Electrochemical probe and method for endoscopy and detection of corrosion state in metal containers of historical artifacts

Abstract

The application discloses an electrochemical probe for metal cultural relic container inner corrosion state endoscopy and detection, and belongs to the technical field of metal cultural relic protection, repair and scientific detection, and comprises a wire endoscope, a probe shell with a screwing ear plate, a ring support and a fine adjustment rod, the bottom of the probe shell is threadedly connected with the center of the ring support, the levelness can be adjusted through the fine adjustment rod, and a lota-kala glue and calcium nitrate are used to make an electrolyte gel block to be attached to the inner wall of the metal cultural relic; the application also adjusts and controls the cavity gas pressure through the bottom end diameter gap difference and the upper end side wall small liquid injection port, so that the wetting condition of the metal cultural relic rust surface is adjusted and controlled by the internal and external gas pressure difference, so that the rust outer layer with different roughness degrees is adapted to obtain the internal metal cultural relic corrosion data signal. The application directly captures the corrosion electrochemical signal in the metal cultural relic container without any destructive condition, including the bottom and the inner wall of the cultural relic, and captures the microscopic morphology of the measured area.

Description

Technical Field

[0001] This invention relates to the field of metal artifact conservation, restoration, and scientific testing technology, and in particular to an electrochemical probe and method for endoscopic detection of corrosion within metal artifact containers. Background Technology

[0002] Internal corrosion of metal artifact containers (such as bronze pots and cauldrons containing ancient wine and grain, as well as long, narrow, or irregularly shaped vessels) has long been a blank area in the research of metal artifact conservation, making related research both necessary and urgent. The internal corrosion environment of metal artifact containers differs significantly from the external burial environment, and this internal corrosion microenvironment carries crucial information about the artifact's age, purpose, and preservation status, possessing irreplaceable value for archaeological research and historical and cultural interpretation.

[0003] However, the cultural relic preservation industry is a niche field, resulting in a lack of specialized testing equipment for corrosion research. Furthermore, research on the internal corrosion of metal artifact containers faces numerous technical challenges, severely hindering research progress. On one hand, cultural relics are inherently fragile. Unlike industrial pipelines and large reaction vessels that can be routinely tested, destructive sampling is strictly prohibited for cultural relic testing. Such sampling would damage valuable information such as residual ancient wine or grains, diminishing the artifact's value. On the other hand, existing patented technologies primarily target the internal corrosion detection of industrial pipelines and large reaction equipment. Their detection principles and operating methods are incompatible with the needs of cultural relic testing, making direct application impossible. Forced application could even damage the internal structure and residues of the artifact, resulting in the loss of historical information. In particular, how to obtain stable electrochemical corrosion signals through the complex and thick rust layer formed over thousands of years on the oxidized and corroded surface of metal artifacts is a key research area.

[0004] Currently, the following patents have been authorized in this field regarding corrosion testing of metal artifacts, but they are not applicable to localized observation and in-situ corrosion detection within artifacts: CN219737354U and CN216560381U. These patents design instrument structures based on the morphology of the electrolyte and controlling the indiscriminate diffusion of liquid electrolytes on rusted surfaces. However, such designs cannot obtain detection information from within metal artifacts. Firstly, they cannot observe the morphology of internal corrosion products; secondly, they cannot detect the electrochemical state of internal corrosion; and thirdly, they cannot establish a correlation between micro-area morphology and electrochemical corrosion information.

[0005] Based on this, this patent will address the gaps in equipment and technical difficulties in actual testing. It focuses on the design of equipment for detecting the corrosion and morphological conditions inside metal artifact containers. The equipment structure is designed from the perspectives of external support frame, central fine-tuning probe, endoscope, dual-electrode internal layout, gel electrolyte wetting method, and multi-angle detection mode for the bottom and inner wall of metal artifact containers. Furthermore, a set of usage methods is designed to facilitate testing in archaeological field and museum storage. Summary of the Invention

[0006] The purpose of this invention is to provide an electrochemical probe and method for endoscopic detection of corrosion within metal artifact containers. This method directly captures the electrochemical corrosion signals inside the metal artifact container, including the bottom and inner wall of the artifact, without any destructive or invasive sampling of the metal artifact, and captures the microscopic morphology of the measured area throughout the process.

