Aluminum alloy welding cleaning agent and preparation method and application thereof

Abstract

The invention relates to the technical field of welding cleaning agents, in particular to an aluminum alloy welding cleaning agent and a preparation method and application thereof. The aluminum alloy welding cleaning agent comprises the following raw materials in parts by mass: 10-20 parts of organic acid, 1-3 parts of modified silicon dioxide, 0.1-0.5 part of a chelating agent, 1-2 parts of an acidic dispersant, 2-5 parts of a corrosion inhibitor, 1.1-3 parts of a penetrant, 5-10 parts of a defoaming agent and 60-100 parts of water. The cleaning agent is reasonable and scientific in formula, simple to prepare, free of special equipment, high in cleaning capacity, capable of achieving an excellent cleaning effect at low temperature, short in time, good in working efficiency and extremely high in cleaning efficiency on oil stains on metal surfaces, especially aluminum alloy surfaces, and the corrosivity is obviously reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of welding cleaning agents, and particularly to an aluminum alloy welding cleaning agent, a preparation method thereof, and an application thereof. Background Art

[0002] The air-conditioning pipeline of a new energy electric vehicle mainly plays the role of conducting and transporting refrigerant and charging refrigerant in the vehicle's refrigeration system, connects relevant functional components such as a compressor, a condenser, an expansion valve, and an evaporator in the system, and monitors and provides real-time feedback on parameters such as temperature and pressure of components at different positions in the system by using sensors, valves, etc.

[0003] The material of the air-conditioning pipeline in an electric vehicle refrigeration system is mainly aluminum alloy. Aluminum alloy is one of the most widely used non-ferrous metal materials in industry. After being processed by stretching, rolling, stamping, welding, etc., some lubricating oil stains are often left on its surface, and flux or / and oxide layer remains.

[0004] After aluminum alloy is welded, it is necessary to remove the dirt on the workpiece surface and at the same time keep it having good corrosion resistance. Traditional degreasing methods include high-temperature alkali chemical degreasing method and organic solvent degreasing method. The high-temperature alkali chemical degreasing method has advantages such as good degreasing effect and low cost, but it corrodes the aluminum alloy surface more seriously; while the organic solvent degreasing method has good degreasing effect, but there are problems such as environmental pollution caused by the volatilization of organic solvents and high cost, and the corrosion resistance of the aluminum alloy after cleaning is poor.

[0005] At present, a water-based surface cleaning agent is used to clean the oil stains on the workpiece surface, which can quickly remove dirt and welding residues such as oil stains, dust, hand sweat, organic substances, and inorganic salts on the aluminum alloy surface. However, due to the strong adsorption and relatively active chemical properties of aluminum alloy, a large amount of residue remains after using an ordinary water-based surface cleaning agent, and the cleaning effect cannot be achieved. At the same time, due to mostly using high-temperature cleaning, the cleaning effect is poor at normal temperature and even low temperature. Summary of the Invention

[0006] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to propose an aluminum alloy welding cleaning agent, a preparation method thereof, and an application thereof.

[0007] An aluminum alloy welding cleaning agent, the raw materials of which by mass include: 10 - 20 parts of organic acid, 1 - 3 parts of modified silica, 0.1 - 0.5 part of chelating agent, 1 - 2 parts of acidic dispersant, 2 - 5 parts of corrosion inhibitor, 1.1 - 3 parts of penetrant, 5 - 10 parts of defoamer, and 60 - 100 parts of water.

[0008] Preferably, the organic acid is methanesulfonic acid or / and citric acid.

[0009] Preferably, the chelating agent includes at least one of maleic acid - acrylic acid copolymer, gluconic acid, ethylenediaminetetraacetic acid, diisopropyltriaminepentaacetic acid, N,N - bis(2 - hydroxyethyl)ethylenediaminetriacetic acid, and polyaspartic acid.

[0010] Preferably, the acidic dispersant is octyl isomeric carboxylate or methyl hydroxyethyl decyl isomeric carboxylate.

[0011] The octyl isomeric carboxylate is preferably sodium isooctylate or potassium isooctylate.

[0012] Preferably, the corrosion inhibitor includes ammonium fluoroborate and isomeric polycarboxylic acid alkanolamine; the mass ratio of ammonium fluoroborate to isomeric polycarboxylic acid alkanolamine is 4 - 6:2 - 4.

