CN111893472A - Chromium-free passivation treatment process for aluminum alloy surface - Google Patents
Chromium-free passivation treatment process for aluminum alloy surface Download PDFInfo
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- CN111893472A CN111893472A CN202010789258.XA CN202010789258A CN111893472A CN 111893472 A CN111893472 A CN 111893472A CN 202010789258 A CN202010789258 A CN 202010789258A CN 111893472 A CN111893472 A CN 111893472A
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/78—Pretreatment of the material to be coated
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Abstract
The invention discloses a chromium-free passivation treatment process for the surface of an aluminum alloy; relates to the technical field of aluminum alloy, comprising: (1) polishing; (2) treating with a tannic acid solution; (3) femtosecond laser processing; (4) passivating; according to the method, a layer of uniform and compact passivation film is formed on the surface of the aluminum alloy through passivation, and after neutral salt spray treatment, the salt spray corrosion resistance of the passivation film is excellent, so that the aluminum alloy can be better protected; the contact angle of the surface of the passivation film formed by the method is greatly increased, which shows that the hydrophobic property of the surface of the aluminum alloy is obviously improved after the passivation treatment by the process.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy, and particularly relates to a chromium-free passivation treatment process for an aluminum alloy surface.
Background
The aluminum alloy has the advantages of high specific strength, good heat conductivity and electrical conductivity, beautiful color, no magnetism, good plasticity, no low-temperature brittleness and the like, and is widely applied to the fields of aerospace, mechanical equipment, household appliances, buildings and the like. The amount of the metal is second to that of steel, and the second metal material is used in the industrial field. However, the chemical property of the aluminum alloy is active, and in an atmospheric environment, a very thin oxide film (the thickness of the oxide film is usually several nanometers) is easily formed on the surface of the aluminum alloy, so that the aluminum alloy has a certain protective effect on a substrate. However, the natural oxide film is too thin and is easily broken, and is very easily corroded in a humid atmosphere, particularly in an environment containing Cl-. Under natural conditions, the corrosion of aluminum and its alloys is usually localized, mainly expressed as: pitting corrosion, galvanic corrosion, filiform corrosion, laminar corrosion, crevice corrosion and intergranular corrosion. The local corrosion has strong concealment, difficult control and rapid damage, and is easy to cause catastrophic accidents, so that the aluminum and the aluminum alloy need to be subjected to necessary surface treatment before use in order to expand the application range of the aluminum alloy and prolong the service life of the aluminum alloy.
Traditionally, chromate treatment is used for the passivation of aluminum alloys. The passive film obtained by the treatment has good corrosion resistance and strong bonding force with an organic coating, but the hexavalent chromium compound has strong toxicity and great harmfulness to human bodies and natural environment, and various strict measures have been established in various countries in the world to limit the application of the hexavalent chromium compound.
Disclosure of Invention
The invention aims to provide a chromium-free passivation treatment process for the surface of an aluminum alloy, which aims to overcome the defects in the prior art.
The technical scheme adopted by the invention is as follows:
a chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant;
(2) treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 80-90 ℃, reacting for 40-50min, then taking out, cleaning to be neutral by using clear water, and drying to be constant weight to obtain the aluminum alloy workpiece;
(3) femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece;
(4) passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation for 1.5-2min at the passivation temperature of 60-66 ℃, taking out, cleaning to be neutral by using clear water, and drying to be constant weight.
And during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment.
The cleaning is carried out by respectively cleaning with acetone and distilled water for 20-25min in an ultrasonic cleaning machine.
The mass fraction of the tannic acid solution is 4-5%.
The vacuum degree in the vacuum reaction kettle is 0.015-0.018 MPa.
The femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 800-900nm, the pulse repetition frequency is 1-1.5KHz, the pulse width is 102-106fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
The femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 850nm, the pulse repetition frequency is 1.2KHz, the pulse width is 105fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
The passivation solution is prepared from the following components in parts by weight: 1-1.6 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 4-6 parts of sodium fluorozirconate, 2.3-2.8 parts of potassium fluorotitanate, 5-7 parts of nitric acid, 0.03-0.06 part of rare earth and 80 parts of deionized water.
The rare earth is lanthanum nitrate.
The passivation process can form a uniform and compact passivation film on the surface of the aluminum alloy, the passivation solution can reduce the surface tension of the aluminum alloy by adding a certain amount of synergistic promotion effect of sodium fluorozirconate and potassium fluorotitanate, so that an aluminum alloy matrix can be more quickly exposed in the passivation solution to generate a passivation reaction, meanwhile, the dissolution of the surface of the aluminum alloy can be accelerated, the formation of the passivation film is promoted, and zirconium compounds can be formed in the passivation film, so that the performance of the passivation film is improved, and particularly, the adhesion force between the passivation film and the aluminum alloy is greatly improved.
