CN110685000B - High-corrosion-resistance coating, preparation method, electrolyte and application thereof - Google Patents

High-corrosion-resistance coating, preparation method, electrolyte and application thereof Download PDF

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CN110685000B
CN110685000B CN201911095364.1A CN201911095364A CN110685000B CN 110685000 B CN110685000 B CN 110685000B CN 201911095364 A CN201911095364 A CN 201911095364A CN 110685000 B CN110685000 B CN 110685000B
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electrolyte
coating
micro
zinc
arc oxidation
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CN110685000A (en
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吴忠振
朱佳宇
杨超
吴忠灿
马正永
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Peking University Shenzhen Graduate School
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/024—Anodisation under pulsed or modulated current or potential
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/026—Anodisation with spark discharge
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic acids
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/26—Anodisation of refractory metals or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/30—Anodisation of magnesium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/36—Phosphatising

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  • Chemical Kinetics & Catalysis (AREA)
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  • Organic Chemistry (AREA)
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Abstract

The invention discloses a high-corrosion-resistance coating, a preparation method, an electrolyte and application thereof. The electrolyte comprises 5-50g/L phosphate, 5-30g/L zinc-containing compound and 1-15g/L complexing agent, and the solvent is water. The electrolyte provided by the invention dissolves phosphate, zinc-containing compound and complexing agent in water, and meets the use requirement of micro-arc oxidation. Meanwhile, by combining the characteristics of self-repair, phosphorization and the like with micro-arc oxidation, the coating obtained by micro-arc oxidation by using the electrolyte disclosed by the invention has better density and self-repair capability, and further the corrosion resistance of the processed workpiece is improved.

Description

High-corrosion-resistance coating, preparation method, electrolyte and application thereof
Technical Field
The invention relates to the field of surface modification of alloy materials, in particular to a high-corrosion-resistance coating, a preparation method, electrolyte and application thereof.
Background
In recent years, light metals and their alloys have been widely used in the automotive industry, military and national defense, aerospace, medical devices and daily 3C products due to well-known characteristics of easy processing design and low price, and mature manufacturing processes and inspection techniques. In order to meet the more severe application requirements, the performances of light metals and their alloys are being improved, wherein the corrosion resistance of light metals and their alloys has been one of the important indexes for measuring their application prospects.
At present, the following surface treatment methods are common for light metals and alloys thereof: chemical plating, electroplating, thermal spraying, anodic oxidation, micro-arc oxidation, vapor deposition and the like, and the corrosion resistance of the light metal and the alloy thereof is improved by changing the surface components of the matrix or forming a protective layer on the surface.
Micro-arc oxidation (abbreviated as MAO), also known as plasma electrolytic oxidation (abbreviated as PEO), has gained more and more attention and research due to its advantages of low cost, environmental protection, high film forming rate, good bonding force, etc. Compared with the common modes of anodic oxidation, chemical plating and the like for manufacturing corrosion-resistant coatings, the coating obtained by the method has more excellent performance.
The micro-arc oxidation method can generate an oxide ceramic coating with high binding force on the surface of the light metal and the alloy thereof, and the latest research shows that the corrosion-resistant coating prepared by micro-arc oxidation in China can keep 600-fold sand for 800 hours in a 3.5% salt spray environment and cannot be corroded and damaged, so that the service life of the light metal and the alloy part thereof is limited, particularly in a high-salt high-temperature environment.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a high-corrosion-resistance coating, a preparation method, an electrolyte and application thereof, and aims to solve the problem that the corrosion-resistance service life of the coating prepared by the existing electrolyte through micro-arc oxidation is not long.
The technical scheme of the invention is as follows:
an electrolyte comprises 5-50g/L phosphate, 5-30g/L zinc-containing compound and 1-15g/L complexing agent, and the solvent is water.
Further, the phosphate is selected from at least one of sodium hexametaphosphate, disodium hydrogenphosphate, sodium dihydrogenphosphate, sodium polyphosphate, trisodium phosphate, and sodium pyrophosphate.
