Clamping device and method for simulating corrosion test of large fouling organisms in laboratory

Abstract

The invention belongs to the technical field of laboratory simulation testing, and particularly relates to a clamping device and method for simulating a large-scale fouling organism corrosion test in a laboratory, the device comprises a supporting unit, a clamping unit and an adjusting unit, and a test electrode is fixed on the supporting unit through the clamping unit; the clamping unit is adjusted to adapt to monitoring of electrodes with different surface areas, and the adjusting unit is used for adhering and fixing large fouling organisms, so that the influence of adhesion of marine large fouling organisms on electrochemical corrosion characteristics of steel is researched in a laboratory environment. The device is simple in structure, easy to operate, suitable for electrodes with different surface areas and capable of simulating fouling organism attachment behaviors in a real sea environment, attachment positions can be freely selected, electrochemical monitoring of different large-scale fouling organisms in the sea environment in a laboratory is achieved, the monitoring efficiency is greatly improved, and the device is suitable for popularization and application. The test limitation caused by the growth cycle of large fouling organisms is solved to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of laboratory simulation testing, and specifically is a clamping device and method for laboratory simulation of large-scale fouling biological corrosion testing, which is suitable for simulating the clamping and fixation of large-scale fouling organisms (such as oysters, barnacles, etc.) in the process of attaching low-alloy high-strength steel in the marine environment, and is used to study the electrochemical characteristics of large-scale fouling organisms when they are attached to the surface of low-alloy high-strength steel electrodes. Background Art

[0002] Low alloy high strength steel is widely used in marine engineering structures due to its excellent mechanical properties and occupies an increasingly important position. However, in practical applications, the attachment of marine fouling organisms (such as oysters and barnacles) has a significant impact on the corrosion process of steel. Fouling organisms are divided into micro and large according to their size. Referring to the standards for large benthic animals, large fouling organisms are defined by whether they can pass through a 0.5 mm mesh screen. Large fouling organisms complete their life cycle by colonizing and growing on the surface of materials, forming large fouling communities to adapt to the marine environment. With the attachment and growth of these organisms, the integrity and function of marine facilities will be significantly affected, the corrosion behavior of steel will change, and the service life of offshore facilities will be reduced, which has brought huge challenges and threats to the development of global marine resources.

[0003] Oysters are typical large fouling organisms. Due to the irregular changes in the shape of their shells, deep crevice corrosion often occurs below and on the edges of the oyster cover. However, the attachment of large fouling organisms is often random and uncertain, which leads to great difficulties in studying the corrosion behavior of steel. Therefore, it is necessary to propose a clamping device and method for laboratory simulation of large fouling organism corrosion testing. The large fouling organisms are fixed on the electrode surface through laboratory simulation methods, so as to systematically study their influence on the electrochemical corrosion process, thereby providing theoretical support for the prediction of steel corrosion development. Summary of the invention

[0004] The object of the present invention is to provide a clamping device and method for laboratory simulation of large-scale fouling biocorrosion testing.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] The clamping device of the present invention comprises a supporting unit, a clamping unit and an adjusting unit. The test electrode is plugged into one end of the supporting unit and is clamped and fixed by the clamping unit arranged on the supporting unit; the adjusting unit is arranged at the other end of the supporting unit, and the large fouling organisms are placed on the electrode surface of the test electrode and are fixed to the electrode surface by the adjusting unit, so as to simulate the attachment state of the large fouling organisms and monitor the surface electrochemical signals.

[0007] Wherein: the support unit is a fixed base, one end of the fixed base is provided with an opening for inserting the test electrode, the other end of the fixed base is provided with a threaded hole A connected to the adjustment unit; a hollow section is provided between the opening on the fixed base and the threaded hole A.

[0008] The fixed base is a cylinder, and the opening for installing the test electrode is cylindrical. The opening and the threaded hole A are hollowed out to form a hollow section. The cylindrical walls on both sides of the hollow section are symmetrically provided with notches. The hollow section and the notches are used for the circulation of electrolyte during testing and are suitable for large fouling organisms of different sizes.

[0009] The clamping unit is a clamping screw, and one end of the support unit is provided with at least one group of clamping screws along the circumferential direction, each group of the clamping screws consists of two, which are respectively threadedly connected to one end of the support unit, and one end of the support unit is provided with threaded holes B, which are the same in number and correspond to the clamping screws; the axial center lines of the two clamping screws in each group are collinear and intersect perpendicularly with the center line of the length direction of the support unit; the test electrodes of different sizes are clamped by rotating the clamping screws.

[0010] The adjustment unit is an adjustment screw, which is threadedly connected to the other end of the support unit, and the axial center line of the adjustment screw is colinear with the center line of the length direction of the support unit; by rotating the adjustment screw, large fouling organisms are attached to the electrode surface on the test electrode, and the attachment pressure can be adjusted according to the biological attachment situation.

[0011] The test electrode is a metal electrode.

[0012] The clamping method of the present invention is: plugging the test electrode into one end of the support unit, and then using the clamping unit to clamp and fix the test electrode; then, placing the large fouling organism on the electrode surface of the test electrode; finally, using the adjustment unit to fix the large fouling organism on the electrode surface.

