CN111139463A - Preparation method of environment-friendly corrosion-resistant magnesium alloy ceramic conversion film - Google Patents
Preparation method of environment-friendly corrosion-resistant magnesium alloy ceramic conversion film Download PDFInfo
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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
- C23C22/40—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 molybdates, tungstates or vanadates
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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
- C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/57—Treatment of magnesium or alloys based thereon
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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
- C23C22/73—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 characterised by the process
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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
Abstract
The invention relates to the field of magnesium alloy surface treatment, in particular to a preparation method of an environment-friendly corrosion-resistant ceramic conversion film applied to magnesium alloy. The method comprises pretreatment, coarsening treatment, homogenization treatment and conversion treatment, wherein the conversion treatment solution comprises 2-20 g/l of zirconate titanate (salt), 2-20 g/l of oxidant and 0.5-10 g/l of film-forming additive, 0.1-5 g/l of silane coupling agent and the balance of water are added, and the pH value of the solution is required to be adjusted to 2-5 before use. The uniform film formation on the surface of the matrix can be realized by adopting a dipping or spraying mode under the normal temperature condition, the corrosion resistance of the coating is equivalent to that of the traditional phosphate conversion film, the coating can be directly used or used for the pretreatment of coating, and the coating has good adhesive force with an organic coating. The process is simple to operate, has low cost, does not discharge polluted ions such as phosphate, chromium, nickel and the like, and is an environment-friendly surface treatment new method suitable for industrial production of magnesium alloy.
Description
Technical Field
The invention relates to the field of magnesium alloy surface treatment, in particular to a preparation method of an environment-friendly corrosion-resistant ceramic conversion film applied to magnesium alloy.
Background
The chemical conversion coating technology has the advantages of simple process, low cost, high automation degree and the like, and is commonly used for the coating pretreatment of metal workpieces. However, the traditional phosphating solution contains a large amount of phosphate and heavy metal ions such as zinc, manganese, nickel and the like, and has great harm to the environment and human bodies. Under the dual drive of 'environmental protection requirement + energy cost', enterprises urgently need a novel environment-friendly chemical conversion process to replace the traditional phosphating technology. In addition, the magnesium alloy has active chemical properties and is easy to corrode, particularly, after a workpiece with a complex structure is subjected to chemical conversion treatment and water washing, secondary rust return is easily caused by water remained at the grooves and the pores, and the subsequent coating quality is seriously influenced. Therefore, the novel conversion coating technology applied to the magnesium alloy is required to have corrosion resistance not weaker than that of the traditional phosphating coating on the premise of meeting the requirements of energy conservation and emission reduction.
In several magnesium alloy chemical conversion processes reported recently, in order to meet the requirements of the protective performance, most of film-forming solutions still use phosphate as the main film-forming agent (publication numbers CN107858675A, CN110172700A, etc.), and the waste liquid discharge still has problems. On the other hand, phosphorus-free and chromium-free treatment solutions using molybdate (publication No. CN107245710A) and cerate (publication No. CN109355651A) as main salts often require heating to form a uniform film on the substrate surface, and thus the economic cost is to be improved. The environment-friendly ceramic conversion treatment solution can form a film at normal temperature, has no sediment and waste residue, and is particularly suitable for industrial production. However, the technology mainly aims at the base materials of galvanized steel, aluminum and aluminum alloy, and the research foundation of the technology applied to magnesium alloy is weak. In addition, the thickness of the ceramic conversion film (publication number CN103184446A) reported at present is only 40-120 nm, the protective performance to the matrix is limited, and the industrial application requirement of the magnesium alloy cannot be met.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a preparation method of an environment-friendly corrosion-resistant ceramic conversion coating applied to magnesium alloy, the ceramic conversion treatment solution is phosphorus-free and chromium-free, has little pollution to the environment, can form a protective coating with uniform color and complete and compact coating on the surface of a magnesium substrate at normal temperature in a short time by adopting a dipping or spraying mode, the thickness of the coating is controllable within the range of 50 nm-3 mu m, the corrosion resistance is equivalent to that of the traditional phosphate conversion coating, the adhesive force is less than or equal to 1 grade after the organic coating is coated, and the use requirement is met.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a preparation method of a magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating comprises the following specific steps:
