A galvanic corrosion sensor, preparation method and application

Abstract

The present invention belongs to the technical field of corrosion detection, and discloses a galvanic corrosion sensor, including an anode, an insulating layer and a cathode stacked in sequence, wherein the anode and the cathode are both connected to electrode lead wires; wherein the insulating layer is hydrophilic. The galvanic corrosion sensor of the embodiment of the present invention modifies the insulating layer from hydrophobic to hydrophilic, thereby increasing the amount of water molecules adsorbed on the surface of the insulating layer, which is beneficial to the establishment of a water film between the two electrodes; moreover, the thickness of the insulating layer is precisely controlled, that is, the gap between the two electrodes is precisely controlled within a smaller range, thereby increasing the ability of the insulating layer surface to adsorb water molecules. Under the same humidity conditions, its surface is more likely to form an adsorbed water film than the electrode surface to make the two electrodes conductive, thereby increasing the sensitivity to the environmental humidity response. The embodiment of the present invention also provides a preparation method and application of a galvanic corrosion sensor.

Description

Technical Field

[0001] The present invention relates to the field of corrosion detection technology, and in particular to a galvanic corrosion sensor for detecting atmospheric corrosion current of metal materials, a method for preparing the galvanic corrosion sensor, a method for detecting atmospheric corrosion current of metal materials, and a detection circuit for atmospheric corrosion current of metal materials. Background Art

[0002] The annual loss caused by corrosion can account for 3.5% of the gross national product, and atmospheric corrosion accounts for more than half of this. Studying the atmospheric corrosion behavior and laws of materials and understanding the corrosion process of materials in the atmospheric environment are very important for improving the level of corrosion protection and reducing the harm caused by atmospheric corrosion.

[0003] However, atmospheric corrosion of materials proceeds at a very slow rate. The accelerated test methods often change the original corrosion behavior and laws, and the test results are quite different from the actual ones. Existing attempts to continuously monitor the atmospheric corrosion rate of materials using various electrochemical methods including electrochemical impedance and electrochemical noise always indirectly reflect the changes in the corrosion rate, but cannot obtain the true corrosion rate.

[0004] Corrosion current is the only parameter that directly reflects the corrosion rate of metals. However, the corrosion current of the metal material itself cannot be detected directly. It can only be reflected by the current between the two electrodes by introducing an artificial cathode to form a galvanic corrosion sensor with the metal. However, after the introduction of the artificial cathode, the detected galvanic corrosion current value exceeds the corrosion current value when the metal material itself exists, and the galvanic corrosion sensor only reflects the change in the corrosion rate of the metal material. In addition, the existing galvanic corrosion sensors can only detect the change in the corrosion rate of metal materials under conditions of high humidity (>70% RH), but have no response to the corrosion changes of metal materials under conditions of low humidity. This is because under low humidity conditions, a continuous liquid film cannot be formed on the surface of the material, and there is an insulating layer between the artificial cathode and the metal anode. The two are difficult to be connected together by the liquid film, and an effective galvanic pair cannot be formed between the two electrodes, and no current can be formed between the two electrodes.

[0005] Therefore, how to provide a sensor that is sensitive to atmospheric humidity and a method that can accurately detect atmospheric corrosion current of metal materials is a problem that needs to be solved urgently. Summary of the invention

[0006] The embodiments of the present invention provide a galvanic corrosion sensor, a preparation method and an application, which solve the technical problem that the sensors in the prior art are insensitive to the humidity of the atmospheric environment. In order to have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important components or to describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a galvanic corrosion sensor is provided.

[0008] In one embodiment, a galvanic corrosion sensor includes an anode, an insulating layer, and a cathode stacked in sequence, wherein the anode and the cathode are both connected to electrode lead wires; wherein the insulating layer is hydrophilic.

[0009] Optionally, the thickness of the insulating layer is 3 μm-25 μm.