Further, the zinc-containing compound is at least one selected from zinc oxalate, zinc citrate, zinc nitrate, zinc sulfate, zinc chloride, zinc acetate and diethyl zinc disulfide.
Further, the complexing agent is at least one selected from ethylene diamine tetraacetic acid, triethanolamine, sodium tartrate, citric acid and oxalic acid.
Further, the pH value of the electrolyte is 6-12; and/or the ionic conductivity of the electrolyte is 5-60mS cm-1。
The invention relates to an application of the electrolyte in micro-arc oxidation.
The invention relates to application of the electrolyte in forming a coating on the surface of a workpiece by using a micro-arc oxidation method.
A preparation method of a high-corrosion-resistance coating on the surface of light metal comprises the following steps: the electrolyte disclosed by the invention is used for forming a coating on the surface of the light metal by a micro-arc oxidation method.
Further, the light metal is valve metal such as aluminum, magnesium, titanium and the like and alloy materials thereof.
Further, the temperature of the electrolyte is controlled to be 10-60 ℃.
Further, the power supply used by the micro-arc oxidation method is a pulse power supply, and the processing parameters of the pulse power supply are as follows: under constant current mode, the current density is 5-20A/dm2The treatment time is 5-30min, and the frequency is 50-3000 Hz; or under the constant voltage mode, the voltage is 300-800V, the processing time is 5-30min, and the frequency is 50-3000 Hz.
The invention relates to a high-corrosion-resistance coating, wherein the coating is a zinc-containing oxide coating prepared by the method.
Has the advantages that: according to the electrolyte disclosed by the invention, the phosphate, the zinc-containing compound and the complexing agent are dissolved in water, so that the use requirement of micro-arc oxidation is met. By introducing phosphate and a zinc-containing compound subjected to phosphating treatment into the electrolyte and combining the characteristics of phosphating treatment, self-repair and the like with micro-arc oxidation, the coating obtained by micro-arc oxidation by using the electrolyte disclosed by the invention has better compactness and a new compound, and the compound enables the coating to have a self-repair effect, so that the corrosion resistance of the coating is improved to a new height.
Drawings
FIG. 1 is an electron microscope scanning image of aluminum alloy treated by the electrolyte of this embodiment in the micro-arc oxidation method for salt spray corrosion for 0h and 3000h in example 1 of the present invention;
FIG. 2 is an electron microscope scanning image of the aluminum alloy treated by the micro-arc oxidation method using the comparative electrolyte of this example in example 1 of the present invention for 0h and 3000h of salt spray corrosion;
FIG. 3 is a 3D confocal picture after salt spray etching in example 1 of the present invention.
FIG. 4 is a graph showing the results of the frictional wear test of the samples in example 2 of the present invention.
FIG. 5 is a 3D confocal picture after salt spray etching in example 2 of the present invention.
Detailed Description
The invention provides a high-corrosion-resistance coating, a preparation method, an electrolyte and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides an electrolyte, which comprises 5-50g/L phosphate, 5-30g/L zinc-containing compound and 1-15g/L complexing agent, wherein the solvent is water (such as distilled water).
According to the electrolyte, the phosphate, the zinc-containing compound and the complexing agent are dissolved in water, so that the use requirement of micro-arc oxidation is met. In the embodiment, phosphate and a zinc-containing compound subjected to phosphating treatment are introduced into the electrolyte, and phosphating treatment, a self-repairing characteristic and micro-arc oxidation are combined, so that the coating obtained by performing micro-arc oxidation by using the electrolyte of the embodiment has better compactness and new compounds (such as zinc-containing compounds such as zinc phosphate and zinc oxide), and the compound enables the coating to have a self-repairing effect, thereby improving the corrosion resistance of the coating to a new height.
In this example, the final concentration of phosphate was 5-50g/L and the final concentration of zinc-containing compound was 5-30 g/L. Within this range, the conductivity and pH of the electrolyte are in appropriate ranges. Too high a phosphate concentration may result in too low a Zn content in the coating prepared by using the electrolyte of this embodiment, thereby losing the effect of doping the zinc element in the electrolyte of this embodiment. On the contrary, too high concentration of zinc-containing compound results in shortened experimental time of the coating prepared by using the electrolyte of this example, and burning phenomenon is very easy to occur to cause coating rejection.
