radial and width dimensions of the first microgaps 22 within a relatively small range, which helps improve the stability of the oxide film.

[0069] In some embodiments, the surface of the workpiece 100 may be pretreated before step S10. The pretreatment steps may include degreasing, alkali biting, dust removal, and polishing. For example, before anodizing the workpiece 100, the surface of the aluminum alloy may be treated with R105 to remove contaminants such as oil and other dirt. Alkaline biting treatment may then be performed by soaking the aluminum alloy in a 55g / L sodium hydroxide solution at 55°C for 20 to 40 seconds to remove the natural oxide film on the surface. Deashing may then be performed by neutralizing the ash on the surface of the workpiece 100 with 25% by mass nitric acid. After this deashing process, the surface of the workpiece 100 may be chemically polished using a dibasic acid polishing agent composed of sulfuric acid and phosphoric acid to improve the gloss of the workpiece 100. After polishing, deashing may be performed again using 25% nitric acid to remove the gray film on the surface of the workpiece 100 resulting from chemical polishing.

[0070] In some embodiments, in the step of performing an anodizing treatment on a workpiece 100 to form a hard oxide film 10 on the surface of the workpiece 100, the temperature of the anodizing treatment is 5°C-20°C; and / or, the voltage applied to the workpiece 100 is in the range of 30V-50V; and / or, the time range of the anodizing treatment is 5min-15min.

[0071] In this way, by adopting a reasonable temperature, voltage and time range, the generation rate, density, thickness, hardness and other characteristics of the oxide film can be adjusted, thereby forming a hard oxide film 10 with appropriate hardness, thickness and pore size.

[0072] Specifically, in step S10, the temperature of the primary anodizing treatment may be 5°C, 8°C, 9°C, 10°C, 11.4°C, 12°C, 15°C, 20°C, or any value within the numerical range consisting of any two of the above values. Within the above temperature range, the voltage applied to the workpiece 100 may be 30V, 33V, 36V, 44V, 47V, 48V, 50V, or any value within the numerical range consisting of any two of the above values ​​between 30V and 50V. The primary anodizing voltage may be a DC voltage. The time of the primary anodizing treatment may be matched with the temperature and voltage of the primary anodizing treatment. For example, the duration of the anodizing treatment may be 5min, 6min, 7.4min, 8.5min, 9min, 10min, 15min, or any value within the numerical range consisting of any two of the above values.

[0073] In some embodiments, in the step of performing an anodizing treatment on the workpiece 100 to form a hard oxide film 10 on the surface of the workpiece 100, the electrolyte used for the anodizing treatment includes one of oxalic acid, tartaric acid or citric acid, one of phosphoric acid or phosphate, one of ethylene glycol, diethylene glycol or propylene glycol, and the balance is water, wherein the concentration range of oxalic acid, tartaric acid or citric acid is 50g / L-200g / L, the mass percentage of phosphoric acid or phosphate is 0.5%-5%, and the mass percentage of ethylene glycol, diethylene glycol or propylene glycol is 1%-5%.

[0074] In this way, oxalic acid at a reasonable concentration can provide hydrogen ions H + , and oxalate (C2O4 2 -) can play a role in corrosion inhibition. A reasonable concentration of phosphoric acid can increase the voltage of anodization and increase the pore size of the first micropores 11 in the hard oxide film 10. A reasonable concentration of ethylene glycol can increase the resistance of the electrolyte, making the electric field distribution during the anodization process more uniform, thereby obtaining an acid-corrosion-resistant hard oxide film 10.

[0075] Specifically, in step S10, the workpiece 100 is immersed in the electrolyte, the oxalic acid concentration in the electrolyte can be 50 g / L, 80 g / L, 84 g / L, 87 g / L, 91 g / L, 95 g / L, 102 g / L, 106 g / L, 113 g / L, 119 g / L, 120 g / L, or 200 g / L, the mass percentage of phosphoric acid can be 0.5%, 0.8%, 1.0%, 1.4%, 1.8%, 2.39%, 3.1%, 3.6%, 4.2%, 5%, or any value within a numerical range consisting of any two of the above values, and the mass percentage of ethylene glycol can be 1%, 1.6%, 1.9%, 2.1%, 2.3%, 2.7%, 3.3%, 3.7%, 4.2%, 4.4%, 5%, or any value within a numerical range consisting of any two of the above values.

[0076] In a preferred embodiment, the electrolyte used for the anodizing treatment includes oxalic acid, phosphoric acid, and ethylene glycol, wherein the concentration of oxalic acid is 100g / L, the mass percentage of phosphoric acid is 1%, the mass percentage of ethylene glycol is 2%, and the balance is water. In this embodiment, the anodizing treatment temperature is 10°C, the anodizing voltage is 45V or 35V, and the anodizing time is 10 minutes.

[0077] Optionally, the hard oxide film 10 has a thickness ranging from 2 μm to 4 μm (including end points).

[0078] Example 1

[0079] The anodizing treatment temperature is 10° C., the anodizing time is 10 min, and the thickness of the formed hard oxide film 10 is 2.2 μm, which is relatively thin.

[0080] Example 2

[0081] The anodizing treatment temperature is 15° C., the anodizing time is 10 min, and the thickness of the formed hard oxide film 10 is 3.5 μm, which is an appropriate thickness.

[0082] Example 3

[0083] The anodizing temperature is 10° C., the anodizing time is 10 min, the anodizing voltage is 30 V, and the thickness of the formed hard oxide film 10 is 2.5 μm, which is a suitable thickness.

