Alloy film layer and preparation method and application thereof

Abstract

The invention provides an alloy film layer and a preparation method and application thereof. The preparation method of the alloy film layer comprises the step of carrying out micro-arc oxidation on an alloy base material in electrolyte, wherein the electrolyte comprises electrolyte, a pH regulator, an additive and an activating agent. According to the preparation method, the micro-arc oxidation time is greatly shortened, the production efficiency is remarkably improved, the Vickers hardness of the prepared alloy film layer can reach 998-1092 HV, the capacity of resisting external force scratching and abrasion is high, and the excellent stable friction performance is achieved under the high-load and high-speed conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and relates to a preparation technology of an alloy surface film layer, and in particular to an alloy film layer and a preparation method and application thereof. Background Art

[0002] With the continuous expansion of the 3C product market and the increasing demand for electronic products by consumers, the quality requirements for alloy surface treatment are gradually increasing. At present, most of the alloy surface films on the market are made by anodizing, spraying and other processes, but these two processes are either costly or have low film bonding strength, poor surface color uniformity, and the surface is prone to scratches and is not resistant to dirt after a long time of use.

[0003] CN101445949A discloses an electrolyte for micro-arc oxidation, that is, a method for micro-arc oxidation. The electrolyte provided is an aqueous solution containing phosphate and silicate, and a method for micro-arc oxidation is provided, the method comprising placing a light metal material in an electrolytic cell containing the electrolyte, using the light metal material as an anode and a stainless steel plate as a cathode, and forming a micro-arc oxidation film on the surface of the light metal material under micro-arc oxidation conditions.

[0004] CN1369577A discloses a surface treatment process for aluminum alloys, comprising placing a pretreated magnesium alloy in an alkaline electrolyte, performing micro-arc oxidation treatment on the surface of the magnesium alloy using a maintenance oxidation device, and forming a ceramic layer on the surface of the magnesium alloy. The formed ceramic coating surface has a μm-level blind micropore distribution, which is beneficial to subsequent powder spraying and coloring treatment.

[0005] CN104593395A discloses a cathode electrophoretic coating. Under certain conditions, carbon black is prepared into a pre-dispersed slurry. In the process of preparing the electrophoretic color paste, the carbon black pre-dispersed slurry is wrapped with a grinding resin for high-speed dispersion and grinding, thereby improving the grinding efficiency of the pigment carbon black in the aqueous slurry, improving the blackness and glossiness of the electrophoretic paint film, and realizing the application of N series granular rubber carbon black in the electrophoretic coating.

[0006] In the prior art, although an alloy film layer can be obtained on the alloy surface through micro-arc oxidation or electrophoresis, the micro-arc oxidation process takes too long, has low production efficiency, and has problems such as poor wear resistance and stain resistance.

[0007] Therefore, it is of great significance to provide a method for preparing an alloy film layer with high production efficiency, good wear resistance and corrosion resistance. Summary of the invention

[0008] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an alloy film layer and its preparation method and application. The preparation method of the alloy film layer provided by the present invention greatly shortens the time of micro-arc oxidation and significantly improves the production efficiency. The Vickers hardness of the prepared alloy film layer can reach 998-1092HV, and it has a strong ability to resist scratches and wear by external forces, and has excellent stable friction performance under high load and high speed conditions. The alloy film layer prepared by the present invention has good bonding force with the alloy substrate, high density, is not easy to fall off, and has good corrosion resistance.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing an alloy film layer, the preparation method comprising micro-arc oxidation of an alloy substrate in an electrolyte, the electrolyte comprising an electrolyte, a pH regulator, an additive and an activator.

[0011] The role of the electrolyte in the present invention is to form an oxide layer on the surface of the alloy substrate under specific voltage and current conditions. The choice of electrolyte has an important influence on the color, thickness, hardness and other properties of the oxide film.

[0012] Preferably, the electrolyte includes any one of sodium silicate, sodium hydroxide, potassium silicate, disodium hydrogen phosphate, monoammonium phosphate, sodium hexametaphosphate, magnesium sulfate or sodium metaborate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of potassium silicate and monoammonium phosphate, a combination of potassium silicate and magnesium sulfate, a combination of magnesium sulfate and sodium metaborate, a combination of potassium silicate and sodium hydroxide, a combination of sodium silicate and disodium hydrogen phosphate, a combination of potassium carbonate and sodium hydroxide, and a combination of sodium silicate, disodium hydrogen phosphate and sodium metaborate.

[0013] The role of the pH regulator in the present invention is to adjust the pH of the electrolyte to ensure that it fluctuates within an appropriate range, thereby avoiding the adverse effects of an overly acidic or overly alkaline environment on the oxidation reaction. Under appropriate pH conditions, the oxidation reaction is more complete, which helps to form a dense and uniform oxide film.