[0007] To achieve the above objectives, this invention provides an electrochemical probe and method for endoscopic detection of corrosion within a metal artifact container. The probe includes a wired endoscope, a probe and housing with a rotating lug, an annular support, and fine-tuning rods. The bottom of the probe housing with the rotating lug has an external thread, and the center of the annular support has an internal thread. The bottom of the probe housing with the rotating lug is threadedly connected to the center of the annular support. Three sleeves are evenly fixed to the bottom of the annular support, and three fine-tuning rods extend into the sleeves and are threadedly connected. The bottoms of the fine-tuning rods are placed on the ground. The probe housing with the rotating lug contains a wired endoscope, a C-type reference electrode with a gold-plated copper connector, and a C-type auxiliary electrode with a gold-plated copper connector.

[0008] Preferably, the probe housing with the screw-on lugs has a hollow column in the inner ring and a hollow column in the outer ring; the wired endoscope extends into the hollow column in the inner ring. The C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector are both semi-circular fan-shaped and located inside the hollow column of the outer ring. The upper outer ends of the C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector expose the conductive metal contacts and are sealed and waterproofed by sealing rubber rings.

[0009] Preferably, the C-type reference electrode with gold-plated copper connecting ends and the C-type auxiliary electrode with gold-plated copper connecting ends are symmetrically arranged; the arc angle of the C-type reference electrode with gold-plated copper connecting ends and the C-type auxiliary electrode with gold-plated copper connecting ends is 30°-150°.

[0010] Preferably, the outer wall of the probe housing with the screw-on ear plate is provided with a liquid injection hole and a rubber stopper. The liquid injection hole is connected to the outer wall of the probe housing with the screw-on ear plate. Electrolyte is injected into the hollow column located on the outer ring through the liquid injection hole. The C-type reference electrode with gold-plated copper connecting end and the C-type auxiliary electrode with gold-plated copper connecting end are completely immersed in the liquid electrolyte.

[0011] Preferably, the hollow column in the outer ring of the probe housing with the screw-on ear plate has a uniform thickness, narrows at the bottom of the hollow column in the outer ring, and forms a narrower annular inner cavity sandwich structure of 0.3mm-1.0mm at the interface with the annular columnar gel, so as to continuously supply solution to the annular columnar gel through the annular inner cavity.

[0012] Preferably, the diameter of the injection hole is in the range of 0.1mm-0.3mm. The electrolyte solution is injected from the injection hole through a disposable syringe and flows slowly down the inner cavity of the hollow column on the outer ring until it contacts the annular columnar gel block. Keeping the injection hole open and the internal and external air pressure are consistent, the annular columnar gel block is kept moist for a long time, which is suitable for the rough rust layer inside the metal artifact and the poor surface smoothness.

[0013] Preferably, the bottom of the probe housing with the screw-on lug is configured as a straight probe or an L-shaped probe. The linear probe is located on the same central axis from the top to the annular columnar gel block, focusing on acquiring the rust morphology and corrosion electrochemical signals of the bottom surface inside the metal artifact; The top of the L-shaped probe and the annular columnar gel block are in a mutually perpendicular state, focusing on acquiring the rust morphology and corrosion electrochemical signals of the inner side of the metal artifact. Both the linear probe and the L-shaped probe rely on the probe shell with the screw-on ear plate to move up and down in the center of the annular support to control the detection depth and detection radius.

[0014] Preferably, a rubber stopper is added to the injection hole. After the injection hole is plugged with the rubber stopper, the solution inside the annular columnar gel block is drawn through the rust layer. A negative pressure is easily formed in the hollow tube interlayer, so the solution no longer flows downward, but the solution is still connected to the annular columnar gel block. This state is suitable for the rust layer inside metal artifacts that is relatively thin and has a relatively flat surface. By opening and closing the injection hole, the supply of electrolyte solution is regulated by the principle of atmospheric pressure balance to accommodate more rusted surfaces.

[0015] Preferably, the annular columnar gel block is designed in the form of a hollow annular column, with the endoscope extending from the hollow annular column of the annular columnar gel block. This not only does not obstruct the observation and recording of the endoscope, but also avoids the phenomenon of loose air layer adhesion caused by using a complete gel block to conform to the shape of the metal artifact.

