Aluminum alloy pre-oxidation treatment liquid and pre-treatment method

Abstract

The application discloses an aluminum alloy pretreatment liquid before oxidation and a pretreatment method. The pretreatment liquid is prepared by mixing fluorine-containing pyridine phosphonic acid corrosion inhibitor, a surfactant, a film forming agent, sodium hydroxide and deionized water; and the fluorine-containing pyridine phosphonic acid corrosion inhibitor has a structure shown in the following formula A. The pretreatment liquid is applied in the oxidation pretreatment of the aluminum alloy. The pretreatment liquid can effectively remove the oil, metal ions and oxide layers on the surface of the aluminum alloy at the same time, improve the surface cleanliness of the aluminum alloy, slow down the corrosion of the alkaline component on the aluminum alloy, and further save the pickling process and reduce the defects of the aluminum alloy. The pretreatment liquid can be widely applied in the field of aluminum alloy surface treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy surface treatment, and particularly relates to an aluminum alloy pre-oxidation treatment solution and a pre-treatment method. BACKGROUND

[0002] Aluminum is one of the six most widely distributed metals in nature, accounting for about 8.0% of the total mass of the earth's crust. It has a small density, a low melting point, and is easy to process into various profiles. However, pure aluminum has very low strength and is not suitable as a structural material. Through long-term production practice and scientific research, people gradually strengthen aluminum by adding alloying elements and using heat treatment, and obtain a series of aluminum alloys. Aluminum alloys have high strength while maintaining the advantages of light weight of pure aluminum, and become an ideal structural material.

[0003] Aluminum alloy is an alloy with aluminum as a base material and a certain amount of other alloying elements, and is one of light metal materials. The specific strength of aluminum alloy is close to that of high alloy steel, and the specific stiffness exceeds that of steel. It has good casting performance and plastic processing performance, good electrical conductivity and thermal conductivity, good corrosion resistance and weldability, and can be used as a structural material. It has a wide range of applications in aerospace, aviation, transportation, construction, machinery, light industry and daily necessities.

[0004] However, as a structural material, aluminum alloy has the disadvantages of soft texture, poor wear resistance, poor corrosion resistance and poor high temperature resistance in special environments. Although aluminum alloy can spontaneously form an Al2O3 film layer on the surface in the air, the thin layer is thin and has many defects, and cannot effectively protect the substrate. Therefore, people have carried out various methods of surface treatment on aluminum alloy profiles to improve their performance. In order to further improve the performance of aluminum alloy, a series of surface oxidation treatment technologies for aluminum alloy have been developed, including anodic oxidation, micro-arc oxidation and electro-thermal chemical oxidation proposed in recent years. After treatment, an oxide film of several microns to several hundred microns can be formed on the surface of the aluminum alloy. Compared with the natural oxide film of the aluminum alloy, the corrosion resistance, wear resistance and decoration of the oxide film are significantly improved.

[0005] The above surface oxidation techniques are all electrochemical oxidation in an electrolyte system, and the aluminum alloy part is used as an anode during treatment, and the surface to be treated is completely immersed in the electrolyte, and an electrochemical oxidation reaction occurs under the action of an external power supply to form an oxide film on the surface to be treated. Therefore, the original state of the surface to be treated of the aluminum alloy part has a direct impact on the treatment effect. For example, the residual oil film in the surface organic processing process, the uneven oxide skin naturally formed, etc., will hinder the contact between the electrolyte and the surface of the aluminum alloy to be treated, and thus lead to poor treatment effect, and cause peeling, spot ablation, uneven roughness, etc. To solve this problem, usually before the surface oxidation treatment, the surface of the aluminum alloy needs to be subjected to certain pretreatment processes, such as sandpaper polishing, alkali washing, acid washing, ultrasonic cleaning, etc. However, the pretreatment liquid and pretreatment process of the aluminum alloy in the prior art have insufficient impurity cleaning ability, cannot meet the cleanliness requirement of the surface of the aluminum alloy, and have insufficient corrosion inhibition ability, which is easy to be corroded during the pretreatment process, affecting the pretreatment effect.