(1) pre-processing: soaking the magnesium alloy in a pretreatment solution at room temperature for 5-10 min to remove residual grease and dirt on the surface;
(2) roughening treatment: soaking the magnesium alloy subjected to the pre-treatment in a roughening treatment solution for 30 s-30 min at room temperature, removing oxide skin and residual alkali liquor on the surface of the sample, and improving the roughness;
(3) homogenizing: the magnesium alloy after the roughening treatment is soaked in the homogenization treatment solution for 5 s-2 min at normal temperature, the microscopic surface state of the matrix is adjusted, the surface active points are increased, and the uniform deposition of film forming substances in the chemical conversion process is facilitated;
(4) and (3) conversion treatment: the magnesium alloy after homogenization treatment is treated by using a conversion treatment solution in a dipping or spraying mode, and a uniform and compact conversion film is formed within 10 s-10 min of normal temperature operation;
wherein the conversion treatment solution comprises: 2-20 g/l of zirconium titanate and/or zirconium titanate, 2-20 g/l of oxidant, 0.5-10 g/l of inorganic film forming additive and/or organic film forming additive, 0.1-5 g/l of silane coupling agent and the balance of water, wherein the pH value is in the range of 2-5; in the conversion treatment solution, the zirconium titanic acid is one or the compound of fluozirconic acid and fluotitanic acid; the zirconium titanate is one of fluozirconate and fluotitanate or the compound of the fluotitanate; the oxidant is one or more than two of manganese salt, molybdate and vanadate; the inorganic film forming assistant is one or more of cerium salt, stannate and calcium salt; the organic film forming auxiliary agent is one or more of phytic acid, tannic acid and citric acid; the silane coupling agent is one or more than two of gamma-aminopropyl triethoxysilane, gamma- (2, 3-epoxypropoxy) propyl trimethoxysilane and gamma- (methacryloyloxy) propyl trimethoxysilane.
The preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy comprises the step (1), wherein the pretreatment solution is one or more of 30-80 g/l hydroxide, 20-60 g/l silicate and 10-50 g/l carbonate compounded alkaline aqueous solution, and the pH value is 11-14.
In the preparation method of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion film, hydroxide is selected from one or compound of sodium hydroxide and potassium hydroxide in a pretreatment solution; the silicate is selected from one or more of sodium silicate, potassium silicate and calcium silicate; the carbonate is selected from one or more of sodium carbonate, potassium carbonate and sodium bicarbonate.
In the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy, in the step (2), the roughening solution comprises the following components: 10-50 g/l of inorganic acid and 5-30 g/l of organic acid or a compound thereof, 10-50 g/l of corrosion inhibitor and the balance of water, wherein the pH value is 2-6.
According to the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy, in the roughening treatment solution, organic acid is selected from one or more of citric acid, DL-malic acid and lactic acid; the inorganic acid is selected from one or more of nitric acid, sulfuric acid and boric acid; the corrosion inhibitor is selected from one or more of sodium fluoride, hexamethylenetetramine and sodium diethyldithiocarbamate.
In the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy, in the step (3), the homogenization treatment solution comprises the following components: 10-50 g/l ammonium salt, 5-30 g/l silicate or their combination, and 10-300 mg/l surfactant, the rest is water, pH value is 5-9.
According to the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy, in the homogenized treatment solution, ammonium salt is one or more than two of ammonium bifluoride, ammonium bicarbonate and ammonium dihydrogen phosphate; the silicate is one of sodium silicate and potassium silicate or the compound thereof; the surfactant is one or more of sodium dodecyl sulfate, tetraethyl ammonium perfluorooctyl sulfonate and alkylphenol polyoxyethylene ether.
According to the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy, after each step of operation of pretreatment, coarsening treatment, homogenization treatment and conversion treatment, water washing is needed, and the solution remained in the previous step is removed; and (3) after the sample is washed, the sample is blown by hot air or treated in a drying furnace at 40-60 ℃ for 10-30 min, the residual free water on the surface is completely removed, and the sample after surface drying is directly used or used for coating pretreatment.
According to the preparation method of the environment-friendly corrosion-resistant ceramic conversion coating made of the magnesium alloy, the thickness of the coating after conversion treatment is controllable within the range of 50 nm-3 mu m, and the corrosion resistance is equivalent to that of the traditional phosphate conversion coating.
According to the preparation method of the environment-friendly corrosion-resistant magnesium alloy ceramic conversion film, the binding force of the conversion-treated ceramic conversion film coated with the organic coating is less than or equal to 1 grade, and the use requirement is met.