[0013] The isomeric polycarboxylic acid alkanolamine is formed by the combination of polycarboxylic acid and organic amine, and does not contain elements such as boron, chlorine, sulfur, and phosphorus.

[0014] Preferably, the penetrant includes modified isomeric alcohol ether quaternary ammonium salt and triethylene glycol monobutyl ether; the mass ratio of modified isomeric alcohol ether quaternary ammonium salt to triethylene glycol monobutyl ether is 1 - 2:0.1 - 1.

[0015] Preferably, the defoamer is an acetylene glycol - modified surfactant, which has the effects of low static and dynamic surface tensions, improving wetting performance and promoting flow and leveling. It can inhibit the foam height in the ultrasonic cleaning process, and it can be Evonik SURFYNOL 485, RianPont 2704, or Superwet - 320.

[0016] Preferably, the modified silica is prepared by the following specific operations: adding mesoporous silica and cerium nitrate to an ethanol - aqueous solution, ultrasonic - treating for 10 - 20 min, adjusting the pH value of the system to 9 - 10, continuing ultrasonic - treating for 1 - 2 h, adjusting the pH value of the system > 8.5, adding dopamine and continuing ultrasonic - treating for 1 - 3 h, centrifuging, washing with water, vacuum - drying, and pulverizing.

[0017] More preferably, the mass ratio of mesoporous silica, cerium nitrate, and dopamine is 5 - 15:1 - 4:1 - 3.

[0018] More preferably, the ultrasonic frequency is 20 - 30 kHz.

[0019] More preferably, the temperature of the ultrasonic treatment after adjusting the pH value of the system to 9 - 10 is 60 - 80 °C.

[0020] The preparation method of the above - mentioned aluminum alloy welding cleaning agent includes the following steps: S1. Add the organic acid and the acidic dispersant to water, stir for 10 - 30 min, the stirring temperature is 60 - 70 °C, heat up to 75 - 80 °C and stir for 1 - 2 h to obtain a premix; S2. Add modified silica, chelating agent, penetrant, corrosion inhibitor to the premix and stir evenly. Then add defoamer and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain an aluminum alloy welding cleaning agent.

[0021] The usage method of the above aluminum alloy welding cleaning agent is to ultrasonically clean the welded aluminum alloy workpiece with the above aluminum alloy welding cleaning agent at an ultrasonic cleaning temperature of 20 - 50°C; then wash with water. After water washing, the aluminum alloy workpiece is subjected to assembly welding.

[0022] Beneficial effects: The formula of the present invention is reasonable and scientific, simple to prepare, without special equipment. At the same time, it has strong cleaning ability, can achieve excellent cleaning effect even at low temperature, has short cleaning time, good working efficiency, has extremely high cleaning efficiency for oil stains on the metal surface, especially the aluminum alloy surface, and significantly reduces the corrosion.

[0023] The present invention uses the compound of mesoporous silica and cerium nitrate to deposit cerium hydroxide on the surface of mesoporous silica in an alkaline environment, and further cooperates with the action of polydopamine. The combination of the two has extremely high stability, and the obtained modified silica has extremely high hydrophilic activity, which can significantly enhance the dispersion stability of silica in the cleaning agent.

[0024] The modified silica used in the present invention has high hydrophilicity and biocompatibility, and cooperates with organic acids that will not erode the aluminum alloy itself, which can effectively remove the metal oxides generated after welding. During the ultrasonic process, with the cooperation of modified silica, even at low temperature, the removal rate of impurities on the aluminum alloy surface is high, and the aluminum alloy surface has better gloss after cleaning.

[0025] The defoamer used in the present invention has low static and dynamic surface tensions, good wetting performance. When compounded with modified silica, it can promote fluidity and leveling, enabling the organic acids in the cleaning agent to better contact and react with the aluminum alloy surface oxides. With the cooperation of rare earth, a rare earth oxide film is formed on the aluminum alloy surface, effectively preventing the surface reaction of the aluminum alloy, having excellent corrosion resistance effect, and can significantly inhibit the foam height in the ultrasonic cleaning process.