[0010] Optionally, the thickness of the insulating layer is 3 μm.

[0011] Optionally, the thickness of the insulating layer is 5 μm.

[0012] Optionally, the thickness of the insulating layer is 10 μm.

[0013] Optionally, the thickness of the insulating layer is 15 μm.

[0014] Optionally, the thickness of the insulating layer is 20 μm.

[0015] Optionally, the thickness of the insulating layer is 25 μm.

[0016] Optionally, the anode is a metal electrode, and the cathode is an inert conductive material electrode.

[0017] Optionally, the cathode is a carbon film electrode.

[0018] Optionally, the cathode is a platinum electrode.

[0019] Optionally, the cathode is a gold electrode.

[0020] According to a second aspect of an embodiment of the present invention, a method for preparing the above-mentioned galvanic corrosion sensor is provided, wherein the insulating layer is surface modified by corona discharge.

[0021] Optionally, the step of surface modifying the insulating layer by corona discharge comprises:

[0022] A needle electrode is used as a high-voltage electrode and is vertically placed on the upper part of the modified surface of the insulating layer; a flat plate electrode is used as a grounding electrode and is placed on the side of the modified surface of the insulating layer and at a height lower than the modified surface of the insulating layer;

[0023] Apply AC or DC voltage between the needle electrode and the plate electrode to form a corona discharge;

[0024] During the discharge process, the needle electrode is moved so that the surface of the insulating layer is completely modified.

[0025] According to a third aspect of an embodiment of the present invention, a method for preparing the above-mentioned galvanic corrosion sensor is provided, wherein the insulating layer is surface-modified by strong acid oxidation.

[0026] According to a fourth aspect of an embodiment of the present invention, a method for detecting atmospheric corrosion current of a metal material is provided.

[0027] In one embodiment, a method for detecting the atmospheric corrosion rate of a metal material is provided, wherein the above-mentioned galvanic corrosion sensor is placed in a test environment to conduct a corrosion experiment, a resistor with a calibrated resistance is connected in series between the detection instrument and the galvanic corrosion sensor, and the corrosion current of the galvanic corrosion sensor is detected. The corrosion current of the galvanic corrosion sensor is the corrosion current of a metal material of the same material as the anode metal of the galvanic corrosion sensor under the test environment.

[0028] Optionally, the calibrated value of the resistor is obtained by the following steps:

[0029] A resistor is set between the galvanic corrosion sensor and the detection instrument, and the galvanic corrosion sensor and a metal test piece of the same material as the anode of the galvanic corrosion sensor are subjected to corrosion test under the same test conditions;

[0030] Adjust the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values;

[0031] A resistor having a calibrated resistance is determined, and a resistance value having a deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece within a preset range is selected as the resistance calibration value.

[0032] Optionally, the initial mass of the metal sample and the mass of the metal sample after corrosion are weighed using the same electronic balance, and the difference from the initial mass is the corrosion amount of the metal sample, which is then converted into the corrosion amount per unit area of ​​the metal sample.

[0033] Optionally, the step of adjusting the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values ​​includes:

[0034] The corrosion electricity under different resistance values ​​is obtained:

[0035] Q = ∑(i·t)

[0036] Q is the corrosion quantity, i is the corrosion current; t is the test time;

[0037] The apparent corrosion amount under different resistance values ​​is calculated from the corrosion quantity under different resistance values:

[0038]

[0039] W is the apparent corrosion amount; Z is the molar mass of the anode metal of the galvanic corrosion sensor; F is the Faraday constant; n is the valence of the anode metal of the galvanic corrosion sensor after corrosion;

[0040] The apparent corrosion amount under different resistance values ​​is converted into the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values:

[0041]

[0042] V is the corrosion amount per unit area of ​​the galvanic corrosion sensor; S is the effective area of ​​the galvanic corrosion sensor.