The design idea of the invention is as follows:
first, fluorozirconic acid (salt) and fluorotitanic acid (salt) generate colloidal zirconium and titanium oxides in an aqueous solution upon exposure to alkali, and these two oxides have high chemical stability and are ideal film-forming substances. However, since the magnesium alloy has a micro-uneven surface structure, a large potential difference is generated between the matrix phase and the intermetallic compound. When the magnesium alloy is soaked in an acidic aqueous solution of zirconium (titanate), the intermetallic compound with the more positive potential is used as a micro-cathode under the action of a micro-couple, and rapid hydrogen evolution reaction occurs around the intermetallic compound, so that OH near the intermetallic compound is caused-And (4) enriching, wherein the deposition amount of the zirconium oxide is obviously higher than that of other positions. This uneven film layer condition can both reduce its protective effect on the substrate and affect subsequent coating performance. In order to solve the problem, a proper amount of oxidant needs to be added into the zirconium-titanium base solution, so that excessive hydrogen evolution reaction in a micro-cathode area on the surface of a substrate is inhibited, and uniform deposition of zirconium-titanium oxide at each position is ensured. Second, corrosion resistance of zirconium-based ceramic conversion coatingThe film forming agent is not ideal and is related to the thickness of an extremely thin film to a certain degree, and a proper amount of inorganic or organic film forming auxiliary agent is added to cooperate with the zirconium-titanium oxide to participate in the film forming reaction, so that the thickness of the film is improved to a certain degree, and the protective performance of the film is improved. Finally, in order to further improve the adhesive force between the conversion coating and the coating paint film, a small amount of silane coupling agent is adopted to modify the film forming liquid, so that a certain amount of organic film forming substances are doped on the surface of the conversion coating, and the conversion coating is easy to be combined with an organic coating better interface.
The invention has the following advantages and beneficial effects:
1. the magnesium alloy ceramic conversion treatment solution does not contain phosphate and chromium, zinc, nickel and other pollution ions, has small pollution to the environment, meets the pollutant discharge standard of enterprises, and belongs to an environment-friendly process.
2. The preparation process of the magnesium alloy ceramic conversion film is simple, the cost is low, the preparation process can be operated under the normal temperature condition, two treatment modes of dipping or spraying can be adopted, the film formation is stable, the treatment solution is easy to control, no sediment, waste residue and the like exist, and the preparation method is suitable for industrial production.
3. The thickness of the magnesium alloy ceramic conversion film is controllable within the range of 50 nm-3 mu m, the magnesium alloy ceramic conversion film has good bonding property with a magnesium substrate, and the corrosion resistance is equivalent to that of the traditional phosphate conversion film.
4. The ceramic conversion treatment solution can be suitable for various brands of magnesium alloy matrixes such as AZ31, AM60, AZ80, AZ91 and the like, has wide application range, and the binding force of the organic coating coated on the magnesium matrix treated by the process is less than or equal to grade 1 (GB/T9286-1998), thereby meeting the use requirement of paint films.
Drawings
FIG. 1 shows the cross-sectional morphology of an environment-friendly corrosion-resistant ceramic conversion coating made of magnesium alloy: (a) example 1 conditions; (b) example 2 conditions.
FIG. 2 shows the macroscopic morphology (the corrosion medium is 3.5 wt% sodium chloride aqueous solution) of the magnesium alloy after 48h of the full-immersion corrosion test of the environment-friendly corrosion-resistant ceramic conversion film and the two phosphate conversion films: (a) ceramic conversion film example 1; (b) example 2; (c) phosphate conversion film comparative example 1; (d) phosphate conversion film comparative example 2.
Detailed Description
In the specific implementation process, the preparation process of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion film mainly comprises the following four steps:
(1) pre-processing: and removing oil stains remained on the surface of the sample by using an alkaline solution, and soaking for 5-10 min at room temperature.