[0014] Preferably, the pH adjuster includes any one of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium dihydrogen phosphate, sodium acetate, sodium bisulfate or sodium bicarbonate, or a combination of at least two thereof.

[0015] The function of the additive in the present invention is to improve the performance of the electrolyte, thereby improving the performance of the oxide film, and enhancing the bonding strength, wear resistance, corrosion resistance, etc. between the film layer and the substrate.

[0016] Preferably, the additive includes any one of ferric citrate, sodium carbonate, sodium fluoride, hydroxyapatite, sodium tungstate, potassium fluorotitanate or ammonium fluorotitanate, or a combination of at least two thereof.

[0017] The function of the activator in the present invention is to reduce the surface tension of the electrolyte, making it easier for the electrolyte to penetrate into the surface of the metal substrate and promote the oxidation reaction. In addition, the activator also has the function of preventing the formation of bubbles and precipitation, and can maintain the stability and uniformity of the electrolyte.

[0018] Preferably, the activator includes any one of polyethylene glycol, polyoxyethylene ether, sodium stearate, sodium oleate, or a combination of at least two thereof.

[0019] Preferably, the electrolyte also includes water.

[0020] Preferably, the electrolyte also includes a colorant.

[0021] In the present invention, the colorant participates in the reaction during the electrolysis process to generate specific compounds, so that the oxide film presents a corresponding color.

[0022] Preferably, the colorant includes any one of ammonium metavanadate, sodium vanadate, ferrous sulfate, potassium permanganate, copper sulfate or copper pyrophosphate, or a combination of at least two thereof.

[0023] Preferably, the method for preparing the electrolyte comprises:

[0024] The electrolyte is dissolved in water to obtain an electrolyte solution, an additive is added to the electrolyte solution, a first stirring is performed until the additive is completely dissolved, an activator is added, a second stirring is performed until the activator is completely dissolved, a pH adjuster is added to adjust the pH to 11-13, and the electrolyte solution is obtained.

[0025] In the present invention, the pH of the electrolyte is 11-13, for example, it can be 11, 11.2, 11.4, 11.6, 11.8, 12, 12.2, 12.4, 12.6, 12.8 or 13, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the method for preparing the electrolyte further comprises adding a colorant after adjusting the pH to 11-13.

[0027] Preferably, in the electrolyte, the concentration of the electrolyte is 10g / L-20g / L, for example, it can be 10g / L, 10.5g / L, 11g / L, 11.5g / Lg / L, 12g / Lg / L, 12.5g / L, 13g / L, 13.5g / L, 14g / L, 14.5g / L, 15g / L, 15.5g / L, 16g / L, 16.5g / L, 17g / L, 17.5g / L, 18g / L, 18.5g / L, 19g / L, 19.5g / L or 20g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, in the electrolyte, the concentration of the electrolyte is 12 g / L-15 g / L.

[0029] Preferably, in the electrolyte, the concentration of the additive is 3g / L-9g / L, for example, it can be 3g / L, 3.5g / L, 4g / L, 4.5g / L, 5g / L, 5.5g / L, 6g / L, 6.5g / L, 7g / L, 7.2g / L, 7.4g / L, 7.6g / L, 7.8g / L, 8g / L, 8.2g / L, 8.4g / L, 8.6g / L, 8.8g / L or 9g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, in the electrolyte, the concentration of the additive is 7 g / L-9 g / L.

[0031] Preferably, in the electrolyte, the concentration of the activator is 1 g / L-5 g / L, for example, it can be 1 g / L, 1.5 g / L, 2 g / L, g / L, 2.2 g / L, 2.4 g / L, 2.6 g / L, 2.8 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L or 5 g / L, including but not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the concentration of the activator in the electrolyte is 2 g / L-3 g / L.

[0033] Preferably, in the electrolyte, the concentration of the colorant is 2g / L-7g / L, for example, it can be 2g / L, 2.5g / L, 3g / L, 3.5g / L, 4g / L, 4.2g / L, 4.4g / L, 4.6g / L, 4.8g / L or 5g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, in the electrolyte, the concentration of the colorant is 4 g / L-5 g / L.

[0035] Preferably, the micro-arc oxidation is carried out under constant pressure conditions.

[0036] Preferably, the voltage of the micro-arc oxidation is 400V-480V, for example, it can be 400V, 405V, 410V, 415V, 420V, 425V, 430V, 435V, 440V, 445V, 450V, 455V, 460V, 465V, 470V, 475V or 480V, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the temperature of the electrolyte is 15°C-30°C, for example, it can be 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] The time of micro-arc oxidation affects the thickness of the prepared micro-arc oxidation film. If the micro-arc oxidation time is too long, the prepared micro-arc oxidation film will be too thick, which will lead to excessive impedance. The present invention greatly shortens the time of micro-arc oxidation and greatly improves the production capacity of micro-arc oxidation by optimizing the process of micro-arc oxidation.

