CN114737236A - Preparation method of micro-arc oxidized aluminum alloy - Google Patents
Preparation method of micro-arc oxidized aluminum alloy Download PDFInfo
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- CN114737236A CN114737236A CN202210391699.3A CN202210391699A CN114737236A CN 114737236 A CN114737236 A CN 114737236A CN 202210391699 A CN202210391699 A CN 202210391699A CN 114737236 A CN114737236 A CN 114737236A
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- 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
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- 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
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- 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
- C25D11/12—Anodising more than once, e.g. in different baths
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- 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
- C25D11/16—Pretreatment, e.g. desmutting
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- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
Abstract
The invention provides a preparation method of micro-arc oxidized aluminum alloy, which comprises the steps of polishing after primary micro-arc oxidation to effectively level the surface of a metal to be processed, reserving a transition layer and a partial compact layer in a micro-arc oxidation layer, and using the transition layer and the partial compact layer as a matrix for secondary micro-arc oxidation, wherein the surface form of an obtained micro-arc oxidation film is mainly the concave form of a volcano lava mouth, amorphous or mixed-hole surface form is effectively avoided, the formation of a surface porous layer is obviously reduced, and the obtained micro-arc oxidation surface is a high-quality coating with high hardness, low roughness Ra and low friction coefficient mu.
Description
Technical Field
The invention belongs to the technical field of surface treatment of aluminum or aluminum alloy materials, and relates to a micro-arc aluminum oxide alloy preparation method.
Background
The aluminum, magnesium, titanium and the alloy thereof have the advantages of small density, high specific strength, easy forming and processing and the like, and are widely applied to the fields of aviation, aerospace, transportation and other industries. However, the wear resistance and the corrosion resistance are poor, so that the application is limited, and the improvement of the wear resistance and the corrosion resistance by carrying out surface modification treatment on the wear resistance and the corrosion resistance under the condition of not changing the overall performance of a base material has important significance for expanding the application field of the wear resistance and the corrosion resistance.
Micro-arc Oxidation (MAO), also known as liquid-phase Plasma Electrolytic Oxidation (PEO), is a surface strengthening technique for preparing ceramic films on the surfaces of aluminum, magnesium, titanium, and their composites by using the instantaneous high-temperature sintering of micro-arc discharge regions. The working process of the method is that aluminum, magnesium, titanium and alloy materials thereof are taken as anode samples, the anode samples are connected and fixed and placed in specific electrolyte solution, a steel electrolytic tank is taken as a cathode material of an oxidation system, the limitation of the traditional anode oxidation voltage is broken through applying a higher voltage value between an anode and a cathode, so that a ceramic-based protective coating is grown on the metal surface in situ, and in the process, a high-binding-force and compact tough nano ceramic oxide layer is formed on an alloy substrate. This is a high voltage anodization process for magnesium, titanium, and aluminum metals and their alloys. The oxide film developed by the method has good dielectric, abrasion, thermal, mechanical and corrosion resistance properties.
The MAO membrane layer is generally classified into a three-layer structure of an inner dense layer, a middle dense layer, and an outer porous layer, or a two-layer structure of an outer porous layer and an inner dense layer. During micro-arc oxidation, the breakdown discharge causes the internal fused oxide and gas to escape outward, resulting in a microporous structure of the MAO membrane. The external porous layer is rough and porous, and the specific surface area is larger; the internal compact layer determines the performance of the ceramic membrane, is in-situ combined with the matrix, has high bonding strength, is a main strengthening layer, and can improve the corrosion resistance of the micro-arc oxidation-waterborne polyurethane composite membrane layer. The change of the electrolyte composition, concentration, reaction time, current density, voltage, frequency and other electrical parameters will affect the thickness, roughness, etc. of the MAO film, and the change of the thickness and structure of the porous layer and the compact layer will change the anticorrosive performance of the MAO film and the binding strength between the MAO film and the paint coated on the surface.