(2) Roughening treatment: the magnesium alloy after the pretreatment is soaked in a roughening solution for removing oxide skin and residual alkali liquor on the surface of a sample, the surface roughness of a matrix can be properly improved, the magnesium alloy is soaked at room temperature, and the soaking time is properly adjusted according to the state of an oxidation product on the surface of a workpiece, generally within the range of 30 s-30 min;
(3) homogenizing: the work piece after the roughening treatment is soaked in the homogenization treatment solution, and the main purpose is to adjust the microscopic surface state of the matrix, increase the surface active points, facilitate the uniform deposition of the subsequent film forming substances, and soak for 5 s-2 min at normal temperature;
(4) and (3) conversion treatment: the magnesium alloy after homogenization treatment can be operated in a dipping or spraying mode, film formation can be realized at normal temperature, the dipping treatment time can be controlled within the range of 10 s-10 min, and the treatment time can be properly prolonged according to the actual workpiece structure and the spraying difficulty if the spraying mode is adopted.
The above four processes are all carried out with water washing after each operation, and are used for removing the residual solution in the previous process. After the sample after the conversion treatment is washed, the sample can be treated for 10-30 min by blowing hot air or a drying furnace at 40-60 ℃. After the surface moisture is completely removed, the paint can be directly used or subjected to subsequent coating according to actual service conditions. The thickness of the ceramic conversion film is controllable within the range of 50 nm-3 mu m, the corrosion resistance is equivalent to that of a phosphate conversion film, and the adhesive force of a paint film is less than or equal to 1 grade after the organic coating is coated.
The technical solution of the present invention will be further specifically described below by way of examples, comparative examples and drawings.
Example 1
In this example, the sample is a modified AZ80 magnesium alloy, and the specific steps are as follows:
(1) pre-processing: the pre-treatment solution is a water solution of 50g/l of sodium hydroxide and 20g/l of sodium silicate, the pH value is 12, and the pre-treatment solution is soaked for 5min at normal temperature;
(2) roughening treatment: the coarsening solution is a water solution of 10g/l of citric acid, 10g/l of DL-malic acid and 20g/l of sodium fluoride, the pH value is 3, and the solution is soaked for 1min at normal temperature;
(3) homogenizing: the homogenization treatment solution is 20g/l of ammonium bifluoride and 50mg/l of alkylphenol polyoxyethylene, the pH value is 7, and the solution is soaked for 1min at normal temperature;
(4) and (3) conversion treatment: the conversion treatment solution is an aqueous solution of 5g/l of potassium fluorozirconate, 5g/l of fluorozirconate, 8g/l of potassium manganate, 1g/l of tannic acid and 5g/l of gamma-aminopropyltriethoxysilane, the temperature is 26 ℃, the pH value is 2.6, and the solution is soaked for 2 min. The conversion film prepared in this way was pale yellow and had a thickness of about 135nm, as shown in FIG. 1 (a).
Example 2
In this example, the sample is a wrought AZ80 magnesium alloy, and the specific steps are as follows:
(1) pre-processing: the pre-treatment solution is an aqueous solution of 40g/l of sodium hydroxide and 40g/l of sodium silicate, the pH value is 13, and the pre-treatment solution is soaked for 5min at normal temperature;
(2) roughening treatment: the coarsening solution is a water solution of 10g/l of citric acid, 10g/l of DL-malic acid and 30g/l of hexamethylenetetramine, the pH value is 4, and the solution is soaked for 1min at normal temperature;
(3) homogenizing: the homogenization treatment solution is an aqueous solution of 30g/l ammonium bifluoride and 50mg/l alkylphenol polyoxyethylene, the pH value is 6, and the solution is soaked for 1min at normal temperature;
(4) and (3) conversion treatment: the conversion treatment solution is an aqueous solution of 10g/l of potassium fluozirconate, 5g/l of potassium fluotitanate, 8g/l of ammonium molybdate, 1g/l of phytic acid and 1g/l of gamma-aminopropyltriethoxysilane, the temperature is 28 ℃, the pH value is 3.5, and the solution is soaked for 8 min. The conversion film prepared in this way was off-white and had a thickness of about 2.4 μm, as shown in FIG. 1 (b).