[0006] Therefore, there is an urgent need for an aluminum alloy oxidation pretreatment liquid and a pretreatment method which have excellent cleaning ability, can improve the cleanliness of the surface of the aluminum alloy, and have strong corrosion inhibition ability. SUMMARY

[0007] The purpose of the present application is to provide an aluminum alloy oxidation pretreatment liquid and a pretreatment method which have excellent cleaning ability, can improve the cleanliness of the surface of the aluminum alloy, and have strong corrosion inhibition ability.

[0008] Technical scheme

[0009] An aluminum alloy oxidation pretreatment liquid is prepared by mixing a fluorine-containing pyridine phosphonic acid corrosion inhibitor, a surfactant, a film former, sodium hydroxide and deionized water.

[0010] The fluorine-containing pyridine phosphonic acid corrosion inhibitor has the following structure shown in formula A:

[0011]

[0012] The present application can simultaneously achieve the effects of degreasing and oil removal and alkali corrosion by mixing the fluorine-containing pyridine phosphonic acid corrosion inhibitor, the surfactant, the film former and the sodium hydroxide to prepare the pretreatment liquid, which not only can reduce the process flow of the aluminum alloy pretreatment, reduce the process difficulty and cost, but also can improve the cleaning effect of the oil and the oxidation layer, and thus improve the cleanliness of the aluminum alloy.

[0013] Further, the fluorine-containing pyridine phosphonic acid corrosion inhibitor is prepared by the following steps: adding 3,5-difluoro-2,6-diaminopyridine, phosphorous acid and deionized water in a reactor, adding a catalyst after heating to 100-110℃, adding a formaldehyde solution after refluxing for 2-3 hours, continuing to reflux for 4-6 hours, and then cooling, filtering, washing, and drying to obtain the fluorine-containing pyridine phosphonic acid corrosion inhibitor.

[0014] The present application uses the fluorine-containing pyridine phosphonic acid corrosion inhibitor as the main component of the pretreatment, which can significantly slow down the corrosion of sodium hydroxide to the aluminum alloy during the pretreatment based on the structure of its polyphosphoric acid, so that the aluminum alloy can maintain a smooth surface in an alkaline environment; on the other hand, its fluorine-containing structure can improve the stability of the corrosion inhibitor in an alkaline environment, so that it can be mixed with sodium hydroxide for a long time and remain stable, and the corrosion inhibition effect can be further improved, which can greatly reduce the occurrence of alkali stains, thereby eliminating the subsequent pickling process.

[0015] Further, the catalyst is selected from one of concentrated hydrochloric acid or concentrated sulfuric acid; the mass concentration of the formaldehyde solution is 30-40wt%.

[0016] Further, the mass ratio of the 3,5-difluoro-2,6-diaminopyridine, phosphorous acid and acetaldehyde is (4-6):(6-8):(3-4).

[0017] In the fluorine-containing pyridine phosphonic acid corrosion inhibitor of the present application, the pyridine structure with a large π bond can provide electron-producing coordination, which can not only further improve the corrosion inhibition effect, but also can complex with free metal ions in the tank solution to form a precipitate, thereby avoiding the re-attachment of metal ions to the surface of the aluminum alloy, and further improving the cleaning ability of the pretreatment process.

[0018] Further, the surfactant is selected from one of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, Tween 60 or Tween 80.

[0019] Further, the film-forming agent is selected from one of hydroxypropyl cellulose, hydroxypropyl methyl cellulose or carboxymethyl cellulose.

[0020] Further, the mass percentage of each component is 100% based on the total mass fraction.

[0021]

[0022] The balance is deionized water.

[0023] A pretreatment method comprising the above-mentioned any one aluminum alloy oxidation pretreatment solution, comprising the following steps:

[0024] (1) The surface of the aluminum alloy is blown with compressed air to remove dust;

[0025] (2) The aluminum alloy of step (1) is placed in an aluminum alloy oxidation pretreatment solution, heated to 40-50℃, and treated under ultrasonic conditions for 5-8 minutes;

[0026] (3) The aluminum alloy of step (2) is rinsed clean with deionized water, and the aluminum alloy oxidation pretreatment is completed.

[0027] Further, the power of the ultrasonic in step (2) is 180-220W, and the frequency is 25-35kHz.

[0028] Further, the temperature of the deionized water in step (3) is 50-60℃.