Disclosure of Invention
The invention provides a preparation method of micro-arc oxidized aluminum alloy, which comprises the steps of polishing after primary micro-arc oxidation to effectively level the surface of a metal to be processed, reserving a transition layer and a partial compact layer in a micro-arc oxidation layer, and using the transition layer and the partial compact layer as a matrix for secondary micro-arc oxidation to obtain a micro-arc oxidation film, wherein the surface form of the micro-arc oxidation film is mainly the concave form of a volcano lava opening, so that amorphous or mixed hole surface is effectively avoidedThe surface form obviously reduces the formation of a surface porous layer, the obtained micro-arc oxidized surface has high hardness, the roughness Ra and the friction coefficient mu are low, the porosity of the surface micro-arc oxidized layer is low, the pore canal distribution is regular, the stability is higher than that of the traditional micro-arc oxidized aluminum alloy coating, and the surface roughness Ra of the aluminum alloy obtained finally is 1.5-2.5 mu m, the pore diameter is 2-5 mu m, the porosity is 4-5%, the thickness is 40-50 mu m, the hardness is 1700 + 1800HV plus 1800HV0.5The friction coefficient mu is 0.45-0.57.
Specifically, the method comprises the following steps:
a preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying.
The heat treatment is to place the aluminum alloy in the inert atmosphere of 350-360 ℃ and to perform constant-temperature standing treatment for 30-40 min.
The mechanical polishing is to sequentially polish the aluminum alloy under 60#, 300#, 1000#, 2000# abrasive paper step by step.
The degreasing and oil removing process is to perform degreasing and oil removing treatment by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing with deionized water at 45 ℃.
The drying treatment is air purging.
(2) Primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5-7g/L, Na2SiO 311-12 g/L, NaF 1-2g/L, 0.2-0.5 g/LP123 surfactant and 0.7-0.9 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 35-37A/dm 2, the negative current is 17-19A/dm 2, the positive pulse time is 3-5ms, the positive pulse off-time is 0.4-0.6ms, the negative pulse is 0.7-0.9ms, the positive pulse off-time is 0.2-0.4ms, the temperature is 15-20 ℃, the total time is 3-5min, and the obtained thickness is 20-25 mu m.
(3) Polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of stearic acid under triple pressure, 10.8wt.% of stearic acid under double pressure, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing wax removes 3/4 the thickness of which is equal to the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate and 5g/L of EDTA, the temperature is 43 ℃, and the time is 15 min.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 4-6g/L, Na2SiO 38-9 g/L, NaF 4-5g/L, 0.2-0.5 g/LP123 surfactant and 0.7-0.9 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 25-27A/dm 2, the negative current is 8-10A/dm 2, the positive pulse time is 3-5ms, the positive pulse off time is 0.8-1.2ms, the negative pulse time is 0.9-1.1ms, the positive pulse off time is 0.3-0.5ms, the temperature is 15-20 ℃, and the total duration is 15-35 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
The aluminum alloy comprises the following components in parts by mass: si 0.7-1.1wt.%, Fe 0.7-0.8wt.%, cu1.8-2.5 wt.%, mn0.4-0.8 wt.%, mg0.4-0.8 wt.%, Ni 0.1-0.2wt.%, Zn 0.3-0.35wt.%, Ti 0.15wt.%, balancing aluminum.
The invention firstly carries out surface pretreatment on the aluminum alloy: the treatment mode comprises heat treatment, mechanical polishing, degreasing and deoiling, water washing and drying treatment in sequence, and the purpose is mainly to release thermal stress, improve the binding force of the coating and the base material and reduce the defects of metal grains; flattening the surface of the metal substrate and removing the oxide film; poor contact between the electrolyte and the substrate caused by the surface grease leads to unevenness on the thickness of the oxide layer, and finally the substrate to be treated is flat, low in stress, high in crystal form and clean.
Then carrying out primary micro-arc oxidation on the aluminum alloy subjected to surface treatment: the micro-arc oxidation electrolyte is NaOH 5-7g/L, Na2SiO38-12 g/L, NaF 1-2g/L, 0.2-0.5 g/LP123 surfactant and 0.7-0.9 g/L ethynyl methanol, adopting a bipolar pulse power supply in a constant current mode, wherein the positive current is 35-37A/dm 2, the negative current is 17-19A/dm 2, the positive pulse time is 3-5ms, the positive pulse off time is 0.4-0.6ms, and the negative current is 17-19A/dm 2Pulse 0.7-0.9ms, forward pulse off-time 0.2-0.4ms, temperature 15-20 deg.C, total duration 3-5min, and obtained thickness 20-25 μm.
