Preparation method of corrosion inhibitor for magnesium alloy cutting fluid

Abstract

The invention discloses a preparation method of a corrosion inhibitor for magnesium alloy cutting fluid, which specifically comprises the following steps: heating dodecenyl succinic anhydride to 80-100 DEG C, adding triethylene glycol monobutyl ether with equal molar ratio into the dodecenyl succinic anhydride, and carrying out esterification reaction for 4-5 hours to obtain the corrosion inhibitor. The corrosion inhibitor prepared by the method disclosed by the invention is added into the magnesium alloy cutting fluid, so that the magnesium alloy cutting fluid has good lubricating performance and also has good hard water resistance and good corrosion inhibition performance, on one hand, a compact adsorption film layer can be formed on the surface of a magnesium alloy; on the other hand, the magnesium alloy cutting fluid can rapidly capture the precipitated magnesium ions and uniformly disperse the magnesium ions in the cutting fluid, so that the conditions of demulsification and failure of the cutting fluid caused by rapid increase of water hardness can be effectively prevented, and the service life of the magnesium alloy cutting fluid is greatly prolonged.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a corrosion inhibitor for a magnesium alloy cutting fluid. BACKGROUND

[0002] As an important structural material, magnesium alloy has the characteristics of light density, high strength, good electric and thermal conductivity, excellent magnetic shielding performance, etc., and is widely used in the fields of automobiles, aerospace, electronics, etc. However, due to the high chemical and electrochemical activity of magnesium alloy, a large amount of heat is easily generated during cutting processing, and the cooling and lubricating performance of the cutting fluid has a high requirement. Meanwhile, a large amount of magnesium ions is generated during the cutting processing of magnesium alloy, which can cause the failure of emulsifiers in the cutting fluid, cause oil-water separation, and thus seriously affect the service life of the cutting fluid.

[0003] At present, the commonly used corrosion inhibitors for magnesium alloy cutting fluids on the market are mostly phosphate ester corrosion inhibitors or silicon corrosion inhibitors. The magnesium alloy cutting fluid using the above-mentioned corrosion inhibitors cannot simultaneously have good hard water resistance and good corrosion resistance while having good lubricating performance, thereby seriously affecting the service life of the cutting fluid. SUMMARY

[0004] The application aims to provide a preparation method of a corrosion inhibitor for a magnesium alloy cutting fluid. The corrosion inhibitor prepared by the method is added to the magnesium alloy cutting fluid, so that the magnesium alloy cutting fluid has good lubricating performance, and simultaneously has good hard water resistance and good corrosion resistance.

[0005] The preparation method of the corrosion inhibitor for the magnesium alloy cutting fluid comprises the following steps: heating dodecenyl succinic anhydride to 80-100 DEG C, adding an equimolar ratio of triethylene glycol butyl ether into the dodecenyl succinic anhydride for esterification reaction, and reacting for 4-5 h to obtain the corrosion inhibitor. The reaction equation of the above method is as follows: .

[0006] The corrosion inhibitor is added to the magnesium alloy cutting fluid at 1-3% of the mass of the magnesium alloy cutting fluid.

[0007] The magnesium alloy cutting fluid containing the above-mentioned corrosion inhibitor comprises the following components in percentage by mass: the corrosion inhibitor 1-3%; water-soluble anti-rust additive 8-12%; base oil 20-30%; surfactant 3-5%; self-emulsifying ester 8-10%; bactericide 0.3-0.4%; defoaming agent 0.1-0.2%; and water in the remainder.

[0008] The water-soluble rust inhibitor is a combination of at least two of sebacic acid, tricarboxylic acid, diethanolamine borate, or triethanolamine borate; the surfactant is an anionic surfactant, specifically at least one of oleyl alcohol ether carboxylic acid (fatty alcohol polyoxyethylene ether carboxylic acid, model AEC-9H), lauryl alcohol ether carboxylic acid, or octanol ether carboxylic acid; the self-emulsifying ester is at least one of Croda self-emulsifying ester Priolube 3955 or self-emulsifying ester Priolube 3952; the bactericide includes 1,2-benzisothiazolin-3-one (BIT) and n-butyl-1,2-benzisothiazolin-3-one (BBIT), with a mass ratio of 3~4:1; the defoamer is an organosilicon polyether defoamer; and the base oil is naphthenic base oil T22.