[0029] Beneficial effects:

[0030] (1) The aluminum alloy oxidation pretreatment solution and pretreatment method provided by the present application, by mixing the fluorine-containing pyridine phosphonic acid corrosion inhibitor, the surfactant, the film-forming agent, the sodium hydroxide and the deionized water to prepare the pretreatment solution, and applying it in the oxidation pretreatment of the aluminum alloy, not only can effectively remove the oil, the metal ions and the oxidation layer on the surface of the aluminum alloy, improve the surface cleanliness of the aluminum alloy, but also can slow down the corrosion of the alkaline component on the aluminum alloy, thereby saving the pickling process and reducing the defects of the aluminum alloy, and can be widely applied in the field of aluminum alloy surface treatment.

[0031] (2) The aluminum alloy oxidation pretreatment solution and pretreatment method provided by the present application, by mixing the fluorine-containing pyridine phosphonic acid corrosion inhibitor, the surfactant, the film-forming agent and the sodium hydroxide to prepare the pretreatment solution, can simultaneously achieve the effects of degreasing and alkali corrosion, not only can reduce the process flow of the aluminum alloy pretreatment, reduce the process difficulty and cost, but also can improve the cleaning effect on the oil and the oxidation layer, thereby improving the cleanliness of the aluminum alloy.

[0032] (3) The aluminum alloy oxidation pretreatment solution and pretreatment method provided by the present application, the fluorine-containing pyridine phosphonic acid corrosion inhibitor is used as the main component of the pretreatment, on the one hand, based on the structure of its polyphosphoric acid, the corrosion of sodium hydroxide on the aluminum alloy in the pretreatment process can be significantly slowed down, so that the aluminum alloy can maintain a smooth surface in the alkaline environment; on the other hand, its fluorine-containing structure can improve the stability of the corrosion inhibitor in the alkaline environment, so that it can be mixed with sodium hydroxide for a long time and remain stable, and the corrosion effect can be further improved, the appearance of alkali stains can be greatly reduced, and the subsequent pickling process can be saved.

[0033] (4) The aluminum alloy pre-oxidation treatment liquid and pre-oxidation treatment method provided by the application contain a fluorine-containing pyridine phosphonic acid corrosion inhibitor, the pyridine structure containing a large π bond can provide coordination effect of electron generation, can further improve the corrosion inhibition effect, and can complex with free metal ions in the tank solution to form a precipitate, so that the metal ions are prevented from adhering to the surface of the aluminum alloy again, and the cleaning capacity of the pre-treatment process is improved. DETAILED DESCRIPTION

[0034] The application will be described in detail below with reference to specific embodiments. It should be noted that the following examples are examples of the application and are only used to illustrate the application, but not to limit the application. Other combinations and various modifications within the concept of the application can be made without departing from the spirit or scope of the application.

[0035] The reagents and equipment in the application are conventional reagents and equipment in the technical field.

[0036] Preparation of the fluorine-containing pyridine phosphonic acid corrosion inhibitor

[0037] The fluorine-containing pyridine phosphonic acid corrosion inhibitor is prepared by the following steps:

[0038] In a reactor equipped with a reflux condenser and a thermometer, 5 g of 3,5-difluoro-2,6-diaminopyridine, 8 g of phosphorous acid and 100 mL of deionized water are added, the temperature is raised to 110°C, 0.3 g of 35 wt% concentrated hydrochloric acid solution is added, reflux reaction is carried out for 3 hours, then 10 g of 30 wt% mass concentration formaldehyde solution is added, reflux reaction is continued for 6 hours, and then the product is obtained after cooling, filtration, washing and drying.

[0039] Mass spectrum data of the fluorine-containing pyridine phosphonic acid corrosion inhibitor: the product is analyzed by LC-MS, and the m / z of the product is 333.01 (100.0%) and 334.13 (10.0%).

[0040] Preparation of the aluminum alloy pre-oxidation treatment liquid-1

[0041] The fluorine-containing pyridine phosphonic acid corrosion inhibitor, sodium dodecyl sulfonate, hydroxypropyl cellulose, sodium hydroxide and deionized water are mixed to prepare the aluminum alloy pre-oxidation treatment liquid-1.