The method is characterized in that the electrolysis parameters are adjusted no matter the primary micro-arc oxidation or the secondary micro-arc oxidation, wherein the components, the forward current, the shutdown time and the like of the electrolyte, the micro-arc oxidation treatment time determine the energy supply condition in the micro-arc oxidation process, and the breakdown frequency of the film layer in the micro-arc oxidation film layer forming process, the duration of a discharge channel, the highest temperature in the discharge process and the like are greatly influenced, so that the porosity, the phase composition, the roughness, the corrosion resistance and the like of the micro-arc oxidation film layer are further influenced.
The alkaline electrolyte system used for micro-arc oxidation is mainly silicate, phosphate, aluminate and other sodium silicates, the growth rate of the film layer is fastest under various electrolyte systems, the addition of different additives can also influence the composition and the corrosion resistance of the micro-arc oxidation film layer, the concentration change can cause the change of the conductivity, acid-base property, stability and the like of the electrolyte, and the influence on the arc starting time, the arc starting voltage, the size, the quantity, the service life and the distribution of sparks and the like, so that the thickness and the structure of the micro-arc oxidation film layer are influenced, and the bonding strength and the corrosion resistance of the double-film layer system are influenced. The increase of the concentration of the sodium silicate can promote the arc discharge on the surface of the aluminum alloy sample and reduce the energy consumption in the micro-arc oxidation arcing process. The higher the concentration of the sodium silicate, the higher the surface roughness obtained, because the primary micro-arc oxidation film can be removed by subsequent polishing, and the total concentration Na2SiO 311-12 g/L of the sodium silicate in the primary micro-arc oxidation solution is higher than the concentration Na2SiO 38-9 g/L of the secondary micro-arc oxidation, and the surface roughness Ra is 7-8 μm after the primary micro-arc oxidation.
The addition of sodium fluoride can increase the film thickness, because after the sodium fluoride is added, the spark discharge phenomenon can be more easily generated, the initial voltage rising rate is increased, the arc starting voltage is reduced, the excessive dissolution of the anode can be inhibited, the film thickness is increased, and the concentration of sodium fluoride NaF 1-2g/L in the primary micro-arc oxidation liquid is lower than that of sodium fluoride NaF 4-5g/L in the secondary micro-arc oxidation liquid.
The concentration of the main film forming agent in the electrolyte has a remarkable influence on the thickness of the ceramic film layer. When the main film forming agent with higher concentration is used, the conductivity of the solution can be enhanced, more discharge central channels are generated, and the film layer can be formed under the condition that electrons continuously enter micropores
The thickness is continuously increased, but when the concentration of the main film forming agent is too high, the electric breakdown is more difficult, so that the arcing voltage is reduced, the arc discharge phenomenon is caused, the micro-arc oxidation effect is inhibited, and even the ablation condition is caused by overlarge local current. As the NaOH concentration increases, the roughness and porosity also increase slightly. With increasing NaOH concentration, ion concentration
The solution conductivity is increased, the conductivity is enhanced, the voltage peak value distributed on the sample surface is large, the current breakdown capability is enhanced, and the film forming rate is increased. Meanwhile, OH-participates in anode chemical reaction, and when the concentration is increased, anode electron transfer is promoted, so that the oxide generation rate is increased, and the film forming rate is increased.
The P123 surfactant is a nonionic surfactant and mainly improves the surface tension of the electrolyte and the contact form of the base material and the electrolyte, and the ethynyl methanol is a corrosion inhibitor, so that the surface of the base material is corroded, and a certain coating leveling effect is achieved.