[0016] A working method for an electrochemical probe used for endoscopic detection of corrosion within a metal artifact container includes the following steps: Step 1: Pre-preparing the gel head: Before each test, prepare the gel head in advance using a mold. Pour 0.60g-2.00g of lota-carrageenan powder into the mold, add water to 100ml, stir and heat at 60℃ until it becomes a paste, cool to room temperature, add 7-10ml of 0.50-0.20mol / L calcium nitrate aqueous solution, stir slowly in the mold, and a transparent gel will be formed in 1-2 minutes. Remove it from the mold and install it on the front end of the probe. Step 2: Inject the test solution: Using a disposable syringe, add 0.013-0.046 mol / L calcium nitrate aqueous solution to the injection hole at the top of the probe, filling it completely without overflowing; the added concentration must be consistent with the effective concentration of calcium nitrate in the gel; calculation formula: C = (C0·V2) / (V1+V2); In the formula: C0 is the initial molar concentration of calcium nitrate aqueous solution, in mol / L; V1 is the volume of lota-carrageenan sol, in mL; V2 is the volume of added calcium nitrate aqueous solution, in mL; C is the final molar concentration of calcium nitrate in the composite gel system, in mol / L; Step 3, Connecting the metal artifact: Use copper foil tape to firmly attach it to the thinner rusted area of ​​the metal artifact, press it firmly with alligator clips, and then connect it to the electrochemical workstation as a working electrode for testing. Step 4, Fix the testing bracket: Select a linear probe or an L-shaped probe bracket according to the part of the metal artifact to be tested, including the inner bottom and inner sidewalls; support the testing bracket directly above the metal artifact to be tested, with the central probe inserted into the metal artifact, and adjust the three fine-tuning rods according to the height of the soil platform around the metal artifact to make the ring bracket horizontal and stable; adjust the probe insertion depth according to the depth of the metal artifact to avoid directly hitting the bottom of the artifact. Step 5: The probe is brought into contact with the test point on the artifact. This can be divided into testing the bottom surface of the metal artifact and testing the internal sidewalls. Testing the bottom surface of the metal artifact: Select the test point on the bottom of the metal artifact, and with the assistance of the fine-tuning threads, slowly press the probe against the test point on the bottom surface by rotating the ear plates on both sides of the probe tip. Testing the internal sidewalls of the metal artifact: Select the test point on the internal sidewall of the metal artifact, and slowly move the annular cylindrical gel block to the same horizontal plane as the test point by adjusting the three fine-tuning rods. Then, slowly press the probe against the test point on the side by rotating the ear plates on both sides of the probe tip. Step 6, Endoscopic observation and recording: The endoscope at the center of the probe is illuminated, and focusing can be assisted by the fine-tuning screw. The rust layer structure of the test point inside the metal artifact is observed and recorded in real time through the display screen. Step 7: Connect the electrodes and start the test: For rough surfaces with large surface undulations, the injection hole on the outer side of the upper end of the probe needs to be opened to balance the internal and external pressures and keep the gel head moist. For smoother surfaces, the injection hole can be kept closed. After pressing the metal artifact into the ground, clamp the alligator clip with copper foil to the working electrode port of the electrochemical workstation, clamp the platinum mesh electrode to the auxiliary electrode port, and clamp the Ag / AgCl-saturated KCl electrode to the reference electrode port before starting the test.

[0017] The advantages and positive effects of the electrochemical probe and method for endoscopic detection of corrosion state inside metal artifact containers described in this invention are as follows: (1) A probe with an external support is used. The ring support is set directly above the metal artifact, without contacting the artifact. The detection probe in the middle of the support is gradually probed downwards from the opening of the metal artifact container through a fine-tuning thread, and the probe reaches the test point through the gel end to perform electrochemical testing. The endoscope in the center of the probe can be focused and observed on the local morphology of the test point, and the image can be taken and recorded by external software.

[0018] (2) For corrosion detection and morphological observation of the internal sidewalls of metal artifacts, this invention also provides an L-shaped probe. The probe is gradually inserted downwards from the opening of the metal artifact container until it reaches the horizontal plane of the point to be measured. The gel end is then finely adjusted using the thread to contact the point on the inner wall, and the detection can begin. By using both the linear and L-shaped probes, in-situ morphological observation and corrosion analysis of various points inside the metal artifact can be achieved, fully extracting internal corrosion information of the artifact even when only the probe is in contact with it.

[0019] (3) A narrow annular inner cavity sandwich structure of 0.3mm-1.0mm is formed at the interface connecting with the annular columnar gel. An injection hole of 0.1-0.3mm is also opened on the upper side wall. The gel block is assembled into the hollow tube, and the solution is injected through the injection hole on the outer wall of the tube by the syringe needle. The gel block just prevents the solution from leaking out and seeping down. The injection hole diameter is in the range of 0.1-0.3mm. After the solution is injected, when it is continuously open, the solution will continuously wet the gel block. This state is suitable for metal artifacts with thick rust layers and large roughness. A large amount of solution needs to be loaded in the gel block to form a circuit. After the solution is injected, when the injection hole is closed, a negative pressure state is formed in the hollow tube. The solution will not continue to wet the gel block. This state is suitable for metal artifacts with thinner rust layers and smoother surfaces. Only a small amount of solution needs to be loaded in the gel block to form a circuit. The sign of whether the injection hole needs to be opened to achieve internal and external pressure balance is whether there are interface bubbles or air layers between the gel and the solution. When the injection port is closed, if the solution in the gel block seeps into the thick, rough corrosion layer, and the load solution in the gel block is insufficient to continue wetting the corrosion layer, it will detach from the solution interface, forming an air layer. This will cause an open circuit, preventing detection. Opening the injection port at this point allows the internal and external pressures to balance, and the solution can re-wet the gel block, thus establishing a continuous circuit.