[0039] Preferably, the micro-arc oxidation time is 10 min-15 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the positive duty cycle of the micro-arc oxidation is 20%-50%, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48% or 50%, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the negative duty cycle of the micro-arc oxidation is 30%-90%, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the positive frequency level of the micro-arc oxidation is 800 Hz-1000 Hz, for example, it can be 800 Hz, 820 Hz, 840 Hz, 860 Hz, 880 Hz, 900 Hz, 920 Hz, 940 Hz, 960 Hz, 980 Hz or 1000 Hz, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the negative frequency level of the micro-arc oxidation is 800 Hz-1000 Hz, for example, it can be 800 Hz, 820 Hz, 840 Hz, 860 Hz, 880 Hz, 900 Hz, 920 Hz, 940 Hz, 960 Hz, 980 Hz or 1000 Hz, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] Preferably, the number of positive electrodes of the micro-arc oxidation is 1-10, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] Preferably, the negative order of the micro-arc oxidation is 1-10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] As a preferred technical method of the present invention, the preparation method of the present invention also includes electrophoresis treatment after the micro-arc oxidation.

[0047] The micro-arc oxidation combined with the electrophoresis treatment in the present invention can prepare an alloy film layer with excellent hydrophobicity and mixed stain resistance, and can further enhance its corrosion resistance and wear resistance.

[0048] Preferably, the electrophoresis treatment is carried out in electrophoretic paint.

[0049] Preferably, the electrophoretic paint comprises a base resin, an additive, a neutralizer and a color paste.

[0050] The function of the base resin in the present invention is to be deposited on the surface of the alloy substrate under the action of the electric field to form a continuous and dense coating film, which can protect the workpiece from corrosion, wear and other damages, while reducing the color difference of the film layer and improving the glossiness of the film layer.

[0051] Preferably, the base resin includes any one of epoxy resin, polyurethane resin, acrylic resin, or a combination of at least two of them.

[0052] The role of the additive in the present invention is to improve the coating performance of the electrophoretic paint and enhance the quality of the alloy film layer. The addition of the additive can enhance the adhesion and corrosion resistance of the film layer; during the preparation process, the pH of the electrophoretic paint can be adjusted to be within a suitable range, and the storage stability of the electrophoretic paint can be improved to prevent deterioration or stratification during storage.

[0053] Preferably, the auxiliary agent includes any one of sodium hexametaphosphate, polyethylene glycol, and polyamide, or a combination of at least two of them.

[0054] In the present invention, the role of the neutralizer is to adjust the pH value of the electrophoretic paint to keep it within a suitable range to ensure the stability and coating performance of the electrophoretic paint. At the same time, the neutralizer can also react with the acidic groups in the resin to enhance the solubility and dispersibility of the coating.

[0055] Preferably, the neutralizing agent includes any one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, diethanolamine, oxalic acid, dimethylethanolamine, and lactic acid, or a combination of at least two thereof.

[0056] Preferably, the color paste is a water-based color paste.

[0057] In the present invention, the color paste used is a commercially available color paste, preferably a water-based color paste.

[0058] Preferably, the preparation method of the electrophoretic paint comprises:

[0059] Water and resin are mixed to obtain a mixture, color paste and additives are added to the mixture in sequence, and after mixing evenly, a neutralizer is added to adjust the pH to 7-8 to obtain an electrophoretic paint precursor solution; the electrophoretic paint precursor solution is filtered using a pretreated anionic resin to obtain an electrophoretic paint.

[0060] In the present invention, the use of pretreated anionic resin to filter the electrophoretic paint precursor solution can remove hard ions in the electrophoretic paint precursor solution, such as calcium ions and / or magnesium ions. These ions will affect the deposition effect and film quality of the electrophoretic paint.

[0061] Anionic resins can also reduce the conductivity of electrophoretic paint, thereby stabilizing the bath performance, helping to maintain the consistency and uniformity of electrophoretic paint deposition and improving the quality of the coating process.

[0062] In the present invention, the number of times the electrophoretic paint precursor solution is filtered using the pretreated anionic resin is based on the conductivity. When the conductivity is 350 μs / cm to 400 μs / cm, the filtration is completed, and there is no specific limitation.

[0063] Preferably, the pretreatment comprises first soaking the anion resin in an alkaline solution and then washing it to a pH value less than 8.

[0064] In the present invention, an alkaline solution is used to soak the anion resin, and the pH of the system is maintained at 12-14. For example, the pH of the system can be 12, 12.2, 12.4, 12.6, 12.8, 13, 13.2, 13.4, 13.6, 13.8 or 14, and the pH of the alkaline solution is no longer specifically limited.

[0065] In the present invention, the purpose of pre-treating the anion resin is to allow the hydroxide ions (OH-) to replace the anions adsorbed on the resin, thereby restoring the ion exchange capacity of the resin. The ion exchange resin with basic groups can remove various ions introduced into the electrophoretic paint during the production process and reduce defects in the film layer.

