Corrosion inhibitor for improving corrosion resistance of cupronickel

Abstract

The invention discloses a corrosion inhibitor for improving the corrosion resistance of cupronickel, and the corrosion inhibitor is prepared from the following components: 1-3g / L of quaternary ammonium salt, 2-5g / L of polyaspartic acid derivative, 8-15g / L of benzotriazole, 0.1-0.6 g / L of dispersing agent and a solvent, and the content of each component is as follows: 1-3g / L of quaternary ammonium salt, 2-5g / L of polyaspartic acid derivative, 8-15g / L of benzotriazole and 0.1-0.6 g / L of dispersing agent. The corrosion inhibitor is a composite corrosion inhibitor with quaternary ammonium salt, a polyaspartic acid derivative and benzotriazole as corrosion inhibition components, and the three corrosion inhibition components are combined according to a specific ratio and can achieve synergistic interaction in the aspect of metal corrosion prevention. The corrosion inhibitor is used for corrosion prevention of cupronickel and has an excellent corrosion inhibition effect.

Description

Technical Field

[0001] The invention relates to a corrosion inhibitor for preventing and delaying metal corrosion, in particular to a corrosion inhibitor for improving the corrosion resistance of white copper. Background Art

[0002] The seawater corrosion and ammonia corrosion resistance of copper-nickel alloy are much better than brass. Therefore, the air extraction area of ​​the condenser of the coastal power plant and the condenser of the inland power plant is often made of white copper tubes (copper-nickel alloy). The commonly used grades in China are white copper B10 and B30, that is, copper and nickel are 10% and 30% respectively (the alloy contains elements such as Fe and Mn). Copper-nickel alloy is used in many industrial fields such as shipbuilding and power stations, especially heat exchangers. However, the chloride ions in the heat exchanger cause serious corrosion to the copper-nickel alloy. Adding corrosion inhibitors to copper-nickel alloys is the best way to inhibit metal corrosion.

[0003] Corrosion inhibitors are a low-cost corrosion protection process. A certain amount of corrosion inhibitor is added to the corrosive medium. The corrosion inhibitor and the corrosive medium compete for adsorption on the metal surface, thereby reducing the concentration of corrosive ions on the medium surface. Some corrosion inhibitors react with metal surface atoms to form a complex film layer, which hinders the mutual diffusion of corrosive medium ions and metal atoms, thereby playing a protective role. Summary of the invention

[0004] The object of the present invention is to provide a corrosion inhibitor for improving the corrosion resistance of white copper, wherein the corrosion inhibitor has an excellent corrosion inhibition effect.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A corrosion inhibitor for improving the corrosion resistance of white copper. The corrosion inhibitor is prepared from quaternary ammonium salt, polyaspartic acid derivative, benzotriazole, dispersant and solvent, wherein the content of each component is: 1-3 g / L of quaternary ammonium salt, 2-5 g / L of polyaspartic acid derivative, 8-15 g / L of benzotriazole and 0.1-0.6 g / L of dispersant.

[0007] Preferably, the quaternary ammonium salt is a mixture of carboxypropyl trimethyl ammonium chloride chitosan and dodecenylamine ethyl imidazoline quaternary ammonium salt. Preferably, the mass ratio of carboxypropyl trimethyl ammonium chloride chitosan to dodecenylamine ethyl imidazoline quaternary ammonium salt in the quaternary ammonium salt is 4:1.

[0008] Preferably, the polyaspartic acid derivative is a mixed solvent of 1,3,5-trimethylbenzene and sulfolane, and the intermediate is prepared by thermal condensation reaction and further condensed to obtain the product.

[0009] Preferably, the dispersant is sodium dodecylbenzene sulfonate.

[0010] Preferably, the solvent is deionized water.

[0011] The beneficial effects of the present invention are:

[0012] The corrosion inhibitor of the present invention is a composite corrosion inhibitor with quaternary ammonium salt, polyaspartic acid derivative and benzotriazole as corrosion inhibition components. The three corrosion inhibition components are combined in a specific ratio to synergistically enhance the effect in metal corrosion prevention. The corrosion inhibitor is used for the corrosion prevention of white copper and has an excellent corrosion inhibition effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the AC impedance diagram (Nyquist diagram) of the white copper electrode in 3.5% NaCl aqueous solution after the white copper was pretreated in the corrosion inhibitor for different time periods.