Example 3
In this example, the sample is an extruded AZ31B magnesium alloy plate, and the specific steps are as follows:
(1) pre-processing: the pre-treatment solution is an aqueous solution of 40g/l of sodium hydroxide and 40g/l of sodium silicate, the pH value is 11, and the pre-treatment solution is soaked for 5min at normal temperature;
(2) roughening treatment: the coarsening solution is 10g/l of DL-malic acid, 10g/l of lactic acid and 20g/l of sodium fluoride, the pH value is 5, and the solution is soaked for 5min at normal temperature;
(3) homogenizing: the homogenization treatment solution is an aqueous solution of 30g/l ammonium bifluoride and 100mg/l sodium dodecyl sulfate, the pH value is 8, and the solution is soaked for 2min at normal temperature;
(4) and (3) conversion treatment: the conversion treatment solution is an aqueous solution of 5g/l of fluozirconic acid, 5g/l of fluotitanic acid, 5g/l of potassium fluotitanate, 6g/l of potassium permanganate, 1g/l of cerium nitrate, 1g/l of phytic acid and 1g/l of gamma-aminopropyltriethoxysilane, the temperature is 30 ℃, the pH value is 3.0, and the conversion treatment solution is treated for 4min by adopting a spraying mode. The conversion film prepared in this way was pale yellow and had a thickness of about 220 nm.
Example 4
In this example, the sample is an extruded AM60 magnesium alloy, and the specific steps are as follows:
(1) pre-processing: the pre-treatment solution is aqueous solution of 50g/l of sodium hydroxide and 50g/l of sodium carbonate, the pH value is 14, and the pre-treatment solution is soaked for 10min at normal temperature;
(2) roughening treatment: the coarsening solution is a water solution of 10g/l of citric acid, 10g/l of lactic acid and 30g/l of sodium fluoride, the pH value is 2, and the solution is soaked for 5min at normal temperature;
(3) homogenizing: the homogenization treatment solution is 20g/l of ammonium dihydrogen phosphate and 100mg/l of sodium dodecyl sulfate aqueous solution, the pH value is 5, and the solution is soaked for 30s at normal temperature;
(4) and (3) conversion treatment: the conversion treatment solution is an aqueous solution of 5g/l potassium fluozirconate, 5g/l potassium fluotitanate, 5g/l sodium orthovanadate, 1g/l citric acid and 2g/l gamma- (2, 3-epoxypropoxy) propyl trimethoxy silane, the temperature is 25 ℃, the pH value is 4.0, and the treatment is carried out for 3min by adopting a spraying mode. The conversion film prepared in this way was pale yellow and had a thickness of about 160 nm.
Example 5
In this example, the sample is an extruded AZ91 magnesium alloy plate, and the specific steps are as follows:
(1) pre-processing: the pre-treatment solution is aqueous solution of 50g/l of sodium hydroxide and 50g/l of sodium carbonate, the pH value is 12, and the pre-treatment solution is soaked for 10min at normal temperature;
(2) roughening treatment: the coarsening solution is an aqueous solution of 5g/l of citric acid, 10g/l of nitric acid and 20g/l of sodium diethyldithiocarbamate, the pH value is 6, and the solution is soaked for 3min at normal temperature;
(3) homogenizing: the homogenization treatment solution is 20g/l of ammonium dihydrogen phosphate and 50mg/l of alkylphenol polyoxyethylene, the pH value is 9, and the solution is soaked for 30s at normal temperature;
(4) and (3) conversion treatment: the conversion treatment solution is an aqueous solution of 10g/l of potassium fluorozirconate, 5g/l of potassium fluorotitanate, 10g/l of sodium molybdate, 3g/l of calcium nitrate, 2g/l of citric acid and 2g/l of gamma- (2, 3-epoxypropoxy) propyl trimethoxy silane, the temperature is 25 ℃, the pH value is 3.5, and the solution is soaked for 6 min. The conversion film prepared in this way was off-white and had a thickness of about 2.2 μm.
Comparative example 1
In this comparative example, the sample was a wrought AZ80 magnesium alloy, comprising the following specific steps:
(1) the conditions of pretreatment, roughening treatment and homogenization treatment are the same as those of the process 2
(2) And (3) conversion treatment: the homogenized sample was immersed in a manganese phosphate solution described in patent publication No. CN1475602A, and the pH was 3.5, the solution temperature was 50 ℃, and a film was formed for 10min, and the formed phosphate conversion film was light gray and had a thickness of about 4.5 μm.
Comparative example 2
In this comparative example, the sample was a wrought AZ80 magnesium alloy, comprising the following specific steps:
(1) the conditions of pretreatment, roughening treatment and homogenization treatment are the same as those of the process 2
(2) And (3) conversion treatment: the homogenized sample is soaked in phosphate solution described in patent publication No. CN102191493A, pH value is adjusted to 2.85, solution temperature is controlled at 50 deg.C, film forming time is 10min, and the obtained film layer is uniform and compact, surface is light gray, and thickness is about 3.5 μm.
