A method for evaluating the protective performance of anti-corrosion coatings

Abstract

The present invention belongs to the technical field of anti-corrosion coatings, and discloses a method for evaluating the protectiveness of anti-corrosion coatings. In the present invention, one end of two electrolytic cells is respectively sealed with the same anti-corrosion coating to be tested, and the other end is respectively sealed with a counter electrode, and the leads of the two counter electrodes are connected in parallel to the electrochemical workstation; the dual electrolytic cell system is used to perform an electrochemical AC impedance test, and the impedance value of the anti-corrosion coating is obtained according to the test results; and the protectiveness of the anti-corrosion coating is evaluated according to the impedance value. The detection method of the present invention can realize non-destructive testing on in-service coatings, and at the same time, the protective performance of the coating can be quickly evaluated according to the impedance value of the coating, so as to achieve the effect of predicting or repairing the coating in advance. The dual electrolytic cell system of the present invention adopts a system without a reference electrode, which can reduce the uncertainty brought about in the test process, and also eliminates the polarization effect brought about by current loading, and reduces the voltage requirements for the detection equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion coatings, and in particular to a method for evaluating the protectiveness of anti-corrosion coatings. Background Art

[0002] Metal materials are susceptible to corrosion from the surrounding media, resulting in a range of adverse effects. Using coatings to prevent metal surface corrosion is an effective anti-corrosion method, currently widely used in production and has led to the development of a range of anti-corrosion coatings. Different anti-corrosion coatings offer varying degrees of protection for metal substrates. Furthermore, as protection time increases, the corrosion rate gradually increases, and protective performance decreases. Therefore, multiple coating tests are necessary to evaluate protective performance, prevent coating damage, and minimize losses during the metal's service life.

[0003] Currently, electrochemical testing is one of the primary methods for studying the protective properties of anti-corrosion coatings. However, electrochemical testing typically requires simulating the corrosion process of the coating and using simulated specimens, which prevents in-situ nondestructive testing of active coatings. Furthermore, existing testing methods take a long time to complete, making them unsuitable for testing the protective properties of large quantities of coatings.

[0004] Therefore, how to provide a fast, accurate and non-destructive in-situ detection method for the protective performance of anti-corrosion coatings is of great value to the development of anti-corrosion technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for evaluating the protectiveness of an anti-corrosion coating, so as to solve the problem that the existing coating protectiveness detection method cannot perform in-situ, non-destructive and rapid detection.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for evaluating the protectiveness of an anti-corrosion coating, comprising the following steps:

[0008] (1) Electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to counter electrode A and counter electrode B, and the leads of counter electrode A and counter electrode B are connected in parallel to the electrochemical workstation; electrolyte is injected into electrolytic cell A and electrolytic cell B respectively to obtain a dual electrolytic cell system;

[0009] (2) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test and obtaining the results of the electrochemical impedance spectroscopy test;

[0010] (3) Obtaining the impedance value of the anti-corrosion coating based on the results of the electrochemical AC impedance test; and evaluating the protectiveness of the anti-corrosion coating based on the impedance value of the anti-corrosion coating.

[0011] Preferably, in the above-mentioned method for evaluating the protectiveness of an anti-corrosion coating, the counter electrode A and the counter electrode B in step (1) are independently platinum electrodes.

[0012] Preferably, in the above-mentioned method for evaluating the protectiveness of an anti-corrosion coating, the electrolytes injected into electrolytic cell A and electrolytic cell B in step (1) are independently 3.5 wt% sodium chloride solutions.

[0013] Preferably, in the above-mentioned method for evaluating the protectiveness of an anti-corrosion coating, the test frequency of the electrochemical AC impedance test in step (2) is 10000 to 0.01 Hz; and the amplitude of the sinusoidal wave disturbance signal is 10 to 20 mV.

[0014] Preferably, in the above-mentioned method for evaluating the protectiveness of an anti-corrosion coating, the impedance value of the anti-corrosion coating in step (3) is half of the maximum impedance modulus value in the result of the electrochemical AC impedance test.

[0015] Preferably, in the above-mentioned method for evaluating the protectiveness of the anti-corrosion coating, the method for evaluating the protectiveness of the anti-corrosion coating according to the impedance value of the anti-corrosion coating in step (3) is as follows: the protectiveness of the anti-corrosion coating is divided into four levels, and when the impedance value of the anti-corrosion coating is ≥10 9 Ω·cm 2 When 10 7 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 9 Ω·cm 2 When 10 3 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 7 Ω·cm 2 When the resistance value of the anti-corrosion coating is less than 10 3 Ω·cm 2 When the corrosion protection is poor.