[0084] Example 4

[0085] The anodizing temperature is 10° C., the anodizing time is 10 min, the anodizing voltage is 40 V, and the thickness of the formed hard oxide film 10 is 3.5 μm, which is a suitable thickness.

[0086] Comparative Example 1

[0087] The anodizing temperature is 5° C., the anodizing time is 10 min, and the thickness of the formed hard oxide film 10 is 1.2 μm, which is too thin.

[0088] Comparative Example 2

[0089] The anodizing temperature is 20° C., the anodizing time is 10 min, and the formed hard oxide film 10 has a thickness of 5.1 μm, which is relatively thick and has a gray surface.

[0090] Comparative Example 3

[0091] The anodizing temperature is 10° C., the anodizing time is 10 min, the anodizing voltage is 20 V, and the thickness of the formed hard oxide film 10 is 0.9 μm, which is too thin.

[0092] Comparative Example 4

[0093] The anodizing temperature is 10° C., the anodizing time is 10 min, and the anodizing voltage is 50 V. The formed hard oxide film 10 has a thickness of 5.6 μm, which is relatively thick and has a slightly gray surface.

[0094] In some embodiments, in the step (S20) of performing a secondary anodizing treatment on the workpiece 100 to form a dyed oxide film 20 under the hard oxide film 10, the temperature of the secondary anodizing treatment is 20°C-30°C; and / or, the voltage applied to the workpiece 100 is in the range of 15V-25V; and / or, the time range of the secondary anodizing treatment is 30min-60min.

[0095] In this way, by changing the parameters during the anodizing treatment, a dye oxide film capable of absorbing dyes is formed under the hard oxide film 10 , thereby increasing the stability of the surface structure of the workpiece 100 .

[0096] Specifically, in step S20, the temperature of the secondary anodizing treatment can be 20°C, 21°C, 24°C, 25.8°C, 27.1°C, 29°C, 30°C, or any value within the numerical range consisting of any two of the above values. During the secondary anodizing treatment, within the above temperature range, the voltage applied to the workpiece 100 can be 15V, 16V, 18V, 20V, 22V, 24V, 25V, or any value within the numerical range consisting of any two of the above values. The time of the secondary anodizing treatment matches the temperature and voltage of the secondary anodizing treatment. For example, the duration of the secondary anodizing treatment can be 30min, 33min, 42min, 48min, 51min, 60min, or any value within the numerical range consisting of any two of the above values.

[0097] In some embodiments, in the step (S20) of performing a secondary anodizing treatment on the workpiece 100 to form a dyed oxide film 20 under the hard oxide film 10, the electrolyte used for the secondary anodizing treatment includes water, sulfuric acid and oxalic acid, wherein the concentration of sulfuric acid is 50g / L-200g / L, the concentration of oxalic acid is 5g / L-50g / L, and the balance is water.

[0098] In this way, sulfuric acid can provide hydrogen ions required for anodic oxidation, and oxalic acid with a reasonable concentration can improve the corrosion resistance of the oxide film, thereby obtaining the second micropores 21 with a suitable pore size.

[0099] Specifically, in step S20, the workpiece 100 is immersed in an electrolyte for secondary anodizing treatment. In the electrolyte for secondary anodizing, the concentration of sulfuric acid can be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 92 g / L, 100 g / L, 104 g / L, 113 g / L, 118 g / L, 120 g / L, 150 g / L, 200 g / L or any value within the numerical range formed by any two of the above values, and the concentration of oxalic acid can be 5 g / L, 10 g / L, 16 g / L, 20 g / L, 27 g / L, 30 g / L, 42 g / L, 50 g / L or any value within the numerical range formed by any two of the above values.

[0100] By changing the electrolyte formula and anodizing treatment parameters in step S10 and step S20, a hard oxide film 10 that is resistant to acid corrosion is formed on the outermost layer of the surface of the workpiece 100, a dyeing oxide film 20 and a dense oxide film 30 for adsorbing dyes are formed on the inner layer, and the innermost layer is a metal substrate 40, thereby ensuring the dye adsorption amount while making the physical and chemical properties of the oxide film layer on the surface of the workpiece 100 stable.

[0101] In a preferred embodiment, the electrolyte concentrations used in step S20 are 100 g / L sulfuric acid and 20 g / L oxalic acid, a voltage of 20 V is applied to the workpiece 100 at 25° C., the anodizing treatment time is 45 minutes, and second micropores 21 capable of adsorbing dye are formed in the dye oxide film.

[0102] Optionally, the dyed oxide film 20 has a thickness ranging from 7 μm to 12 μm (both inclusive).

[0103] Examples 5-7

[0104] The following table shows the thickness of the dyed oxide film 20 generated in Examples 5-7, where the secondary anodizing treatment time is 45 min, the secondary anodizing treatment voltage is 25 V, and the secondary anodizing treatment temperatures are 20° C., 25° C., and 30° C., respectively.

[0105] Table 1. Comparison of the effects of secondary anodizing treatment in Examples 5-7 and Comparative Example 5

[0106] Temperature Time Voltage Dyed oxide film thickness Example 5 20℃ 45 min 25V 7.5 μm Example 6 25℃ - - 8.5 μm Example 7 30℃ - - 9.0 μm Comparative Example 5 15℃ - - 4.5 μm

[0107] In Table 1, “-” indicates that the same conditions as in Example 5 were adopted.

[0108] Comparative Example 5

[0109] The difference between Comparative Example 5 and Examples 5-7 is the temperature of the secondary anodizing treatment. In the comparative example, the temperature of the secondary anodizing treatment is 15 degrees. When other parameters of the secondary anodizing treatment are the same, the temperature is too low, resulting in the thickness of the dyed oxide film 20 being too thin.