Micro-arc oxidation time: the rate of increase in film thickness increases with increasing reaction time, presumably related to the increased rate of film thickness growth with increasing porosity and roughness as the reaction proceeds, resulting in the same oxide formation rate. The micro-arc oxidation treatment time is that the thickness of the micro-arc oxidation film layer is continuously increased along with the increase of time in the micro-arc oxidation treatment process, so that the increase of the film layer impedance causes the reduction of the film layer discharge channel, the charge quantity is increased in a single discharge process, and the breakdown voltage is continuously improved. As single breakdown becomes increasingly difficult, the energy consumption for film growth also increases. And more heat is generated by each discharge on average, and the molten substance generated by the reaction and the high heat make more molten substance melted in the original film layer gush out from the discharge channel, so that a rougher surface area and a larger porosity are formed after the molten substance is in contact with the electrolyte and cooled.
Shutdown time: the shutdown time of the positive pulse in the first micro-arc oxidation is 0.4-0.6ms, the shutdown time of the negative pulse is 0.2-0.4ms, the shutdown time of the positive pulse in the second micro-arc oxidation is 0.8-1.2ms, and the shutdown time of the negative pulse in the second micro-arc oxidation is 0.3-0.5ms, so that the shutdown time of the second micro-arc oxidation is longer than the shutdown time of the first micro-arc oxidation, because the time of the first micro-arc oxidation is short, the surface discharge phenomenon of the film layer of the first micro-arc oxidation is relatively weak, the surface discharge phenomenon of the film layer of the second micro-arc oxidation is relatively severe, and the increase of the shutdown time can ensure that the sprayed oxide is more fully cooled and is not melted by the next discharge, thereby being beneficial to forming smooth pore canals and avoiding forming amorphous, loose and rough pore canals.
The micro-arc oxidation film layer is prepared by using a micro-arc oxidation film layer, a micro-arc oxidation film layer and a discharge channel, wherein the micro-arc oxidation film layer is prepared by using a micro-arc oxidation film layer, and the micro-arc oxidation film layer is prepared by using a micro-arc oxidation film layer. Therefore, the current density of the first micro-arc oxidation is obviously higher than that of the second micro-arc oxidation.
Polishing with polishing wax: as mentioned above, the micro-arc oxidation film is a transition layer, a compact layer and a porous layer from bottom to top, during the micro-arc oxidation process, the thickness of the micro-arc oxidation film layer increases, the roughness increases, and the discharge channel decreases, the current increase of single discharge becomes difficult with single breakdown, the energy consumption of film layer growth increases, and the film layer becomes coarse, wherein the main internal resistance energy consumption is originated from the compact layer and the transition layer, when the compact layer and the transition layer are not flat, the heat release is not uniform, the discharge is not uniform, for example, the thicker position is difficult to breakdown the discharge, and the thinner position is easy to oxidize, the porous layer is completely removed by polishing treatment after the micro-arc oxidation, the compact layer of the cutting part is removed, the thickness of the obtained surface micro-arc oxidation layer is obviously flat in the cross section direction, the discharge channel is homogenized in the subsequent micro-arc process, which is beneficial to obtaining a flat and uniform micro-arc oxidation crater, the accumulation of peripheral oxides is less, amorphous or rough pore canals are less, cracks are less, the integral void ratio is lower, so the corresponding compactness, corrosion resistance and hardness are good, and the polishing removal thickness is 3/4 which is the thickness of one-time micro-arc oxidation.
Here, attention is paid to a patent document: CN107604411A discloses an aluminum alloy micro-arc oxidation treatment method, which is characterized by comprising the following steps:
(1) after the surface of the aluminum alloy is polished, ultrasonic cleaning is carried out for 15-20min by ethanol and 15-20min by distilled water in sequence, and then the aluminum alloy is dried by clean and dry compressed air;
(2) putting the aluminum alloy treated in the step (1) into a rare earth micro-arc oxidation electrolyte, performing first micro-arc oxidation treatment, and growing a ceramic film layer on the surface of the aluminum alloy in situ;
(3) carrying out secondary surface grinding and polishing on the aluminum alloy subjected to micro-arc oxidation in the step (2), ultrasonically cleaning the aluminum alloy by using distilled water until a water film is continuous, uniform and free from fracture, and then drying the aluminum alloy by using clean and dry compressed air;
(4) and (4) placing the aluminum alloy treated in the step (3) into a rare earth micro-arc oxidation electrolyte, performing second micro-arc oxidation treatment, and continuously growing a uniform and compact ceramic film layer on the surface of the aluminum alloy in situ.
