CN112609219A - Bath solution for red anodic oxidation of aluminum alloy material and process method - Google Patents
Bath solution for red anodic oxidation of aluminum alloy material and process method Download PDFInfo
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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
- C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
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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
- C25D11/16—Pretreatment, e.g. desmutting
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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
- C25D11/18—After-treatment, e.g. pore-sealing
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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
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/20—Electrolytic after-treatment
- C25D11/22—Electrolytic after-treatment for colouring layers
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Abstract
The invention belongs to the technical field of aluminum alloy anodic oxidation, and provides bath solution for red anodic oxidation of an aluminum alloy material and a process method. The problem of poor corrosion resistance of a red anodic oxide film layer obtained by the existing method is solved, and the bath solution comprises the following components: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl‑: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/L and deionized water as solvent. The process method comprises the steps of part acceptance, part mounting and hanging, pretreatment of anodizing, sending to an anodic oxidation line, sulfuric acid anodizing, cleaning, coloring, sealing, secondary sealing and the like. The invention passes through the sulfuric acid anode before oxidationBy adopting post-treatment methods such as treatment, coloring, sealing and the like, the obtained film layer has no corrosion on the surface of the matrix metal after being subjected to a neutral salt spray test for 336 hours, and the film layer is uniform, continuous and complete, has no looseness and has uniform and consistent color.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy anodic oxidation, relates to a process method for aluminum alloy anodic oxidation, and particularly relates to bath solution and a process method for red anodic oxidation of an aluminum alloy material.
Background
Aluminum and aluminum alloys can form oxide films with oxygen in the atmosphere, and the natural oxide films are extremely thin and have low corrosion resistance, so that the aluminum and aluminum alloys can not meet the requirements of industrial application. In order to improve the protection, decoration and other functions of the aluminum and the aluminum alloy, the aluminum and the aluminum alloy are subjected to anodic oxidation treatment by direct current or alternating current in dilute sulfuric acid electrolyte, and a porous, colorless and transparent oxide film with strong adsorption force can be obtained; and the anodic oxide film layer is treated by adopting a chemical or electrochemical coloring method, so that the attractive appearance and the decorative property of the anodic oxide film layer are enhanced. The corrosion resistance of the anodic oxide film layer can be enhanced by adopting a sealing treatment method. At present, a filling chemical coloring method is generally adopted, the red anodic oxide film obtained by the method has poor corrosion resistance, and the surface of a part has corrosion points after a neutral salt spray test is carried out for 336 hours. The red anodic oxide film dye is weak in acidity, dye particles are too large when the red anodic oxide film dye is filled and sealed, coloring is not uniform, pore plugging is incomplete, the film is not compact enough, colors are not uniform, and when corrosion resistance inspection is carried out, corrosion is formed due to pores of the film of each pore, and the corrosion resistance inspection-salt spray test is unqualified. In order to overcome the problems, a steam sealing method is generally adopted, but the steam sealing has high requirements on equipment, strict regulations on temperature and pressure, high energy consumption, high cost and low operability.
Disclosure of Invention
The invention provides bath solution for red anodic oxidation of an aluminum alloy material and a process method, aiming at solving the problem that a red anodic oxide film obtained by the existing method has poor corrosion resistance. By the methods of sulfuric acid anodic oxidation pretreatment and post-treatment such as coloring and sealing, the surface of the base metal does not corrode after 336 hours of the neutral salt spray test of the obtained film. And the film layer is uniform, continuous and complete, has no looseness, and has uniform and consistent color. Compared with a method adopting steam sealing, the sealing method has the advantages of low requirement on equipment, low energy consumption, low cost and strong operability.
The principle of the invention is as follows:
mechanism of formation of anodic oxide film of aluminum and its alloy: under the action of corresponding electrolyte and specific technological conditions, a layer of Al is formed on the product (part) of aluminium and its alloy under the action of external current2O3And (5) oxidizing the film. In principle, all parts are used as anodes, two different reactions of electrochemical growth of an oxide film and chemical dissolution of the film are controlled in an acid solution to interact, and the dissolution speed of the film is controlled and the growth speed of the film is increased in the process, so that the process of obtaining a thick and compact film layer is achieved.