[0043] Optionally, the step of selecting a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range as the resistance calibration value comprises:

[0044] Among the obtained corrosion amounts per unit area of ​​the galvanic corrosion sensor, the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal test piece is selected;

[0045] Using the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor closest to the corrosion amount per unit area of ​​the metal test sample as a reference, the resistance value is adjusted upward or downward to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor corresponding to the adjusted resistance value;

[0046] Repeat the above steps until the deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range, and select the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor as the resistance calibration value.

[0047] Optionally, the preset range is 3% to 10%.

[0048] Optionally, the step of subjecting the galvanic corrosion sensor and a metal specimen made of the same material as the anode of the galvanic corrosion sensor to corrosion testing under the same test conditions is: placing the galvanic corrosion sensor and the metal specimen in an atmospheric environment test chamber at the same time, setting temperature and humidity conditions, and conducting an atmospheric environment corrosion test.

[0049] According to a fifth aspect of an embodiment of the present invention, a detection circuit for atmospheric corrosion current of a metal material is provided.

[0050] In one embodiment, a detection circuit for atmospheric corrosion current of metal materials includes the above-mentioned galvanic corrosion sensor and detection instrument, and a resistor with a calibrated resistance is connected in series between the galvanic corrosion sensor and the detection instrument.

[0051] Optionally, the calibration value of the resistor is a resistance value at which the deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range.

[0052] Optionally, one end of the resistor is connected to one of the lead wires of the galvanic corrosion sensor, and the other end is connected to one end of the detection instrument, and the other end of the detection instrument is connected to another lead wire of the galvanic corrosion sensor;

[0053] The resistor is arranged close to the detection instrument, or close to the galvanic corrosion sensor.

[0054] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0055] A galvanic corrosion sensor is proposed. The insulating layer of the galvanic corrosion sensor is hydrophilic, which increases the amount of water molecules adsorbed on the surface of the insulating layer, which is conducive to the establishment of a water film between the two electrodes. Under the same humidity conditions, the surface of the insulating layer is more likely to form an adsorbed water film than the electrode surface to make the two electrodes conductive, thereby improving the sensitivity of the response to environmental humidity and realizing accurate detection of the corrosion current of metal materials under a wide humidity range.

[0056] The present invention also provides a method and circuit for detecting atmospheric corrosion current of metal materials. A resistor is connected in series in the detection circuit to weaken the accelerating effect of the cathode on the corrosion of the metal material. The resistance value whose deviation between the corrosion amount per unit area of ​​the series-connected galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test sample is within a preset range is used as the resistance calibration value. This makes the current value between the galvanic couples the same as the corrosion current value when the metal material exists alone, and the corrosion current of the metal material can be accurately detected.

[0057] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0059] Figure 1 is a schematic structural diagram of a galvanic corrosion sensor according to an exemplary embodiment;

[0060] Figure 2 is a flow chart of a method for obtaining a resistance calibration value according to an exemplary embodiment;

[0061] Figure 3 is a schematic diagram of an experimental principle for obtaining a resistance calibration value according to an exemplary embodiment;

[0062] Figure 4 The diagram is a schematic diagram of a detection circuit for atmospheric corrosion current of metal materials according to an exemplary embodiment. DETAILED DESCRIPTION

[0063] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0064] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0065] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0066] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0067] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0068] Figure 1 One embodiment of the galvanic corrosion sensor of the present invention is shown.

[0069] In this embodiment, the galvanic corrosion sensor comprises an anode 3, an insulating layer 2 and a cathode 1 stacked in sequence, the anode 3 and the cathode 1 are both connected to electrode lead wires 4, and the insulating layer is hydrophilic.