[0009] In neutral to weakly alkaline solutions with pH = 7~10, a Mg(OH)2 / MgO oxide film can form on the surface of magnesium alloys, but the film is loose and porous, with limited protective properties. The isoelectric point of Mg(OH)2 is approximately pH = 10.5. If the pH of the cutting fluid is > 10.5, although it can effectively reduce the corrosion of magnesium alloys, the stability of the cutting fluid system itself will be greatly reduced. Therefore, the pH of the cutting fluid needs to be less than 10.5. Under the condition that the pH of the cutting fluid is < 10.5, it is easy to cause corrosion to magnesium alloys. Under conditions where the cutting fluid pH < 10.5, the corrosion product Mg(OH)2 on the magnesium alloy surface is positively charged. When the cutting fluid uses the dodecenyl succinate half-ester prepared in this invention as a corrosion inhibitor, the multiple negatively charged polar groups (ester, ether, and carboxyl groups) in the inhibitor structure are firmly adsorbed onto the Mg(OH)2 film, neutralizing the charge on the Mg(OH)2 crystal surface, reducing interfacial tension, lowering nucleation energy, and promoting nucleation, thereby forming a dense Mg(OH)2 film, which passivates the surface and prevents corrosion. Simultaneously, the dodecenyl succinate half-ester corrosion inhibitor prepared in this invention has a special molecular structure; the polyether and carboxyl groups can effectively chelate and stabilize magnesium ions, thus effectively preventing emulsifier failure and oil-water separation caused by magnesium ion precipitation, significantly improving the service life and stability of the cutting fluid.

[0010] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The corrosion inhibitor prepared by the method of the present invention, when added to magnesium alloy cutting fluid, enables the magnesium alloy cutting fluid to have good lubrication performance, as well as good hard water resistance and good corrosion inhibition performance. On the one hand, it can form a dense adsorption film layer on the surface of magnesium alloy, thereby effectively inhibiting magnesium alloy corrosion and reducing the precipitation of magnesium ions in magnesium alloy. On the other hand, it can quickly capture the precipitated magnesium ions and disperse them evenly in the cutting fluid, thereby effectively preventing the cutting fluid from demulsifying and failing due to the rapid increase in water hardness, and thus greatly improving the service life of magnesium alloy cutting fluid. Attached Figure Description

[0011] Figure 1 The infrared spectrum of the dodecenyl succinic acid half ester corrosion inhibitor prepared in Example 1 is shown. Detailed Implementation

[0012] Example 1 The preparation method of the corrosion inhibitor for magnesium alloy cutting fluid of the present invention is as follows: 1 mol of dodecenyl succinic anhydride is heated to 80~100℃, and 1 mol of triethylene glycol butyl ether is slowly added to it. The reaction is carried out for 4 hours to obtain the corrosion inhibitor dodecenyl succinic anhydride half ester. The structural formula of dodecenyl succinate half ester is: .

[0013] The reaction equation for the above method is: .

[0014] The product obtained in Example 1 was added at 3% by weight of water to 5000 ppm hard water (it disperses well in water, forming a homogeneous system). After being placed in 5000 ppm hard water for 24 hours, no stratification or floating oil phenomenon was observed, and it remained in a homogeneous state. When the product obtained in Example 1 was added at 3% by weight of water to 5000 ppm hard water, the bubble volume did not exceed 2 mL after standing for 10 seconds, demonstrating excellent defoaming performance. When the product obtained in Example 1 was added at 3% by weight of water to 5000 ppm hard water, and a magnesium alloy was placed in the above hard water, after 8 hours, the surface of the magnesium alloy remained bright, with no corrosion. Simultaneously, the magnesium ion concentration in the water was measured, and no significant increase was observed. When the product obtained in Example 1 was placed at 3% by weight of water in 100°C water, after 4 hours, the appearance of the water remained unchanged, remaining in a homogeneous state, indicating its excellent thermal stability and lack of oxidation at high temperatures.