The passive film formed by the process can prevent the corrosion of external corrosive substances such as oxygen, moisture, chloride ions and the like, thereby playing a good role in protecting the aluminum alloy matrix, and greatly prolonging the service life of the passive film. According to the invention, the aluminum alloy is treated in a vacuum environment by adopting the tannic acid solution, so that a micro-corrosion effect can be generated on the surface of the aluminum alloy, and then the femtosecond laser treatment is carried out, so that fine textures can be generated on the surface of the aluminum alloy, the formation of a subsequent passivation film is facilitated, and the binding force between the passivation film and an aluminum alloy substrate is improved.
Has the advantages that:
according to the method, a layer of uniform and compact passivation film is formed on the surface of the aluminum alloy through passivation, and after neutral salt spray treatment, the salt spray corrosion resistance of the passivation film is excellent, so that the aluminum alloy can be better protected; the contact angle of the surface of the passivation film formed by the method is greatly increased, which shows that the hydrophobic property of the surface of the aluminum alloy is obviously improved after the passivation treatment by the process.
Detailed Description
A chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant;
(2) treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 80-90 ℃, reacting for 40-50min, then taking out, cleaning to be neutral by using clear water, and drying to be constant weight to obtain the aluminum alloy workpiece;
tannic acid:
the characteristics are as follows: yellow or brown yellow amorphous loose powder, which gradually darkens in air and has strong hygroscopicity;
flash point (q): 198.89, respectively;
self ignition point or ignition temperature (° C): 526.67, respectively;
molar refractive index: 379.60, respectively;
molar volume (cm)3/mol）：799.0；
Isospecific volume (90.2K): 3016.6, respectively;
surface tension (dyne/cm) 203.1;
solubility: dissolved in water and ethanol. The ellagic acid is almost insoluble in ether, benzene, chloroform and petroleum ether, contains four phenolic hydroxyl groups, has weak acidity, and is soluble in alkaline aqueous solution and organic solvents such as benzene and ethyl acetate;
(3) femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece;
(4) passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation for 1.5-2min at the passivation temperature of 60-66 ℃, taking out, cleaning to be neutral by using clear water, and drying to be constant weight.
And during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment.
The cleaning is carried out by respectively cleaning with acetone and distilled water for 20-25min in an ultrasonic cleaning machine.
The mass fraction of the tannic acid solution is 4-5%.
The vacuum degree in the vacuum reaction kettle is 0.015-0.018 MPa.
The femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 800-900nm, the pulse repetition frequency is 1-1.5KHz, the pulse width is 102-106fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
The femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 850nm, the pulse repetition frequency is 1.2KHz, the pulse width is 105fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
The passivation solution is prepared from the following components in parts by weight: 1-1.6 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 4-6 parts of sodium fluorozirconate, 2.3-2.8 parts of potassium fluorotitanate, 5-7 parts of nitric acid, 0.03-0.06 part of rare earth and 80 parts of deionized water.
Potassium fluotitanate: analytically pure shanghai petit chemical agents, ltd;
sodium fluorozirconate: analytically pure shanghai petit chemical agents, ltd;
the rare earth is lanthanum nitrate.
The main components are as follows: the content is more than or equal to 99.0 percent;
appearance and properties: white granular crystals, deliquescent;
melting Point (. degree. C.): 40;
boiling point (. degree. C.): 126;
relative density (water = 1): 2.05;
solubility: is easily soluble in water and ethanol.
The following will clearly and completely describe the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant; and during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment. The cleaning is carried out by respectively cleaning with acetone and distilled water for 20min in an ultrasonic cleaning machine.
(2) Treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 80 ℃, reacting for 40min, then taking out, cleaning with clear water to be neutral, and drying to constant weight to obtain the aluminum alloy workpiece; the mass fraction of the tannic acid solution is 4-5%. The vacuum degree in the vacuum reaction kettle is 0.015 MPa.
(3) Femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece; the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 800nm, the pulse repetition frequency is 1KHz, the pulse width is 102fs, the diameter of a focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
(4) Passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation, wherein the passivation time is 1.5min, the passivation temperature is 60 ℃, taking out, cleaning to be neutral by using clear water, and drying to be constant in weight. The passivation solution is prepared from the following components in parts by weight: 1 of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 4 of sodium fluorozirconate, 2.3 of potassium fluorotitanate, 5 of nitric acid, 0.03 of rare earth and 80 of deionized water. The rare earth is lanthanum nitrate.
Example 2
A chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant; and during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment. The cleaning is carried out by respectively cleaning with acetone and distilled water for 25min in an ultrasonic cleaning machine.
