A kind of room temperature pickling brightening liquid for aviation aluminum tube

Abstract

The invention discloses a room temperature pickling brightening liquid for aviation aluminum tubes, comprising the following raw materials in parts by weight: the following components in weight percentage: 2-3% citric acid, 0.5-1% aminosulfonic acid, 0.1-0.2% cerium nitrate, 0.2-0.5% corrosion inhibitor, 0.1-0.3% brightener, 0.03-0.05% surfactant, 0.1-0.2% quaternary ammonium salt modified nano aluminum oxide, and the balance is water. The pickling brightening liquid of the invention is used to pickle the aviation aluminum tube, and the treated aluminum tube has the advantages of good corrosion resistance, uniform gloss, and good appearance effect, and can be pickled at room temperature, with high environmental protection and safety.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, in particular to a room-temperature pickling brightening liquid for aviation aluminum tubes. Background Art

[0002] With the development of the aerospace industry, the metal materials used in it have become a focus of attention. Due to weight restrictions and high requirements for mechanical properties, high-strength and lightweight metal materials are usually required in the aviation field, and aluminum alloys have been widely used in aviation parts because they have both. Aviation aluminum tubes are made of aluminum alloys through extrusion into metal tubular parts that are hollow along their entire longitudinal length. They can be used for exhaust and other purposes and are a type of aviation aluminum alloy parts with a large demand. Because the environment is often harsh under aviation conditions, it is easy to accelerate the corrosion of aluminum tubes. In order to ensure the safety of aviation aluminum tubes, improve the service life of aluminum tubes, reduce the replacement of aluminum tubes, and reduce costs, it is usually necessary to perform certain surface treatments on them before installation, such as pickling and passivation treatment, so as to improve the corrosion resistance of aluminum tubes. However, during the treatment process, the pickling and passivation liquid is prone to excessive corrosion, which makes the gloss of the processed aluminum tube worse or even black, and the appearance effect is significantly worse. Therefore, in order to obtain aviation aluminum tubes with good gloss, strong corrosion resistance, and good appearance, it is necessary to further explore and improve its pickling and passivation process. Summary of the invention

[0003] The purpose of the present invention is to remedy the defects of the prior art and provide a room temperature pickling brightening liquid for aviation aluminum tubes.

[0004] The present invention is achieved through the following technical solutions:

[0005] A room temperature pickling brightening liquid for aviation aluminum tubes comprises the following components in percentage by weight: 2-3% of citric acid, 0.5-1% of aminosulfonic acid, 0.1-0.2% of cerium nitrate, 0.2-0.5% of corrosion inhibitor, 0.1-0.3% of brightening agent, 0.03-0.05% of surfactant, 0.1-0.2% of quaternary ammonium salt modified nano aluminum oxide, and the balance is water.

[0006] Preferably, the preparation method of the quaternary ammonium salt modified nano alumina is:

[0007] (1) adding nano-alumina to a mixed solvent and dispersing the nano-alumina uniformly, then adding vinyltriethoxysilane, heating and stirring to react, and then centrifuging, washing, and drying to obtain vinyltriethoxysilane-modified nano-alumina;

[0008] (2) adding the vinyl triethoxysilane modified nano-alumina and acryloyloxyethyl trimethyl ammonium chloride into water and uniformly dispersing them by ultrasonication, then adding an initiator, heating and stirring the mixture under an inert atmosphere for reaction, and centrifuging, washing and drying to obtain quaternary ammonium salt modified nano-alumina.

[0009] Preferably, in step (1), the temperature of the heating and stirring reaction is 60-80°C and the time is 30-40h.

[0010] Preferably, in step (1), the weight ratio of nano-alumina to vinyltriethoxysilane is 1:(0.1-0.2).

[0011] Preferably, in step (1), the ratio of nano-alumina to the mixed solvent is 1 g: (20-30) mL, and the mixed solvent is composed of anhydrous ethanol, ammonia water and water in a volume ratio of (3-4): (1-3): 50.

[0012] Preferably, in step (2), the temperature of the heating and stirring reaction is 60-80° C. and the time is 5-10 h.