[0014] Figure 2 This is the AC impedance diagram (Bode diagram) of the white copper electrode in 3.5% NaCl aqueous solution after the white copper was pretreated in the corrosion inhibitor for different time periods.

[0015] Figure 3 This is the polarization curve of the white copper electrode in 3.5% NaCl aqueous solution after the white copper was pretreated in the corrosion inhibitor for different time periods. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0017] The corrosion inhibitor of the invention is prepared from quaternary ammonium salt, polyaspartic acid derivative, benzotriazole, dispersant and solvent, wherein the quaternary ammonium salt is a mixture of carboxypropyltrimethylammonium chloride chitosan and dodecenylamineethylimidazoline quaternary ammonium salt; the polyaspartic acid derivative is preferably sodium polyaspartate; the dispersant is sodium dodecylbenzene sulfonate; and the solvent is deionized water.

[0018] The composition of the quaternary ammonium salt is a mixture of carboxypropyltrimethylammonium chloride chitosan and dodecenylamineethylimidazoline quaternary ammonium salt in a mass ratio of 4:1.

[0019] Polyaspartic acid derivatives are corrosion inhibitors that mainly inhibit anodes and have excellent corrosion inhibition performance. After adding polyaspartic acid derivatives, a relatively complete protective film is formed on the electrode surface, showing a certain corrosion inhibition and protection ability. In the present invention, the preparation process of the polyaspartic acid derivatives is as follows:

[0020] Raw material preparation: Aspartic acid is used as the raw material. 1,3,5-trimethylbenzene and sulfolane are used as a mixed solvent, the mass ratio of sulfolane to 1,3,5-trimethylbenzene is 5:12, and phosphoric acid is selected as a catalyst.

[0021] Thermal condensation reaction: Aspartic acid, mixed solvent and phosphoric acid are added to the reactor and the polymerization reaction is carried out by microwave heating. After the reaction is completed, the polymer is precipitated with ethanol solution, and then the unreacted monomers and catalysts are removed by filtration and acetone washing.

[0022] Preparation of intermediate: dissolve the obtained polysuccinimide (PSI) in water, and simultaneously add 2-aminoethanesulfonate and glutamate aqueous solution, and adjust the solution pH to 8-10. Control the reaction temperature at 10-30°C, and the reaction time for 18-26 hours to obtain a reddish brown transparent solution.

[0023] Preparation of polyaspartic acid derivatives: Use anhydrous ethanol to precipitate solids, and then filter under reduced pressure and wash with acetone to obtain a yellow-brown solid product. After vacuum drying, a polyaspartic acid derivative containing sulfonic acid groups and carboxylic acid groups is obtained.

[0024] Post-treatment: Take an appropriate amount of polysuccinimide (PSI) and place it in a conical flask, add a 3% sodium hydroxide aqueous solution by mass, and let it stand for 30 minutes at room temperature and pressure. It is observed that the water-insoluble PSI begins to change color and completely dissolves in water, indicating that the hydrolysis has been completed. Add a dilute hydrochloric acid solution to adjust the pH value to 7, pour the solution into a vigorously stirred ethanol solution, precipitate again, and obtain a polyaspartic acid derivative.

[0025] Benzotriazole has an anti-corrosion effect on metal materials such as copper, aluminum, cast iron, nickel, and zinc. In the present invention, 1,2,3-benzotriazole is selected, and 1,2,3-benzotriazole forms covalent bonds and coordination bonds with copper atoms, and mutually replaces each other to form a chain polymer, and forms a multi-layer protective film on the surface of copper, so that the surface of copper does not undergo redox reaction and has an anti-corrosion effect.

[0026] As an embodiment of the present invention, the components and contents of the corrosion inhibitor are: 1-3 g / L of quaternary ammonium salt, 2-5 g / L of polyaspartic acid derivative, 8-15 g / L of benzotriazole, and 0.1-0.6 g / L of sodium dodecylbenzene sulfonate.