[0110] In some embodiments, the first etching solution includes at least one weak acid and at least one quaternary ammonium compound, wherein the concentration of the weak acid is 0.2 g / L-1 g / L, the concentration range of the quaternary ammonium compound is 0.05 g / L-0.5 g / L, the etching temperature range is 8° C.-15° C.; and / or the frequency of the ultrasound is 96 kHz-144 kHz; and / or the etching time range is 5 min-15 min.

[0111] Thus, within this power range, the ultrasonic wave can effectively improve the uniformity of the lateral dimensions of the second micro-gap 31, thereby not easily damaging the dyed oxide film 20 and enhancing the stability of the dyed oxide film 20. In addition, the appropriate acid concentration can balance the generation of H + The corrosion rate is further adjusted by adjusting the rate of the anodic oxide film and the rate of dissolving the anodic oxide film to generate Al3+, which is beneficial to controlling the size of the first micro-gap 22 and the uniformity of its distribution.

[0112] Specifically, the first etching solution may include at least one weak acid selected from nicotinic acid, salicylic acid, phytic acid, and sulfamic acid, and may include at least one quaternary ammonium compound selected from benzalkonium chloride, benzalkonium bromide, and quaternary ammonium salts. For example, in the case where the second etching solution includes nicotinic acid and benzalkonium chloride, nicotinic acid not only provides hydrogen ions but also acts as a dye medium, increasing the affinity of the dyed oxide film 20 for the dye. Benzalkonium chloride can increase the electropositivity of the oxide film, thereby enhancing the electrostatic adsorption of the dye to the second micropores 21.

[0113] In step S30, the concentration of the weak acid can be 0.2g / L-1g / L, and the concentration of the quaternary ammonium salt compound can be in the range of 0.05g / L-0.5g / L.

[0114] In step S30, ultrasonic vibration combined with weak acid etching forms first microgaps 22 on the walls of the second micropores 21, thereby increasing the specific surface area and improving the adsorption of the dye on the surface of the workpiece 100. The ultrasonic frequency can, for example, be 96 kHz, 108 kHz, 112 kHz, 116 kHz, 120 kHz, 128 kHz, 136 kHz, 144 kHz, or any value within a range consisting of any two of the above values. The etching temperature can be 8°C, 9°C, 10°C, 12°C, 13°C, 14.5°C, 15°C, etc. The etching time can be 5 minutes, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 13 minutes, or 15 minutes.

[0115] In a preferred embodiment, the first etching solution includes nicotinic acid at a concentration of 0.5 g / L and benzalkonium chloride at a concentration of 0.2 g / L, the frequency of the ultrasonic wave is 120 kHz, the etching temperature is 15° C., and the etching time is 15 minutes.

[0116] In a preferred embodiment, the first etching solution includes nicotinic acid at a concentration of 0.2 g / L and benzalkonium chloride at a concentration of 0.2 g / L, the frequency of the ultrasonic wave is 120 kHz, the etching temperature is 15° C., and the etching time is 15 minutes.

[0117] Example 8

[0118] The frequency of the ultrasonic wave is 120KHZ, the corrosion temperature is 15°C, the corrosion time is 15min, and the L value after dyeing is 4.

[0119] Table 2. Comparative table of corrosion effects of Example 8 and Comparative Examples 6-8 on the wall of the second micropore 21

[0120] Ultrasonic frequency Etching temperature Etching time L value after dyeing Example 8 120 KHZ 15℃ 15 min 4 Comparative Example 6 28 KHZ - - 12 Comparative Example 7 48 KHZ - - 9 Comparative Example 8 1 MHZ - - 10

[0121] In Table 2, “-” indicates that the same conditions as in Example 8 were adopted.

[0122] Comparative Example 6

[0123] The frequency of the ultrasonic wave is 28KHZ, the corrosion temperature is 15℃, the corrosion time is 15min, and the L value after dyeing is 12.

[0124] Comparative Example 7

[0125] The frequency of the ultrasonic wave is 48KHZ, the corrosion temperature is 15°C, the corrosion time is 15min, and the L value after dyeing is 9.

[0126] Comparative Example 8

[0127] The frequency of the ultrasonic wave is 120KHZ, the corrosion temperature is 15°C, the corrosion time is 15min, and the L value after dyeing is 10.

[0128] In Comparative Examples 6-8, the frequency of the ultrasound is too high or too low, which results in the L value after dyeing being significantly higher than the L value in Example 8 under the same conditions. This shows that when the ultrasound frequency is controlled within a reasonable frequency range, the color brightness of the surface of the workpiece 100 after dyeing can be reduced, making it appear darker, deeper, or closer to black.

[0129] See also Figure 2 、 Figure 3 and Figure 6 In some embodiments, after the step (S20) of performing a secondary anodizing treatment on the workpiece 100, and before the step (S30) of corroding the surface of the workpiece 100 with a first corrosive solution and applying ultrasonic waves to the workpiece 100, the anodizing dyeing method includes:

[0130] Step S50, roughening the surface structure of the workpiece 100 to form the compact oxide film 30 with the second micro gap 31 under the dyeing oxide layer.

[0131] In this way, by forming the compact oxide film 30 with the second micro gap 31 under the dyeing oxide layer, the surface roughness of the compact oxide film 30 is increased.

[0132] It should be noted that after step S20, the surface structure of the workpiece 100 can include the hard oxide film 10, the dyeing oxide film 20 and the compact oxide film 30 stacked in turn from the outermost layer to the inside of the workpiece 100, the hard oxide film 10 and the dyeing oxide film 20 are both porous structures, and the compact oxide film 30 forms a compact structure.