[0016] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The detection method of the present invention can realize non-destructive testing on in-service coatings without the need for simulated specimens and will not cause irreversible effects on the coatings. At the same time, the protective performance of the coatings can be quickly evaluated based on the impedance value of the coatings, thereby achieving the effect of predicting or repairing the coatings in advance, avoiding the uncertain risks of repairing the coatings after they are damaged.

[0018] (2) The dual electrolytic cell system of the present invention adopts a system without a reference electrode, which can reduce the uncertainty brought about by the test process, eliminate the polarization effect caused by current loading, and reduce the voltage requirement of the detection equipment. DETAILED DESCRIPTION

[0019] The present invention provides a method for evaluating the protectiveness of an anti-corrosion coating, comprising the following steps:

[0020] (1) Electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to counter electrode A and counter electrode B, and the leads of counter electrode A and counter electrode B are connected in parallel to the electrochemical workstation; electrolyte is injected into electrolytic cell A and electrolytic cell B respectively to obtain a dual electrolytic cell system;

[0021] (2) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test and obtaining the results of the electrochemical impedance spectroscopy test;

[0022] (3) Obtaining the impedance value of the anti-corrosion coating based on the results of the electrochemical AC impedance test; and evaluating the protectiveness of the anti-corrosion coating based on the impedance value of the anti-corrosion coating.

[0023] In the present invention, the anti-corrosion coating to be tested in step (1) also includes cleaning before setting up the dual electrolytic cell system; the cleaning method is preferably to use water to rinse for 30 to 200 seconds, more preferably 70 to 170 seconds, and more preferably 130 seconds.

[0024] In the present invention, the counter electrode A and the counter electrode B in step (1) are preferably independently platinum electrodes.

[0025] In the present invention, the electrolytes injected into electrolytic cell A and electrolytic cell B in step (1) are preferably independently 3.5 wt% sodium chloride solutions.

[0026] In the present invention, the method for sealingly connecting the anti-corrosion coating to be tested, the electrolytic cell, and the counter electrode in step (1) is not limited by the present invention, and the connection can be performed using the existing sealed detection device in the art.

[0027] In the present invention, the test frequency of the electrochemical impedance spectroscopy test in step (2) is preferably 10000-0.01 Hz; the amplitude of the sinusoidal wave disturbance signal is preferably 10-20 mV, more preferably 12-17 mV, and even more preferably 15 mV.

[0028] In the present invention, the result of the electrochemical impedance spectroscopy test in step (3) is analyzed according to the Randle equivalent circuit model.

[0029] In the present invention, the impedance value of the anti-corrosion coating in step (3) is preferably half of the maximum impedance modulus value in the results of the electrochemical AC impedance test.

[0030] In the present invention, the method for evaluating the protectiveness of the anti-corrosion coating according to the impedance value of the anti-corrosion coating in step (3) is as follows: the protectiveness of the anti-corrosion coating is divided into four levels, and when the impedance value of the anti-corrosion coating is ≥10 9 Ω·cm 2 When 10 7 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 9 Ω·cm 2 When 10 3 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 7 Ω·cm 2 When the resistance value of the anti-corrosion coating is less than 10 3 Ω·cm 2 When the corrosion protection is poor.

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] (1) The anti-corrosion coating A was cleaned with deionized water for 100 seconds and then dried to obtain the anti-corrosion coating to be tested;

[0034] (2) electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to platinum electrode A and platinum electrode B, and the leads of platinum electrode A and platinum electrode B are connected in parallel to the electrochemical workstation; electrolyte (3.5wt% sodium chloride solution) is injected into electrolytic cell A and electrolytic cell B respectively, so that the electrolyte is in full contact with the anti-corrosion coating to be detected, thereby obtaining a dual electrolytic cell system;

[0035] (3) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test at a test frequency of 10,000 to 0.01 Hz and a sinusoidal wave disturbance signal amplitude of 10 mV, and obtaining the results of the electrochemical impedance spectroscopy test;

[0036] (4) The impedance value of the anti-corrosion coating is calculated to be 2.7×10 9 Ω·cm 2 , thus it can be seen that the protection of the anti-corrosion coating A is extremely excellent.

[0037] Example 2

[0038] (1) The anti-corrosion coating B was cleaned with deionized water for 60 seconds and then dried to obtain the anti-corrosion coating to be tested;

[0039] (2) electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to platinum electrode A and platinum electrode B, and the leads of platinum electrode A and platinum electrode B are connected in parallel to the electrochemical workstation; electrolyte (3.5wt% sodium chloride solution) is injected into electrolytic cell A and electrolytic cell B respectively, so that the electrolyte is in full contact with the anti-corrosion coating to be detected, thereby obtaining a dual electrolytic cell system;

[0040] (3) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test at a test frequency of 10,000 to 0.01 Hz and a sinusoidal wave disturbance signal amplitude of 20 mV, and obtaining the results of the electrochemical impedance spectroscopy test;

[0041] (4) The impedance value of the anti-corrosion coating is calculated to be 6.1×10 8 Ω·cm 2 , thus it can be seen that the protection of the anti-corrosion coating B is good.