[0027] Example 1

[0028] In this embodiment, the components and contents of the corrosion inhibitor are: 2 g / L quaternary ammonium salt, 3 g / L polyaspartic acid derivative, 10 g / L benzotriazole, and 0.3 g / L dispersant. The quaternary ammonium salt is a mixture of carboxypropyltrimethylammonium chloride chitosan and dodecenylamineethylimidazoline quaternary ammonium salt in a mass ratio of 4:1.

[0029] 1. Solution preparation and electrode preparation

[0030] The components of the corrosion inhibitor were put into a beaker according to the above-mentioned component contents and immersed in a water bath at 60-80°C and stirred for 20-30 minutes to obtain three corrosion inhibitors, namely, a quaternary ammonium salt corrosion inhibitor, a quaternary ammonium salt and benzotriazole compound corrosion inhibitor, and a quaternary ammonium salt, benzotriazole and polyaspartic acid derivative compound corrosion inhibitor.

[0031] Implementation system: 3.5% NaCl aqueous solution.

[0032] All the utensils used in the experiment were washed with deionized water, and the solutions were prepared with deionized water.

[0033] The nickel silver electrode is made of pure copper material for the test, and the area of ​​the nickel silver electrode is 1cm 2 Before measuring, the white copper electrode is 0 # ~8 # The surface was polished step by step with metallographic sandpaper, rinsed with deionized water, and then degreased with anhydrous ethanol. After being rinsed with deionized water and blown dry, it was immersed in the prepared corrosion inhibitor solution for 2 hours. Finally, the immersed nickel silver was rinsed with deionized water, blown dry and placed in the electrolytic cell.

[0034] 2. Experimental test

[0035] Instrument: The AC impedance and polarization curves were measured using the VersaaSTAT4 electrochemical workstation. The AC impedance test frequency range was 10 -2 Hz~10 5 Hz, the amplitude of the disturbance signal is 10mV (vsOCP); the scanning frequency of the polarization curve is 1mV / s. The classic three-electrode system is used in the experiment, with the working electrode being a white copper electrode, the reference electrode being an Ag / AgCl electrode, and the auxiliary electrode being a platinum electrode. The measurements of the AC impedance and polarization curves are both performed at open circuit potential with the white copper electrode immersed in a 3.5% NaCl aqueous solution.

[0036] Figure 1 This is the AC impedance diagram measured in 3.5% NaCl aqueous solution after cupronickel was immersed in different kinds of corrosion inhibitors (curve a is the blank control sample, b is the sample immersed in quaternary ammonium salt as corrosion inhibitor, c is the sample immersed in quaternary ammonium salt and benzotriazole as corrosion inhibitor, d is the sample immersed in quaternary ammonium salt, benzotriazole and polyaspartic acid derivative as corrosion inhibitor). When cupronickel is immersed in the corrosion inhibitor solution, the corrosion inhibitor reacts with the metal to form a protective film, which shows the corrosion inhibition effect. The corresponding AC impedance test result is the impedance spectrum (Nyquist diagram). The impedance spectrum is an irregular capacitive arc, indicating that the corrosion of cupronickel in the studied system is mainly controlled by charge transfer. The arc shape and the chord length on the Z axis correspond to the membrane resistance Rf of the B30 electrode. The larger Ri is, the better the corrosion inhibition effect is. From Figure 1It can be seen that compared with the blank solution, the chord length of the impedance spectrum corresponding to the copper-nickel electrode with the addition of corrosion inhibitor increases significantly, indicating that the corrosion inhibitor has a significant corrosion inhibition effect on copper-nickel corrosion. Figure 1 It can also be seen that after the white copper is immersed in the corrosion inhibitor composed of quaternary ammonium salt, benzotriazole and polyaspartic acid derivative, the chord length of the corresponding impedance spectrum increases significantly, Ri is the largest, and the corrosion inhibition effect is the best.