[0133] In step S50, the roughening treatment of the compact oxide film 30 includes two processes of electrical breakdown and crystal phase precipitation. Specifically, the workpiece 100 is placed in a weak acid electrolyte, a roughing voltage is applied, the compact oxide film 30 is anodized to achieve slight corrosion of the surface of the compact oxide film 30, and at the same time, the surface of the compact oxide film 30 is precipitated by high voltage and weak acid environment. Aluminum salt crystal phase, further improve the roughness of the surface of the compact oxide film 30.

[0134] Alternatively, the second micro gap 31 can be a micro crack structure formed by polarization dissolution of the surface of the compact oxide layer under voltage and weak acid environment. The second micro gap 31 extends in a dendritic shape along the thickness direction of the compact oxide film 30, the length of the second micro gap 31 is much smaller than the thickness of the compact oxide film 30, and the width of the second gap is smaller than the pore size of the second micro hole 21.

[0135] In some embodiments, the roughening treatment of the surface structure of the workpiece 100 includes: using a second etching liquid to etch the compact oxide film 30,

[0136] The second etching liquid includes one of water, boric acid or boric acid salt and one of polyethylene glycol 200, propylene glycol or glycerol, wherein the concentration of boric acid or boric acid salt is in the range of 10g / L-100g / L, the mass percentage of polyethylene glycol 200, propylene glycol or glycerol is in the range of 0.1%-1%, and the balance is water.

[0137] In this way, boric acid or boric acid salt can provide electrolyte and at the same time form aluminum borate crystals to increase the adsorption capacity of dyes, polyethylene glycol 200, propylene glycol or glycerol can play a role in corrosion inhibition and at the same time improve the uniformity of the electric field to promote uniform distribution of the second micro gap 31.

[0138] Specifically, boric acid or a borate salt, as the primary electrolyte, can create a high-voltage, low-current environment in the first etching solution. Aluminum borate crystals are also formed on the surfaces of the dense oxide film 30 and the second microgap 31, increasing surface roughness. Dyes can also be adsorbed within the second microgap 31, thereby increasing the surface roughness of the dense oxide film 30 and the second microgap 31, thereby enhancing the dye adsorption capacity of the second microgap 31. For example, the concentration of boric acid in the second etching solution is 10 g / L, 22 g / L, 27 g / L, 29 g / L, 30 g / L, 31 g / L, 33 g / L, 45 g / L, 60 g / L, and 100 g / L, and the concentration of polyethylene glycol-200 is 0.1%, 0.21%, 0.42%, 0.5%, 0.53%, 0.56%, 0.7%, 0.8%, and 1%.

[0139] In some embodiments, in the step (S50) of roughening the surface structure of the workpiece 100, the temperature range of the roughening treatment is 4°C-6°C; and / or, the range of the roughening voltage applied to the workpiece 100 is 300V-500V; and / or, the range of the roughening treatment time is 300s-900s.

[0140] In this way, the roughening voltage is high voltage, which can achieve electrical breakdown and + The ions play a guiding role. When a reasonable roughening treatment temperature and time range are adopted, the second micro-gaps 31 can be distributed more evenly, and the distribution range and size are more appropriate, thereby achieving an ideal roughening effect.

[0141] Specifically, the roughening voltage can be the highest voltage after the voltage is increased, and is also the final voltage of the entire process of electrolyzing the dense oxide film 30. In step S50, the voltage increase rate can be 0.1V / s to 0.5V / s. For example, the voltage increase rate can be 0.1V / s, 0.18V / s, 0.2V / s, 0.21V / s, 0.3V / s, 0.42V / s, 0.5V / s or any value within the numerical range composed of any two of the above values. The roughening treatment time is the length of time the highest voltage is maintained after the voltage is increased. For example, the roughening treatment time can be 300s, 400s, 600s, 660s, 700s, 780s, 800s, 890s, or 900s. Furthermore, the range of the roughening treatment time can be 300s-600s, 400s-700s, 660s-900s, etc.

[0142] In a preferred embodiment, the second etching solution includes boric acid and polyethylene glycol 200, wherein the concentration of boric acid is 30 g / L, the mass percentage of polyethylene glycol 200 is 0.5%, the roughening voltage is 300 V, and the roughening treatment time is 300 s.

[0143] Example 9

[0144] The boost rate is 0.2 V / s, and the maximum voltage after boosting, that is, the roughening voltage, is 300 V. The time for maintaining the maximum voltage is 300 s. After the electrolysis is completed, a matte effect is formed at the bottom of the surface structure of the workpiece 100, that is, the surface of the dense oxide film 30 under the hard oxide film 10 and the dyed oxide film 20. There is no powdering phenomenon, and the oxide film (including the hard oxide film 10, the dyed oxide film 20 and the dense oxide film 30) is not broken down, thereby achieving the purpose of roughening.

[0145] Example 10

[0146] The boost rate is 0.4V / s, the maximum voltage after boosting is 300V, and the time of maintaining the maximum voltage is 300s. After the electrolysis is completed, a matte effect is formed on the surface of the dense oxide film 30 under the hard oxide film 10 and the dyed oxide film 20. There is no powdering phenomenon and the oxide film is not broken down, thus achieving the purpose of roughening.

[0147] Table 3. Comparison of the roughening effects of Examples 9 and 10 and Comparative Examples 9-11

[0148] Ramp rate Roughening temperature Roughening voltage Maximum voltage duration Roughening effect Example 9 0.2 V / s 5℃ 300V 300s OK Example 10 0.4 V / s - - - OK Comparative Example 9 0.6 V / s - - - Local pitting Comparative Example 10 0.8 V / s - - - Local pitting Comparative Example 11 1.0 V / s - - - Oxide film breakdown

[0149] In Table 3, “-” indicates that the same conditions as in Example 8 were adopted.