[0013] Preferably, in step (2), the weight ratio of the vinyl triethoxysilane modified nano alumina to acryloxyethyl trimethyl ammonium chloride is 1:(0.2-0.5), the weight ratio of the vinyl triethoxysilane modified nano alumina to the initiator is 1:(0.1-0.2), the ratio of the vinyl triethoxysilane modified nano alumina to water is (0.5-1) g:100 mL, and the initiator is a mixture of one or more of ammonium persulfate and potassium persulfate.

[0014] Preferably, the corrosion inhibitor is a mixture of one or more of urotropine, benzotriazole, and propargyl alcohol; the brightener is butynediol; and the surfactant is a mixture of one or more of dodecylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

[0015] A pickling method for an aviation aluminum tube comprises soaking the aviation aluminum tube in the pickling brightening liquid at 20-30° C. for 20-60 minutes.

[0016] The advantages of the present invention are:

[0017] The invention first grafts vinyl triethoxysilane onto nano alumina to obtain vinyl triethoxysilane modified nano alumina, thereby obtaining a nano alumina material containing vinyl on the surface; then the nano alumina material and acryloyloxyethyl trimethyl ammonium chloride are co-dispersed in an aqueous phase; under the action of an initiator, acryloyloxyethyl trimethyl ammonium chloride is grafted onto the surface of the nano alumina, thereby introducing a dendritic ammonium chloride group on the surface of the nano alumina, thereby obtaining a quaternary ammonium salt modified nano alumina; and the nano alumina is added as an additive into a formula of a pickling solution, and is compounded with a proper amount of a mixed acid of citric acid and aminosulfonic acid, a cerium nitrate passivator, a corrosion inhibitor, a brightener and a surfactant to obtain a pickling brightening solution for aluminum alloys. Since the ammonium chloride groups on the surface of nano-alumina contain nitrogen atoms, they can be better adsorbed on the surface of the substrate, and the dendritic polymer long chains can improve the dispersion uniformity of nano-alumina, thereby promoting the effect of nano-alumina to enhance the passivation film, which is conducive to the rapid formation of a passivation film with good density and uniformity, and alleviates the unevenness of the passivation film caused by the excessively fast corrosion rate and the formation of silica fume on the surface of the aluminum alloy, and can retain a good appearance effect, and has a good corrosion protection effect. Therefore, the pickling brightening liquid of the present invention is used to pickle the aviation aluminum tube, and the treated aluminum tube has the advantages of good corrosion resistance, uniform gloss, and good appearance effect, and can be pickled at room temperature, with high environmental safety. DETAILED DESCRIPTION

[0018] Example 1

[0019] A room temperature pickling brightening liquid for aviation aluminum tubes comprises the following components in percentage by weight: 2% citric acid, 1% aminosulfonic acid, 0.1% cerium nitrate, 0.2% urotropine, 0.1% butynediol, 0.03% dodecylphenol polyoxyethylene ether, 0.1% quaternary ammonium salt modified nano aluminum oxide, and the balance is water.

[0020] The preparation method of quaternary ammonium salt modified nano alumina is:

[0021] (1) adding nano-alumina to a mixed solvent and dispersing the mixture uniformly, then adding vinyl triethoxysilane and heating and stirring the mixture at 60°C for 30 hours, centrifuging, washing, and drying to obtain vinyl triethoxysilane-modified nano-alumina, wherein the weight ratio of nano-alumina to vinyl triethoxysilane is 1:0.1, the ratio of nano-alumina to the mixed solvent is 1 g:20 mL, and the mixed solvent is composed of anhydrous ethanol, ammonia water, and water in a volume ratio of 3:1:50;

[0022] (2) The vinyl triethoxysilane modified nano alumina and acryloxyethyl trimethyl ammonium chloride are added to water for ultrasonic dispersion, and then ammonium persulfate is added. The mixture is heated and stirred at 60° C. under an inert atmosphere for reaction for 5 hours. After centrifugation, washing, and drying, quaternary ammonium salt modified nano alumina is obtained, wherein the weight ratio of the vinyl triethoxysilane modified nano alumina to acryloxyethyl trimethyl ammonium chloride is 1:0.2, the weight ratio of the vinyl triethoxysilane modified nano alumina to ammonium persulfate is 1:0.1, and the ratio of the vinyl triethoxysilane modified nano alumina to water is 0.5 g:100 mL.