[0013] The advantages and positive effects of the present invention are:

[0014] 1. The clamping device of the present invention has a simple structure, is easy to operate, can adjust the clamping size according to the test electrode, and is suitable for electrodes with different surface areas.

[0015] 2. The clamping device of the present invention can simulate the attachment behavior of large fouling organisms in a real sea environment, and the attachment position can be freely selected on the working surface of the test electrode to fix the large fouling organisms.

[0016] 3. The present invention can fully simulate the actual sea test in the laboratory, realize the electrochemical monitoring of different large fouling organisms in the marine environment in the laboratory, and provide a new means for studying the corrosion behavior of metal materials in the ocean. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the clamping device of the present invention;

[0018] Figure 2A It is a schematic diagram of the three-dimensional structure of the support unit in the clamping device of the present invention;

[0019] Figure 2B It is a structural front view of the support unit in the clamping device of the present invention;

[0020] Figure 2C It is a structural side view of the support unit in the clamping device of the present invention;

[0021] Figure 2D A bottom view of the structure of the support unit in the clamping device of the present invention;

[0022] Figure 3 A comparison diagram of the cyclic anodic polarization curves obtained by the clamping device of the present invention in a laboratory simulation environment and a real sea environment;

[0023] Figure 4 This is a Nyquist comparison diagram of the impedance spectrum obtained by the clamping device of the present invention in a laboratory simulation environment and a real sea environment;

[0024] Among them: 1 is the test electrode, 2 is the fixed base, 3 is the clamping screw, 4 is the hollow section, 5 is the electrode surface, 6 is the adjusting screw, 7 is the orifice, 8 is the threaded hole A, 9 is the notch, and 10 is the threaded hole B. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the clamping device of the present invention includes a supporting unit, a clamping unit and an adjusting unit. The test electrode 1 is plugged into one end of the supporting unit and is clamped and fixed by the clamping unit arranged on the supporting unit; the adjusting unit is arranged at the other end of the supporting unit, and the large fouling organisms are placed on the electrode surface 5 of the test electrode 1 and are fixed to the electrode surface 5 by the adjusting unit, so as to simulate the attachment state of the large fouling organisms and monitor the surface electrochemical signals.

[0027] like Figure 1 and Figures 2A to 2DAs shown, the support unit of this embodiment is a fixed base 2, which is a cylinder with an outer diameter of 30 mm and a height of 55 mm. A hole 7 for inserting the test electrode 1 is provided at one end of the fixed base 2, and the hole 7 for installing the test electrode 1 is cylindrical, with a diameter of 20 mm and a height of 20 mm; a threaded hole A8 connected to the adjustment unit is provided at the other end of the fixed base 2, and the threaded hole A8 has a diameter of 14 mm and a height of 10 mm; a hollow section 4 is formed between the hole 7 and the threaded hole A8 on the fixed base 2, and the maximum wall thickness of the hollow section 4 is 3 mm. Notches 9 are provided on the cylindrical walls on both sides of the hollow section 4 symmetrically, and the hollow section 4 and the notch 9 are used for the circulation of electrolyte during testing and are suitable for large fouling organisms of different sizes.

[0028] like Figure 1 and Figures 2A to 2D As shown, the clamping unit of this embodiment is a clamping screw 3, the size of the clamping screw 3 is Φ4×10mm, and one end of the support unit (i.e., the fixed base 2) is provided with at least one group of clamping screws 3 along the circumferential direction, and each group of clamping screws 3 is two, respectively threadedly connected to one end of the support unit, and one end of the support unit is provided with threaded holes B10 that are the same number and one-to-one corresponding to the clamping screws 3; the axial center lines of the two clamping screws 3 in each group are collinear and perpendicularly intersect with the center line of the length direction of the support unit. This embodiment is a group of two clamping screws 3, and accordingly, one end of the fixed base 2 is provided with two threaded holes B10, the axial center lines of the two threaded holes B10 are collinear and perpendicularly intersect with the axial center line of the fixed base 2. Test electrodes 1 of different sizes are clamped by rotating the clamping screws 3 on the left and right sides.

[0029] like Figure 1 and Figures 2A to 2D As shown, the adjustment unit of this embodiment is an adjustment screw 6, the size of the adjustment screw 6 is Φ12×43mm, and it is threadedly connected to the threaded hole A8 opened at the other end of the support unit (i.e., the fixed base 2), and the axial center line of the adjustment screw 6, the axial center line of the threaded hole A8 and the center line of the length direction of the support unit are collinear; by rotating the adjustment screw 6, the large fouling organisms are attached to the electrode surface 5 on the test electrode 1, and the attachment pressure can be adjusted according to the attachment conditions of the organisms.

[0030] The test electrode 1 of this embodiment is a metal electrode, which is held stable by a clamping unit. The data unit (electrochemical workstation) is used to connect the signal lead of the test electrode 1 to monitor the electrochemical state under the target research state. The data unit of this embodiment is prior art and will not be described in detail here.