[0150] Comparative Example 9

[0151] The voltage boost rate was 0.6 V / s, the maximum voltage after boosting was 300 V, and the time for maintaining the maximum voltage was 300 s. After the electrolysis was completed, the surface structure of the workpiece 100 was partially powdered, and the roughening treatment failed.

[0152] Comparative Example 10

[0153] The voltage boost rate was 0.8 V / s, the maximum voltage after boosting was 300 V, and the time for maintaining the maximum voltage was 300 s. After the electrolysis was completed, the surface structure of the workpiece 100 was partially powdered, and the roughening treatment failed.

[0154] Comparative Example 11

[0155] The boost rate is 1.0 V / s, the maximum voltage after boosting is 300 V, and the time of maintaining the maximum voltage is 300 s. After the electrolysis is completed, the oxide film on the surface of the workpiece 100 (including the hard oxide film 10, the dyed oxide film 20 and the dense oxide film 30) is broken down, and the roughening treatment fails.

[0156] In some embodiments, dyeing the workpiece 100 so that dye is adsorbed in the second micropores 21 and the first microgap 22 ( S40 ) includes:

[0157] The workpiece 100 is dyed in the first stage, the second stage and the third stage using dyes with increasing concentrations.

[0158] Wherein, during the first stage of dyeing, the dyeing temperature range is 36°C-54°C, the dyeing time is 2 min-3 min, and the dye concentration is 0.8 g / L-1.2 g / L; and / or,

[0159] During the second stage of dyeing, the dyeing temperature is 36° C.-54° C., the dyeing time is 2.4 min-3.6 min, and the dye concentration is 2.4 g / L-3.6 g / L; and / or,

[0160] During the third stage of dyeing, the dyeing temperature is 20° C.-30° C., the dyeing time is 8 min-12 min, and the dye concentration is 4 g / L-6 g / L.

[0161] In this way, dyeing in stages using dyes with increasing concentrations can reduce congestion during the dye diffusion process, avoid blocking the upper micropores when high-concentration dyes are directly used, and affect the adsorption of the dye at the bottom of the dyeing oxide film 20. At the same time, it can also make the adsorption of the dye in the second micropores 21 more uniform and sufficient.

[0162] Specifically, the dye concentration gradient used in the first stage dyeing, the second stage dyeing, and the third stage dyeing increases step by step, and the dyeing time can also be increased step by step. For example, the dye concentration of the first stage dyeing is 1.05g / L, the dyeing temperature is 35°C, and the dyeing time is 3min; the dye concentration of the second stage dyeing is 3.2g / L, the dyeing temperature is 45°C, and the dyeing time is 3.2min; the dye concentration of the third stage dyeing is 5.1g / L, the dyeing temperature is 22°C, and the dyeing time is 11min. For another example, the dye concentration of the first stage dyeing is 0.9g / L, the dyeing temperature is 40°C, and the dyeing time is 2.5min; the dye concentration of the second stage dyeing is 2.9g / L, the dyeing temperature is 42°C, and the dyeing time is 2.9min; the dye concentration of the third stage dyeing is 4.8g / L, the dyeing temperature is 28°C, and the dyeing time is 9min.

[0163] Example 11

[0164] Workpiece 100 was dyed in a first, second, and third stage using dyes of increasing concentrations. The first stage had a dye concentration of 1 g / L, a dyeing temperature of 45°C, and a dyeing time of 2 minutes; the second stage had a dye concentration of 3 g / L, a dyeing temperature of 45°C, and a dyeing time of 3 minutes; the third stage had a dye concentration of 5 g / L, a dyeing temperature of 25°C, and a dyeing time of 10 minutes. The total dyeing time for the three stages was 15 minutes. The L value of the dyed color was 15.

[0165] Comparative Example 12

[0166] Using a dye with a concentration of 5 g / L, a dyeing temperature of 45° C., a dyeing time of 15 min, and an L value of 4 for the dyed color.

[0167] Example 11 improves the adsorption capacity of the bottom layer of the dyed oxide film 20 for dyes by gradient dyeing, and the dyed L value is significantly higher than that in Comparative Example 12, which directly uses high-concentration dyes to dye the L value, thereby obtaining a deeper coloring effect.

[0168] See also Figure 2 In some embodiments, after dyeing the workpiece 100 so that the dye is adsorbed in the second micropores 21 and the first microgap 22 ( S40 ), the anodic oxidation dyeing method includes:

[0169] Step S60: Using a color fixing agent to fix the workpiece 100.

[0170] The color fixing agent includes an agglomeration inducing agent, an acid-base balancing agent, a first corrosion inhibitor and water, and the mass percentages of the agglomeration inducing agent, the acid-base balancing agent, the first corrosion inhibitor and the water are (0.2%-5%): (0.2%-2%): (0.5%-5%): the balance;

[0171] Among them, the agglomeration inducing agent includes one or more combinations of cocamidopropyl betaine, sodium lauryl polyether sulfate, polyquaternium salt, hexadecyltrimethylammonium chloride and dodecyldimethylbenzylmethylammonium chloride; the acid-base balancer includes one or more combinations of weak acid substances such as nicotinic acid, salicylic acid, tartaric acid, tannic acid, and ascorbic acid; the first corrosion inhibitor includes one or more combinations of nitrate, benzotriazole (BTA), and thiourea; the fixing time ranges from 2 min to 10 min, and the fixing temperature ranges from 60°C to 90°C.