The electrochemical generation and the chemical dissolution of the oxide film are simultaneous, and the oxide film can grow and thicken only when the generation speed of the oxide film is greater than the chemical dissolution speed of the oxide film; the thickness of the porous layer depends on the type, concentration and process conditions of the electrolyte, the growth of the oxide film also follows Faraday's law, the thickness is increased in proportion to time under a certain current density, but the dissolution speed of the porous layer is accelerated because the temperature of the electrolyte is increased due to the heat generated by oxidation and the joule heat generated when the current passes through; when the rate of formation and dissolution of the porous layer are balanced, the thickness of the film is not increased any more, so forced cooling of the electrolyte is required to obtain a thick film.
The coloring and dyeing of metal is a process of chemically or electrochemically making the metal surface have a film layer with a color different from that of the original substrate surface in a specific solution and keeping the metal luster, and is mainly used for decorating metal products to improve the appearance and the corrosion resistance of the metal products. The adsorption coloring method of the anodic oxide film, also called dyeing method, is to utilize the porosity and activity of the anodic oxide film to adsorb dye for dyeing, and the oxide film adsorbing the dye must be colorless, transparent and uniform, and also should have high porosity and strong adsorption capacity. In the production process, factors influencing the performance and quality of the film layer are many, and the following factors are mainly included:
a. concentration of the electrolyte: in the anodic oxidation solution, when the concentration of sulfuric acid is at the upper limit value, the obtained oxidation film layer has small hardness, more pores and high growth speed of the initial film; however, the growth rate of the film in the solution is rather slower than that of the film in the dilute solution along with the prolonging of the time, so the invention adopts the upper limit value of the process specified concentration so as to obtain a better film layer under the normal process temperature condition.
b. Temperature: the influence of the temperature of the electrolyte on the generation of an oxide film and the property of the oxide film is similar to the change of concentration, so that the temperature of the electrolyte needs to be strictly controlled when the anode oxidation is carried out, refrigeration equipment needs to be used for controlling the temperature of the electrolyte, and the temperature is properly reduced or increased when necessary; the invention adopts lower temperature to ensure the quality of the oxide film. And setting the slow starting time of the current when the oxidation starts and finishes so as to improve the quality of the film layer.
c. And (3) oxidation time: the choice of oxidation time must be determined by the formulation composition, bath temperature, current density and the desired thickness of the film, and under normal conditions, the thickness increase of the oxide film is directly proportional to the time over a certain period of time. The process adopts a method of controlling voltage instead of current, so that the best method for controlling the quality of a film layer is realized by controlling the oxidation time under the condition of ensuring certain voltage.
d. Stirring: the process adopts dry compressed air for stirring, so that on one hand, the heat near the anode can be rapidly dissipated, and on the other hand, the solution flows to reduce the generation of air bags.
e. And (3) sealing: the alumina is hydrated with water in boiling water and converted into boehmite hydrated alumina, namely Al2O3·H2O; the structure is larger than the molecular volume of the original anodic oxide film, so that the anodeThe pores of the alumina film are easily blocked, the impedance and the dielectric constant of the film are increased, and the surface performance of the anodic oxide film is improved to a certain degree. The process adopts the boiling deionized water for sealing, so that the corrosion resistance of the anodic oxide film layer can be better improved; however, when the boiling deionized water is used for sealing the anodic oxide film layer, the requirement on the deionized water is high, most of the treated anodic oxide film layer is attached with frost, the film after hole sealing is accompanied by microcracks, the hardness and the wear resistance are reduced, and the corrosion resistance in the environment of strong acid and strong alkali is poor.
Based on the above analysis, the technical scheme of the invention is to provide a bath solution for red anodic oxidation of an aluminum alloy material, which is characterized by comprising the following components: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl-: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/L and deionized water as solvent.