The beneficial technical effect of the document is that a uniform and compact ceramic film layer can be grown on the surface of the aluminum alloy by performing micro-arc oxidation on the aluminum alloy in a rare earth mixed salt solution. The method has simple treatment process, and the prepared ceramic film has high hardness. "the above document does not have any description in any drawing, and does not have any description about the technical effect of the polishing treatment after the primary micro-arc oxidation, whether the technical effect of the polishing treatment is derived from the rare earth mixed salt, and further, does not have any description about the degree of polishing, so that the present invention performs the test using example 1 of the document as comparative example 1, and performs the SEM characterization of the effect.
Advantageous technical effects
(1) The invention effectively obtains a flat surface with low roughness and a surface with low friction coefficient by polishing after the primary micro-arc oxidation.
(2) The micro-arc oxidation surface morphology is further improved by adding P123 and ethynyl methanol in the electroplating solution, the obtained regular surface is beneficial to the improvement of the film quality, and the film is more compact and flat, see figure 2.
Drawings
FIG. 1 is an SEM image of an aluminum material in accordance with different processing steps of example 2 of the present invention.
FIG. 2 is an SEM photograph of an aluminum material corresponding to examples of the present invention and comparative examples.
Detailed Description
The technical scheme of the invention is further explained by combining specific examples, and the aluminum alloy to be treated used in the examples and the comparative examples of the invention comprises the following components in parts by mass: si 0.7-1.1wt.%, Fe 0.7-0.8wt.%, cu1.8-2.5 wt.%, mn0.4-0.8 wt.%, mg0.4-0.8 wt.%, Ni 0.1-0.2wt.%, Zn 0.3-0.35wt.%, Ti 0.15wt.%, balancing aluminum, no labeling for some very low concentrations of impurities, not representing absence.
Example 1
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in an inert atmosphere at 350 ℃ and to perform standing treatment at constant temperature for 30 min;
the mechanical polishing is to sequentially polish the aluminum alloy under the conditions of 60#, 300#, 1000#, 2000# abrasive paper step by step;
the degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing by using deionized water at 45 ℃;
the drying treatment is air purging;
(2) primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5g/L, Na2SiO 311 g/L, NaF 1g/L, 0.2g/L P123 g/L surfactant and 0.7g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 35A/dm2, the negative current is 17A/dm 2, the positive pulse time is 3ms, the positive pulse off-time is 0.4ms, the negative pulse is 0.7ms, the negative pulse off-time is 0.2ms, the temperature is 15 ℃, and the total duration is 3 min.
(3) Polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of triple-pressure stearic acid, 10.8wt.% of double-pressure stearic acid, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing removes 3/4 with the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ and 15min of time.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 4g/L, Na2SiO 38g/L, NaF 4g/L, 0.2g/LP123 surfactant and 0.7g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 25A/dm 2, the negative current is 8A/dm2, the positive pulse time is 3ms, the positive pulse shutdown time is 0.8ms, the negative pulse is 0.9ms, the negative pulse shutdown time is 0.3ms, the temperature is 15 ℃, and the total time duration is 15 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
Example 2
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in an inert atmosphere at 355 ℃ and to perform standing treatment at constant temperature for 35 min.
The mechanical polishing is to sequentially polish the aluminum alloy under 60#, 300#, 1000#, 2000# abrasive paper step by step.
The degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing with deionized water at 45 ℃.
The drying treatment is air purging.
(2) Primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 6g/L, Na2SiO311.5 g/L, NaF 1.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 36A/dm 2, the negative current is 18A/dm2, the positive pulse time is 4ms, the positive pulse off-time is 0.5ms, the negative pulse is 0.8ms, the negative pulse off-time is 0.3ms, the temperature is 17.5 ℃, and the total time duration is 4 min.