In one embodiment, the final concentration of phosphate is 5-20g/L, the final concentration of zinc-containing compound is 5-30g/L, and the final concentration of complexing agent is 1-15 g/L. Within this range, the conductivity and pH of the electrolyte are within relatively suitable ranges. The excessively high phosphate concentration inhibits the content of Zn element in the coating prepared by the electrolyte of the embodiment, but the high phosphate concentration promotes the increase of alumina of a crystalline phase in the coating, so that after part of the corrosion resistance of the coating is sacrificed, the wear resistance of the coating is improved, and the wear and corrosion resistant effects are achieved.
The wear-resistant effect in the coating refers to that the energy falling on the coating as a whole is greatly different due to different concentrations of the added phosphate, and the increase of the energy density enables the crystallinity of alumina in the coating to be high, so that the coating is hardened, and the wear resistance is greatly improved.
The corrosion resistance of the sacrificial coating is improved by adding phosphate, namely, the zinc content in the coating is reduced to deteriorate the self-repairing effect of the coating after the phosphate proportion is increased.
In one embodiment, the phosphate is selected from at least one of sodium hexametaphosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium polyphosphate, trisodium phosphate, and sodium pyrophosphate, without limitation thereto.
Further in one embodiment, the phosphate is sodium hexametaphosphate. The hydrolysis degree of the sodium hexametaphosphate leads the conductivity and the pH of the electrolyte to be more suitable for the generation of the surface coating of the workpiece.
In one embodiment, the zinc-containing compound is selected from at least one of zinc oxalate, zinc citrate, zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, diethyl zinc disulfide, and the like, without limitation thereto.
Further in one embodiment, the zinc-containing compound is zinc acetate. The zinc acetate has small influence on the conductivity of the electrolyte, and zinc ions can enter the coating more easily in the micro-arc oxidation process.
In one embodiment, the complexing agent is selected from at least one of disodium ethylenediaminetetraacetate, triethanolamine, sodium tartrate, citric acid, oxalic acid, and the like, without limitation thereto.
Further in one embodiment, the complexing agent is disodium edetate. The complexing agent can effectively reduce the phosphate precipitation in the subsequent reaction.
In one embodiment, the electrolyte has a pH of 6 to 12. At this pH, the initial stage of micro-arc oxidation proceeds more gradually and easily, the duration of micro-arc oxidation is prolonged, and the thickness of the coating and the content of P and Zn elements on the surface can be increased greatly.
In one embodiment, the electrolyte has an ionic conductivity of 5 to 60mS cm-1. Under the conductivity, the initial stage of micro-arc oxidation is more gradual and easier, the micro-arc oxidation duration is prolonged, and the coating thickness and the P and Zn element content on the surface can be greatly increased.
The embodiment of the invention provides application of the electrolyte in micro-arc oxidation.
The electrolyte is applied to micro-arc oxidation, and on the basis of the combination of phosphating treatment and micro-arc oxidation, a zinc-containing compound which is easier to form a corrosion-resistant compound is added, so that on one hand, a compact coating can be formed, the thickness of the coating can be ensured, and a coating with the thickness of 5-40 micrometers can be obtained; on the other hand, the formed coating generates a new compound, and the compound enables the coating to have a self-repairing effect, so that the corrosion resistance is greatly improved, and the thickness of a loose layer in micro-arc oxidation is not influenced, so that the roughness of the coating is influenced.
The embodiment of the invention provides application of the electrolyte in forming an anticorrosive coating on the surface of a workpiece by using a micro-arc oxidation method. The workpiece can be titanium, titanium alloy, magnesium alloy, aluminum alloy and the like.
According to the electrolyte, phosphate, a zinc-containing compound and a complexing agent are dissolved in water, so that the use requirement of the micro-arc oxidation electrolyte is met, and the characteristics of self repair, phosphorization and the like are combined with micro-arc oxidation; the coating obtained by the micro-arc oxidation of the electrolyte has better density and self-repairing capability, and the corrosion resistance of the processed workpiece is further improved.