[0026] The cleaning agent system of the present invention is weakly acidic, safe and environmentally friendly, and has excellent penetration ability, good solubilization performance, excellent water washability. The cleaning efficiency for aluminum alloy materials is greatly improved, it can effectively remove the oil stains and oxide films on the surface of aluminum alloy workpieces, and the aluminum alloy surface is clean, which is very suitable for the production enterprises of air-conditioning pipelines in electric vehicle refrigeration systems. Description of the drawings

[0027] Figure 1 It is a comparison chart of the wetting force and defoaming performance of the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3.

[0028] Figure 2 Cleaning ability comparison chart of the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1-3.

[0029] Figure 3 States of the aluminum alloy workpieces in the Example 5 group before and after cleaning; among them, (1) is the state of the aluminum alloy workpieces in the Example 5 group before cleaning, and (2) is the state of the aluminum alloy workpieces in the Example 5 group after cleaning.

[0030] Figure 4 Comparison chart of the corrosion weight loss rate and corrosion current density of the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1-3. Detailed implementation manners

[0031] The present invention will be further explained below in conjunction with specific embodiments.

[0032] The following isomeric polycarboxylic acid alkanolamines are purchased from a certain Xuxin New Materials (Guangzhou) Co., Ltd., with the model DX308, which is a non-ionic surfactant, presenting a light yellow to colorless transparent liquid, with a density (20 °C) of 1.19 g / cm 3 , and the pH value (1% aqueous solution) is 8.0 - 10.0. The alkynediol-modified surfactant is purchased from a certain Kaibang Chemical Materials Co., Ltd. in Sichuan, with the model RianPont2704. The octyl isomeric carboxylate, methyl hydroxyethyl decyl isomeric carboxylate, and modified isomeric alcohol ether quaternary ammonium salt are all products purchased from a certain Ning Technology (Shenzhen) Co., Ltd.

[0033] Example 1 An aluminum alloy welding cleaning agent, the raw materials of which include: 1000 g of methanesulfonic acid, 100 g of modified silica, 5 g of maleic acid-acrylic acid copolymer, 5 g of gluconic acid, 100 g of sodium isooctanoate, 200 g of ammonium fluoroborate, 100 g of isomeric polycarboxylic acid alkanolamine, 100 g of modified isomeric alcohol ether quaternary ammonium salt, 10 g of triethylene glycol monobutyl ether, 500 g of alkynediol-modified surfactant, and 6000 g of water.

[0034] The modified silica is prepared by the following specific operations: adding 50 g of mesoporous silica and 10 g of cerium nitrate to 400 g of an ethanol aqueous solution with a mass fraction of 50% and ultrasonically treating for 10 min, with an ultrasonic frequency of 20 kHz, adjusting the pH value of the system to 9 - 10 with a 1 mol / L sodium hydroxide solution, continuing to ultrasonically treat for 1 h, with an ultrasonic temperature of 60 °C, adjusting the pH value of the system > 8.5, adding 10 g of dopamine and continuing to ultrasonically treat for 1 h, centrifuging, washing with water, vacuum drying, and pulverizing.

[0035] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add methanesulfonic acid and sodium isooctanoate to water and stir for 10 min, with a stirring temperature of 60 °C, and raise the temperature to 75 °C and stir for 1 h to obtain a premix; S2. Add modified silica, maleic acid-acrylic acid copolymer, gluconic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoroborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add the alkynediol-modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0036] Example 2 An aluminum alloy welding cleaning agent, whose raw materials include: 1000 g of methanesulfonic acid, 1000 g of citric acid, 300 g of modified silica, 50 g of ethylenediaminetetraacetic acid, 200 g of potassium isooctanoate, 300 g of ammonium fluoroborate, 200 g of isomeric polycarboxylic acid alkanolamine, 200 g of modified isomeric alcohol ether quaternary ammonium salt, 100 g of triethylene glycol monobutyl ether, 1000 g of alkynediol-modified surfactant, and 10000 g of water.

[0037] The modified silica is prepared by the following specific operations: Add 150 g of mesoporous silica and 40 g of cerium nitrate to 800 g of an ethanol aqueous solution with a mass fraction of 70%, and perform ultrasonic treatment for 20 min at an ultrasonic frequency of 30 kHz. Adjust the pH value of the system to 9 - 10 with 2 mol / L sodium hydroxide, continue ultrasonic treatment for 2 h at an ultrasonic temperature of 80 °C, adjust the pH value of the system > 8.5, add 30 g of dopamine, and continue ultrasonic treatment for 3 h. Then centrifuge, wash with water, dry under vacuum, and pulverize.