[0066] Preferably, the alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0067] Preferably, in the electrophoretic paint precursor solution, the concentration of the base resin is 320g / L-380g / L, for example, it can be 320g / L, 325g / L, 330g / L, 335g / L, 340g / L, 345g / L, 350g / L, 355g / L, 360g / L, 365g / L, 370g / L, 375g / L or 380g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] Preferably, in the electrophoretic paint precursor solution, the concentration of the additive is 1g / L-3g / L, for example, it can be 1g / L, 1.2g / L, 1.4g / L, 1.6g / L, 1.8g / L, 2.0g / L, 2.2g / L, 2.4g / L, 2.6g / L, 2.8g / L or 3g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] In the present invention, the concentration of the neutralizer is not particularly limited, and the pH of the electrophoretic paint precursor solution is adjusted to 7-8.

[0070] Preferably, in the electrophoretic paint precursor solution, the concentration of the color paste is 10g / L-30g / L, for example, it can be 10g / L, 12g / L, 14g / L, 16g / L, 18g / L, 20g / L, 22g / L, 24g / L, 26g / L, 28g / L or 30g / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0071] Preferably, the voltage of the electrophoresis treatment is 160V-200V, for example, it can be 160V, 165V, 170V, 175V, 180V, 185V, 190V, 195V or 200V, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] Preferably, the electrophoresis treatment time is 60s-120s, for example, it can be 60s, 65s, 70s, 75s, 80s, 85s, 90s, 95s, 100s, 105s, 110s, 115s or 120s, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] Preferably, the temperature of the electrophoretic paint is 25°C-30°C, for example, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] Preferably, the preparation method further comprises sealing the alloy substrate.

[0075] Preferably, the sealing treatment is performed after the micro-arc oxidation and before the electrophoresis treatment.

[0076] Preferably, the sealing treatment includes pure water sealing.

[0077] In a second aspect, the present invention provides an alloy film layer, which is prepared by the preparation method described in the first aspect.

[0078] In a third aspect, the present invention provides an alloy workpiece, the surface of which has an alloy film layer as described in the second aspect.

[0079] Compared with the prior art, the present invention has the following beneficial effects:

[0080] In the preparation method provided by the present invention, by optimizing the process of micro-arc oxidation, the time of micro-arc oxidation is greatly shortened, the production capacity of the micro-arc oxidation process is improved, and the production efficiency of preparing the alloy film layer is improved. The Vickers hardness of the alloy film layer prepared by the present invention can reach above 998HV, has excellent ability to resist external scratches and wear, and has good wear resistance under high load and high speed conditions. The alloy film layer has strong bonding force with the alloy substrate, high density, is not easy to fall off and has good corrosion resistance. The micro-arc oxidation process provided by the present invention is combined with electrophoresis treatment, and the water drop angle of the alloy film layer obtained is greater than 86°, which has excellent hydrophobicity, significantly improves the anti-fouling performance of the alloy film layer, and further improves the aesthetics, wear resistance and corrosion resistance of the alloy film layer. DETAILED DESCRIPTION

[0081] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0082] Example 1

[0083] This embodiment provides a method for preparing a black alloy film layer and a black alloy workpiece, and the steps of the preparation method are as follows:

[0084] (1) Preparation of micro-arc oxidation electrolyte

[0085] Potassium silicate and sodium hydroxide electrolytes are added to deionized water, and after being fully stirred until completely dissolved, sodium carbonate and sodium fluoride additives are added, and stirring is continued. Bubbles are avoided during stirring, and the additives are stirred until they are fully dissolved without precipitation. Then, a polyethylene glycol activator is added, and stirring is continued until the polyethylene glycol is completely dissolved. A potassium hydroxide pH adjuster is used to adjust the pH to 12, and a sodium vanadate colorant is added. After being fully stirred until completely dissolved, a micro-arc oxidation electrolyte is obtained.

[0086] Among them, the concentration of electrolyte is 12g / L, the concentration of additive is 9g / L, the concentration of activator is 3g / L, and the concentration of colorant is 4g / L.

[0087] (2) Micro-arc oxidation

[0088] The micro-arc oxidation electrolysis temperature was controlled to be 20° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0089] Among them, the voltage of micro-arc oxidation is 430V, the positive duty cycle of micro-arc oxidation is 50%, the negative duty cycle is 80%, the positive frequency level is 900Hz, the negative frequency level is 1000Hz, the positive number of poles is 10, the negative number of poles is 1, and the micro-arc oxidation time is 12min.

[0090] The total substrate after micro-arc oxidation was placed in pure water for 3600s of sealing treatment to obtain a black alloy workpiece.