In the embodiment, the micro-arc oxidation method is used, so that the negative influence of strong acid reaction caused by phosphorization on the environment is prevented, and meanwhile, the thickness of the coating is increased from several micrometers to 20-35 micrometers, so that the advantages of phosphorization treatment and micro-arc oxidation are simultaneously taken into consideration.
The embodiment of the invention provides a preparation method of a high-corrosion-resistance coating on the surface of a light metal, which comprises the following steps: and forming a coating on the surface of the light metal by using the electrolyte through a micro-arc oxidation method.
Compared with the traditional corrosion-resistant coating prepared on the surface of the light metal by utilizing micro-arc oxidation, the corrosion-resistant coating generated by the micro-arc oxidation treatment of the embodiment has the self-repairing effect, so that the corrosion resistance of the coating is improved to a new height.
In one embodiment, the light metal is a valve metal such as aluminum, magnesium, titanium, or an alloy thereof.
In one embodiment, the method for preparing the high-corrosion-resistance coating on the surface of the light metal comprises the following steps:
1) pretreating the light metal;
2) putting the light metal into electrolyte, connecting the light metal with the anode of a power supply, connecting the cathode of the power supply with a working electrode, contacting the working electrode with the electrolyte, and starting the power supply to perform micro-arc oxidation treatment;
3) after the micro-arc oxidation treatment, washing with deionized water, and air-drying to obtain the high-corrosion-resistant coating on the surface of the light metal.
In one embodiment, in step 1), the pretreatment comprises sanding, degreasing and deionized water washing. Wherein the degreasing is carried out by ultrasonic dissolving with organic solvent, the organic solvent comprises ethanol, acetone, diethyl ether, trichloroethylene or the mixture of the above organic solvents, and the ultrasonic time is 10-30 min.
In one embodiment, in step 2), the temperature of the electrolyte is controlled to be in the range of 10 ℃ to 60 ℃. At the temperature, Zn and P elements can enter the coating more easily, and local burning loss of the coating in the preparation process caused by overheating is prevented.
In one embodiment, in step 2), the power source used in the micro-arc oxidation method is a pulse power source, and the pulse power source processing parameters are as follows: under constant current mode, the current density is 5-20A/dm2The treatment time is 5-30min, and the frequency is 50-3000 Hz; or under the constant voltage mode, the voltage is 300-800V, the processing time is 5-30min, and the frequency is 50-3000 Hz. Further in one embodiment, the micro-arc oxidation treatment is performed in a constant current mode.
The embodiment of the invention provides a high-corrosion-resistant coating, wherein the high-corrosion-resistant coating is a zinc-containing oxide coating prepared by the method. The elements contained in the high corrosion resistant coating are mainly light metal elements, the other main elements comprise P and Zn, and C, O and other elements are also contained in the coating.
Different from the existing coating formed by micro-arc oxidation, in the coating of the embodiment, the content of the P element is 10% -20% and the content of the Zn element is 2.5% -25% in atomic percentage, which means that the coating of the embodiment forms a new compound (a new zinc-containing compound, such as zinc phosphate, zinc oxide, and the like) which is more difficult to dissolve in water, and the compound has a self-repairing function, so that the corrosion resistance of the coating is greatly improved.
A large number of micropores exist on the surface of the coating formed by micro-arc oxidation, and researches show that a corrosion medium opens a corrosion channel in pores, penetrates through the coating and directly reaches a matrix, so that the coating falls off in a large area, and the corrosion effect is achieved. The coating prepared by the electrolyte and the micro-arc oxidation method contains 5-20% of Zn element, a compound which is more insoluble than light metal and oxidized metal thereof is generated on the surface, the compound covers the surface layer, the pores are sealed, and the pores are protected at one time, so that the corrosion resistance effect is achieved.