[0172] This fixative treatment reduces the diffusion rate of dyes during the high-temperature sealing process, minimizing discoloration after sealing and paving the way for the next step of ultra-deep color sealing. Furthermore, the fixative is fluorine-free, contributing to environmental benefits.

[0173] Specifically, the fixing agent utilizes the dispersed suspension properties of weak dyes to slightly aggregate the dyes, reducing thermal diffusion and fading. For example, the fixing agent includes 0.2% by weight of cocamidopropyl betaine, 0.2% by weight of salicylic acid, and 0.5% by weight of nitrate. Another example is a fixing agent containing 5% by weight of sodium laureth sulfate, 2% by weight of tartaric acid, and 5% by weight of BTA.

[0174] Exemplarily, in step S60, the fixing time can be 2 min, 3 min, 5 min, 6 min, 8 min, 9 min, or 10 min, and the fixing temperature range is 60°C, 64°C, 70°C, 80°C, 82°C, 83°C, or 90°C.

[0175] In the related art, anodic oxide films are usually fixed with fluorine-containing color fixing agents, such as fluorine-containing zirconium salts. The fixing principle of fluorine-containing color fixing agents is to combine fluorine with aluminum ions in the oxide film to form an insoluble precipitate of fluorine-aluminum compounds, thereby achieving local filling of the oxide film, increasing the diffusion resistance of the dye, and coordinating the hydrolysis and sealing of nickel salts in the sealing process to achieve a coordinated sealing treatment of the oxide film. However, since there is an upper limit to the amount of dye adsorbed by the oxide film, even if the fluorine-containing color fixing process can reduce the loss of the dye during the high-temperature diffusion process by improving the sealing efficiency, its final dyeing depth L value is only between 25-27, and it is impossible to achieve ultra-deep dyeing with an L value below 18.

[0176] The anodizing dyeing method of the embodiment of the present application, based on the structure of forming a stacked hard oxide film 10, a dyed oxide film 20, and a dense oxide film 30, adopts a fluorine-free color fixing agent to increase the anchoring effect of the dye in the second micropores 21, the first microgap 22, and the second microgap 31, and ultimately achieve ultra-deep dyeing.

[0177] See also Figure 2 In some embodiments, after the step of fixing the workpiece 100 with a color fixing agent (S60), the anodizing dyeing method includes:

[0178] In step S70 , a sealing agent is used to seal the workpiece 100 to close the first micropores 11 in the hard oxide film 10 .

[0179] In this way, by sealing the first micropores 11 in the hard oxide film 10, the influence of high-temperature hydration on the second micropores 21 is reduced, so that the adsorption capacity and adsorption amount of the dyed oxide film 20 for the dye are not easily reduced, thereby increasing the depth and stability of the color and improving the stability of the dyed oxide film 20.

[0180] In step S70 , the first micropores 11 in the hard oxide film 10 are hydrated and expanded by high-temperature hydration, thereby blocking the second micropores 21 in the dyed oxide film 20 and then sealing the first micropores 11 .

[0181] In certain embodiments, the sealing agent includes a hydration reaction accelerator, an acid-base stabilizer, a surface deashing agent, and a second corrosion inhibitor, and the mass percentages of the hydration reaction accelerator, the acid-base stabilizer, the surface deashing agent, and the second corrosion inhibitor are (0.1%-5%): (0.01%-0.5%): (0.5%-2%): (0.01%-0.05%), and the balance is a solvent;

[0182] Among them, the hydration reaction promoter includes at least one amine organic matter, the acid-base stabilizer includes acetate, the surface dust inhibitor includes at least one organic ester compound, the second corrosion inhibitor includes one or more of benzotriazole (BTA), thiourea, phosphine carboxylic acid, sulfonated lignin, carboxyhydroxy cellulose, and octadecylamine, the sealing time ranges from 90min to 120min, and the sealing temperature ranges from 90℃ to 95℃.

[0183] In this way, the sealing agent is a nickel-free formula, which can achieve nickel-free sealing, thereby eliminating the influence of nickel ions on the color deviation of the oxide layer after sealing, improving the dyeing effect, and ensuring the physical and chemical properties of the hard oxide film 10 and the dyed oxide film 20.

[0184] Specifically, the amine organic matter in the sealing agent can be one or more combinations of triethanolamine, diethanolamine, pentamethylenediamine, etc.; the acetate can be ammonium acetate, sodium acetate, etc., and can include a combination of one or more acetates; the organic ester compound can be one or more combinations of ethyl acetate, dimethyl glutarate, dimethyl succinate, etc.

[0185] For example, the sealing agent includes triethanolamine, ammonium acetate, ethyl acetate, and BTA, and the mass percentages of triethanolamine, ammonium acetate, ethyl acetate, and BTA are 0.1%:0.01%:0.5%:0.01%. For another example, the sealing agent includes diethanolamine, sodium acetate, dimethyl glutarate, and thiourea, and the mass percentages of diethanolamine, sodium acetate, dimethyl glutarate, and thiourea are 5%:0.5%:2%:0.05%.

[0186] Optionally, the sealing time may be 90 min, 95 min, 100 min, 107 min, 118 min, or 120 min, and the sealing temperature may be 90°C, 91°C, 92°C, 94°C, or 95°C.

[0187] In related art, sealing agents using the same principle contain nickel acetate. The mechanism of action of nickel-containing sealing agents is to accelerate the hydration and sealing process through the synergistic effect of nickel ions. However, nickel-containing sealing agents are not environmentally friendly. The nickel-free sealing agent provided in the embodiments of the present application can achieve a good sealing effect while improving environmental friendliness.