[0023] Example 2

[0024] A room temperature pickling brightening liquid for aviation aluminum tubes comprises the following components in percentage by weight: 3% citric acid, 0.5% aminosulfonic acid, 0.2% cerium nitrate, 0.5% urotropine, 0.3% butynediol, 0.05% dodecylphenol polyoxyethylene ether, 0.2% quaternary ammonium salt modified nano aluminum oxide, and the balance is water.

[0025] The preparation method of quaternary ammonium salt modified nano alumina is:

[0026] (1) adding nano-alumina to a mixed solvent and dispersing the mixture uniformly, then adding vinyl triethoxysilane and heating and stirring the mixture at 80°C for 40 hours, centrifuging, washing, and drying to obtain vinyl triethoxysilane-modified nano-alumina, wherein the weight ratio of nano-alumina to vinyl triethoxysilane is 1:0.2, the ratio of nano-alumina to the mixed solvent is 1 g:30 mL, and the mixed solvent is composed of anhydrous ethanol, ammonia water, and water in a volume ratio of 4:3:50;

[0027] (2) The vinyl triethoxysilane modified nano alumina and acryloxyethyl trimethyl ammonium chloride are added to water for ultrasonic dispersion, and then ammonium persulfate is added. The mixture is heated and stirred at 80° C. under an inert atmosphere for reaction for 10 hours. After centrifugation, washing, and drying, quaternary ammonium salt modified nano alumina is obtained, wherein the weight ratio of the vinyl triethoxysilane modified nano alumina to acryloxyethyl trimethyl ammonium chloride is 1:0.5, the weight ratio of the vinyl triethoxysilane modified nano alumina to ammonium persulfate is 1:0.2, and the ratio of the vinyl triethoxysilane modified nano alumina to water is 1 g:100 mL.

[0028] Example 3

[0029] A room temperature pickling brightening liquid for aviation aluminum tubes comprises the following components in percentage by weight: 2.5% of citric acid, 0.8% of aminosulfonic acid, 0.15% of cerium nitrate, 0.3% of urotropine, 0.2% of butynediol, 0.04% of dodecylphenol polyoxyethylene ether, 0.15% of quaternary ammonium salt modified nano aluminum oxide, and the balance is water.

[0030] The preparation method of quaternary ammonium salt modified nano alumina is:

[0031] (1) adding nano-alumina to a mixed solvent and dispersing the mixture uniformly, then adding vinyl triethoxysilane and heating and stirring the mixture at 70°C for 35 hours, centrifuging, washing, and drying to obtain vinyl triethoxysilane-modified nano-alumina, wherein the weight ratio of nano-alumina to vinyl triethoxysilane is 1:0.15, the ratio of nano-alumina to the mixed solvent is 1 g:25 mL, and the mixed solvent is composed of anhydrous ethanol, ammonia water, and water in a volume ratio of 3.5:1.5:50;

[0032] (2) The vinyl triethoxysilane modified nano alumina and acryloxyethyl trimethyl ammonium chloride are added to water for ultrasonic dispersion, and then ammonium persulfate is added. The mixture is heated and stirred at 75° C. for reaction for 8 h under an inert atmosphere. After centrifugation, washing, and drying, quaternary ammonium salt modified nano alumina is obtained, wherein the weight ratio of the vinyl triethoxysilane modified nano alumina to acryloxyethyl trimethyl ammonium chloride is 1:0.3, the weight ratio of the vinyl triethoxysilane modified nano alumina to ammonium persulfate is 1:0.15, and the ratio of the vinyl triethoxysilane modified nano alumina to water is 0.6 g:100 mL.

[0033] Comparative Example 1

[0034] The difference between Comparative Example 1 and Example 3 is that nano-alumina is used instead of quaternary ammonium salt-modified nano-alumina, as follows:

[0035] A room temperature pickling brightening liquid for aviation aluminum tubes comprises the following components in percentage by weight: 2.5% of citric acid, 0.8% of aminosulfonic acid, 0.15% of cerium nitrate, 0.3% of urotropine, 0.2% of butynediol, 0.04% of dodecylphenol polyoxyethylene ether, 0.15% of nano aluminum oxide, and the balance is water.