It should be noted that the self-repairing effect mentioned above means that, with the coating formed by using the electrolyte and the micro-arc oxidation method of this embodiment, as the corrosion time is prolonged, the interaction between the corrosion medium entering the micropores and the coating only exists the interaction generated by the surface energy, whereas the coating prepared by this embodiment has super-hydrophilicity, the contact angle is less than 10 °, the surface tension promotes the corrosion medium to diffuse rapidly when contacting, so that the zinc-containing compound dissolved therein remains in the pores to repair the corrosion channels, and the pores are protected secondarily. This is a characteristic that other micro-arc oxidation coatings do not have at present.
In one embodiment, the thickness of the corrosion protection coating is 5-100 μm.
The invention is further illustrated by the following specific examples.
Example 1
In the embodiment, the LY12 aluminum alloy material is taken as an example for micro-arc oxidation, and the size of the aluminum alloy is 25 multiplied by 50 multiplied by 2mm3。
In the electrolyte of this example, sodium hexametaphosphate was used as the phosphate, zinc acetate was used as the zinc-containing compound, and disodium ethylenediaminetetraacetate (i.e., Na) was used as the complexing agent2EDTA), the electrolyte preparation method is as follows: sodium hexametaphosphate, zinc acetate and Na are weighed2EDTA, which was added to distilled water and dissolved by stirring. So that the final concentration of sodium hexametaphosphate is 10g/L, the final concentration of zinc acetate is 15g/L, Na2The final concentration of EDTA was 10 g/L. Namely, the electrolytic solution of the present example was obtained.
The micro-arc oxidation method of the embodiment comprises the following steps:
1) pretreatment: polishing the aluminum alloy, removing burrs on the surface and corners of the alloy by using abrasive paper, removing foreign matters on the surface and reducing the roughness of the alloy; then sequentially carrying out ultrasonic cleaning on the alloy for 10min by using 20mL of acetone and 50mL of ethanol as organic solvents to remove organic pollutants on the surface, and then forbidding directly contacting the surface of the sample with hands to avoid secondary pollution; and finally, washing off organic residues on the surface by using deionized water, and air-drying.
2) Micro-arc oxidation: the sample is immersed in the electrolyte prepared in the embodiment, a 20KW high-voltage pulse power supply is adopted, the constant current mode is adopted, and the current density is 20A/dm2Frequency 100Hz, reaction time 15 min. The reaction temperature is controlled within 60 ℃ by a cooling system.
3) And (3) post-treatment: the prepared coating was washed with deionized water and air-dried naturally, to obtain the surface-treated LY12 aluminum alloy of this example, which was defined as a test sample.
Meanwhile, the electrolyte of this example was prepared by using a control electrolyte without adding zinc acetate as a comparison, and the electrolyte having zinc acetate concentrations of 5g/L, 10g/L and 15g/L was designed, and the remaining components and amounts were the same as those of the electrolyte of this example. The micro-arc oxidation method is also the same as the aforementioned method. The LY12 aluminum alloy treated by the electrolytic micro-arc oxidation without adding zinc acetate was defined as a control sample.
The results of the corrosion tests on the test sample and the control sample of this example are shown in fig. 1 and fig. 2, wherein fig. 1 is an electron microscope scan of the test sample prepared by using an electrolyte with a zinc acetate concentration of 15g/L for salt spray tests of 0h and 3000h, and fig. 2 is an electron microscope scan of the control sample for salt spray tests of 0h and 3000 h. Wherein 0h and 3000h respectively refer to the time of the salt spray test. Comparing the two results, it can be seen that in the sample without zinc acetate, after 3000h of corrosion, a large amount of spongiform matter appears on the surface, and the surface is severely corroded, as shown in fig. 1; after adding zinc acetate, holes appear on the surface of the obtained coating, and after 3000h of corrosion, spongiform bodies hardly appear, which indicates that the corrosion is very little, as shown in figure 2. And the test sample of this example, i.e., the coating obtained by micro-arc oxidation using the electrolyte of this example, had a thickness of 25 μm.