Comparative example 3
In this comparative example, the sample was a wrought AZ80 magnesium alloy, comprising the following specific steps:
(1) the conditions of pretreatment, roughening treatment and homogenization treatment are the same as those of the process 2
(4) And (3) conversion treatment: the homogenized sample is soaked in a general ceramic treatment solution disclosed in patent CN103184446A, the pH value is 4.5, and the sample is soaked for 2min at normal temperature, so that the formed ceramic conversion film is light gray, the thickness of each position of the film layer is not uniform, and the thickness is not uniform within the range of 50 nm-1 μm.
1. State of conversion film
The films prepared according to the examples 1 to 5 and the comparative examples 1 to 2 are uniform and compact, complete in coating, free from ash hanging phenomenon and good in bonding performance with a magnesium substrate. Comparative example 3 conditions the film layer had a high surface roughness and had a floating ash. The thickness of the ceramic conversion film in the embodiments 1-5 is in the range of 135 nm-2.4 μm, and when the thickness of the film layer is more than 2 μm, the surface of the ceramic film presents an obvious micro-crack structure, and the cross-sectional morphology of the film layer in the embodiment 2 is shown in figure 1 (b). In comparative examples 1 to 2, the thickness of the phosphate conversion film was slightly increased to 4.5 μm and 3.5. mu.m, respectively. Comparative example 3 conditions the film thickness was not uniform at each position, most of the positions were about 50 to 120nm, and the individual positions even reached more than 1 μm.
2. Corrosion resistance test
According to GB10124-88 full immersion corrosion test standard, the magnesium alloy conversion film samples prepared by the methods of examples 1-5 and comparative examples 1-3 and the corresponding magnesium matrix samples are completely immersed in 3.5 wt% NaCl solution, and the ratio of the volume of the corrosion medium to the working area of the samples is more than 20ml/cm2And controlling the pH value to be 6.5-7 and the temperature to be 25 +/-1 ℃. And observing the corrosion morphology of the film after 48 hours, wherein more than 10 corrosion points appear on the surface of the blank magnesium matrix, individual corrosion pits are deep, 1-2 corrosion points are dispersedly distributed on the surfaces of the ceramic conversion films in the embodiments 1, 3 and 4, the corrosion morphology of the embodiment 1 is shown in figure 2(a), the ceramic conversion films under the conditions of the embodiments 2 and 5 are not obviously corroded, and the corrosion morphology of the embodiment 2 is shown in figure 2 (b). As shown in fig. 2(c), after the sample of comparative example 1 is soaked for 48 hours, the surface color is changed from light gray to yellow brown, and 2 local corrosion points appear on the test surface; as shown in fig. 2(d), in comparative example 2, the surface color change is not obvious under the same corrosion conditions, but pitting corrosion with radius less than 1mm occurs at 4-5 places; comparative example 3 the sample surface has 7-8 corrosion pits, and the integral appearance is different from the blank matrix corrosion appearanceNot large.
3. Adhesion test after application of organic coating
According to GB/T9286-1998 standards, the conversion films prepared in the processes of the examples 1-5 and the comparative examples 1-3 are treated by the same spraying process, the thickness of the organic coating is controlled to be 80 +/-5 mu m, the paint film is cut at a constant speed of 2mm by using a QFH type single-edge hundred-grid knife until a magnesium substrate is exposed, and the paint film is cut in parallel at an equal number at an angle of 90 degrees to form a grid. Cleaning the surface with a soft brush, adhering the film with a 3M adhesive tape in parallel to the paint film scribe line, tearing the adhesive tape at an angle of approximately 60 degrees within 0.5-1.0 s, and checking the state of the cut part. The paint film adhesion force of the conversion film condition of the comparative examples 1, 2 and 4 is 0 grade, the conversion film condition of the comparative examples 2 is 1 grade, the adhesion force between the conversion film and the paint film meets the use requirement, and the paint film adhesion force of the comparative example 3 is 3 grade, which does not meet the use standard.
The results show that the corrosion resistance of the environment-friendly corrosion-resistant ceramic conversion film of the magnesium alloy is not lower than that of a phosphate conversion film, and the corrosion resistance of the ceramic conversion film is even higher than that of the phosphate conversion film by a ceramic film process with the partial thickness of more than 2 mu m. Moreover, the adhesive force of the organic coating coated on the environment-friendly corrosion-resistant ceramic conversion coating is less than or equal to level 1, the use requirement of a paint film in GB/T9286-plus 1998 standard is met, and the performance is obviously improved compared with a general ceramic treatment process.