[0091] Example 2

[0092] This embodiment provides a method for preparing a black alloy film layer and a black alloy workpiece, and the steps of the preparation method are as follows:

[0093] (1) Prepare micro-arc oxidation electrolyte

[0094] Sodium silicate and disodium hydrogen phosphate electrolytes are added to deionized water, and after being fully stirred until completely dissolved, ferric citrate and sodium fluoride additives are added, and stirring is continued. Avoid generating bubbles during stirring, and stir until the additives are fully dissolved without precipitation. Then, a polyoxyethylene ether activator is added, and stirring is continued until the polyoxyethylene ether is completely dissolved. The pH is adjusted to 13 using a sodium hydroxide pH adjuster, and an ammonium metavanadate colorant is added. After being fully stirred until completely dissolved, a micro-arc oxidation electrolyte is obtained.

[0095] Among them, the concentration of electrolyte is 12.5g / L, the concentration of additive is 8g / L, the concentration of activator is 2g / L, and the concentration of colorant is 5g / L.

[0096] (2) Micro-arc oxidation

[0097] The micro-arc oxidation electrolysis temperature was controlled at 30° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0098] Among them, the voltage of micro-arc oxidation is 420V, the positive duty cycle of micro-arc oxidation is 20%, the negative duty cycle is 90%, the positive frequency level is 1000Hz, the negative frequency level is 1000Hz, the positive pole number is 1, the negative pole number is 1, and the micro-arc oxidation time is 13min.

[0099] The total substrate after micro-arc oxidation was placed in pure water for 3800s of sealing treatment to obtain a black alloy workpiece.

[0100] Example 3

[0101] This embodiment provides a method for preparing a black alloy film layer and a black alloy workpiece, and the steps of the preparation method are as follows:

[0102] (1) Preparation of micro-arc oxidation electrolyte

[0103] Potassium carbonate and sodium hydroxide electrolytes are added to deionized water, and after being fully stirred until completely dissolved, sodium tungstate and ferric citrate additives are added, and stirring is continued. Avoid generating bubbles during stirring, and stir until the additives are fully dissolved without precipitation. Then, sodium stearate activator is added, and stirring is continued until the sodium stearate is completely dissolved. Sodium bicarbonate pH adjuster is used to adjust the pH to 11, and sodium vanadate colorant is added. After being fully stirred until completely dissolved, a micro-arc oxidation electrolyte is obtained.

[0104] Among them, the concentration of electrolyte is 12g / L, the concentration of additive is 7g / L, the concentration of activator is 1g / L, and the concentration of colorant is 4g / L.

[0105] (2) Micro-arc oxidation

[0106] The micro-arc oxidation electrolysis temperature was controlled at 15° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0107] Among them, the voltage of micro-arc oxidation is 420V, the positive duty cycle of micro-arc oxidation is 20%, the negative duty cycle is 30%, the positive frequency level is 800Hz, the negative frequency level is 900Hz, the positive pole number is 1, the negative level number is 1, and the micro-arc oxidation time is 15min.

[0108] The total substrate after micro-arc oxidation was placed in pure water for 3900s of sealing treatment to obtain a black alloy workpiece.

[0109] Example 4

[0110] This embodiment provides a method for preparing a white alloy film layer and a white alloy workpiece, and the steps of the preparation method are as follows:

[0111] (1) Preparation of micro-arc oxidation electrolyte

[0112] Potassium silicate and sodium hydroxide electrolytes are added to deionized water, and after being fully stirred until completely dissolved, sodium carbonate and sodium fluoride additives are added, and stirring is continued. Bubbles are avoided during stirring, and the additives are stirred until they are fully dissolved without precipitation. Then, a polyethylene glycol activator is added, and stirring is continued until the polyethylene glycol is completely dissolved. A potassium hydroxide pH adjuster is used to adjust the pH to 12 to obtain a micro-arc oxidation electrolyte.

[0113] Among them, the concentration of electrolyte is 12g / L, the concentration of additive is 9g / L, and the concentration of activator is 3g / L.

[0114] (2) Micro-arc oxidation

[0115] The micro-arc oxidation electrolysis temperature was controlled to be 20° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0116] Among them, the voltage of micro-arc oxidation is 430V, the positive duty cycle of micro-arc oxidation is 50%, the negative duty cycle is 80%, the positive frequency level is 900Hz, the negative frequency level is 1000Hz, the positive number of poles is 10, the negative number of poles is 1, and the micro-arc oxidation time is 12min.

[0117] The total substrate after micro-arc oxidation was placed in pure water for 3600 seconds for sealing treatment to obtain an alloy substrate to be treated with electrophoresis.

[0118] (3) Preparation of electrophoretic paint

[0119] The anion resin was soaked in a sodium hydroxide solution with a pH of 14 for 1 hour, and the anion resin was rinsed with clean water until the pH reached 8 to obtain a pretreated anion resin.