[0020] (4) The present invention stabilizes the support horizontally by adjusting the three fine-tuning rods of the ring support. Considering the special nature of archaeological site excavation, it is necessary to collect comprehensive original data before the artifacts are unearthed. Therefore, the artifacts are left in the soil at the site to complete surveying and other work. As a result, the soil layers around the metal artifacts are generally not on the same horizontal plane. Therefore, it is necessary to adjust the horizontal plane before starting subsequent tests.

[0021] (5) Using alligator clips to hold copper foil tape as a conductive connection and to fix it to prevent it from falling off, the metal artifact is used as a working electrode to connect it, thus constructing a three-electrode system without damaging the original state of the metal artifact's surface. This operation penetrates the thick and complex rust layer to reach the interior of the metal, realizing electrical signal conduction, while avoiding damage to the rust layer and the metal artifact itself.

[0022] (6) An electrolyte gel capable of detecting the corrosion status of metal artifacts was constructed using a combination of lota-carrageenan (A) and calcium nitrate (B). This modified the liquid electrolyte detection system, ensuring stable circuit connection for the metal artifacts while achieving flexible contact. It also avoided the introduction of electrolyte ions such as chlorine and sulfur, which are detrimental to the preservation of metal artifacts. Multiple gel tips can be pre-customized before each use to ensure continuous testing.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is an overall schematic diagram of the linear detection probe assembled in this invention; Figure 2 This is an overall schematic diagram of the L-shaped detection probe assembled in this invention; Figure 3 for Figure 1 The main view; Figure 4 for Figure 1 A sectional view; Figure 5 for Figure 4 Enlarged view of point A; Figure 6 This is a schematic diagram of the assembly of the C-type reference electrode and the C-type auxiliary electrode of the linear detection probe of the present invention; Figure 7 This is a schematic diagram of the assembly of the C-type reference electrode and the C-type auxiliary electrode of the L-type detection probe of the present invention; Figure 8 for Figure 4 Enlarged view of point B; Figure 9 for Figure 4 Enlarged view of point C; Figure 10 This is an enlarged view of the detection end of the L-shaped detection probe; Figure 11 A schematic diagram of the injection hole and rubber cap on the outer side of the probe tip; Figure 12 The Nyquist impedance curves of the simulated samples tested for different gel-electrolyte ratios in the first to fourth groups of this invention are shown. Figure 13 The Nyquist impedance curves of the simulated samples tested for different gel-electrolyte ratios in the fifth to seventh groups of this invention are shown. Figure 14 Impedance Bode (modulus) curves of simulated samples with different gel electrolyte ratios in the first to fourth groups of this invention; Figure 15 Impedance Bode (modulus) curves of simulated samples with different gel electrolyte ratios in groups 5 to 7 of this invention; Figure 16 Impedance Bode (phase angle) curves of simulated samples with different gel electrolyte ratios in the first to fourth groups of this invention; Figure 17 Impedance Bode (phase angle) curves of simulated samples with different gel electrolyte ratios for groups 5 to 7 of this invention; Figure 18 The equivalent circuit diagram of the simulated sample impedance detected for the first group of electrolyte ratios in this invention; Figure 19 The equivalent circuit diagram of the simulated sample impedance detected for the gel electrolyte ratios of groups 2-7 of this invention; Figure 20 The open circuit potential curves for corrosion on the internal and external sidewalls of the bronze pot; Figure 21 Electrochemical impedance spectroscopy curves showing corrosion on the internal and external sidewalls of the bronze pot; Figure 22 Equivalent circuit diagram of electrochemical impedance curves for corrosion of the inner and outer sidewalls of the bronze pot; Figure 23 The corrosion potential kinetic scan curves of the inner and outer sidewalls of the bronze pot; Figure 24 The open circuit potential curves are shown for the bottom and sidewalls inside the silver vial. Figure 25 The Nyquist plots show the electrochemical impedance spectroscopy of the bottom and sidewalls inside the silver vial. Figure 26 The electrochemical impedance spectroscopy (Baud rate) curves of the bottom and sidewalls inside the silver vial are shown. Figure 27 The electrochemical impedance Bode (phase angle) curves of the bottom and sidewalls inside the silver vial are shown. Figure 28 The equivalent circuit diagram of electrochemical impedance of the bottom and sidewalls inside the silver vial; Figure 29 This is a scan curve of the electrokinetic potential inside the bottom and sidewalls of a silver vial.