[0188] Example 12

[0189] The color fixing agent described in step S60 and the sealing agent described in step S70 are used to fix and seal the two dyed workpieces 100 in sequence. The color fixing temperature is 80°C, the color fixing time is 5 minutes, and the sealing temperature is 95°C, and the sealing time is 120 minutes. The 20Lab values ​​of the dyed oxide film of one of the workpieces 100 before color fixing and sealing are as follows: L value is 5.22, a is -0.33, and b is 0.39; the workpiece 100 is subjected to fluorine-free color fixing and nickel-free sealing, and the L value is 17.69, a is -0.17, and b is 0.23. The 20Lab values ​​of the dyed oxide film of the other workpiece 100 before color fixing and sealing are as follows: L value is 5.25, a is -0.35, and b is 0.40; the workpiece 100 is subjected to fluorine-free color fixing and nickel-free sealing, and the L value is 17.56, a is -0.13, and b is 0.27.

[0190] Comparative Example 13

[0191] Two dyed metal substrates of the same material were fixed and sealed using a fluorine-containing fixing agent and a nickel-containing sealing agent. The fixing temperature, time, sealing temperature, and time were consistent with those in Example 12. Before fixing and sealing, the Lab values ​​of one of the metal substrates were: L value was 5.32, a was -0.36, and b was 0.36; after the fluorine-containing fixing and nickel-containing sealing treatments, the Lab values ​​of the metal substrates were: L value was 21.62, a was -0.09, and b was 0.11. The Lab values ​​of the other metal substrates were: L value was 5.32, a was -0.36, and b was 0.36; after the fluorine-containing fixing and nickel-containing sealing treatments, the Lab values ​​of the metal substrates were: L value was 22.03, a was -0.05, and b was 0.20.

[0192] Table 4. Comparative table of color fixing effects of Example 12 and Comparative Example 13

[0193]

[0194] In Table 3, “-” indicates that the same conditions as in Example 8 were adopted.

[0195] Compared with the comparative example 13, the Lab value of the dyed oxide film 20 in Example 12 changes less before and after color fixing and sealing, the color change of the dyed oxide film 20 is not obvious, the color stability is more stable, and the physicochemical properties of the dyed oxide film 20 are more stable.

[0196] See also Figures 1-3In the second aspect, the present application provides a metal part 1000, which includes a substrate 40 and a hard oxide film 10 and a dyed oxide film 20 stacked on the surface of the substrate 40. The hard oxide film 10 is located on the outer layer of the dyed oxide film 20 away from the substrate 40. The hard oxide film 10 has a plurality of first micropores 11, and the dyed oxide film 20 has a plurality of second micropores 21. The pore walls of the second micropores 21 are formed with second microgaps 31, and the second micropores 21 are used to adsorb dyes.

[0197] In related technologies, in order to increase the specific surface area, the oxide film is usually slightly corroded. The corrosion area is mainly concentrated on the surface of the oxide film, which will also lead to a decrease in the physical and chemical properties of the surface of the oxide film. At the same time, the corrosion microcrack structure on the surface of the oxide film will make it difficult to seal the pores of the oxide film, thereby further reducing the physical and chemical properties of the oxide film. After dyeing, the L value is only between 22-26.

[0198] The anodizing dyeing method of the embodiment of the present application and the metal part 1000 treated by the dyeing method can form a structure in which a hard oxide film 10, a dyed oxide film 20 and a dense oxide film 30 are stacked on the surface of a substrate 40. The first micro-gap 22, the second micro-gap 31 and the second micropore 21 can adsorb dyes, thereby increasing the specific surface area and improving the adsorption amount of the dye. In addition, the color fixing treatment is performed by a fluorine-free color fixing agent to increase the anchoring effect of the dye at the adsorption position and reduce the desorption of the dye during the high-temperature sealing process. Finally, ultra-deep dyeing of the aluminum alloy anodizing is achieved through nickel-free high-temperature sealing, enriching and expanding the appearance color of the aluminum alloy anode workpiece 100.

[0199] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically specified.

[0200] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. An anodic oxidation dyeing method, characterized in that, include: Performing an anodic oxidation treatment on the workpiece to form a hard oxide film on the surface of the workpiece, wherein the hard oxide film has a plurality of first micropores; performing a secondary anodizing treatment on the workpiece to form a dyed oxide film under the hard oxide film, wherein the dyed oxide film has a plurality of second micropores; corroding the workpiece with a first corrosive liquid and applying ultrasonic waves to the workpiece to form a first microgap on the wall of the second micropore; The workpiece is dyed so that dye is adsorbed in the second micropores and the first microgap.

2. The anodic oxidation dyeing method according to claim 1, wherein In the step of performing an anodizing treatment on the workpiece to form a hard oxide film on the surface of the workpiece, the temperature of the anodizing treatment is 5°C-20°C; and / or the voltage applied to the workpiece is in the range of 30V-50V; and / or the time range of the anodizing treatment is 5min-15min.

3. The anodic oxidation dyeing method according to claim 2, wherein The electrolyte used in the primary anodizing treatment includes one of oxalic acid, tartaric acid or citric acid, one of phosphoric acid or phosphate, one of ethylene glycol, diethylene glycol or propylene glycol, and the balance is water, wherein the concentration of oxalic acid, tartaric acid or citric acid is 50g / L-200g / L, the mass percentage of phosphoric acid or phosphate is 0.5%-5%, and the mass percentage of ethylene glycol, diethylene glycol or propylene glycol is 1%-5%.