[0015] Infrared spectrum Figure 1 It can be seen that the dodecenyl succinate half-ester prepared in Example 1 has a temperature range of 1730-1750 cm⁻¹. -1 It exhibits a strong C=O absorption peak at 3000 cm⁻¹. -1 A strong -CH3 absorption peak is observed nearby, in the range of 1000-1300 cm⁻¹. -1 It exhibits a strong CO absorption peak, and the spectrum shows that the prepared corrosion inhibitor has typical ester and ether group structural characteristics.

[0016] Example 2 The magnesium alloy cutting fluid of the present invention comprises the following components in weight percentage: 1% dodecenyl succinate half-ester obtained in Example 1, 4% sebacic acid, 8% triethanolamine borate, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 45.5% water.

[0017] The formula amounts of dodecenyl succinate half ester, sebacic acid, triethanolamine borate ester, naphthenic base oil T22, oleyl alcohol ether carboxylic acid, self-emulsifying ester Priolube 3955, BIT, BBIT, organosilicon polyether defoamer (%), and water are mixed and stirred evenly to obtain magnesium alloy cutting fluid.

[0018] Example 3 The magnesium alloy cutting fluid of the present invention comprises the following components in weight percentage: 2% dodecenyl succinate half-ester, 4% sebacic acid, 8% triethanolamine borate ester, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 44.5% water.

[0019] Example 3: The preparation method of magnesium alloy cutting fluid is the same as that in Example 2.

[0020] Example 4 The magnesium alloy cutting fluid of the present invention comprises the following components in weight percentage: 3% dodecenyl succinate half-ester, 4% sebacic acid, 8% triethanolamine borate ester, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 43.5% water.

[0021] Example 4: The preparation method of magnesium alloy cutting fluid is the same as that in Example 2.

[0022] Comparative Example 1 A magnesium alloy cutting fluid comprises the following components in weight percentage: 0.5% dodecenyl succinate half-ester obtained in Example 1, 4% sebacic acid, 8% triethanolamine borate, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 46% water.

[0023] The preparation method of the magnesium alloy cutting fluid in Comparative Example 1 is the same as that in Example 2.

[0024] Comparative Example 2 A magnesium alloy cutting fluid comprises the following components in weight percentage: 4% dodecenyl succinate half-ester, 4% sebacic acid, 8% triethanolamine borate, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 42.5% water.

[0025] The preparation method of the magnesium alloy cutting fluid in Comparative Example 2 is the same as that in Example 2.

[0026] Comparative Example 3 A magnesium alloy cutting fluid comprises the following components in weight percentage: 2% phosphate ester ADDCO CP-NF-12 (Lubrizol magnesium alloy corrosion inhibitor), 4% sebacic acid, 8% triethanolamine borate, 30% naphthenic base oil T22, 3% oleyl alcohol ether carboxylic acid, 8% self-emulsifying ester Priolube 3955, 0.3% BIT, 0.1% BBIT, 0.1% silicone polyether defoamer, and 44.5% water.

[0027] The preparation method of the magnesium alloy cutting fluid in Comparative Example 3 is the same as that in Example 2.

[0028] Comparative Example 4 A magnesium alloy cutting fluid comprises the following components in weight percentage: dodecenyl succinate half ester T747 2%, sebacic acid 4%, triethanolamine borate 8%, naphthenic base oil T22 30%, oleyl alcohol ether carboxylic acid 3%, self-emulsifying ester Priolube 3955 8%, BIT 0.3%, BBIT 0.1%, silicone polyether defoamer 0.1%, and water 44.5%.

[0029] The preparation method of the magnesium alloy cutting fluid in Comparative Example 4 is the same as that in Example 2.

[0030] Table 1 shows the performance data of the magnesium alloy cutting fluids in Examples 2-4 and Comparative Examples 1-5.