The corrosion resistance of the aluminum alloy subjected to the micro-arc oxidation treatment by adopting salt spray corrosion is tested, wherein the four electrolytes respectively refer to electrolytes with zinc acetate concentrations of 0g/L, 5g/L, 10g/L and 15g/L, and the result is shown in FIG. 3. FIG. 3 is a 3D confocal picture after salt spray corrosion, wherein Zn-0, Zn-5, Zn-10 and Zn-15 refer to aluminum alloys obtained by treatment with electrolytes having zinc acetate concentrations of 0g/L, 5g/L, 10g/L and 15g/L, and 0h, 1000h, 2200h, 3400h, 4600h and 5500h refer to salt spray corrosion time, respectively. The results in FIG. 3 show that the test sample of this example, i.e., the coating obtained by micro-arc oxidation using the electrolyte of this example with zinc acetate concentration of 15g/L, is still intact after 5500 hours of salt spray corrosion, and it can be seen that the corrosion resistance can be improved by micro-arc oxidation using the electrolyte of this example; in addition, the electrolyte with the zinc acetate concentration of 10g/L has a slight corrosion phenomenon after the salt fog corrosion for 3400 hours, and the corrosion resistance time is doubled compared with the electrolyte with the zinc acetate concentration of 0 g/L.
Example 2
In the embodiment, the same LY12 aluminum alloy material as that in embodiment 1 is adopted for micro-arc oxidation. Except that the final concentration of the phosphate sodium hexametaphosphate in the electrolyte of the embodiment is 60g/L, the zinc-containing compound adopts zinc citrate with the final concentration of 20g/L, and the complexing agent adopts triethanolamine with the final concentration of 8 g/L. In addition, in the micro-arc oxidation method, the current density of the constant current mode is 12A/dm2Frequency 200Hz, reaction time 15 min. The rest is the same as in example 1.
Meanwhile, electrolytes with phosphate concentrations of 10g/L, 20g/L, 30g/L, 40g/L and 50g/L are designed, and the rest components and the use amount are the same as the electrolyte in the embodiment. The micro-arc oxidation method is also the same as the aforementioned method. Wherein, sodium hexametaphosphate with the phosphate concentration of 10g/L is designed as a control group.
And (3) performing friction wear test on the prepared sample by adopting a ball mill, wherein the test conditions are as follows: the load force is 5N, the rotating speed is 100r/min, and the rotating diameter is 5 mm. The ball body is made of silicon nitride. The test result is shown in fig. 4, and the wear-resistant time length in the picture is the test result of preparing the coating by adopting 10g/L, 20g/L, 30g/L, 40g/L and 50g/L sodium hexametaphosphate and adding 8g triethanolamine and 20g/L zinc citrate to prepare the electrolyte through reaction under the condition of the electrical parameters. From the test results, it can be seen that samples prepared with 10g/L phosphate have worn through within 20s of the test, samples prepared with 20g/L and 30g/L phosphate have a time of between 1000s and 4000s, samples prepared with 40g/L phosphate can stand 8500s without being worn through under this test condition, while samples prepared with 50g/L and 60g/L phosphate can stand 18000s without being worn through under this test condition. Compared with the sample of 10g/L, the wear resistance is improved qualitatively.
The test results of the test of 60g/L phosphate samples by using salt spray corrosion are shown in FIG. 5, and FIG. 5 is 3D confocal pictures after salt spray corrosion, wherein 0h and 2600h refer to the salt spray corrosion time. As can be seen from the figures, the sample prepared from the electrolyte was not corroded at 2600h, which is almost the same as the corrosion resistance time that can be achieved in other published micro-arc oxidation studies. This demonstrates that the coating has certain corrosion resistance properties.
In conclusion, the wear-resistant and corrosion-resistant coating can be prepared by changing the concentrations of the phosphate and the zinc-containing compound.
Example 3
In the embodiment, the same LY12 aluminum alloy material as that in embodiment 1 is adopted for micro-arc oxidation. Except that the final concentration of the phosphate sodium hexametaphosphate in the electrolyte of the embodiment is 20g/L, the zinc-containing compound adopts zinc citrate with the final concentration of 20g/L, and the complexing agent adopts triethanolamine with the final concentration of 8 g/L. In addition, in the micro-arc oxidation method, the current density of the constant current mode is 12A/dm2Frequency 200Hz, reaction time 15 min. The rest is the same as in example 1.