In addition, the film forming solution (conversion treatment solution) can realize uniform film formation on the surface of the substrate at normal temperature by adopting a dipping or spraying mode, has the corrosion resistance equivalent to that of the traditional phosphate conversion film, can be directly used or used for coating pretreatment, and has good adhesive force with an organic coating. The process is simple to operate, has low cost, does not discharge polluted ions such as phosphate, chromium, nickel and the like, and is an environment-friendly surface treatment new method suitable for industrial production of magnesium alloy.
Claims (10)
1. The preparation method of the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy is characterized by comprising the following specific steps of:
(1) pre-processing: soaking the magnesium alloy in a pretreatment solution at room temperature for 5-10 min to remove residual grease and dirt on the surface;
(2) roughening treatment: soaking the magnesium alloy subjected to the pre-treatment in a roughening treatment solution for 30 s-30 min at room temperature, removing oxide skin and residual alkali liquor on the surface of the sample, and improving the roughness;
(3) homogenizing: the magnesium alloy after the roughening treatment is soaked in the homogenization treatment solution for 5 s-2 min at normal temperature, the microscopic surface state of the matrix is adjusted, the surface active points are increased, and the uniform deposition of film forming substances in the chemical conversion process is facilitated;
(4) and (3) conversion treatment: the magnesium alloy after homogenization treatment is treated by using a conversion treatment solution in a dipping or spraying mode, and a uniform and compact conversion film is formed within 10 s-10 min of normal temperature operation;
wherein the conversion treatment solution comprises: 2-20 g/l of zirconium titanate and/or zirconium titanate, 2-20 g/l of oxidant, 0.5-10 g/l of inorganic film forming additive and/or organic film forming additive, 0.1-5 g/l of silane coupling agent and the balance of water, wherein the pH value is in the range of 2-5; in the conversion treatment solution, the zirconium titanic acid is one or the compound of fluozirconic acid and fluotitanic acid; the zirconium titanate is one of fluozirconate and fluotitanate or the compound of the fluotitanate; the oxidant is one or more than two of manganese salt, molybdate and vanadate; the inorganic film forming assistant is one or more of cerium salt, stannate and calcium salt; the organic film forming auxiliary agent is one or more of phytic acid, tannic acid and citric acid; the silane coupling agent is one or more than two of gamma-aminopropyl triethoxysilane, gamma- (2, 3-epoxypropoxy) propyl trimethoxysilane and gamma- (methacryloyloxy) propyl trimethoxysilane.
2. The preparation method of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating according to claim 1, wherein in the step (1), the pretreatment solution is one or more of 30-80 g/l hydroxide, 20-60 g/l silicate and 10-50 g/l carbonate compounded alkaline aqueous solution, and the pH value is 11-14.
3. The preparation method of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating according to claim 2, wherein in the pretreatment solution, the hydroxide is selected from one or a combination of sodium hydroxide and potassium hydroxide; the silicate is selected from one or more of sodium silicate, potassium silicate and calcium silicate; the carbonate is selected from one or more of sodium carbonate, potassium carbonate and sodium bicarbonate.
4. The method for preparing an environmentally friendly corrosion resistant ceramic conversion coating of magnesium alloy according to claim 1, wherein in the step (2), the roughening solution comprises: 10-50 g/l of inorganic acid and 5-30 g/l of organic acid or a compound thereof, 10-50 g/l of corrosion inhibitor and the balance of water, wherein the pH value is 2-6.
5. The method for preparing the environment-friendly corrosion-resistant ceramic conversion coating of the magnesium alloy according to claim 4, wherein in the roughening solution, the organic acid is one or more of citric acid, DL-malic acid and lactic acid; the inorganic acid is selected from one or more of nitric acid, sulfuric acid and boric acid; the corrosion inhibitor is selected from one or more of sodium fluoride, hexamethylenetetramine and sodium diethyldithiocarbamate.
6. The method for preparing an environmentally friendly corrosion resistant ceramic conversion coating of magnesium alloy according to claim 1, wherein in the step (3), the homogenizing solution comprises: 10-50 g/l ammonium salt, 5-30 g/l silicate or their combination, and 10-300 mg/l surfactant, the rest is water, pH value is 5-9.