Further, the components are as follows: sulfuric acid H2SO4: 190 g/l, aluminum ion Al3+Less than 12 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
Further, the components are as follows: sulfuric acid H2SO4: 190 g/l, 4 g/l < Al ion Al3+Less than 8 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
The invention also provides a process method for red anodic oxidation of the aluminum alloy material, which is characterized by comprising the following steps:
step 1, part acceptance:
after the part is qualified, executing the step 2;
step 2, hanging parts:
a fixture made of titanium alloy is adopted and hung according to the requirements of a drawing;
step 3, pre-treatment of anodization:
step 3.1, chemical degreasing: cleaning the parts with deoiling solution at 60-80 deg.c for 0.3-3 min; removing oil stains on the surface of the part;
step 3.2, cleaning: cleaning the deoiled part in hot water at a temperature of not lower than 50 ℃ for 0.3-3 minutes, and then cleaning in flowing cold water for 0.3-3 minutes until the water film continuous time reaches a set time;
step 3.3, soaking: soaking the cleaned part in light at room temperature for 1-3 min;
step 3.4, cleaning: immediately cleaning the dipped parts in flowing cold water until the water film continuous time reaches the set time;
and 4, sending to an anode oxidation line: firstly, checking whether the anodic oxidation tank leaks or is abnormal, and then checking the concentration of the tank liquor to ensure that the concentration of each component in the tank liquor meets the following conditions: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl-: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/l; and checking whether the temperature of the bath solution is within a process specified range; secondly, checking whether the cathode plate is hung at a fixed position in the middle part and whether the area ratio of the cathode to the anode is proper; after the conditions are met, the part hanger is conveyed to a plating bath and is immersed in bath solution;
step 5, sulfuric acid anodizing: setting sulfuric acid anodic oxidation process parameters, replacing control current with control voltage, ensuring the voltage to be constant, and increasing the voltage from 0 to 16 +/-2V at the speed of 6 +/-2V per minute; temperature: 16-18 ℃; slow start time: 2-3 minutes; anodization time (including slow start time): 30-40 minutes; stirring: stirring with clean compressed air and marking the position; the verification proves that when the temperature of bath solution is lower than 16 ℃ in the anodizing process, the oxidation time is long, exceeds the time specified by the process, and when the temperature is higher than 18 ℃, the film layer is easy to loosen and pulverize. The bottom of the sulfuric acid anodizing tank body is provided with a through hole pipeline, after a valve of compressed air is opened, the compressed air flows out of a pipeline hole and drives the sulfuric acid anodizing tank liquid to stir, and the marking position refers to marking on a switch valve of the compressed air so as to ensure that the valve is in the same position when being opened every time.
Step 6, cleaning: immediately cleaning the parts with flowing cold water at room temperature for 0.3-3 minutes after the parts are taken out of the groove; then immediately carrying out coloring treatment to ensure that the surface of the part is wet; the water for cleaning is deionized water, the pH value of the deionized water is 6-8, and the deionized water is ensured to be flowing and is replaced every day; stirring with clean compressed air;
and 7, coloring: selecting an aluminum anodic oxidation dye H103 as a dye, adding water to prepare a coloring solution, detecting the temperature and the pH value of the coloring solution, and ensuring that the temperature is 11-26 ℃ and the pH value is 5.5-6.0; then placing the part in a coloring solution for 15 +/-1 minutes; if the pH value of the coloring solution is not qualified, the coloring treatment can be carried out after the pH value is adjusted to be qualified. The dye is commonly known as aluminum anodic oxidation dye, has high coloring speed, high color fastness and bright color, can be used after being opened, does not flow or change color when being closed, and has the color meeting the process requirement;
step 8, cleaning: after coloring the parts, immediately cleaning the parts for 0.3 to 3 minutes by using flowing cold deionized water; the water for cleaning is deionized water, the pH value of the deionized water is 6-8, and the deionized water is ensured to be flowing and is replaced every day; stirring with clean compressed air;
step 9, sealing: sealing the part treated in the step 8 in deionized water at the temperature of 97-99 ℃ and the pH of 5.5-7.0 for 30-45 minutes; note: checking the temperature and the pH value of the sealing solution before sealing, and if the pH value of the sealing solution is unqualified, adjusting the pH value to be qualified and then sealing;
step 10, drying: and sealing and drying by using clean compressed air.
Step 11, secondary sealing: and (3) placing the part dried in the step (10) in a drying oven with the temperature of 90-99 ℃ for 35 +/-5 minutes.
Further, in the step 4, the concentration of each component in the bath solution is ensured to meet the following conditions: sulfuric acid H2SO4: 190 g/l, aluminum ion Al3+: less than 12 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
Further, in the step 4, the concentration of each component in the bath solution is ensured to meet the following conditions: sulfuric acid H2SO4: 190 g/l, 4 g/l < Al ion Al3+Less than 8 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
To further enhance the coloring effect, the concentration of the aluminum anodizing dye H103 in the coloring solution in step 7 was 3 g/L.