[0070] The above embodiment changes the insulating layer from hydrophobic to hydrophilic, increases the amount of water molecules adsorbed on the surface of the insulating layer, and is conducive to the establishment of a water film between the two electrodes. In addition, the thickness of the insulating layer is precisely controlled, that is, the gap between the two electrodes is precisely controlled within a small range, which increases the ability of the insulating layer surface to adsorb water molecules. Under the same humidity conditions, its surface is more likely to form an adsorbed water film than the electrode surface to make the two electrodes conductive, thereby improving the sensitivity of the response to environmental humidity and realizing accurate detection of the corrosion current of metal materials under a wide range of humidity conditions.

[0071] Optionally, the anode is a metal electrode. Optionally, the cathode is an inert conductive material electrode. Optionally, the anode is a zinc electrode. Optionally, the anode is a steel electrode. Of course, those skilled in the art can also use metals of other materials as anodes according to the needs of detection. Optionally, the cathode is a carbon film electrode. Of course, those skilled in the art can also use other inert conductive materials as cathodes, such as gold or platinum, according to the needs of detection. Optionally, the thickness of the insulating layer is 3μm-25μm.

[0072] Optionally, the thickness of the insulating layer is 3 μm.

[0073] Optionally, the thickness of the insulating layer is 5 μm.

[0074] Optionally, the thickness of the insulating layer is 10 μm.

[0075] Optionally, the thickness of the insulating layer is 15 μm.

[0076] Optionally, the thickness of the insulating layer is 20 μm.

[0077] Optionally, the thickness of the insulating layer is 25 μm.

[0078] Optionally, a plurality of through holes penetrating the anode 3, the insulating layer 2 and the cathode 1 are provided on the galvanic corrosion sensor body.

[0079] In another embodiment, a method for preparing the galvanic corrosion sensor is provided, wherein the insulating layer is surface-modified by corona discharge to change the insulating layer from being hydrophobic to being hydrophilic.

[0080] Optionally, the step of surface modification of the insulating layer by corona discharge comprises: before the sensor is assembled, using a needle electrode as a high-voltage electrode and vertically placing it on the upper part of the modified surface of the insulating layer; using a flat electrode as a grounding electrode, placing it on the side of the modified surface of the insulating layer, and the height is slightly lower than the modified surface of the insulating layer, for example, the flat electrode is placed on one of the four sides of the modified surface of the insulating layer, namely the front, rear, left and right, or the flat electrode is placed on the back of the modified surface of the insulating layer, and the height is slightly lower than the modified surface of the insulating layer; applying an AC or DC voltage, preferably an AC or DC high voltage, between the needle electrode and the flat electrode to form a corona discharge; during the discharge process, slowly moving the needle electrode to completely modify the modified surface of the insulating layer.

[0081] In another embodiment, a method for preparing the galvanic corrosion sensor is also proposed, wherein the insulating layer is surface-modified by strong acid oxidation to change the insulating layer from hydrophobic to hydrophilic. Optionally, a strong acid solution is applied to the modified surface of the insulating layer of the galvanic corrosion sensor to change the insulating layer from hydrophobic to hydrophilic. Optionally, the strong acid solution is a sulfuric acid solution or a nitric acid solution.

[0082] In another embodiment, a method for detecting atmospheric corrosion current of metal materials is also proposed. The galvanic corrosion sensors of the above embodiments are placed in a test environment for corrosion experiments. A resistor with a calibrated resistance is connected in series between the galvanic corrosion sensor and the detection instrument to detect the corrosion current of the galvanic corrosion sensor. The corrosion current of the galvanic corrosion sensor is the corrosion current of the metal material of the same material as the anode metal of the galvanic corrosion sensor under the test environment. Optionally, a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range is selected as the resistance calibration value.

[0083] In the detection method of the embodiment of the present invention, a resistor with a calibrated resistance is connected in series between the galvanic corrosion sensor and the detection instrument, which weakens the accelerating effect of the cathode on the corrosion of the metal material, and realizes the accurate detection of the corrosion current of the metal material by the galvanic corrosion sensor. One end of the resistor is connected to the galvanic corrosion sensor, and the other end is connected to one end of the detection instrument, and the other end of the detection instrument is connected to the galvanic corrosion sensor.