[0038] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add methanesulfonic acid, citric acid, and potassium isooctanoate to water and stir for 30 min at a stirring temperature of 70 °C, then raise the temperature to 80 °C and stir for 2 h to obtain the premix. S2. Add modified silica, ethylenediaminetetraacetic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoroborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add the alkynediol-modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0039] Example 3 An aluminum alloy welding cleaning agent, whose raw materials include: 1200 g of citric acid, 250 g of modified silica, 20 g of polyaspartic acid, 170 g of methyl hydroxyethyl decyl isomerate, 220 g of ammonium fluoroborate, 170 g of isomeric polycarboxylic acid alkanolamine, 120 g of modified isomeric alcohol ether quaternary ammonium salt, 70 g of triethylene glycol monobutyl ether, 700 g of alkynediol-modified surfactant, and 9000 g of water.

[0040] The modified silica is prepared by the following specific operations: Add 80 g of mesoporous silica and 30 g of cerium nitrate to 500 g of an ethanol aqueous solution with a mass fraction of 65%, and perform ultrasonic treatment for 12 min at an ultrasonic frequency of 27 kHz. Adjust the pH value of the system to 9 - 10 with 1.3 mol / L sodium hydroxide, continue ultrasonic treatment for 100 min at an ultrasonic temperature of 65 °C, adjust the pH value of the system > 8.5, add 25 g of dopamine and continue ultrasonic treatment for 1.5 h, then centrifuge, wash with water, dry in vacuum, and pulverize.

[0041] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add citric acid and methyl hydroxyethyl decyl isomerate to water and stir for 25 min at a stirring temperature of 62 °C, then raise the temperature to 79 °C and stir for 80 min to obtain a premix. S2. Add modified silica, polyaspartic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoroborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add an alkynediol modified surfactant and stir evenly, and adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0042] Example 4 An aluminum alloy welding cleaning agent, whose raw materials include: 1800 g of methanesulfonic acid, 150 g of modified silica, 40 g of N,N - bis(2 - hydroxyethyl)ethylenediaminetriacetic acid, 130 g of methyl hydroxyethyl decyl isomerate, 280 g of ammonium fluoroborate, 130 g of isomeric polycarboxylic acid alkanolamine, 180 g of modified isomeric alcohol ether quaternary ammonium salt, 30 g of triethylene glycol monobutyl ether, 900 g of alkynediol modified surfactant, and 7000 g of water.

[0043] The modified silica is prepared by the following specific operations: Add 120 g of mesoporous silica and 20 g of cerium nitrate to 700 g of an ethanol aqueous solution with a mass fraction of 55%, and perform ultrasonic treatment for 18 min at an ultrasonic frequency of 21 kHz. Adjust the pH value of the system to 9 - 10 with 1.7 mol / L sodium hydroxide, continue ultrasonic treatment for 80 min at an ultrasonic temperature of 75 °C, adjust the pH value of the system > 8.5, add 15 g of dopamine and continue ultrasonic treatment for 2.5 h, then centrifuge, wash with water, dry in vacuum, and pulverize.

[0044] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add methanesulfonic acid and methyl hydroxyethyl decyl isomerate to water and stir for 15 min at a stirring temperature of 68 °C, then raise the temperature to 77 °C and stir for 100 min to obtain a premix. S2. Add modified silica, N,N-bis(2-hydroxyethyl)ethylenediaminetriacetic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add the alkynediol-modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0045] Example 5 An aluminum alloy welding cleaning agent, whose raw materials include: 1500 g of citric acid, 200 g of modified silica, 20 g of maleic acid-acrylic acid copolymer, 10 g of gluconic acid, 150 g of methyl hydroxyethyl isodecanoate, 250 g of ammonium fluoborate, 150 g of isomeric polycarboxylic acid alkanolamine, 150 g of modified isomeric alcohol ether quaternary ammonium salt, 50 g of triethylene glycol monobutyl ether, 800 g of alkynediol-modified surfactant, and 8000 g of water.