Further, step 11 is followed by an inspection step, including appearance inspection, thickness inspection and corrosion resistance inspection:
1) and (3) appearance inspection: the part must be inspected visually at 100%. The color of the oxide film after coloring treatment should accord with the natural color-red of the dye. A. Defects are not allowed: damage, local absence of film, residue, burns, over-corrosion, closed stained putty, and loose film that can be rubbed off by hand. B. Allowed defects: different oxidation colors are allowed on the same part due to the unevenness of the material of the part and the difference of the surface state; slight watermarking, inevitable fixture marking; the film layer defects caused by the defects of the metal matrix and the color depth of parts in different grooves are different;
2) and (3) thickness inspection: the fischer mp40 thickness gauge was recalibrated and the thickness measurements had to be made three times as shown on the plane of one location on the part. The average value thus calculated is used to represent the effective thickness of a part.
3) And (3) corrosion resistance inspection: 2% of the parts were drawn from each batch and subjected to a salt spray corrosion test for at least 336 hours as required by ASTM B117 specification.
Further, to balance film quality with reaction time, the temperature of sulfuric acid anodization in step 5 was 18 ℃.
The invention has the beneficial effects that:
1. according to the invention, through sulfuric acid anodic oxidation pretreatment and post-treatment methods such as coloring and sealing, the obtained film layer has no corrosion on the surface of the matrix metal after 336 hours of neutral salt spray test, and the film layer is uniform, continuous and complete, has no looseness and uniform color.
2. The invention particularly needs to ensure the copper ion Cu by adjusting the components and the concentration of the anodic oxidation bath solution2+: less than 0.015 g/L to obtain high quality oxide film. Because the copper content in the aluminum alloy material is higher, when the copper content is higher, the current efficiency is reduced in the sulfuric acid anodic oxidation process, the electric conduction is poor, the local oxidation film is thinner, and black spots are easy to generate.
3. The invention maintains the temperature at 16-18 ℃ by optimizing the sulfuric acid anodizing temperature, and obtains the optimal oxide film layer on the premise of ensuring reasonable process time. Meanwhile, when the oxidation starts and ends, the slow starting time of the current is set, and the quality of the film layer is improved.
4. The invention adopts a secondary sealing method, firstly sealing in boiling deionized water, and then carrying out secondary sealing in a drying oven, thus ensuring that the pores of the film are completely blocked, the film is compact and has strong corrosion resistance. Compared with a method adopting steam sealing, the method has the advantages of low requirement on equipment, low energy consumption, low cost and strong operability.
5. The invention replaces control current with control voltage, which ensures constant voltage and uniform sulfuric acid anodic oxide film.
Detailed Description
The invention is further described below with reference to specific examples.
In the following embodiment, the aluminum alloy material BS L168 is selected for testing, the method can be used for all aluminum and aluminum alloy materials, the test result is stable, and the operability is strong.
The process flow of the oxidation process method for the BS L168 red anode of the aluminum alloy material in the embodiment is as follows:
1. checking and accepting in the factory: compare with chart paper. The surface of the part should not have the defects of rust, burr, dirt, oil stain, metal chips, mechanical damage (pressure damage, bruise, scratch) and the like. The defective parts and the non-conformity of the drawings are returned.
2. Installing and hanging parts: the fixture prepared from the titanium alloy is hung according to the requirements of drawings, so that good conductivity is ensured, and the fixture is prevented from scratching the surface of a part. The clamp has good contact and good heat dissipation effect when being hung, avoids overlarge contact surface of the clamp and air bag generation, and avoids clamping and deformation of parts. When the clamp is hung, an old oxide film on the clamp is removed, and the minimum clamp mark is ensured.
3. Pretreatment of anodizing: fixing the part hanger on the copper bar by using an aluminum wire, and checking whether the hanger shakes and the conductivity of the copper bar; using a traveling crane to hoist the hanger to perform chemical degreasing at the temperature of 60-80 ℃ for 0.3-3 minutes; cleaning, cleaning in hot water at a temperature of not lower than 50 ℃ for 0.3-3 minutes, then cleaning in flowing cold water for 0.3-3 minutes, and checking whether the water film is continuous for 30 seconds; thirdly, soaking and polishing for 1-3 minutes at room temperature; and fourthly, immediately washing in flowing cold water for 0.3 to 3 minutes, and checking whether the water film is continuous for 30 seconds. After the above treatment is passed, the following steps are carried out.