[0120] After mixing water and epoxy resin evenly, add white color paste and sodium hexametaphosphate in turn, continue to stir and mix, add diethanolamine to adjust the pH to 7.5, continue to stir for 1 hour, and obtain an electrophoretic paint precursor solution, wherein the concentration of epoxy resin is 320g / L, the concentration of white color paste is 20g / L, and the concentration of sodium hexametaphosphate is 1g / L.

[0121] The electrophoretic paint precursor solution is filtered once using the pretreated anionic resin to obtain the electrophoretic paint.

[0122] (4) Electrophoresis treatment

[0123] The temperature of the electrophoretic paint was controlled at 30°C, and the alloy substrate to be electrophoretically treated was placed in the electrophoretic paint for electrophoretic treatment at a voltage of 160V and a time of 120s.

[0124] Example 5

[0125] This embodiment provides a method for preparing a white alloy film layer and a white alloy workpiece, and the steps of the preparation method are as follows:

[0126] (1) Prepare micro-arc oxidation electrolyte

[0127] Potassium silicate and sodium hydroxide electrolytes are added to deionized water, and after being fully stirred until completely dissolved, sodium carbonate and sodium fluoride additives are added, and stirring is continued. Bubbles are avoided during stirring, and the additives are stirred until they are fully dissolved without precipitation. Then, a polyethylene glycol activator is added, and stirring is continued until the polyethylene glycol is completely dissolved. A potassium hydroxide pH adjuster is used to adjust the pH to 12 to obtain a micro-arc oxidation electrolyte.

[0128] Among them, the concentration of electrolyte is 12g / L, the concentration of additive is 9g / L, and the concentration of activator is 3g / L.

[0129] (2) Micro-arc oxidation

[0130] The micro-arc oxidation electrolysis temperature was controlled to be 20° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0131] Among them, the voltage of micro-arc oxidation is 430V, the positive duty cycle of micro-arc oxidation is 50%, the negative duty cycle is 80%, the positive frequency level is 900Hz, the negative frequency level is 1000Hz, the positive number of poles is 10, the negative number of poles is 1, and the micro-arc oxidation time is 12min.

[0132] The total substrate after micro-arc oxidation was placed in pure water for 3600 seconds for sealing treatment to obtain an alloy substrate to be treated with electrophoresis.

[0133] (3) Preparation of electrophoretic paint

[0134] The anion resin was soaked in a sodium hydroxide solution with a pH of 13 for 2 hours, and the anion resin was rinsed with clean water until the pH reached 7.8 to obtain a pretreated anion resin.

[0135] After mixing water and polyurethane resin evenly, add white color paste and polyethylene glycol in turn, continue to stir and mix until evenly mixed, add oxalic acid to adjust the pH to 7.5, continue to stir for 1 hour, and obtain an electrophoretic paint precursor solution, wherein the concentration of polyurethane resin is 350g / L, the concentration of white color paste is 20g / L, and the concentration of polyethylene glycol is 3g / L.

[0136] The electrophoretic paint precursor solution was filtered three times using the pretreated anionic resin to obtain the electrophoretic paint.

[0137] (4) Electrophoresis treatment

[0138] The temperature of the electrophoretic paint was controlled to be 25° C., and the alloy substrate to be electrophoretically treated was placed in the electrophoretic paint for electrophoretic treatment. The voltage of the electrophoretic treatment was 180 V, and the time was 90 seconds.

[0139] Example 6

[0140] This embodiment provides a method for preparing a white alloy film layer and a white alloy workpiece, and the steps of the preparation method are as follows:

[0141] (1) Preparation of micro-arc oxidation electrolyte

[0142] Potassium silicate and sodium hydroxide electrolytes are added to deionized water, and after being fully stirred until completely dissolved, sodium carbonate and sodium fluoride additives are added, and stirring is continued. Bubbles are avoided during stirring, and the additives are stirred until they are fully dissolved without precipitation. Then, a polyethylene glycol activator is added, and stirring is continued until the polyethylene glycol is completely dissolved. A potassium hydroxide pH adjuster is used to adjust the pH to 12 to obtain a micro-arc oxidation electrolyte.

[0143] Among them, the concentration of electrolyte is 12g / L, the concentration of additive is 9g / L, and the concentration of activator is 3g / L.

[0144] (2) Micro-arc oxidation

[0145] The micro-arc oxidation electrolysis temperature was controlled to be 20° C. and the alloy substrate was placed in the micro-arc oxidation electrolyte for micro-arc oxidation.

[0146] Among them, the voltage of micro-arc oxidation is 430V, the positive duty cycle of micro-arc oxidation is 50%, the negative duty cycle is 80%, the positive frequency level is 900Hz, the negative frequency level is 1000Hz, the positive number of poles is 10, the negative number of poles is 1, and the micro-arc oxidation time is 12min.

[0147] The total substrate after micro-arc oxidation was placed in pure water for 3600 seconds for sealing treatment to obtain an alloy substrate to be treated with electrophoresis.