(3) Polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of triple-pressure stearic acid, 10.8wt.% of double-pressure stearic acid, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing removes 3/4 with the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ and 15min of time.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5g/L, Na2SiO38.9 g/L, NaF 4.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 26A/dm 2, the negative current is 9A/dm 2, the positive pulse time is 4ms, the positive pulse off time is 1ms, the negative pulse off time is 0.4ms, the temperature is 17.5 ℃, and the total duration is 20 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
Example 3
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in an inert atmosphere at 360 ℃ and to perform constant-temperature standing treatment for 40 min;
the mechanical polishing is to sequentially polish the aluminum alloy stage by stage under 60#, 300#, 1000#, 2000# abrasive paper conditions;
the degreasing and oil removing process is to perform degreasing and oil removing treatment by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing by using deionized water at 45 ℃;
the drying treatment is air purging;
(2) primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH7g/L, Na2SiO 312 g/L, NaF 2g/L, 0.5 g/LP123 surfactant and 0.9 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 37A/dm 2, the negative current is 19A/dm 2, the positive pulse time is 5ms, the positive pulse shutdown time is 0.6ms, the negative pulse is 0.9ms, the negative pulse shutdown time is 0.4ms, the temperature is 20 ℃, and the total time duration is 5 min.
(3) Polishing with polishing wax, degreasing, hot washing and drying: the polishing wax consists of 13.2wt.% of triple-pressure stearic acid, 10.8wt.% of double-pressure stearic acid, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing removes 3/4 with the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ and 15min of time.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 6g/L, Na2SiO 39 g/L, NaF 5g/L, 0.5 g/LP123 surfactant and 0.9 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 27A/dm 2, the negative current is 10A/dm 2, the positive pulse time is 5ms, the positive pulse shutdown time is 1.2ms, the negative pulse is 1.1ms, the negative pulse shutdown time is 0.5ms, the temperature is 17.5 ℃, and the total time duration is 30 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
Comparative example 1
The micro-arc oxidation treatment method of the aluminum alloy comprises the following steps:
(1) after the surface of the aluminum alloy is polished, ultrasonic cleaning is sequentially carried out for 15min by ethanol and 15min by distilled water, and then clean and dry compressed air is used for drying;
(2) putting the aluminum alloy treated in the step (1) into a rare earth micro-arc oxidation electrolyte, performing first micro-arc oxidation treatment at 35 ℃ for 25min, and growing a 20-micron-thick ceramic film layer on the surface of the aluminum alloy in situ, wherein the rare earth micro-arc oxidation electrolyte comprises the following components: 12g/L sodium silicate, 2g/L potassium fluoride, 4g/L sodium hydroxide and 2.5g/L cerium nitrate;
(3) carrying out secondary surface grinding and polishing on the aluminum alloy subjected to micro-arc oxidation in the step (2), ultrasonically cleaning the aluminum alloy by using distilled water until a water film is continuous, uniform and free from fracture, and then drying the aluminum alloy by using clean and dry compressed air;
(4) putting the aluminum alloy treated in the step (3) into a rare earth micro-arc oxidation electrolyte, performing a second micro-arc oxidation treatment at 35 ℃ for 25min, and continuously growing a 20-micrometer-thick ceramic film layer on the surface of the aluminum alloy in situ, wherein the rare earth micro-arc oxidation electrolyte comprises the following components: 12g/L sodium silicate, 2g/L potassium fluoride, 4g/L sodium hydroxide and 2.5g/L cerium nitrate.
Comparative example 2
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in 355 ℃ inert atmosphere and keep standing for 35min at constant temperature.
The mechanical polishing is to sequentially polish the aluminum alloy under 60#, 300#, 1000#, 2000# abrasive paper step by step.
The degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing with deionized water at 45 ℃.
The drying treatment is air purging.
(2) Primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is 6g/L of NaOH and 6g/L of Na2SiO311.5 g/L, NaF 1.5.5 g/L, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 36A/dm 2, the negative current is 18A/dm2, the positive pulse time is 4ms, the positive pulse off time is 0.5ms, the negative pulse time is 0.8ms, the negative pulse off time is 0.3ms, the temperature is 17.5 ℃, and the total duration is 4 min.
(3) Polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of triple-pressure stearic acid, 10.8wt.% of double-pressure stearic acid, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing removes 3/4 with the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ and 15min of time.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5g/L and Na2SiO38.9 g/L, NaF 4.5.5 g/L, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 26A/dm 2, the negative current is 9A/dm 2, the positive pulse time is 4ms, the positive pulse off-time is 1ms, the negative pulse off-time is 0.4ms, the temperature is 17.5 ℃, and the total time is 20 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
Comparative example 3
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in an inert atmosphere at 355 ℃ and to perform standing treatment at constant temperature for 35 min.