[0084] The galvanic corrosion current value obtained by the detection method in the embodiment of the present invention achieves that the current value between the galvanic couples is the same as the corrosion current value when the metal material exists alone, can truly reflect the metal corrosion rate value, and realize the leap from qualitative to quantitative detection of metal material corrosion rate by galvanic corrosion sensors.

[0085] For atmospheric corrosion environments, different metal materials need to obtain the calibration value of the resistor connected in series between the galvanic corrosion sensor and the detection instrument. For atmospheric corrosion environments, the difference in corrosive factors has little effect on the calibration value of the resistor connected in series between the galvanic corrosion sensor and the detection instrument. The calibration value of the resistor obtained by the corrosion test under a set of corrosive factor conditions can also be applied to other set corrosive factor conditions.

[0086] In one embodiment, Figure 2 and Figure 3 As shown, the calibration value of the above resistor is obtained by the following steps:

[0087] Step S1, setting a resistor between the galvanic corrosion sensor and the detection instrument;

[0088] Step S2, placing the galvanic corrosion sensor and the metal sample into a corrosion test box, wherein the metal sample and the anode of the galvanic corrosion sensor are made of the same material, and performing a corrosion test under controlled environmental conditions;

[0089] Step S3, cleaning the corrosion products on the surface of the metal sample and weighing it. The difference between the weight and the initial weight is the corrosion amount of the metal sample, and the corrosion amount is converted into the corrosion amount per unit area of ​​the metal sample;

[0090] Step S4, adjusting the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor corresponding to different resistance values;

[0091] Step S5, determining a resistor whose resistance is a calibration value, and selecting a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range as the resistance calibration value.

[0092] The resistance calibration value is obtained by the method of the above embodiment. Connecting the resistance of the calibration value in series between the galvanic corrosion sensor and the detection instrument can weaken the accelerating effect of the cathode on the corrosion of the metal material, so that the current value between the galvanic couple is the same as the corrosion current value when the metal material exists alone. The galvanic corrosion current value can truly reflect the metal corrosion rate value, thereby realizing the leap from qualitative to quantitative detection of the corrosion rate of metal materials by the galvanic corrosion sensor.

[0093] Optionally, the corrosion products on the surface of the metal specimen are cleaned according to the method of standard GB / T16545-2015.

[0094] Optionally, in step S3, the initial mass of the metal sample and the mass of the metal sample after corrosion are weighed using the same electronic balance, and the difference from the initial mass is the corrosion amount of the metal sample, which is then converted into the corrosion amount per unit area of ​​the metal sample.

[0095] Optionally, in step S4, the step of adjusting the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values ​​includes: accumulating the corrosion current detected under different resistance values ​​to obtain the corrosion quantity under different resistance values ​​respectively:

[0096] Q = ∑(i·t)

[0097] Q is the corrosion quantity, i is the corrosion current; t is the test time;

[0098] According to Faraday's law, the apparent corrosion amount under different resistance values ​​is calculated from the corrosion electricity under different resistance values:

[0099]

[0100] W is the apparent corrosion amount, i.e., the corrosion amount calculated according to the detection results of the galvanic corrosion sensor; Z is the molar mass of the anode metal of the galvanic corrosion sensor; F is the Faraday constant; n is the valence of the anode metal of the galvanic corrosion sensor after corrosion. For example, if copper is selected as the anode metal material of the galvanic corrosion sensor, the valence of copper after corrosion is 2; if iron is selected as the anode metal material of the galvanic corrosion sensor, the valence of iron during the corrosion process includes 2 and 3, and n is the final valence of iron after corrosion, i.e., 3;

[0101] The apparent corrosion amount under different resistance values ​​is converted into the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values:

[0102]

[0103] V is the corrosion amount per unit area of ​​the galvanic corrosion sensor; S is the effective area of ​​the galvanic corrosion sensor.