(2) Treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 90 ℃, reacting for 50min, then taking out, cleaning with clear water to be neutral, and drying to constant weight to obtain the aluminum alloy workpiece; the mass fraction of the tannic acid solution is 5%. The vacuum degree in the vacuum reaction kettle is 0.018 MPa.
(3) Femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece; the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 900nm, the pulse repetition frequency is 1.5KHz, the pulse width is 106fs, the diameter of a focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
(4) Passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation, wherein the passivation time is 2min, the passivation temperature is 66 ℃, taking out, cleaning to be neutral by using clear water, and drying to be constant in weight. The passivation solution is prepared from the following components in parts by weight: 1.6 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 6 parts of sodium fluorozirconate, 2.8 parts of potassium fluorotitanate, 7 parts of nitric acid, 0.06 part of rare earth and 80 parts of deionized water. The rare earth is lanthanum nitrate.
Example 3
A chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant; and during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment. The cleaning is carried out by respectively cleaning with acetone and distilled water in an ultrasonic cleaning machine for 22 min.
(2) Treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 85 ℃, reacting for 45min, then taking out, cleaning with clear water to be neutral, and drying to constant weight to obtain the aluminum alloy workpiece; the mass fraction of the tannic acid solution is 4.5%. The vacuum degree in the vacuum reaction kettle is 0.016 MPa.
(3) Femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece; the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 830nm, the pulse repetition frequency is 1.2KHz, the pulse width is 104fs, the diameter of a focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
(4) Passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation, wherein the passivation time is 1.6min, the passivation temperature is 63 ℃, taking out the workpiece, cleaning the workpiece to be neutral by using clear water, and drying the workpiece to be constant in weight. The passivation solution is prepared from the following components in parts by weight: 1.2 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 5 parts of sodium fluorozirconate, 2.5 parts of potassium fluorotitanate, 6 parts of nitric acid, 0.04 part of rare earth and 80 parts of deionized water. The rare earth is lanthanum nitrate.
Example 4
A chromium-free passivation treatment process for the surface of an aluminum alloy comprises the following steps:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant; and during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment. The cleaning is carried out by respectively cleaning with acetone and distilled water in an ultrasonic cleaning machine for 22 min.
(2) Treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 88 ℃, reacting for 50min, then taking out, cleaning with clear water to be neutral, and drying to constant weight to obtain the aluminum alloy workpiece; the mass fraction of the tannic acid solution is 5%. The vacuum degree in the vacuum reaction kettle is 0.016 MPa.
(3) Femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece; the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 850nm, the pulse repetition frequency is 1.2KHz, the pulse width is 105fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
(4) Passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation, wherein the passivation time is 1.8min, the passivation temperature is 65 ℃, taking out the workpiece, cleaning the workpiece to be neutral by using clear water, and drying the workpiece to be constant in weight. The passivation solution is prepared from the following components in parts by weight: 1.4 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 5 parts of sodium fluorozirconate, 2.6 parts of potassium fluorotitanate, 6 parts of nitric acid, 0.05 part of rare earth and 80 parts of deionized water. The rare earth is lanthanum nitrate.
Test of
According to the requirements of artificial atmosphere corrosion experiment-salt spray experiment (NSS) in national standard GB/T10125-1997, sodium chloride solution with the mass fraction of 5% is adopted as the solution, the pH is adjusted to 6.8, workpieces treated in examples and comparative examples are placed in a salt spray box, salt spray is allowed to freely settle on the surface of the workpiece, the settlement amount of every 90cm is kept to be 3.2ml/h, the placing angle of the workpiece is 15 degrees, the test temperature is 38 ℃, the continuous spraying is carried out for 24 hours, the test time is 35 days, and the corrosion resistance of the workpiece is evaluated according to the white spot occurrence time on the surface of the workpiece;
the examples, the comparative examples and the blank sample groups were tested, 10 of each group were obtained, and the average value was obtained;
TABLE 1
| 7d | 15d | 35d | |
| Example 1 | Without change | Large increase in white spots | Complete whitening |
| Example 2 | Without change | White spots appear | Large increase in white spots |
| Example 3 | Without change | White spots appear | Large increase in white spots |
| Example 4 | Without change | Without change | White spots appear |
| Comparative example 1 | White spots appear | Large increase in white spots | Become white completely and thin film |
| Blank group | The corrosion reaches 81 percent | The corrosion area reaches 96 percent | Complete corrosion |
Comparative example 1: the difference from the embodiment 1 is that the bis- [3- (triethoxy) silicon propyl ] tetrasulfide is not added into the passivation solution;
as can be seen from Table 1, the method disclosed by the invention forms a uniform and compact passivation film on the surface of the aluminum alloy through passivation, and after neutral salt spray treatment, the passivation film has excellent salt spray corrosion resistance and can better protect the aluminum alloy.