[0031] Test methods: The magnesium corrosion test and hard water adaptability test of AZ91D were conducted according to the test methods in GB / T6144 standard. The magnesium ion leaching amount was detected by ICP ion chromatography according to GB / T6144. The lubricity was tested using a tapping torque tester according to ASTM D5619 standard. The higher the tapping efficiency, the better the lubricity.

[0032] As shown in Table 1, the dodecenyl succinate half-ester prepared in Example 1 exhibits excellent corrosion inhibition performance in magnesium alloy cutting fluids. The multi-group adsorption effect effectively inhibits the corrosion and dissolution of magnesium ions, while also significantly improving the cutting fluid's resistance to hard water (maintaining the stability of the cutting fluid system even at high magnesium ion concentrations). When the amount of dodecenyl succinate half-ester added to the cutting fluid is too low, the adsorption at the metal interface is insufficient to form a complete adsorption film, resulting in decreased corrosion inhibition performance. When the amount of dodecenyl succinate half-ester added to the cutting fluid is too high, the steric hindrance effect between molecules is large, causing incomplete adsorption and thus decreasing corrosion inhibition performance, although lubricity is still improved. Compared with traditional phosphate ester corrosion inhibitors and commercially available phosphorus-containing magnesium alloy cutting fluids, although they have better slow-release performance and protect magnesium alloys from discoloration, the amount of magnesium ion dissolution remains high, continuously increasing the magnesium ion content of the cutting fluid, leading to a continuous increase in water hardness. Simultaneously, the poor resistance to hard water severely affects the stability of the cutting fluid, thereby affecting its service life. In contrast, the dodecenyl succinate half ester T747 in Comparative Example 4 was synthesized by esterification reaction of butanol and dodecenyl succinic anhydride. Due to the lack of hydrophilic ether structure, its adsorption capacity is weak and it cannot effectively disperse magnesium ions. Compared with the dodecenyl succinate half ester prepared in Example 1, its ability to protect magnesium alloys and resist magnesium ion hard water is significantly reduced.

Claims

1. A method for preparing a corrosion inhibitor for magnesium alloy cutting fluid, characterized in that, Specifically, dodecenyl succinic anhydride is heated to 80-100℃, and triethylene glycol butyl ether is added in an equimolar ratio to carry out an esterification reaction. The reaction is carried out for 4-5 hours to obtain a corrosion inhibitor. The reaction equation for the above method is: 。 2. The preparation method according to claim 1, characterized in that: Add corrosion inhibitor to magnesium alloy cutting fluid at a rate of 1-3% of the fluid's mass.

3. A magnesium alloy cutting fluid containing the corrosion inhibitor prepared by the method of claim 1, characterized in that, It includes the following components by weight percentage: corrosion inhibitor 1-3%; water-soluble rust inhibitor 8-12%; base oil 20-30%; surfactant 3-5%; self-emulsifying ester 8-10%; bactericide 0.3-0.4%; defoamer 0.1-0.2% and water balance.

4. The magnesium alloy cutting fluid according to claim 3, characterized in that: The water-soluble rust inhibitor is a combination of at least two of sebacic acid, tricarboxylic acid, diethanolamine borate, or triethanolamine borate.

5. The magnesium alloy cutting fluid according to claim 3, characterized in that: The surfactant is at least one of oleyl ether carboxylic acid, lauryl ether carboxylic acid, or octanol ether carboxylic acid.

6. The magnesium alloy cutting fluid according to claim 3, characterized in that: The self-emulsifying ester is at least one of the self-emulsifying esters Priolube 3955 or Priolube 3952.

7. The magnesium alloy cutting fluid according to claim 3, characterized in that: The bactericide includes 1,2-benzisothiazolin-3-one and n-butyl-1,2-benzisothiazolin-3-one.

8. The magnesium alloy cutting fluid according to claim 7, characterized in that: The mass ratio of 1,2-benzisothiazolin-3-one to n-butyl-1,2-benzisothiazolin-3-one is 3~4:

1.

9. The magnesium alloy cutting fluid according to claim 3, characterized in that: The defoamer is an organosilicone polyether defoamer.

10. The magnesium alloy cutting fluid according to claim 3, characterized in that: The base oil is a naphthenic base oil T22.

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