The mechanical polishing is to sequentially polish the aluminum alloy under 60#, 300#, 1000#, 2000# abrasive paper step by step.
The degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is rinsing with deionized water at 45 ℃.
The drying treatment is air purging.
(2) Primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 6g/L, Na2SiO311.5 g/L, NaF 1.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 36A/dm 2, the negative current is 18A/dm2, the positive pulse time is 4ms, the positive pulse off-time is 0.5ms, the negative pulse is 0.8ms, the negative pulse off-time is 0.3ms, the temperature is 17.5 ℃, and the total time duration is 4 min.
(3) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5g/L, Na2SiO38.9 g/L, NaF 4.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a bipolar pulse power supply in a constant current mode is adopted, the positive current is 26A/dm 2, the negative current is 9A/dm 2, the positive pulse time is 4ms, the positive pulse off time is 1ms, the negative pulse off time is 0.4ms, the temperature is 17.5 ℃, and the total duration is 20 min.
(4) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
Comparative example 4
A preparation method of micro-arc oxidized aluminum alloy comprises the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in an inert atmosphere at 355 ℃ and to perform standing treatment at constant temperature for 35 min.
The mechanical polishing is to sequentially polish the aluminum alloy under the conditions of 60#, 300#, 1000#, 2000# sand paper step by step.
The degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time.
The water washing is washing with deionized water at 45 ℃.
The drying treatment is air purging.
(2) Primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 6g/L, Na2SiO311.5 g/L, NaF 1.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a power supply in a constant current mode is adopted, the current is 36A/dm 2, the temperature is 17.5 ℃, and the total time is 4 min.
(3) Polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of stearic acid under triple pressure, 10.8wt.% of stearic acid under double pressure, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide, and the polishing wax removes 3/4 the thickness of which is equal to the thickness of primary micro-arc oxidation; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate and 5g/L of EDTA, the temperature is 43 ℃, and the time is 15 min.
The drying is air purging.
(4) Secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5g/L, Na2SiO38.9 g/L, NaF 4.5.5 g/L, 0.35g/LP123 surfactant and 0.8 g/L ethynyl methanol, a constant current mode power supply is adopted, the current is 26A/dm 2, the temperature is 17.5 ℃, and the total time is 20 min.
(5) And (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
As shown in the attached figure 1, the SEM images of the aluminum material after pretreatment, primary micro-arc oxidation, polishing and secondary micro-arc oxidation are respectively corresponding to the aluminum substrate, wherein the surface of the aluminum substrate contains a large amount of natural porous alumina, the metallic luster is exposed after the pretreatment, then the primary micro-arc oxidation is performed on the surface of the aluminum material, the micro-pores and the loose pores on the surface of the aluminum material obtained after the oxidation are removed by polishing, the loose porous layer and a part of the dense layer on the surface of the primary micro-arc oxidation film are left, the surface is flat, and then the secondary micro-arc oxidation is performed, so that the surface film of the micro-arc oxidation film is flat, the pores are regular, and particularly, the porous pores are not loose. As shown in the attached figure 2, the micro-arc oxidation films obtained in the comparative examples 1 to 4 have a plurality of loose porous channels and rough surfaces, and compared with the micro-arc oxidation films obtained in the example 2, the micro-arc oxidation films have compact micro-arc oxidation layers and no loose channels, i.e. compared with the comparative examples 1 to 4, the micro-arc oxidation coatings obtained in the invention have better effects.