[0104] Optionally, in step S5, the step of selecting a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal specimen is within a preset range as the resistance calibration value includes: selecting the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal specimen from the acquired corrosion amounts per unit area of ​​the galvanic corrosion sensor; adjusting the resistance value upward or downward using the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal specimen as a reference, and further obtaining the corrosion amount per unit area of ​​the galvanic corrosion sensor corresponding to the adjusted resistance value; repeating the above steps until the deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal specimen is within a preset range, and selecting the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor as the resistance calibration value.

[0105] Optionally, the preset range is 3% to 10%. Optionally, the preset range is 3%. Optionally, the preset range is 4%. Optionally, the preset range is 5%. Optionally, the preset range is 6%. Optionally, the preset range is 7%. Optionally, the preset range is 8%. Optionally, the preset range is 9%. Optionally, the preset range is 10%.

[0106] A specific embodiment of the method for obtaining the above resistance calibration value is given below.

[0107] A zero internal resistance ammeter is used as the detection instrument, and the anode of the galvanic corrosion sensor is made of pure zinc.

[0108] An adjustable resistor is connected in series between the galvanic corrosion sensor and the zero internal resistance ammeter, and the resistance values ​​are selected as 20Ω, 200Ω, 2000Ω, 10MΩ and 80MΩ respectively.

[0109] The corrosion test piece is made of pure zinc, which is the same material as the anode in the galvanic corrosion sensor. The initial mass of the pure zinc test piece is weighed with an electronic balance with an accuracy of 0.00001g. The galvanic corrosion sensor and the zinc test piece are placed in the atmospheric environment test chamber at the same time, and the temperature and humidity are set to the set values ​​to conduct the atmospheric environment corrosion test. The adjustable resistor is set outside the atmospheric environment test chamber.

[0110] According to the method of standard GB / T16545-2015, the corrosion products on the surface of the zinc test piece were cleaned, and the mass of the zinc test piece after corrosion was weighed with the same electronic balance. The difference between the mass and the initial mass was the corrosion amount, which was then converted into the corrosion amount per unit area.

[0111] The resistance value of the adjustable resistor is adjusted, and the continuous detection current values ​​under different resistance values ​​are accumulated to calculate the corrosion quantity corresponding to different resistance values. According to Faraday's law, the apparent corrosion quantity under different resistance values ​​is calculated from the corrosion quantity under different resistance values, and the apparent corrosion quantity under different resistance values ​​is combined with the surface area of ​​the galvanic corrosion sensor to convert it into the corrosion quantity per unit area of ​​the galvanic corrosion sensor under different resistance values.

[0112] Compare the obtained corrosion amount per unit area of ​​the galvanic corrosion sensor with the corrosion amount per unit area of ​​the zinc sample, and select the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal sample from among the multiple corrosion amounts per unit area of ​​the galvanic corrosion sensors obtained, and adjust the resistance value upward or downward based on the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal sample; repeat the above steps until the deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal sample is within 5%, and select the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor as the resistance calibration value.

[0113] Optionally, the metal test piece may also be made of other metal materials, such as steel.

[0114] In another embodiment, the present invention also provides a metal material corrosion current detection circuit, such as Figure 4 As shown, the detection circuit includes the above-mentioned galvanic corrosion sensor and the detection instrument, and a resistor with a calibrated resistance is connected in series between the galvanic corrosion sensor and the detection instrument. The calibrated resistance is obtained based on the method of determining the resistor with a calibrated resistance in each of the above-mentioned embodiments. The resistor with the calibrated resistance is connected in series between the galvanic corrosion sensor and the detection instrument to achieve accurate detection of atmospheric corrosion of metal materials by the galvanic corrosion sensor. The resistor with the calibrated resistance connected in series in the detection circuit can weaken the accelerating effect of the cathode on the corrosion of the metal material, achieve the same current value between the galvanic couples as the corrosion current value when the metal material exists alone, and achieve accurate detection of the corrosion current of the metal material.