4. Sending to an anode oxidation line: first check whether the anodizing bath is leaking or otherwise abnormal, and then check the sulfuric acid anodizing bath solution concentration, in this example: the bath solution comprises the following components: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl-: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/L and deionized water as solvent. The copper content in the material is high, and when the copper content is high, the current efficiency is reduced in the sulfuric acid anodic oxidation process, the electric conduction is poor, a local oxidation film is thin, and black spots are easy to generate; and verified by tests when Cu2+When the ion content exceeds 0.015, the material is easy to generate black spots after sulfuric acid anodic oxidation, so that the bath solution of the embodiment needs to ensure copper ion Cu2+: < 0.015 g/l. Checking whether the temperature is within a process specified range; and secondly, checking whether the cathode plate is hung at the middle fixed position and whether the area ratio of the cathode to the anode is proper. The part hanger can be conveyed to the plating bath and immersed in the anodizing bath solution when the conditions are met.
5. Sulfuric acid anodizing: setting the technological parameters of anodic oxidation of sulfuric acid according to the control power supply operating instruction, replacing the control current with control voltage, and raising from 0 to 18V at the speed of 6 +/-2V per minute; temperature: 18 ℃; slow start time: 2-3 minutes; anodization time (including slow start time): for 40 minutes. Stirring: stirring with clean compressed air and marking the position. In other embodiments, the temperature is set between 16 ℃ and 18 ℃ and the anodization time is 30 to 40 minutes.
6. Cleaning: immediately cleaning the parts with flowing cold water for 0.3-3 minutes after the parts are taken out of the groove; and immediately performing coloring treatment to ensure that the surface of the part is wet. The water for cleaning is deionized water, the pH value of the deionized water is 6-8, and the deionized water is ensured to be flowing and is replaced every day; and stirred with clean compressed air.
7. Coloring: preparing a coloring solution by using an aluminum anodic dye H103 (red), wherein the concentration of the aluminum anodic oxidation dye H103 in the coloring solution is 3 g/L, and the temperature of the coloring solution is as follows: room temperature (11 ℃), coloring time: 15 minutes, pH of coloring solution: 5.5-6.0. Note: before coloring, the temperature (between 11 and 26 ℃) and the pH value of the coloring solution are checked, and if the pH value of the coloring solution is unqualified, the pH value is adjusted to be qualified, and then coloring treatment can be carried out.
8. Cleaning: after coloring the parts, immediately cleaning the parts for 0.3 to 3 minutes by using flowing cold water; the water for cleaning is deionized water, the pH value of the deionized water is 6-8, and the deionized water is ensured to be flowing and is replaced every day; and stirred with clean compressed air.
9. And (3) sealing: sealing the part treated in the step 8 in deionized water at the temperature of 97-99 ℃ and the pH of 5.5-7.0 for 30-45 minutes; note: before sealing, checking the temperature (between 97 and 99 ℃) and the pH value of the sealing solution, and if the pH value of the sealing solution is unqualified, adjusting the pH value to be qualified and then sealing.
10. And (3) drying: and sealing and drying by using clean compressed air.
11. Secondary sealing: the part dried in step 10 was placed in a drying oven at 94 ℃ for 36 minutes. The pore which is not completely sealed in one-time sealing is plugged again, so that the corrosion resistance of the pore is improved. In other embodiments, the temperature of the drying oven is 90-99 deg.C, and the drying time is 35 + -5 minutes.
12. And (4) checking:
1) and (3) appearance inspection: the part must be inspected visually at 100%. The color of the oxide film after coloring treatment should accord with the natural color-red of the dye. A. Defects are not allowed: damage, local absence of film, residue, burns, over-corrosion, closed stained putty, and loose film that can be rubbed off by hand. B. Allowed defects: different oxidation colors are allowed on the same part due to the unevenness of the material of the part and the difference of the surface state; slight watermarking, inevitable fixture marking; the film layer defects caused by the defects of the metal matrix and the color depth of parts in different grooves are different;
2) and (3) thickness inspection: the fischer mp40 thickness gauge was recalibrated and the thickness measurements had to be made three times as shown on the plane of one location on the part. The average value thus calculated is used to represent the effective thickness of a part.
3) And (3) corrosion resistance inspection: 2% of the parts were drawn from each batch and subjected to a salt spray corrosion test for at least 336 hours as required by ASTM B117 specification.