Corresponding tests were performed on the above-mentioned example 2 and comparative examples 1 to 4, and comparative examples 1 to 4 are briefly described, wherein comparative example 1 was example 1 of the reference, and comparative example 2 was different from example 2 in the electrolyte, in terms of surface roughness, friction coefficient, and wear amount (unit of wear amount is 10)-10cm3(N.m)-1) There is no essential difference, but because the surfactant and the corrosion inhibitor are added, the surface appearance of the micro-arc oxidation film is improved to a certain extent, and the micro-arc oxidation film has corresponding positive effect, the comparative example 3 has no polishing, the surface roughness, the friction coefficient and the abrasion loss are obviously deteriorated, the positive effect of the primary micro-arc oxidation on the subsequent regular micro-arc oxidation film is further proved, the power supply with constant current in the comparative example 4 further proves the influence of the bipolar pulse current on the micro-arc oxidation film, the embodiment 2 of the invention has the best experimental effect, and the corresponding surface roughness, the friction coefficient, the abrasion loss and the hardness are respectively 1.67 mu m, 0.48 and 2.1310 mu m, respectively-10cm3(N.m)-1、1786 HV0.5。
Although the present invention has been described above by way of examples of preferred embodiments, the present invention is not limited to the specific embodiments, and can be modified as appropriate within the scope of the present invention.
Claims (3)
1. The preparation method of the micro-arc oxidized aluminum alloy is characterized by comprising the following steps:
(1) surface pretreatment of the aluminum alloy: heat treatment, mechanical polishing, degreasing and deoiling, washing and drying;
the heat treatment is to place the aluminum alloy in the inert atmosphere of 350-360 ℃, and to perform constant temperature standing treatment for 30-40 min;
the mechanical polishing is to sequentially polish the aluminum alloy stage by stage under 60#, 300#, 1000#, 2000# abrasive paper conditions;
the degreasing and oil removing are performed by using alkaline degreasing liquid, and the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ of temperature and 5min of time;
the water washing is washing by using deionized water at 45 ℃;
the drying treatment is air purging;
(2) primary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 5-7g/L, Na2SiO311-12 g/L, NaF 1-2g/L, 0.2-0.5 g/L LP123 surfactant and 0.7-0.9 g/L ethynyl methanol, and adopts a bipolar pulse power supply in a constant current mode, wherein the forward current is 35-37A/dm2And negative current of 17-19A/dm2The positive pulse time is 3-5ms, the positive pulse off-time is 0.4-0.6ms, the negative pulse time is 0.7-0.9ms, the negative pulse off-time is 0.2-0.4ms, the temperature is 15-20 ℃, and the total time is 3-5 min;
(3) polishing with polishing wax, degreasing, hot water washing and drying: the polishing wax consists of 13.2wt.% of stearic acid, 10.8wt.% of stearic acid, 8.2wt.% of fatty acid, 0.9wt.% of oleic acid and 66.9wt.% of chromium oxide; the degreasing and degreasing are degreasing and degreasing treatment by using alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 42g/L of sodium bicarbonate, 38g/L of sodium carbonate, 5g/L of EDTA, 43 ℃ and 15 min;
the drying is air blowing;
(4) secondary micro-arc oxidation treatment: the micro-arc oxidation electrolyte is NaOH 4-6g/L, Na2SiO38-9 g/L, NaF 4-5g/L, 0.2-0.5 g/L LP123 surfactant and 0.7-0.9 g/L ethynyl methanol, adopting a bipolar pulse power supply in a constant current mode, wherein the forward current is 25-27A/dm2And negative current of 8-10A/dm2Is right3-5ms of forward pulse time, 0.8-1.2ms of positive pulse shutdown time, 0.9-1.1ms of negative pulse, 0.3-0.5ms of negative pulse shutdown time, 15-20 ℃ of temperature and 15-35min of total duration;
(5) and (3) post-treatment: sequentially cleaning with ethanol, ultrasonic cleaning, and blow-drying with cold air.
2. The method for preparing the micro-arc oxidized aluminum alloy according to claim 1, wherein the aluminum alloy comprises the following components in parts by mass: si 0.7-1.1wt.%, Fe 0.7-0.8wt.%, cu1.8-2.5 wt.%, mn0.4-0.8 wt.%, mg0.4-0.8 wt.%, Ni 0.1-0.2wt.%, Zn 0.3-0.35wt.%, Ti 0.15wt.%, balancing aluminum.
3. The method for preparing micro-arc oxidized aluminum alloy according to claim 1, wherein the polishing removal thickness is about 3/4 of the thickness of the primary micro-arc oxidation coating in the polishing process of polishing wax.
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