[0037] Figure 2 The Bode graphs of the electrochemical impedance spectroscopy (Bode) of the white copper without immersion and after immersion in the corrosion inhibitor for different time periods were measured in a 3.5% NaCl aqueous solution (curve a is a blank control sample, curve b is a sample immersed in a quaternary ammonium salt as a corrosion inhibitor, curve c is a sample immersed in a quaternary ammonium salt and benzotriazole as a corrosion inhibitor, and curve d is a sample immersed in a quaternary ammonium salt, benzotriazole and polyaspartic acid derivative as a corrosion inhibitor). The corrosion resistance of the electrode can be characterized by the impedance film value |Z| at the low frequency point. The larger the impedance film value |Z|, the stronger the corrosion resistance of the electrode. Figure 2 It can also be seen that the corrosion inhibitor has a certain corrosion inhibition effect on white copper, and after white copper is immersed in the corrosion inhibitor compounded with quaternary ammonium salt, benzotriazole and polyaspartic acid derivatives, the impedance film value |Z| is the largest and the corrosion inhibition effect is the best.

[0038] Figure 3 The polarization curves of white copper without immersion and immersion in different corrosion inhibitors in 3.5% NaCl aqueous solution are shown in Table 1 (where η = (I o corr -I corr ) / I o corr ), where I o corr ,I corr Each represents the corrosion current density without and with corrosion inhibitors. Table 1 is a table of corrosion potential, corrosion current density and corrosion rate of white copper measured in 3.5% NaCl aqueous solution without immersion and after immersion in corrosion inhibitors for different time periods.

[0039] Table 1

[0040] Corrosion Inhibitor Type <![CDATA[E corr / V]]> <![CDATA[I corr / μA·cm -2 ]]> η / % blank -0.226 3.041 0 Quaternary ammonium salt -0.209 2.315 23.87 Quaternary ammonium salt + polyaspartic acid derivative -0.199 0.163 94.64 Quaternary ammonium salt + polyaspartic acid derivative + benzotriazole -0.171 0.114 96.25

[0041] From Table 1, it can be seen that the corrosion current of the unsoaked white copper in a 3.5% NaCl aqueous solution is 3.041μA·cm-2, and the corrosion current of the white copper soaked in a 3.5% NaCl aqueous solution with a compound of quaternary ammonium salt, benzotriazole and polyaspartic acid derivative as corrosion inhibitor is 0.114μA·cm-2, and the corrosion inhibition efficiency is 96.25%, indicating that the corrosion inhibitor has a significant corrosion inhibition effect on white copper, and has a better corrosion inhibition effect than other corrosion inhibitors. This result is consistent with the conclusion drawn by the AC impedance method. In addition, it can be seen from the polarization curve that the corrosion potential of the white copper electrode after soaking is positively shifted, and the cathode polarization curve has a significant positive shift, indicating that the corrosion inhibitor is an anodic corrosion inhibitor.

[0042] The above contents are only basic descriptions of the concept of the present invention, and any equivalent changes made according to the technical solution of the present invention belong to the protection scope of the present invention.

Claims

1. A corrosion inhibitor for improving the corrosion resistance of white copper, characterized in that: The corrosion inhibitor is prepared from quaternary ammonium salt, polyaspartic acid derivative, benzotriazole, dispersant and solvent, wherein the content of each component is: quaternary ammonium salt 1-3g / L, polyaspartic acid derivative 2-5g / L, benzotriazole 8-15g / L, dispersant 0.1-0.6g / L.

2. The corrosion inhibitor according to claim 1, characterized in that The quaternary ammonium salt is a mixture of carboxypropyltrimethylammonium chloride chitosan and dodecenylamineethylimidazoline quaternary ammonium salt.

3. The corrosion inhibitor according to claim 2, characterized in that The mass ratio of carboxypropyltrimethylammonium chloride chitosan to dodecenylamineethylimidazoline quaternary ammonium salt in the quaternary ammonium salt is 4:

1.

4. The corrosion inhibitor according to any one of claims 1 to 3, characterized in that The polyaspartic acid derivative is a mixed solvent of 1,3,5-trimethylbenzene and cyclopentane sulfone, and is prepared by a thermal condensation reaction to prepare an intermediate, which is further condensed to obtain the product.

5. The corrosion inhibitor according to any one of claims 1 to 3, characterized in that The dispersant is sodium dodecylbenzene sulfonate.

6. The corrosion inhibitor according to any one of claims 1 to 3, characterized in that The solvent is deionized water.

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