[0042] The mass percentage of each component is 100% based on the total mass fraction.

[0043] Fluorine-containing pyridine phosphonic acid corrosion inhibitor 15%

[0044] Sodium dodecyl sulfonate 3%

[0045] Hydroxypropyl cellulose 2%

[0046] Sodium hydroxide 25%

[0047] The remainder is deionized water.

[0048] Preparation of Aluminum Alloy Oxidation Pretreatment Solution-2

[0049] The preparation method is basically the same as that of aluminum alloy oxidation pretreatment solution-1, except that the fluorinated pyridine phosphonic acid corrosion inhibitor is replaced with an equal amount of deionized water.

[0050] Preparation of Aluminum Alloy Oxidation Pretreatment Solution-3

[0051] The preparation method is basically the same as that of aluminum alloy oxidation pretreatment solution-1, except that the fluorinated pyridine phosphonic acid corrosion inhibitor is replaced with an equal amount of diethylenetriamine pentamethylphosphonic acid.

[0052] Example 1

[0053] LY12 aluminum alloy profiles were cut into uniformly sized test pieces (100mm×100mm×2.0mm). The surfaces of the test pieces were cleaned with acetone and rinsed with water. They were then dried at 105℃ to constant weight to obtain clean test pieces, and their weight was recorded as m0. A layer of grease (lubricating oil, rust-preventive oil, and mineral oil in a mass ratio of 1:1:1) was evenly applied to the surface of the clean test pieces and dried at 105℃ to constant weight. The grease-coated test pieces were then placed in an open-air environment at room temperature for 30 days. The grease on the surface absorbed dust and formed oil stains, resulting in simulated test pieces, the weight of which was recorded as m1.

[0054] The simulated test piece was subjected to oxidation pretreatment using the following steps:

[0055] (1) Use compressed air to blow away dust from the aluminum alloy surface;

[0056] (2) Place the aluminum alloy from step (1) in aluminum alloy oxidation pretreatment solution-1, heat it to 50°C, and treat it for 8 minutes under ultrasonic conditions with a power of 220W and a frequency of 30kHz.

[0057] (3) Rinse the aluminum alloy from step (2) with deionized water at 60°C to complete the pre-oxidation treatment of the aluminum alloy. Weigh the treated sample and record it as m2.

[0058] Example 2

[0059] The process is basically the same as in Example 1, except that in step (2), the temperature is 45°C, the ultrasonic power is 200W, and the frequency is 35kHz.

[0060] Example 3

[0061] The process is basically the same as in Example 1, except that in step (2), the temperature is 40°C, the ultrasonic power is 180W, and the frequency is 25kHz.

[0062] Comparative Example 1

[0063] The same as example 1, except that the aluminum alloy pre-oxidation treatment liquid-1 is replaced by an equal amount of aluminum alloy pre-oxidation treatment liquid-2.

[0064] Comparative example 2

[0065] The same as example 1, except that the aluminum alloy pre-oxidation treatment liquid-1 is replaced by an equal amount of aluminum alloy pre-oxidation treatment liquid-3.

[0066] Performance test

[0067] Cleaning capacity detection: the values of m0, m1 and m2 in examples 1-3 and comparative examples 1-2 are recorded respectively, and the oil removal rate is calculated, oil removal rate = (m1-m2) / (m1-m0), and the detection results are as follows:

[0068] m0(g) m1(g) m2(g) Oil removal rate (%) Example 1 55.927 56.505 55.929 99.65 Example 2 55.897 56.488 55.899 99.66 Example 3 55.905 56.536 55.907 99.68 Comparative Example 1 55.904 56.524 56.052 71.13 Comparative Example 2 55.913 56.493 55.982 88.10

[0069] According to the detection results of examples 1-3, the aluminum alloy pre-oxidation treatment liquid and the pre-treatment method provided by the application can effectively remove the oil on the surface of the aluminum alloy, improve the surface cleanliness of the aluminum alloy, and can be widely applied in the field of aluminum alloy surface treatment.

[0070] According to the comparison of the detection results of examples 1-3 and comparative examples 1-2, in the aluminum alloy pre-oxidation treatment liquid and the pre-treatment method provided by the application, by adding a fluorine-containing pyridine phosphonic acid corrosion inhibitor in the pre-treatment, the cleaning capacity can be significantly improved, and the surface cleanliness of the aluminum alloy can be improved.