[0046] The modified silica is prepared by the following specific operation: Add 100 g of mesoporous silica and 25 g of cerium nitrate to 600 g of an ethanol aqueous solution with a mass fraction of 60% and perform ultrasonic treatment for 15 min. The ultrasonic frequency is 24 kHz. Adjust the pH value of the system to 9 - 10 with 1.5 mol / L sodium hydroxide, continue ultrasonic treatment for 90 min, and the ultrasonic temperature is 70 °C. Adjust the pH value of the system > 8.5, add 20 g of dopamine and continue ultrasonic treatment for 2 h, then centrifuge, wash with water, dry in vacuum, and pulverize.

[0047] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add citric acid and methyl hydroxyethyl isodecanoate to water and stir for 20 min. The stirring temperature is 65 °C, and then heat up to 78 °C and stir for 90 min to obtain the premix. S2. Add modified silica, maleic acid-acrylic acid copolymer, gluconic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add the alkynediol-modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0048] Comparative Example 1 An aluminum alloy welding cleaning agent, whose raw materials include: 1500 g of citric acid, 200 g of mesoporous silica, 20 g of maleic acid-acrylic acid copolymer, 10 g of gluconic acid, 150 g of methyl hydroxyethyl isodecanoate, 250 g of ammonium fluoborate, 150 g of isomeric polycarboxylic acid alkanolamine, 150 g of modified isomeric alcohol ether quaternary ammonium salt, 50 g of triethylene glycol monobutyl ether, 800 g of alkynediol-modified surfactant, and 8000 g of water.

[0049] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add citric acid and methyl hydroxyethyl decyl isomerate to water and stir for 20 min at a stirring temperature of 65 °C. Then heat up to 78 °C and stir for 90 min to obtain a premix. S2. Add mesoporous silica, maleic acid - acrylic acid copolymer, gluconic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add an alkynediol - modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain an aluminum alloy welding cleaning agent.

[0050] Comparative Example 2 An aluminum alloy welding cleaning agent, whose raw materials include: 1500 g of citric acid, 200 g of modified silica, 20 g of maleic acid - acrylic acid copolymer, 10 g of gluconic acid, 150 g of methyl hydroxyethyl decyl isomerate, 250 g of ammonium fluoborate, 150 g of isomeric polycarboxylic acid alkanolamine, 150 g of modified isomeric alcohol ether quaternary ammonium salt, 50 g of triethylene glycol monobutyl ether, 800 g of alkynediol - modified surfactant, and 8000 g of water.

[0051] The modified silica is prepared by the following specific operations: Add 100 g of mesoporous silica and 25 g of cerium nitrate to 600 g of an ethanol aqueous solution with a mass fraction of 60% and perform ultrasonic treatment for 15 min at an ultrasonic frequency of 24 kHz. Adjust the pH value of the system to 9 - 10 with 1.5 mol / L sodium hydroxide, continue ultrasonic treatment for 90 min at an ultrasonic temperature of 70 °C, then centrifuge, wash with water, dry in vacuum, and pulverize.

[0052] The preparation method of the above - mentioned aluminum alloy welding cleaning agent includes the following steps: S1. Add citric acid and methyl hydroxyethyl decyl isomerate to water and stir for 20 min at a stirring temperature of 65 °C. Then heat up to 78 °C and stir for 90 min to obtain a premix. S2. Add modified silica, maleic acid - acrylic acid copolymer, gluconic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoborate, and isomeric polycarboxylic acid alkanolamine to the premix and stir evenly. Then add an alkynediol - modified surfactant and stir evenly. Adjust the pH of the system to 5.8 - 6.8 to obtain an aluminum alloy welding cleaning agent.

[0053] Comparative Example 3 An aluminum alloy welding cleaning agent, whose raw materials include: 1500 g of citric acid, 200 g of modified silica, 20 g of maleic acid - acrylic acid copolymer, 10 g of gluconic acid, 150 g of methyl hydroxyethyl decyl isomerate, 250 g of ammonium fluoborate, 150 g of isomeric polycarboxylic acid alkanolamine, 150 g of modified isomeric alcohol ether quaternary ammonium salt, 50 g of triethylene glycol monobutyl ether, 800 g of alkynediol - modified surfactant, and 8000 g of water.

[0054] The modified silica is prepared by the following specific operations: Add 100 g of mesoporous silica into 600 g of an ethanol aqueous solution with a mass fraction of 60%, adjust the pH value of the system to be > 8.5, add 20 g of dopamine, perform ultrasonic treatment for 2 h, the ultrasonic frequency is 24 kHz, centrifuge, wash with water, dry in vacuum, and pulverize.