Example two
The difference between the present embodiment and the first embodiment is: and 4, ensuring that the concentration of each component in the bath solution meets the following conditions: sulfuric acid H2SO4: 190 g/l, aluminum ion Al3+: less than 12 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
This example is identical to the process of example one except that in step 5 the oxidation voltage in sulfuric acid anodization is increased from 0 to 16V at a rate of 6 + -2V per minute; anodizing time was 30 minutes; the temperature of the coloring solution in the step 7 is 26 ℃; in the step 9, the sealing temperature is 99 ℃, and the sealing time is 30 minutes; and in the step 11, secondary sealing is carried out, the temperature of the drying box is 90 ℃, and the drying time is 40 minutes.
EXAMPLE III
The difference between the present embodiment and the first embodiment is: and 4, ensuring that the concentration of each component in the bath solution meets the following conditions: sulfuric acid H2SO4: 190 g/l, 4 g/l < Al ion Al3+Less than 8 g/l, chloride ion Cl-：＜0.12G/l, copper ion Cu2+: less than 0.012 g/l, and the solvent is deionized water.
This example is identical to the process of example one except that in step 5 the oxidation voltage in sulfuric acid anodization is increased from 0 to 14V at a rate of 6 + -2V per minute; the oxidation time was 35 minutes; the temperature of the coloring solution in the step 7 is 20 ℃; in the step 9, the sealing temperature is 99 ℃, and the sealing time is 45 minutes; and in the step 11, secondary sealing is carried out, the temperature of a drying box is 99 ℃, and the drying time is 30 minutes.
Through multiple experiments of the above embodiment, the invention verifies that attention is paid to the red anodizing process:
during the sulfuric acid anodizing process, the voltage should be raised to the normal oxidation voltage within 1-3 minutes after the power is supplied, and if the voltage is uniformly raised along with the progress of the oxidation time and the increase of the thickness of the film layer, the anodizing process is normal. If the voltage stops rising, the faults such as local heating or dissolution of the film layer, poor insulation and the like occur; if the voltage is reduced, the breakdown of the film or the insulator is proved; at the moment, the power is cut off immediately, and the fault is rapidly eliminated by checking.
Secondly, the bath solution is analyzed once a week (whether the liquid level of the bath solution is in a specified range is checked during analysis and sampling), analysis items comprise the content of sulfuric acid and aluminum ions, the content of copper ions and the content of chloride ions, analysis and adjustment records are made, and the analysis and adjustment records are properly stored. If the bath solution is abnormal, the bath solution is adjusted in time and is used after being adjusted to be qualified.
And thirdly, the anodic oxidation time can be adjusted according to the thickness of the film layer of the part, when the film layer thickness needs to be measured (the thickness is measured by a thickness gauge) in the anodic oxidation process, the voltage is reduced, 1-2 parts are taken out for measurement, and if the thickness is not enough, the voltage is allowed to be slowly started to the normal range again to continue the anodic oxidation.
And fourthly, immediately taking out the part from the anodizing tank within three minutes under the conditions of stopping air (compressed air) and power failure, and immediately carrying out static cleaning and flowing cleaning processes.
Fifthly, covering the sulfuric acid anodizing bath when the parts are not processed, and preventing the bath solution from cross contamination.
Sixthly, the water for cleaning the parts is flowing water, the parts are replaced before processing each time, and the pH value is measured to be 6-8.
Claims (9)
1. The bath solution for red anodic oxidation of the aluminum alloy material is characterized by comprising the following components: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl-: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/L and deionized water as solvent.