[0031] The clamping method of the clamping device used for laboratory simulation of large-scale fouling biocorrosion testing of the present invention is as follows:

[0032] Insert the test electrode 1 into one end of the support unit, and then use the clamping unit to clamp and fix the test electrode 1; then, place the large fouling organism on the electrode surface 5 of the test electrode 1; finally, use the adjustment unit to fix the large fouling organism on the electrode surface 5.

[0033] Experimental example

[0034] In order to verify the feasibility of the clamping device and method of the present invention in studying the influence of large fouling organisms (oysters) attachment on metal corrosion behavior, a simulation test will be conducted in the laboratory and compared with the real sea test conducted at the real sea experimental station to detect the electrochemical impedance spectrum and cyclic anodic polarization curve changes of the test electrode (AISI 4135 steel) used. The large biological fouling oysters are fixed on the electrode surface 5 of the test electrode 1 by using the clamping device, immersed in the seawater electrolyte (the electrolyte of this embodiment is natural seawater), and the electrochemical performance is tested. After one month of exposure in the real sea test, oysters are attached to the surface of the sample, and no other large fouling organisms are obviously attached. Figure 3 The electrochemical impedance spectra of the attached samples under the natural conditions of one month of laboratory simulation and one month of sea exposure are compared, which are obtained by data fitting (the test electrochemical impedance is known, and the charge transfer resistance is obtained by fitting with existing software). The charge transfer resistance R under the conditions simulated by the clamping device of the present invention is ct is 549.8Ω, R ct It is 569.6Ω, which is less than 5% different from the actual sea conditions, proving that the data measured by the clamping device of the present invention is reasonable and has little difference from the actual marine environment. Figure 4 This is a comparison chart of the cyclic anodic polarization of attachment under natural conditions of two months of laboratory simulation immersion and two months of exposure in the real sea. In the cyclic anodic polarization curve, hysteresis loops appear in both the simulation test and the real sea test for the attachment of oysters, indicating that the attachment of oysters increases the tendency of pitting corrosion of metal materials. Studies have shown that the attachment of large fouling organisms will promote local corrosion such as crevice corrosion of metal materials, especially pitting corrosion, so the data measured by the clamping device of the present invention is reasonable and feasible.

Claims

1. A clamping device for laboratory simulation of large-scale fouling biocorrosion testing, characterized in that: The device comprises a support unit, a clamping unit and an adjustment unit. The test electrode (1) is plugged into one end of the support unit and is clamped and fixed by the clamping unit provided on the support unit. The adjustment unit is provided at the other end of the support unit. Large fouling organisms are placed on an electrode surface (5) of the test electrode (1) and are fixed to the electrode surface (5) by the adjustment unit, so as to simulate the attachment state of large fouling organisms and monitor surface electrochemical signals.

2. The clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claim 1, characterized in that: The support unit is a fixed base (2), one end of the fixed base (2) is provided with an opening (7) for inserting a test electrode (1), and the other end of the fixed base (2) is provided with a threaded hole A (8) connected to the adjustment unit; a hollow section (4) is provided between the opening (7) on the fixed base (2) and the threaded hole A (8).

3. The clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claim 2, characterized in that: The fixed base (2) is a cylinder, the opening (7) for mounting the test electrode (1) is cylindrical, the opening (7) and the threaded hole A (8) are hollowed out to form a hollow section (4), the cylindrical wall on both sides of the hollow section (4) are symmetrically provided with notches (9), the hollow section (4) and the notches (9) are used for the circulation of electrolyte during testing and are suitable for large fouling organisms of different sizes.

4. The clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claim 1, characterized in that: The clamping unit is a clamping screw (3), one end of the support unit is provided with at least one group of clamping screws (3) along the circumferential direction, each group of the clamping screws (3) is two, each of which is threadedly connected to one end of the support unit, and one end of the support unit is provided with threaded holes B (10) which are the same in number and correspond to the clamping screws (3); the axial center lines of the two clamping screws (3) in each group are collinear and intersect perpendicularly with the center line of the length direction of the support unit; and the test electrodes (1) of different sizes are clamped by rotating the clamping screws (3).

5. The clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claim 1, characterized in that: The adjustment unit is an adjustment screw (6) which is threadedly connected to the other end of the support unit, and the axial center line of the adjustment screw (6) is colinear with the center line of the length direction of the support unit; by rotating the adjustment screw (6), large fouling organisms are attached to the electrode surface (5) on the test electrode (1), and the attachment pressure can be adjusted according to the attachment conditions of the organisms.

6. The clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claim 1, characterized in that: The test electrode (1) is a metal electrode.

7. A clamping method for the clamping device for laboratory simulation of large-scale fouling biocorrosion testing according to claims 1 to 6, characterized in that: The test electrode (1) is plugged into one end of a support unit, and the test electrode (1) is clamped and fixed using the clamping unit; then, a large fouling organism is placed on an electrode surface (5) of the test electrode (1); and finally, the large fouling organism is fixed on the electrode surface (5) using the adjustment unit.

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