[0055] The preparation method of the above aluminum alloy welding cleaning agent includes the following steps: S1. Add citric acid and methyl hydroxyethyl isodecylate into water and stir for 20 min, the stirring temperature is 65 °C, heat up to 78 °C and stir for 90 min to obtain a premix; S2. Add modified silica, maleic acid-acrylic acid copolymer, gluconic acid, modified isomeric alcohol ether quaternary ammonium salt, triethylene glycol monobutyl ether, ammonium fluoroborate, and isomeric polycarboxylic acid alkanolamine into the premix and stir evenly, then add an acetylenic diol modified surfactant and stir evenly, adjust the pH of the system to 5.8 - 6.8 to obtain the aluminum alloy welding cleaning agent.

[0056] Refer to GB / T 11983-2008 "Determination of wetting power of surface active agents - Immersion method" to record the time from the start of wetting to complete sedimentation of the standard canvas piece in the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3. Refer to JB / T 4323-2019 "Water-based metal cleaning agents" to measure the defoaming performance of the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3.

[0057] As Figure 1 shown, the wetting power and defoaming performance of the aluminum alloy welding cleaning agent obtained in Example 5 are both better than those of Comparative Examples 1 - 3 (P < 0.05).

[0058] Perform high and low temperature stability tests on the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3. Place each group of specimens in an environment of 60 ± 1 °C for 6 h, and place each group of specimens in an environment of -5 ± 1 °C for 24 h, and observe the states of each group of specimens.

[0059] Table 1 States of the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3

[0060] Select 12 identical aluminum alloy workpieces (made of 7075 aluminum alloy) used in the air-conditioning pipeline of a certain new energy vehicle refrigeration system as specimens, clean all the specimens with an organic solvent, dry and cool them, and then weigh them (m 1 ), accurate to 0.1 mg. Immerse the cleaned aluminum alloy workpieces in the stamping lubricating oil used in the factory for 30 min, take them out, hang them to drain for 15 min, use filter paper to absorb the excess oil droplets at the bottom of the workpieces, and accurately weigh the weight of the oil-contaminated workpiece specimens (m 2). Randomly divided into 4 groups (Example 5 group, Comparative Example 1 group, Comparative Example 2 group, Comparative Example 3 group), and the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3 were used to ultrasonically clean the above oil - stained workpiece specimens for 5 min, and the ultrasonic cleaning temperature was room temperature (23 °C); then after water washing, they were placed in an oven at 70 ± 2 °C and dried for 40 min, cooled, and the aluminum alloy workpieces after cleaning were accurately weighed (m 3 ).

[0061] The cleaning ability is expressed by the oil - washing rate η, η = (m 2 - m 3 ) ÷ (m 2 - m 1 ) × 100%.

[0062] As Figure 2 shown, the oil - washing rate of the aluminum alloy welding cleaning agent obtained in Example 5 is the highest, and its cleaning ability is better than that of Comparative Examples 1 - 3 (P < 0.05). Among them, the states of the aluminum alloy workpieces in the Example 5 group before and after cleaning are as Figure 3 shown.

[0063] The aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3 were sent for inspection, and the testing unit selected LY12 hard aluminum as the experimental object. Copper wires were welded to the LY12 aluminum sheet, and the non - working area was encapsulated with epoxy resin / polyamide resin. First, it was polished with 240# sandpaper, and then successively polished with 400# - 2000# water - resistant sandpapers step by step until it was polished to a mirror surface, degreased with acetone, cleaned with distilled water, ultrasonically cleaned with absolute ethanol, and finally dried for standby; then the corrosion weight loss experiment was carried out to calculate the corrosion weight loss rate; and an electrochemical test was carried out at room temperature in the cleaning agents (i.e., the aluminum alloy welding cleaning agents obtained in Example 5 and Comparative Examples 1 - 3) using a CS310 electrochemical workstation.

[0064] As Figure 4 shown, the corrosion weight loss rate and corrosion current density of the aluminum alloy welding cleaning agent obtained in Example 5 are the smallest, confirming that its corrosivity is the smallest.