2. The red anodizing bath solution of aluminum alloy material according to claim 1, wherein H sulfuric acid2SO4: 190 g/l, aluminum ion Al3+: less than 12 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
3. The red anodizing bath solution of aluminum alloy material according to claim 2, wherein sulfuric acid H2SO4: 190 g/l, 4 g/l < Al ion Al3+Less than 8 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
4. A process method for red anodic oxidation of an aluminum alloy material is characterized by comprising the following steps:
step 1, checking and accepting parts;
after the part is qualified, executing the step 2;
step 2, mounting and hanging parts;
a titanium alloy special tool is adopted, and parts are mounted and hung according to the requirements of a drawing;
step 3, anodizing pretreatment;
step 3.1, chemical degreasing: cleaning the parts with deoiling solution at 60-80 deg.c for 0.3-3 min; removing oil stains on the surface of the part;
step 3.2, cleaning: cleaning the deoiled part in hot water at a temperature of not lower than 50 ℃ for 0.3-3 minutes, and then cleaning in flowing cold water until the water film continuous time reaches a set time;
step 3.3, soaking: soaking the cleaned part in light at room temperature for 1-3 min;
step 3.4, cleaning: immediately cleaning the dipped parts in flowing cold water until the water film continuous time reaches the set time;
and 4, sending to an anode oxidation line: firstly, checking whether the anodic oxidation tank leaks or is abnormal, and then checking the concentration of the tank liquor to ensure that the concentration of each component in the tank liquor meets the following conditions: sulfuric acid H2SO4: 185-195 g/l, 0 g/l < Al ion Al3+Less than 15 g/l, chloride ion Cl-: less than 0.15 g/l, copper ion Cu2+: less than 0.015 g/l; and checking whether the temperature of the bath solution is within a process specified range; secondly, checking whether the cathode plate is hung at a fixed position in the middle part and whether the area ratio of the cathode to the anode is proper; after the conditions are met, the part hanger is conveyed to a plating bath and is immersed in bath solution;
step 5, sulfuric acid anodizing: setting sulfuric acid anodizing process parameters, and controlling the voltage to rise from 0 to 16 +/-2V at the speed of 6 +/-2V per minute; temperature: 16-18 ℃; slow start time: 2-3 minutes; anodizing time: 30-40 minutes; stirring: stirring with clean compressed air and marking the position;
step 6, cleaning: immediately cleaning the part with flowing cold deionized water for 0.3-3 minutes after the part is taken out of the tank, wherein the temperature of the cold deionized water is room temperature, and the pH value is 6-8; then immediately executing the step 7 to perform coloring treatment to ensure that the surface of the part is wet; stirring with clean compressed air;
and 7, coloring: selecting an aluminum anodic oxidation dye H103 as a dye, adding water to prepare a coloring solution, detecting the temperature and the pH value of the coloring solution, and ensuring that the temperature is 11-26 ℃ and the pH value is 5.5-6.0; then placing the part in a coloring solution for 15 +/-1 minutes;
step 8, cleaning: after coloring the parts, immediately cleaning the parts for 0.3 to 3 minutes by using flowing cold deionized water, wherein the temperature of the cold deionized water is room temperature, and the pH value is 6 to 8; stirring with clean compressed air;
step 9, sealing: sealing the part treated in the step 8 in deionized water at the temperature of 97-99 ℃ and the pH of 5.5-7.0 for 30-45 minutes;
step 10, drying: sealing and drying with clean compressed air;
step 11, secondary sealing: and (3) placing the part dried in the step (10) in a drying oven with the temperature of 90-99 ℃ for 35 +/-5 minutes.
5. The process method for red anodic oxidation of aluminum alloy material according to claim 4, wherein the concentration of each component in the bath solution is ensured to satisfy the following condition in step 4: sulfuric acid H2SO4: 190 g/l, aluminum ion Al3+: less than 12 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
6. The process method for red anodic oxidation of aluminum alloy material according to claim 5, wherein the concentration of each component in the bath solution is ensured to satisfy the following condition in step 4: sulfuric acid H2SO4: 190 g/l, 4 g/l < Al ion Al3+Less than 8 g/l, chloride ion Cl-: less than 0.12 g/l, Cu ions2+: less than 0.012 g/l, and the solvent is deionized water.
7. The process method for red anodizing of aluminum alloy material according to claim 4, wherein the concentration of aluminum anodizing dye H103 in the coloring solution in step 7 is 3 g/L.
8. The process of claim 4, wherein step 11 is followed by inspection steps comprising visual inspection, thickness inspection and corrosion resistance inspection:
visual inspection is carried out by adopting a visual inspection method, and inspection indexes comprise colors, unallowable defects and allowable defects;
color: the color of the oxide film accords with the natural color of the dye;
defects are not allowed: damage, partial non-film layer, residue, burn, over-corrosion, closed colored hanging ash and loose film layer which can be wiped off by hands;
allowed defects: allowing different oxidation colors on the same part; unavoidable clamp marks; the film layer defects caused by the defects of the metal matrix and the color depth of parts in different grooves are different;
thickness inspection was performed using a fischer mp40 thickness gauge: carrying out three thickness measurements on a plane at one position of the part according to a drawing, and calculating an average value for representing the effective thickness of the part;
and (3) corrosion resistance inspection: salt spray corrosion testing was performed for at least 336 hours as required by ASTM B117 specification.
9. A process for red anodic oxidation of aluminium alloy material according to any one of claims 4 to 8, wherein the temperature of sulphuric acid anodising in step 5 is 18 ℃.
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