[0148] (3) Preparation of electrophoretic paint

[0149] The anion resin was soaked in a sodium hydroxide solution with a pH of 12.5 for 1 hour, and the anion resin was rinsed with clean water until the pH reached 8 to obtain a pretreated anion resin.

[0150] After mixing water and acrylic resin evenly, add white color paste and polyamide in turn, continue to stir and mix until evenly mixed, add lactic acid to adjust the pH to 7.5, continue to stir for 1 hour, and obtain an electrophoretic paint precursor solution, wherein the concentration of acrylic resin is 380g / L, the concentration of white color paste is 20g / L, and the concentration of polyamide is 2g / L.

[0151] The electrophoretic paint precursor solution is filtered twice using the pretreated anionic resin to obtain the electrophoretic paint.

[0152] (4) Electrophoresis treatment

[0153] The temperature of the electrophoretic paint was controlled to be 25° C., and the alloy substrate to be electrophoretically treated was placed in the electrophoretic paint for electrophoretic treatment at a voltage of 200 V and a time of 60 seconds.

[0154] Example 7

[0155] This embodiment provides a method for preparing a black alloy film layer and a black alloy workpiece. The preparation method is the same as that of Embodiment 4, except that the white color paste used in the electrophoretic paint is replaced by a black color paste.

[0156] The alloy film layers prepared in Examples 1 to 6 of the present invention were tested for Vickers hardness using a Vickers hardness tester. The test method was as follows: a diamond-made square pyramid indenter (with an angle of 136° between two opposite faces) was pressed into the tested metal surface under a pressure of 0.01 kgf, then unloaded and the diagonal length of the indentation was measured, and the Vickers hardness value was obtained by calculation. The test results are shown in Table 1.

[0157] The alloy film layers prepared by Examples 1 to 6 of the present invention were tested for color difference, glossiness, water drop angle and flatness using the color difference, glossiness, water drop angle and roughness testing methods commonly used in the art. In the color difference, a positive L value indicates that the color is white, and a negative L value indicates that the color is black; a positive a value indicates that the color is red, and a negative a value indicates that the color is green; a positive b value indicates that the color is yellow, and a negative b value indicates that the color is blue. Gloss is the glossiness of the film layer. The larger the value, the higher the glossiness of the film layer and the brighter the film layer. CA indicates the water drop angle of the film layer. The larger the CA value, the higher the hydrophobicity of the film layer. Ft indicates the thickness of the film layer. The larger the value, the thicker the film layer. Sq indicates the roughness of the film layer. The larger the value, the rougher the film layer. Sal indicates the maximum height difference on the surface of the film layer. The smaller the value, the better the flatness of the film layer. The test results are shown in Table 1.

[0158] Table 1

[0159]

[0160] Table 2

[0161] L a b Gloss Ft CA(d°) Example 4 92.33 -1.17 -0.62 10.5 6.6 86.94 Example 5 91.68 -1.19 -0.89 11.1 5.7 87.31 Example 6 92.17 -1.09 -0.78 10.7 6.2 86.69 Example 7 27.4 0.04 -0.41 10.2 6.5 87.2

[0162] The present invention significantly reduces the micro-arc oxidation time by optimizing the micro-arc oxidation process, and greatly improves the production capacity of the micro-arc oxidation process. In addition, the L value of the alloy film layer made by micro-arc oxidation in Examples 1 to 3 of the present invention is less than 26.04, has a high blackness, a Vickers hardness greater than 998HV, has a stronger ability to resist external scratches and wear, and can maintain stable friction performance for a long time under high load and high speed conditions.

[0163] According to the data results of Examples 3 to 6, when the micro-arc oxidation preparation process provided by the present invention is combined with electrophoresis treatment to prepare a white film layer, the prepared film layer has an L value of about 91 to 93, an a value of -1.17 to -1.09, and a b value of -0.89 to -0.62, with higher whiteness, and a Gloss value of more than 10, with high gloss, and a water drop angle of the film layer is more than 86.68°, with good hydrophobicity, and the anti-fouling performance of the film layer is greatly improved. It is not easy for dirt or fingerprints to remain on the surface of the film layer, and the cleaning process can be simplified.

[0164] According to the data results of Example 7, when the micro-arc oxidation preparation process provided by the present invention is combined with electrophoresis treatment to prepare a black film layer, the L value of the prepared film layer is 27.4, which has a relatively high blackness.

[0165] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an alloy film layer, characterized in that: The preparation method comprises performing micro-arc oxidation on an alloy substrate in an electrolyte, wherein the electrolyte comprises an electrolyte, a pH regulator, an additive and an activator.