[0042] Example 3

[0043] (1) The anti-corrosion coating C was cleaned with deionized water for 200 seconds and then dried to obtain the anti-corrosion coating to be tested;

[0044] (2) electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to platinum electrode A and platinum electrode B, and the leads of platinum electrode A and platinum electrode B are connected in parallel to the electrochemical workstation; electrolyte (3.5wt% sodium chloride solution) is injected into electrolytic cell A and electrolytic cell B respectively, so that the electrolyte is in full contact with the anti-corrosion coating to be detected, thereby obtaining a dual electrolytic cell system;

[0045] (3) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test at a test frequency of 10,000 to 0.01 Hz and a sinusoidal wave disturbance signal amplitude of 10 mV, and obtaining the results of the electrochemical impedance spectroscopy test;

[0046] (4) The impedance value of the anti-corrosion coating is calculated to be 3.9×10 4 Ω·cm 2 , thus it can be concluded that the protective performance of the anti-corrosion coating C is acceptable.

[0047] Example 4

[0048] (1) The anti-corrosion coating D was cleaned with deionized water for 180 seconds and then dried to obtain the anti-corrosion coating to be tested;

[0049] (2) electrolytic cell A and electrolytic cell B are placed side by side on the same anti-corrosion coating to be detected, one end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to the same anti-corrosion coating to be detected, and the other end of electrolytic cell A and electrolytic cell B are respectively sealed and connected to platinum electrode A and platinum electrode B, and the leads of platinum electrode A and platinum electrode B are connected in parallel to the electrochemical workstation; electrolyte (3.5wt% sodium chloride solution) is injected into electrolytic cell A and electrolytic cell B respectively, so that the electrolyte is in full contact with the anti-corrosion coating to be detected, thereby obtaining a dual electrolytic cell system;

[0050] (3) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test at a test frequency of 10,000 to 0.01 Hz and a sinusoidal wave disturbance signal amplitude of 15 mV, and obtaining the results of the electrochemical impedance spectroscopy test;

[0051] (4) The impedance value of the anti-corrosion coating is calculated to be 72Ω·cm based on half of the maximum impedance modulus value in the electrochemical AC impedance test results. 2 , it can be concluded that the protection of the anti-corrosion coating D is poor and the anti-corrosion coating is damaged.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for evaluating the protectiveness of an anti-corrosion coating, characterized in that: The following steps are involved: (1) Place electrolytic cell A and electrolytic cell B side by side on the same anti-corrosion coating to be tested. One end of electrolytic cell A and electrolytic cell B are respectively sealed with the same anti-corrosion coating to be tested. The other end of electrolytic cell A and electrolytic cell B are respectively sealed with counter electrode A and counter electrode B. The leads of counter electrode A and counter electrode B are connected in parallel to the electrochemical workstation. The electrolyte is injected into electrolytic cell A and electrolytic cell B respectively to obtain a dual electrolytic cell system; (2) starting the dual electrolytic cell system to perform an electrochemical impedance spectroscopy test and obtaining the results of the electrochemical impedance spectroscopy test; (3) Obtaining the impedance value of the anti-corrosion coating based on the results of the electrochemical AC impedance test; evaluating the protectiveness of the anti-corrosion coating based on the impedance value of the anti-corrosion coating; In step (1), both the counter electrode A and the counter electrode B are platinum electrodes; In step (1), the electrolyte injected into electrolytic cell A and electrolytic cell B is a 3.5 wt% sodium chloride solution; The method for evaluating the protectiveness of the anti-corrosion coating according to the impedance value of the anti-corrosion coating in step (3) is as follows: the protectiveness of the anti-corrosion coating is divided into four levels, and when the impedance value of the anti-corrosion coating is ≥10 9 Ω·cm 2 When 10 7 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 9 Ω·cm 2 When 10 3 Ω·cm 2 ≤Impedance value of anti-corrosion coating<10 7 Ω·cm 2 When the resistance value of the anti-corrosion coating is less than 10 3 Ω·cm 2 When the corrosion protection is poor.

2. The method for evaluating the protectiveness of an anti-corrosion coating according to claim 1, characterized in that: The test frequency of the electrochemical AC impedance test in step (2) is 10000~0.01Hz; the amplitude of the sinusoidal wave disturbance signal is 10~20mV.

3. The method for evaluating the protectiveness of an anti-corrosion coating according to claim 2, wherein: The impedance value of the anti-corrosion coating in step (3) is half of the maximum impedance modulus value in the result of the electrochemical AC impedance test.