[0115] One end of the resistor is connected to the metal electrode 3 of the galvanic corrosion sensor through an electrode lead wire, and one end is connected to a detection instrument, and the other end of the detection instrument is connected to the carbon film electrode 1 through another electrode lead wire; or one end of the resistor is connected to the carbon film electrode 1 through an electrode lead wire, and one end is connected to a detection instrument, and the other end of the detection instrument is connected to the metal electrode 3 of the galvanic corrosion sensor through another electrode lead wire.

[0116] The resistor can be arranged close to the galvanic corrosion sensor and arranged together with the galvanic corrosion sensor in the environmental test chamber. The resistor can also be arranged close to the detection instrument and arranged outside the environmental test chamber. Optionally, the above resistor is a package resistor.

[0117] Optionally, the above-mentioned detection instrument is a zero-resistance ammeter.

[0118] The current value between the galvanic couples obtained by the detection circuit according to the embodiment of the present invention is the same as the corrosion current value when the metal material exists alone, thereby achieving accurate detection of the corrosion current of the metal material.

[0119] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for detecting atmospheric corrosion current of metal materials, characterized in that: The galvanic corrosion sensor is placed in a test environment to conduct a corrosion experiment, a resistor with a calibrated resistance is connected in series between the detection instrument and the galvanic corrosion sensor, and the corrosion current of the galvanic corrosion sensor is detected. The corrosion current of the galvanic corrosion sensor is the corrosion current of the metal material of the same material as the anode metal of the galvanic corrosion sensor in the test environment; The resistor with a calibrated resistance is obtained by the following steps: a resistor is set between the galvanic corrosion sensor and the detection instrument, and the galvanic corrosion sensor and a metal test piece made of the same material as the anode of the galvanic corrosion sensor are subjected to corrosion tests under the same test conditions; Adjust the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values; Selecting a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range as a resistance calibration value, and the resistance corresponding to the resistance calibration value is the resistance whose resistance value is the calibration value; The galvanic corrosion sensor comprises an anode, an insulating layer and a cathode stacked in sequence, and both the anode and the cathode are connected to electrode lead wires; the insulating layer is hydrophilic; the insulating layer is surface modified by corona discharge or by strong acid oxidation.

2. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The step of adjusting the resistance value to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor corresponding to different resistance values ​​includes: obtaining the corrosion quantity under different resistance values ​​respectively: Q = ∑(i·t) Q is the corrosion quantity, i is the corrosion current; t is the test time; The apparent corrosion amount under different resistance values ​​is calculated from the corrosion quantity under different resistance values: W is the apparent corrosion amount; Z is the molar mass of the anode metal of the galvanic corrosion sensor; F is the Faraday constant; n is the valence of the anode metal of the galvanic corrosion sensor after corrosion; The apparent corrosion amount under different resistance values ​​is converted into the corrosion amount per unit area of ​​the galvanic corrosion sensor under different resistance values: V is the corrosion amount per unit area of ​​the galvanic corrosion sensor; S is the effective area of ​​the galvanic corrosion sensor.

3. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The step of selecting a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal sample is within a preset range as the resistance calibration value comprises: selecting the corrosion amount per unit area of ​​the galvanic corrosion sensor that is closest to the corrosion amount per unit area of ​​the metal sample from the obtained corrosion amount per unit area of ​​the galvanic corrosion sensor; Using the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor closest to the corrosion amount per unit area of ​​the metal test sample as a reference, the resistance value is adjusted upward or downward to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor corresponding to the adjusted resistance value; Repeat the above steps until the deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range, and select the resistance value corresponding to the corrosion amount per unit area of ​​the galvanic corrosion sensor as the resistance calibration value.

4. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The preset range is 3% to 10%.

5. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The steps of subjecting the galvanic corrosion sensor and a metal specimen made of the same material as the anode of the galvanic corrosion sensor to corrosion testing under the same test conditions are as follows: placing the galvanic corrosion sensor and the metal specimen in an atmospheric environment test chamber at the same time, setting temperature and humidity conditions, and conducting an atmospheric environment corrosion test.

6. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The thickness of the insulating layer is 3 μm-25 μm.

7. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The thickness of the insulating layer is 3 μm, or 5 μm, or 10 μm, or 15 μm, or 20 μm, or 25 μm.

8. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The anode is a metal electrode, and the cathode is an inert conductive material electrode.

9. A method for detecting atmospheric corrosion current of a metal material as claimed in claim 1, characterized in that: The step of surface modification of the insulating layer by corona discharge comprises: A needle electrode is used as a high-voltage electrode and is vertically placed on the upper part of the modified surface of the insulating layer; a flat plate electrode is used as a grounding electrode and is placed on the side of the modified surface of the insulating layer and at a height lower than the modified surface of the insulating layer; Apply AC or DC voltage between the needle electrode and the plate electrode to form a corona discharge; During the discharge process, the needle electrode is moved so that the surface of the insulating layer is completely modified.

10. A detection circuit for atmospheric corrosion current of metal materials, characterized in that: It comprises a galvanic corrosion sensor and a detection instrument, wherein a resistor with a calibrated resistance value is connected in series between the galvanic corrosion sensor and the detection instrument; the resistor with the calibrated resistance value is obtained by the following steps: a resistor is set between the galvanic corrosion sensor and the detection instrument, and the galvanic corrosion sensor and a metal test piece made of the same material as the anode of the galvanic corrosion sensor are subjected to corrosion tests under the same test conditions; the resistance value is adjusted to obtain the corrosion amount per unit area of ​​the galvanic corrosion sensor under conditions of different resistance values; a resistance value whose deviation between the corrosion amount per unit area of ​​the galvanic corrosion sensor and the corrosion amount per unit area of ​​the metal test piece is within a preset range is selected as the resistance calibration value, and the resistor corresponding to the resistance calibration value is the resistor with the calibrated resistance value; wherein the galvanic corrosion sensor comprises an anode, an insulating layer and a cathode stacked in sequence, and the anode and the cathode are both connected to electrode lead wires; wherein the insulating layer is hydrophilic; and the insulating layer is surface modified by corona discharge or by strong acid oxidation.

11. A metal material atmospheric corrosion current detection circuit as claimed in claim 10, characterized in that: One end of the resistor is connected to one of the lead wires of the galvanic corrosion sensor, and the other end is connected to one end of the detection instrument, and the other end of the detection instrument is connected to the other lead wire of the galvanic corrosion sensor; The resistor is arranged close to the detection instrument, or close to the galvanic corrosion sensor.

12. A metal material atmospheric corrosion current detection circuit as claimed in claim 10, characterized in that: The thickness of the insulating layer is 3 μm-25 μm.

13. A metal material atmospheric corrosion current detection circuit as claimed in claim 10, characterized in that: The thickness of the insulating layer is 3 μm, or 5 μm, or 10 μm, or 15 μm, or 20 μm, or 25 μm.

14. A metal material atmospheric corrosion current detection circuit as claimed in claim 10, characterized in that: The anode is a metal electrode, and the cathode is an inert conductive material electrode.

15. A metal material atmospheric corrosion current detection circuit as claimed in claim 10, characterized in that: The step of surface modification of the insulating layer by corona discharge comprises: A needle electrode is used as a high-voltage electrode and is vertically placed on the upper part of the modified surface of the insulating layer; a flat plate electrode is used as a grounding electrode and is placed on the side of the modified surface of the insulating layer and at a height lower than the modified surface of the insulating layer; Apply AC or DC voltage between the needle electrode and the plate electrode to form a corona discharge; During the discharge process, the needle electrode is moved so that the surface of the insulating layer is completely modified.

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