[0065] The applicant believes that: This is because the present invention uses the compounding of mesoporous silica and cerium nitrate to deposit cerium hydroxide on the surface of mesoporous silica under an alkaline environment, and further cooperates with the action of polydopamine. The combination of the two has extremely high stability, and the obtained modified silica has extremely high hydrophilic activity, which can significantly enhance the dispersion stability of silica in the cleaning agent, and has good hydrophilicity and biocompatibility. The present invention uses organic acids that will not erode the aluminum alloy itself, which can effectively remove the metal oxides generated after welding. During the ultrasonic process, it cooperates with the modified silica, and even at low temperatures, it can have a high rate of removing impurities on the surface of the aluminum alloy, and the aluminum alloy has a better gloss after cleaning. The static and dynamic surface tensions of the defoaming agent used in the present invention are low, and it has good wetting performance. When compounded with the modified silica, it can promote flow leveling, so that the organic acid in the cleaning agent can better contact and react with the surface oxide of the aluminum alloy, and cooperate with the rare earth to form a rare earth oxide film on the surface of the aluminum alloy, effectively preventing the surface reaction of the aluminum alloy, and having excellent corrosion resistance effect. At the same time, it can significantly inhibit the foam height in the ultrasonic cleaning process.

[0066] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. An aluminum alloy welding cleaning agent, characterized in that: The raw materials include, by mass, 10-20 parts of organic acid, 1-3 parts of modified silicon dioxide, 0.1-0.5 parts of chelating agent, 1-2 parts of acidic dispersant, 2-5 parts of corrosion inhibitor, 1.1-3 parts of penetrant, 5-10 parts of defoaming agent and 60-100 parts of water.

2. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: The organic acid is methanesulfonic acid and / or citric acid.

3. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: Chelating agents include: At least one of maleic acid acrylic acid copolymer, gluconic acid, ethylenediaminetetraacetic acid, diisopropyltriaminepentaacetic acid, N,N-di(2-hydroxyethyl)ethylenediaminetriacetic acid, and polyaspartic acid.

4. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: The acidic dispersant is an octa-isomeric carboxylate or a methyl hydroxyethyl decanoate.

5. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: Corrosion inhibitors include: Ammonium fluoroborate and isomeric polycarboxylic acid alcohol amines; the mass ratio of ammonium fluoroborate and isomeric polycarboxylic acid alcohol amines is 4-6:2-4.

6. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: The penetrant comprises: modified isomeric alcohol ether quaternary ammonium salt and triethylene glycol monobutyl ether; the mass ratio of the modified isomeric alcohol ether quaternary ammonium salt and triethylene glycol monobutyl ether is 1-2:0.1-1.

7. The aluminum alloy welding cleaning agent according to claim 1, characterized in that: The modified silica is prepared by the following specific operation: adding mesoporous silica and cerium nitrate to an ethanol aqueous solution and ultrasonically treating for 10-20 minutes, adjusting the pH value of the system to 9-10, continuing the ultrasonic treatment for 1-2 hours, adjusting the pH value of the system to >8.5, adding dopamine and continuing the ultrasonic treatment for 1-3 hours, centrifuging, washing with water, vacuum drying, and crushing.

8. The aluminum alloy welding cleaning agent according to claim 7, characterized in that: The mass ratio of mesoporous silica, cerium nitrate and dopamine is 5-15:1-4:1-3; the ultrasonic frequency is 20-30kHz; and the temperature of ultrasonic treatment is 60-80℃ after the pH value of the system is adjusted to 9-10.

9. A method for preparing the aluminum alloy welding cleaning agent according to any one of claims 1 to 8, characterized in that: The steps include: S1. Add organic acid and acidic dispersant into water and stir for 10-30 min at a stirring temperature of 60-70°C, then heat to 75-80°C and stir for 1-2h to obtain a premix; S2. Add modified silica, chelating agent, penetrant and corrosion inhibitor to the premix and stir evenly, add defoaming agent thereto and stir evenly, adjust the pH of the system to 5.8-6.8, and obtain an aluminum alloy welding cleaning agent.

10. A method for using the aluminum alloy welding cleaning agent according to any one of claims 1 to 8, characterized in that: The aluminum alloy welding cleaning agent according to any one of claims 1 to 8 is used to ultrasonically clean the aluminum alloy workpiece after welding, and the ultrasonic cleaning temperature is 20-50° C.; and water washing.

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