The aluminum alloy treated by micro-arc oxidation in this example was observed by electron microscope scanning and Energy Dispersive Spectroscopy (EDS), and the result showed that a dense coating was formed on the surface of the aluminum alloy, the thickness of the coating was 23 μm, and the EDS found that a large amount of P and Zn elements existed in the coating. The aluminum alloy treated by micro-arc oxidation of this example was also tested by salt spray corrosion. The test result shows that the aluminum alloy subjected to micro-arc oxidation treatment by using the electrolyte of the embodiment has good corrosion resistance, and no obvious corrosion trace is found after 5500 hours of salt spray corrosion.
Example 4
In this embodiment, the 6063 aluminum alloy material is taken as an example for micro-arc oxidation, and the size of the aluminum alloy is 25X 50X 2mm3. In the electrolyte of this example, the final concentration of sodium phosphate hexametaphosphate was 5g/L, zinc chloride was used as the zinc-containing compound at a final concentration of 25g/L, triethanolamine was used as the complexing agent at a final concentration of 5mL/L, and Na was used as the complexing agent at a final concentration of 5g/L2EDTA. In addition, in the micro-arc oxidation method, the pulse power supply adopts a constant voltage mode, the voltage is 450V, the frequency is 500Hz, and the reaction time is 10 min. The rest is the same as in example 1.
The aluminum alloy treated by micro-arc oxidation in this example was observed by scanning with an electron microscope, and the result showed that a dense coating was formed on the surface of the aluminum alloy, and the thickness of the coating was 30 μm. EDS found significant amounts of P and Zn elements in the coating. The same method as in the example was also used to test the corrosion resistance of the aluminum alloy subjected to micro-arc oxidation treatment, and the results show that the aluminum alloy subjected to micro-arc oxidation treatment by using the electrolyte of the example has good corrosion resistance, and no obvious corrosion trace is found after 7000 hours of salt spray corrosion.
Example 5
In the embodiment, the 6063 aluminum alloy material which is the same as the 6063 aluminum alloy material in the embodiment 3 is adopted for micro-arc oxidation. In contrast, in the electrolyte of this example, disodium hydrogen phosphate and sodium dihydrogen phosphate were used at a final concentration of 5g/L, zinc acetate was used at a final concentration of 10g/L as the phosphate, and Na was used at a final concentration of 5g/L as the complexing agent2EDTA. In addition, in the micro-arc oxidation method, the pulse power supply adopts a constant current mode, and the current density is 5A/dm2Frequency 800Hz, reaction time 20 min. The rest is the same as in example 1.
The aluminum alloy treated by micro-arc oxidation in this example was observed by scanning with an electron microscope, and the result showed that a dense coating was formed on the surface of the aluminum alloy, and the thickness of the coating was 25 μm. EDS found significant amounts of P and Zn elements in the coating. The corrosion resistance test of the aluminum alloy subjected to micro-arc oxidation treatment in the embodiment is also carried out by the same method as in the embodiment, and the result shows that the aluminum alloy subjected to micro-arc oxidation treatment by using the electrolyte in the embodiment has good corrosion resistance, and no obvious corrosion mark is found after 5500 hours of salt spray corrosion.
Example 6
In the embodiment, the same LY12 aluminum alloy material as that in embodiment 1 is adopted for micro-arc oxidation. In contrast, in the electrolyte of this example, disodium hydrogen phosphate and sodium dihydrogen phosphate were used at a final concentration of 5g/L, zinc chloride was used at a final concentration of 8g/L, and sodium tartrate was used as a complexing agent at a final concentration of 8 g/L. In addition, micro-arc oxidation methodCurrent density of 10A/dm in medium and constant current mode2Frequency 1000Hz, reaction time 15 min. The rest is the same as in example 1.