[0071] Corrosion inhibition detection: the clean test pieces in examples 1-3 and comparative examples 1-2 are not oiled, and the clean test pieces are directly subjected to pre-oxidation treatment, the treated test pieces are weighed, recorded as m3, and the corrosion weight loss rate is calculated, corrosion weight loss rate = (m0-m3) / m0, and the detection results are as follows:

[0072]

[0073]

[0074] According to the detection results of examples 1-3, the aluminum alloy pre-oxidation treatment liquid and the pre-treatment method provided by the application can effectively slow down the corrosion phenomenon of the aluminum alloy in the alkaline environment, and improve the stability and treatment effect of the pre-treatment process.

[0075] According to the comparison of the detection results of examples 1-3 and comparative examples 1-2, in the aluminum alloy pre-oxidation treatment liquid and the pre-treatment method provided by the application, by adding a fluorine-containing pyridine phosphonic acid corrosion inhibitor in the pre-treatment, the corrosion inhibitor has more excellent corrosion inhibition effect than the corrosion inhibitor in the prior art.

[0076] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. An aluminum alloy pre-oxidation treatment solution, characterized by, The fluorine-containing pyridine phosphonic acid corrosion inhibitor is prepared by mixing a fluorine-containing pyridine phosphonic acid corrosion inhibitor, a surfactant, a film forming agent, sodium hydroxide and deionized water. The fluorine-containing pyridine phosphonic acid corrosion inhibitor has the following structure shown in formula A: 。 2. The aluminum alloy pre-oxidation treatment solution of claim 1, wherein The fluorine-containing pyridine phosphonic acid corrosion inhibitor is prepared by the following steps: in a reactor, 3,5-difluoro-2,6-diaminopyridine, phosphorous acid and deionized water are added, a catalyst is added after being heated to 100-110℃, and then refluxed for 2-3 hours, a formaldehyde solution is added, and then refluxed for 4-6 hours, and then cooled, filtered, washed, dried to obtain the fluorine-containing pyridine phosphonic acid corrosion inhibitor.

3. The aluminum alloy pretreatment liquid oxidation solution of claim 2, wherein The catalyst is selected from one of concentrated hydrochloric acid or concentrated sulfuric acid; the mass concentration of the formaldehyde solution is 30-40wt%.

4. The aluminum alloy pretreatment liquid oxidation solution of claim 2, wherein The mass ratio of the 3,5-difluoro-2,6-diaminopyridine, phosphorous acid and formaldehyde is (4-6):(6-8):(3-4).

5. The aluminum alloy pretreatment liquid oxidation solution of claim 1, wherein The surfactant is selected from one of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, Tween 60 or Tween 80.

6. The aluminum alloy pretreatment liquid oxidation solution of claim 1, wherein The film forming agent is selected from one of hydroxypropyl cellulose, hydroxypropyl methyl cellulose or carboxymethyl cellulose.

7. The aluminum alloy pretreatment liquid oxidation solution of claim 1, wherein The mass percentage of each component is as follows, based on a total mass fraction of 100%: Fluorine-containing pyridine phosphonic acid corrosion inhibitor 12-15% Surfactant 3-5% Film forming agent 1-3% Sodium hydroxide 25-30% The balance is deionized water.

8. A pretreatment method comprising the pretreatment solution for aluminum alloy before oxidation according to any one of claims 1 to 7, characterized by, The method comprises the following steps: (1) The surface of the aluminum alloy is blown with compressed air to remove dust; (2) The aluminum alloy of step (1) is placed in an aluminum alloy oxidation pretreatment solution, heated to 40-50℃, and treated under ultrasonic conditions for 5-8 minutes; (3) The aluminum alloy of step (2) is rinsed with deionized water to complete the aluminum alloy oxidation pretreatment.

9. The pre-treatment method according to claim 8, characterized in that, The power of the ultrasonic in step (2) is 180-220W, and the frequency is 25-35kHz.

10. The pre-treatment method according to claim 8, characterized in that, The temperature of the deionized water in step (3) is 50-60℃.

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