2. The preparation method according to claim 1, characterized in that: The electrolyte includes any one or a combination of at least two of sodium silicate, sodium hydroxide, potassium silicate, disodium hydrogen phosphate, monoammonium phosphate, sodium hexametaphosphate, magnesium sulfate or sodium metaborate; Preferably, the pH adjuster includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium dihydrogen phosphate, sodium acetate, sodium bisulfate or sodium bicarbonate; Preferably, the additive includes any one or a combination of at least two of ferric citrate, sodium carbonate, sodium fluoride, hydroxyapatite, sodium tungstate, potassium fluorotitanate or ammonium fluorotitanate; Preferably, the activator comprises any one of polyethylene glycol, polyoxyethylene ether, sodium stearate, sodium oleate, or a combination of at least two thereof; Preferably, the electrolyte also includes water; Preferably, the electrolyte further comprises a colorant; Preferably, the colorant includes any one of ammonium metavanadate, sodium vanadate, ferrous sulfate, potassium permanganate, copper sulfate or copper pyrophosphate, or a combination of at least two thereof.

3. The preparation method according to claim 1 or 2, characterized in that: The preparation method of the electrolyte comprises: Dissolving an electrolyte in water to obtain an electrolyte solution, adding an additive to the electrolyte solution, performing a first stirring until the additive is completely dissolved, adding an activator, performing a second stirring until the activator is completely dissolved, and adding a pH adjuster to adjust the pH to 11-13 to obtain the electrolyte solution; Preferably, the method for preparing the electrolyte further comprises adding a colorant after adjusting the pH to 11-13; Preferably, in the electrolyte, the concentration of the electrolyte is 10 g / L-20 g / L, preferably 12 g / L-15 g / L; Preferably, in the electrolyte, the concentration of the additive is 3 g / L-9 g / L, preferably 7 g / L-9 g / L; Preferably, in the electrolyte, the concentration of the activator is 1g / L-5g / L, 2g / L-3g / L; Preferably, in the electrolyte, the concentration of the colorant is 2 g / L-7 g / L, preferably 4 g / L-5 g / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The micro-arc oxidation is carried out under constant pressure conditions; Preferably, the voltage of the micro-arc oxidation is 400V-480V; Preferably, the temperature of the electrolyte is 15°C-30°C; Preferably, the micro-arc oxidation time is 10min-15min; Preferably, the positive duty cycle of the micro-arc oxidation is 20%-50%; Preferably, the negative duty cycle of the micro-arc oxidation is 30%-90%; Preferably, the positive frequency level of the micro-arc oxidation is 800Hz-1000Hz; Preferably, the negative frequency level of the micro-arc oxidation is 800Hz-1000Hz; Preferably, the number of positive electrodes of the micro-arc oxidation is 1-10; Preferably, the negative order of the micro-arc oxidation is 1-10.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The preparation method further comprises an electrophoresis treatment after the micro-arc oxidation; Preferably, the electrophoresis treatment is carried out in an electrophoretic paint; Preferably, the electrophoretic paint comprises a base resin, an additive, a neutralizer and a color paste; Preferably, the base resin comprises one or a combination of at least two of epoxy resin, polyurethane resin and acrylic resin; Preferably, the auxiliary agent includes one or a combination of at least two of sodium hexametaphosphate, polyethylene glycol, and polyamide; Preferably, the neutralizing agent includes any one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, diethanolamine, oxalic acid, dimethylethanolamine, and lactic acid, or a combination of at least two thereof; Preferably, the color paste is a water-based color paste.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The preparation method of the electrophoretic paint comprises: Mixing water and resin to obtain a mixture, adding color paste and additives to the mixture in sequence, mixing evenly, adding a neutralizer to adjust the pH to 7-8 to obtain an electrophoretic paint precursor solution; filtering the electrophoretic paint precursor solution using a pretreated anionic resin to obtain an electrophoretic paint; Preferably, the pretreatment comprises first soaking the anion resin in an alkaline solution, and then washing it to a pH <8; Preferably, the alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution; Preferably, in the electrophoretic paint precursor solution, the concentration of the base resin is 320 g / L-380 g / L; Preferably, in the electrophoretic paint precursor solution, the concentration of the additive is 1 g / L-3 g / L; Preferably, in the electrophoretic paint precursor solution, the concentration of the color paste is 10 g / L-30 g / L.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The voltage of the electrophoresis treatment is 160V-200V; Preferably, the electrophoresis treatment time is 60s-120s; Preferably, the temperature of the electrophoretic paint is 25°C to 30°C.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The preparation method further comprises performing a pore sealing treatment on the alloy substrate; Preferably, the sealing treatment is performed after the micro-arc oxidation and before the electrophoresis treatment; Preferably, the sealing treatment includes pure water sealing.

9. An alloy film layer, characterized in that: The alloy film layer is prepared by the preparation method according to any one of claims 1 to 8.

10. An alloy workpiece, characterized in that: The surface of the alloy workpiece has the alloy film layer as claimed in claim 9.

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