4. The anodic oxidation dyeing method according to claim 1, wherein In the step of performing a secondary anodizing treatment on the workpiece to form a dyed oxide film under the hard oxide film, the temperature of the secondary anodizing treatment is 20°C-30°C; and / or the voltage applied to the workpiece is in the range of 15V-25V; and / or the time range of the secondary anodizing treatment is 30min-60min.

5. The anodic oxidation dyeing method according to claim 1, wherein The electrolyte used in the secondary anodizing treatment includes water, sulfuric acid and one of oxalic acid, citric acid or tartaric acid, wherein the concentration of sulfuric acid is 50g / L-200g / L, the concentration of oxalic acid, citric acid or tartaric acid is 5g / L-50g / L, and the balance is water.

6. The anodic oxidation dyeing method according to claim 1, wherein The first etching liquid comprises at least one weak acid and at least one quaternary ammonium salt compound, wherein the concentration of the weak acid is 0.2g / L-1g / L, the concentration range of the quaternary ammonium salt compound is 0.05g / L-0.5g / L, the etching temperature range is 8°C-15°C; and / or the frequency of the ultrasonic wave is 96KHZ-144KHZ; and / or the etching time range is 5min-15min.

7. The anodic oxidation dyeing method according to claim 1, wherein After the step of performing secondary anodizing treatment on the workpiece, corroding the surface of the workpiece with a first corrosive solution, and before the step of applying ultrasonic waves to the workpiece, the anodizing dyeing method includes: The surface structure of the workpiece is roughened to form a dense oxide film with second microgaps under the dyed oxide layer.

8. The anodic oxidation dyeing method according to claim 7, wherein: The roughening treatment of the surface structure of the workpiece includes: etching the dense oxide film with a second etching solution, The second etching solution includes one of water, boric acid or borate and one of polyethylene glycol 200, propylene glycol or glycerol, wherein the concentration range of boric acid or borate is 10g / L-100g / L, the mass percentage range of polyethylene glycol 200, propylene glycol or glycerol is 0.1%-1%, and the balance is water. The temperature range of the roughening treatment is 4°C-6°C; and / or the roughening voltage applied to the workpiece is in the range of 300V-500V; and / or the roughening treatment time is in the range of 300s-900s.

9. The anodic oxidation dyeing method according to claim 1, wherein: The workpiece is dyed so that the second micropores and the first microgap absorb dye, comprising: The workpiece is dyed in the first stage, the second stage and the third stage by using dyes with increasing concentrations. Wherein, during the first stage of dyeing, the dyeing temperature ranges from 36°C to 54°C, the dyeing time ranges from 2 min to 3 min, and the dye concentration ranges from 0.8 g / L to 1.2 g / L; and / or, During the second stage of dyeing, the dyeing temperature is 36° C.-54° C., the dyeing time is 2.4 min-3.6 min, and the dye concentration is 2.4 g / L-3.6 g / L; and / or, During the third stage dyeing, the dyeing temperature is 20° C.-30° C., the dyeing time is 8 min-12 min, and the dye concentration is 4 g / L-6 g / L.

10. The anodic oxidation dyeing method according to claim 1, characterized in that: After dyeing the workpiece so that dye is adsorbed in the second micropores and the first microgap, the anodic oxidation dyeing method includes: The workpiece is subjected to color fixing treatment using a color fixing agent. The color fixing agent includes an agglomeration inducing agent, an acid-base balancing agent, a first corrosion inhibitor and water, and the mass percentages of the agglomeration inducing agent, the acid-base balancing agent, the first corrosion inhibitor and water are (0.2%-5%): (0.2%-2%): (0.5%-5%): the balance; Among them, the agglomeration inducing agent includes one or more combinations of cocamidopropyl betaine, sodium lauryl polyether sulfate, polyquaternium salt, hexadecyltrimethylammonium chloride, dodecyldimethylbenzylmethylammonium chloride, the acid-base balancer includes one or more combinations of weak acid substances such as nicotinic acid, salicylic acid, tartaric acid, tannic acid, and ascorbic acid, the first corrosion inhibitor includes one or more combinations of nitrate, benzotriazole, and thiourea, the fixing time ranges from 2 min to 10 min, and the fixing temperature ranges from 60°C to 90°C.

11. The anodic oxidation dyeing method according to claim 10, characterized in that: After the step of fixing the workpiece with a color fixing agent, the anodic oxidation dyeing method includes: Performing a sealing treatment on the workpiece with a sealing agent to close the first micropores in the hard oxide film; The sealing agent includes a hydration reaction accelerator, an acid-base stabilizer, a surface ash inhibitor and a second corrosion inhibitor, wherein the mass percentages of the hydration reaction accelerator, the acid-base stabilizer, the surface ash inhibitor and the second corrosion inhibitor are (0.1%-5%): (0.01%-0.5%): (0.5%-2%): (0.01%-0.05%), and the balance is a solvent; Among them, the hydration reaction accelerator includes at least one amine organic matter, the acid-base stabilizer includes acetate, the surface dust suppressant includes at least one organic ester compound, the second corrosion inhibitor includes one or more of benzotriazole, thiourea, phosphine carboxylic acid, sulfonated lignin, carboxyhydroxy cellulose, and octadecylamine, the sealing time ranges from 90min to 120min, and the sealing temperature ranges from 90℃ to 95℃.

12. A metal part, characterized in that: The metal part includes a substrate and a hard oxide film and a dyed oxide film stacked on the surface of the substrate, the hard oxide film is located on the outer layer of the dyed oxide film away from the substrate, the hard oxide film has a plurality of first micropores, the dyed oxide film has a plurality of second micropores, the pore walls of the second micropores are formed with second microgaps, and the second micropores are used to adsorb dyes.

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