Surface contact angle:
the contact angle detection is carried out on the samples of the above examples and comparative examples by using a contact angle measuring instrument, the adopted solution is distilled water, 4 different points are selected on the surface of each sample for measurement, and the average value is taken:
TABLE 2
| Contact angle ° | |
| Example 1 | 122.1 |
| Example 2 | 121.2 |
| Example 3 | 123.0 |
| Example 4 | 125.7 |
| Comparative example 1 | 112.1 |
| Blank group | 89.2 |
Comparative example 1: the difference from the embodiment 1 is that the bis- [3- (triethoxy) silicon propyl ] tetrasulfide is not added into the passivation solution;
as can be seen from Table 2, the contact angle of the surface of the passivation film formed by the method of the invention is greatly increased, which shows that the hydrophobic property of the surface of the aluminum alloy is obviously improved after passivation treatment by the process of the invention.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the present invention is not limited to the illustrated embodiments, and all the modifications and equivalents of the embodiments may be made without departing from the spirit of the present invention.
Claims (9)
1. The aluminum alloy surface chromium-free passivation treatment process is characterized by comprising the following steps of:
(1) polishing:
the surface of an aluminum alloy workpiece is polished, 600#, 800#, 1200 # silicon carbide abrasive paper is sequentially used for polishing by adding water, then an automatic polishing machine is used for polishing, and then cleaning and drying are carried out until the weight is constant;
(2) treating with a tannic acid solution:
adding a tannic acid solution into a vacuum reaction kettle, then immersing the polished aluminum alloy workpiece into the tannic acid solution, then sealing, vacuumizing, adjusting the temperature in the reaction kettle to 80-90 ℃, reacting for 40-50min, then taking out, cleaning to a neutral position by using clear water, and drying to a constant weight to obtain the aluminum alloy workpiece;
(3) femtosecond laser processing:
scanning the surface of the aluminum alloy workpiece treated in the step (2) by adopting femtosecond laser to obtain a pretreated aluminum alloy workpiece;
(4) passivation:
and (3) immersing the obtained pre-treated aluminum alloy workpiece into a passivation solution for passivation for 1.5-2min at the passivation temperature of 60-66 ℃, taking out, cleaning to be neutral by using clear water, and drying to be constant weight.
2. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: and during polishing, water-soluble diamond polishing paste with the granularity of 1 mu m is adopted for auxiliary polishing treatment.
3. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: the cleaning is carried out by respectively cleaning with acetone and distilled water for 20-25min in an ultrasonic cleaning machine.
4. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: the mass fraction of the tannic acid solution is 4-5%.
5. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: the vacuum degree in the vacuum reaction kettle is 0.015-0.018 MPa.
6. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 800-900nm, the pulse repetition frequency is 1-1.5KHz, the pulse width is 102-106fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
7. The aluminum alloy surface chromium-free passivation treatment process according to claim 6, characterized in that: the femtosecond laser treatment comprises the following steps: the femtosecond laser wavelength is 850nm, the pulse repetition frequency is 1.2KHz, the pulse width is 105fs, the diameter of the focusing spot is 20 μm, the laser power is 50mW, and the scanning speed is 1.8 mm/s.
8. The aluminum alloy surface chromium-free passivation treatment process according to claim 1, characterized in that: the passivation solution is prepared from the following components in parts by weight: 1-1.6 parts of bis- [3- (triethoxy) silicon propyl ] tetrasulfide, 4-6 parts of sodium fluorozirconate, 2.3-2.8 parts of potassium fluorotitanate, 5-7 parts of nitric acid, 0.03-0.06 part of rare earth and 80 parts of deionized water.
9. The aluminum alloy surface chromium-free passivation treatment process according to claim 8, characterized in that: the rare earth is lanthanum nitrate.
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Cited By (2)
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|---|---|---|---|---|
| CN114774903A (en) * | 2022-03-29 | 2022-07-22 | 浙江工业大学 | Zirconium-titanium-based composite passivation solution suitable for chromium-free passivation of aluminum alloy and passivation process |
| CN114789365A (en) * | 2022-04-06 | 2022-07-26 | 江苏中川通大科技有限公司 | Alloy surface treatment method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114774903A (en) * | 2022-03-29 | 2022-07-22 | 浙江工业大学 | Zirconium-titanium-based composite passivation solution suitable for chromium-free passivation of aluminum alloy and passivation process |
| CN114789365A (en) * | 2022-04-06 | 2022-07-26 | 江苏中川通大科技有限公司 | Alloy surface treatment method |
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