7. The preparation method of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating according to claim 6, wherein in the homogenization treatment solution, the ammonium salt is one or more of ammonium bifluoride, ammonium bicarbonate and ammonium dihydrogen phosphate; the silicate is one of sodium silicate and potassium silicate or the compound thereof; the surfactant is one or more of sodium dodecyl sulfate, tetraethyl ammonium perfluorooctyl sulfonate and alkylphenol polyoxyethylene ether.
8. The method for preparing an environmentally friendly corrosion-resistant ceramic conversion coating of magnesium alloy according to claim 1, wherein each of the pretreatment, roughening, homogenization and conversion is followed by water washing to remove the solution remaining in the previous step; and (3) after the sample is washed, the sample is blown by hot air or treated in a drying furnace at 40-60 ℃ for 10-30 min, the residual free water on the surface is completely removed, and the sample after surface drying is directly used or used for coating pretreatment.
9. The method for preparing the magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating according to claim 1, wherein the thickness of the coating after conversion treatment is controllable within the range of 50 nm-3 μm, and the corrosion resistance is equivalent to that of the traditional phosphate conversion coating.
10. The preparation method of the magnesium alloy environment-friendly corrosion-resistant ceramic conversion coating according to claim 1, wherein the bonding force of the ceramic conversion coating after conversion treatment coated with the organic coating is not more than 1 grade, so that the use requirement is met.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113718240A (en) * | 2021-08-18 | 2021-11-30 | 东风商用车有限公司 | Surface treatment method for magnesium alloy before painting |
| CN114574844A (en) * | 2022-02-23 | 2022-06-03 | 深圳市豪龙新材料技术有限公司 | Magnesium alloy surface composite film conversion treatment agent and application thereof |
| CN114606486A (en) * | 2022-03-11 | 2022-06-10 | 重庆大学 | Magnesium alloy CaCO3Conversion film treating agent and treating method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2123366A1 (en) * | 2008-05-23 | 2009-11-25 | Mattthias Koch | Coated substrate and method for its production |
| CN102851659A (en) * | 2012-09-29 | 2013-01-02 | 西安建筑科技大学 | Magnesium alloy surface phosphorus-free chromium-free conversion coating and application method thereof |
| CN104561970A (en) * | 2014-12-31 | 2015-04-29 | 苏州禾川化学技术服务有限公司 | Corrosion-resistant magnesium aluminum alloy chromium-free passivation solution |
| CN108456884A (en) * | 2017-02-21 | 2018-08-28 | 中国科学院金属研究所 | A kind of pre-treating method of magnesium alloy chromium-free conversion film homogenization |
| CN109913923A (en) * | 2019-04-29 | 2019-06-21 | 东莞市慧泽凌化工科技有限公司 | Surface treatment liquid and method for the surface treatment of magnesium alloy aluminium alloy compound part |
-
2020
- 2020-02-27 CN CN202010121983.XA patent/CN111139463A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2123366A1 (en) * | 2008-05-23 | 2009-11-25 | Mattthias Koch | Coated substrate and method for its production |
| CN102851659A (en) * | 2012-09-29 | 2013-01-02 | 西安建筑科技大学 | Magnesium alloy surface phosphorus-free chromium-free conversion coating and application method thereof |
| CN104561970A (en) * | 2014-12-31 | 2015-04-29 | 苏州禾川化学技术服务有限公司 | Corrosion-resistant magnesium aluminum alloy chromium-free passivation solution |
| CN108456884A (en) * | 2017-02-21 | 2018-08-28 | 中国科学院金属研究所 | A kind of pre-treating method of magnesium alloy chromium-free conversion film homogenization |
| CN109913923A (en) * | 2019-04-29 | 2019-06-21 | 东莞市慧泽凌化工科技有限公司 | Surface treatment liquid and method for the surface treatment of magnesium alloy aluminium alloy compound part |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113718240A (en) * | 2021-08-18 | 2021-11-30 | 东风商用车有限公司 | Surface treatment method for magnesium alloy before painting |
| CN114574844A (en) * | 2022-02-23 | 2022-06-03 | 深圳市豪龙新材料技术有限公司 | Magnesium alloy surface composite film conversion treatment agent and application thereof |
| CN114606486A (en) * | 2022-03-11 | 2022-06-10 | 重庆大学 | Magnesium alloy CaCO3Conversion film treating agent and treating method thereof |
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