The aluminum alloy treated by micro-arc oxidation in this example was observed by scanning with an electron microscope, and the result showed that a dense coating was formed on the surface of the aluminum alloy, and the thickness of the coating was 19 μm. EDS found significant amounts of P and Zn elements in the coating. The corrosion resistance test of the aluminum alloy subjected to micro-arc oxidation treatment in the embodiment is also carried out by the same method as in the embodiment, and the result shows that the aluminum alloy subjected to micro-arc oxidation treatment by using the electrolyte in the embodiment has good corrosion resistance, and no obvious corrosion mark is found after 5500 hours of salt spray corrosion.
Example 7
In the embodiment, the same LY12 aluminum alloy material as that in embodiment 1 is adopted for micro-arc oxidation. In contrast, in the electrolyte of this example, sodium pyrophosphate and sodium dihydrogen phosphate were used at final concentrations of 10g/L and 15g/L, zinc oxalate was used at a final concentration of 5g/L for the zinc-containing compound, and Na was used at a final concentration of 5g/L for the complexing agent2EDTA. The rest is the same as in example 1.
The aluminum alloy treated by micro-arc oxidation in this example was observed by scanning with an electron microscope, and the result showed that a dense coating was formed on the surface of the aluminum alloy, and the thickness of the coating was 18 μm. EDS found significant amounts of P and Zn elements in the coating. The corrosion resistance test of the aluminum alloy subjected to micro-arc oxidation treatment in the embodiment is also carried out by the same method as in the embodiment, and the result shows that the aluminum alloy subjected to micro-arc oxidation treatment by using the electrolyte in the embodiment has good corrosion resistance, and no obvious corrosion mark is found after 5500 hours of salt spray corrosion.
In conclusion, the high-corrosion-resistance coating, the preparation method, the electrolyte and the application thereof provided by the invention have the advantages that the phosphate, the zinc-containing compound and the complexing agent are dissolved in water, and the use requirement of micro-arc oxidation is met. Meanwhile, by combining the characteristics of self-repair, phosphorization and the like with micro-arc oxidation, the coating obtained by micro-arc oxidation by using the electrolyte disclosed by the invention has better density and self-repair capability, and further the corrosion resistance of the processed workpiece is improved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (9)

1. The electrolyte is characterized by comprising 20-50g/L phosphate, 5-30g/L zinc-containing compound and 1-15g/L complexing agent, wherein the solvent is water;
the pH value of the electrolyte is 6-12; and/or the ionic conductivity of the electrolyte is 5-60mS cm-1。
2. The electrolyte of claim 1, wherein the phosphate is selected from at least one of sodium hexametaphosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium polyphosphate, trisodium phosphate, and sodium pyrophosphate.
3. The electrolyte of claim 1, wherein the zinc-containing compound is selected from at least one of zinc oxalate, zinc citrate, zinc nitrate, zinc sulfate, zinc chloride, and zinc acetate.
4. The electrolyte of claim 1, wherein the complexing agent is selected from at least one of disodium ethylenediaminetetraacetate, triethanolamine, sodium tartrate, citric acid, and oxalic acid.
5. Use of the electrolyte according to any of claims 1-4 in micro-arc oxidation.
6. Use of the electrolyte according to any of claims 1 to 4 for forming a coating on a workpiece surface by micro-arc oxidation.
7. A preparation method of a high-corrosion-resistance coating on the surface of light metal is characterized by comprising the following steps: the electrolyte according to any one of claims 1 to 4 is used for forming a coating on a light metal surface by a micro-arc oxidation method.
8. The preparation method according to claim 7, wherein the temperature of the electrolyte is controlled at 10-60 ℃; and/or
The power supply used by the micro-arc oxidation method is a pulse power supply, and the processing parameters of the pulse power supply are as follows: under constant current mode, the current density is 5-20A/dm2The treatment time is 5-30min, and the frequency is 50-3000 Hz; or under the constant voltage mode, the voltage is 300-800V, the processing time is 5-30min, and the frequency is 50-3000 Hz.
9. A highly corrosion-resistant coating, characterized in that it is a coating obtained by the method according to any one of claims 7 to 8.
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CN104264204A (en) * 2014-09-29 2015-01-07 赵全明 Method for directly preparing micro-arc oxidation ceramic membrane containing zinc oxide on surface of magnesium alloy

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* Cited by examiner, † Cited by third party
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