[0036] Test example

[0037] The pickling brightening liquid prepared in Examples 1-3 and Comparative Example 1 was used to soak and pickle the aluminum samples for aviation aluminum tubes made of 7075. The specific treatment method is as follows: the aluminum samples for aviation aluminum tubes are soaked in the pickling brightening liquid at 25°C for 30 minutes, then taken out, cleaned and dried.

[0038] The samples after pickling were observed and tested for corrosion resistance, wherein the corrosion resistance test was a neutral salt spray test, specifically referring to GB 6458-1986. The results are shown in Table 1.

[0039] Table 1

[0040]

[0041] It can be seen that after the pickling brightening liquid of the present invention is used to pickle the aluminum material, a uniform, dense and glossy passivation film can be formed on the surface of the aluminum material, which can retain a good appearance effect and has a good corrosion resistance and protection effect; in Comparative Example 1, due to the excessively fast pickling corrosion rate of the substrate, the corrosion reaction is unstable, and a uniform passivation layer cannot be formed in time, and black silicon ash is formed on the surface of the aluminum material, making the surface of the aluminum material after pickling black, forming a dark gray and uneven surface morphology, not only the appearance effect and corrosion resistance are not good, but also due to the poor uniformity and bonding strength of the film layer on the surface of the aluminum material, it is not conducive to subsequent coating and other treatments.

Claims

1. A room temperature pickling brightening liquid for aviation aluminum tubes, characterized in that: The invention comprises the following components in weight percentage: 2-3% citric acid, 0.5-1% aminosulfonic acid, 0.1-0.2% cerium nitrate, 0.2-0.5% corrosion inhibitor, 0.1-0.3% brightener, 0.03-0.05% surfactant, 0.1-0.2% quaternary ammonium salt modified nano alumina, and the balance is water; The preparation method of the quaternary ammonium salt modified nano alumina is: (1) adding nano-alumina into a mixed solvent and dispersing the mixture uniformly, then adding vinyltriethoxysilane, heating and stirring the mixture for reaction, and then centrifuging, washing and drying the mixture to obtain vinyltriethoxysilane-modified nano-alumina; (2) Add the vinyl triethoxysilane modified nano-alumina and acryloyloxyethyl trimethyl ammonium chloride into water and disperse them uniformly by ultrasonication, then add an initiator, heat and stir to react under an inert atmosphere, and centrifuge, wash and dry to obtain quaternary ammonium salt modified nano-alumina.

2. The room temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: In step (1), the temperature of the heating and stirring reaction is 60-80°C and the time is 30-40 hours.

3. The room temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: In step (1), the weight ratio of nano-alumina to vinyltriethoxysilane is 1:(0.1-0.2).

4. The room temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: In step (1), the ratio of nano-alumina to mixed solvent is 1 g: (20-30) mL, and the mixed solvent is composed of anhydrous ethanol, ammonia water and water in a volume ratio of (3-4): (1-3):

50.

5. The normal temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: In step (2), the temperature of the heating and stirring reaction is 60-80°C and the time is 5-10 hours.

6. The normal temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: In step (2), the weight ratio of the vinyl triethoxysilane modified nano alumina to acryloxyethyl trimethyl ammonium chloride is 1: (0.2-0.5), the weight ratio of the vinyl triethoxysilane modified nano alumina to the initiator is 1: (0.1-0.2), the ratio of the vinyl triethoxysilane modified nano alumina to water is (0.5-1) g: 100 mL, and the initiator is a mixture of one or more of ammonium persulfate and potassium persulfate.

7. The room temperature pickling brightening liquid for aviation aluminum tubes according to claim 1, characterized in that: The corrosion inhibitor is a mixture of one or more of urotropine, benzotriazole, and propargyl alcohol; the brightener is butynediol; and the surfactant is a mixture of one or more of dodecylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

8. A pickling method for aviation aluminum tubes, characterized in that: The aviation aluminum tube is immersed in the pickling brightening solution described in any one of claims 1 to 7 at 20 to 30° C. for 20 to 60 minutes.

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