[0025] Figure Labels 1. Endoscope with wire; 2. Probe housing with screw-on lugs; 3. External thread; 4. Ring support; 5. Fine adjustment rod; 6. Type C reference electrode with gold-plated copper connector; 7. Type C auxiliary electrode with gold-plated copper connector; 8. Sealing rubber ring; 9. Annular columnar gel block; 10. Injection hole and rubber stopper. Detailed Implementation

[0026] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] like Figures 1-29 As shown, an electrochemical probe for endoscopic and detection of corrosion within a metal artifact container includes a wired endoscope 1, a probe housing 2 with a screw-on lug, an annular support 4, and fine-tuning rods 5. The probe housing 2 with the screw-on lug has an external thread 3 at its bottom, and the annular support 4 has an internal thread at its center. The bottom of the probe housing 2 with the screw-on lug is threadedly connected to the center of the annular support 4. Three sleeves are also evenly fixed to the bottom of the annular support 4, and three fine-tuning rods 5 extend into the sleeves and are threadedly connected. The bottom of the fine-tuning rods 5 rests on the ground. Inside the probe housing 2 with the screw-on lug, there is a wired endoscope 1, a C-type reference electrode 6 with a gold-plated copper connecting end, and a C-type auxiliary electrode 7 with a gold-plated copper connecting end.

[0029] The probe housing 2 with a screw-on lug has an inner hollow column and an outer hollow column inside. The wired endoscope 1 extends into the hollow column in the inner circle.

[0030] Both the C-type reference electrode 6 and the C-type auxiliary electrode 7 with gold-plated copper connectors are semi-circular fan-shaped and located within the hollow column of the outer ring. The upper outer ends of both the C-type reference electrode 6 and the C-type auxiliary electrode 7 with gold-plated copper connectors expose conductive metal contacts and are sealed and waterproofed by a sealing rubber ring 8.

[0031] Specifically, the C-type reference electrode 6 with gold-plated copper connectors is preferably a C-type reference electrode based on silver / silver chloride-saturated potassium chloride, and the outer shell is made of glass or polytetrafluoroethylene, but is not limited to these two materials. The C-type auxiliary electrode 7 with gold-plated copper connectors is preferably an auxiliary electrode based on a platinum mesh column shape, but is not limited to this material.

[0032] A C-type reference electrode 6 with gold-plated copper connectors and a C-type auxiliary electrode 7 with gold-plated copper connectors are symmetrically arranged. The arc angle of the C-type reference electrode 6 and the C-type auxiliary electrode 7 with gold-plated copper connectors is 30°-150°.

[0033] The outer wall of the probe housing 2 with the screw-on ear plate is provided with a liquid injection hole and a rubber stopper 10. The liquid injection hole is connected to the outer wall of the probe housing 2 with the screw-on ear plate. Electrolyte is injected into the hollow column located on the outer ring through the liquid injection hole. The C-type reference electrode 6 with gold-plated copper connection end and the C-type auxiliary electrode 7 with gold-plated copper connection end are completely immersed in the liquid electrolyte.

[0034] The hollow column inside the probe housing 2 with the screw-on ear plate has a uniform thickness in the outer ring. It narrows at the bottom of the hollow column in the outer ring and forms a narrower annular inner cavity sandwich structure of 0.3mm-1.0mm at the interface with the annular columnar gel block 9. The solution is continuously supplied to the annular columnar gel through the annular inner cavity.

[0035] The diameter of the injection hole is in the range of 0.1mm-0.3mm. The electrolyte solution is injected through the injection hole using a disposable syringe and flows slowly down the inner cavity of the hollow column on the outer ring until it contacts the annular columnar gel block 9. Keeping the injection hole open and the internal and external air pressure are consistent, the annular columnar gel block 9 is kept moist for a long time, which is suitable for the rough rust layer inside the metal artifact and the poor surface smoothness.

[0036] The bottom of the probe housing 2 with the screw-on lug is configured as a linear probe or an L-shaped probe.

[0037] The linear probe is located along the same central axis from the top to the annular columnar gel block 9, focusing on acquiring the rust morphology and corrosion electrochemical signals of the bottom surface inside the metal artifact.

[0038] The top of the L-shaped probe and the annular columnar gel block 9 are in a mutually perpendicular state, focusing on acquiring the rust morphology and corrosion electrochemical signals of the inner side of the metal artifact. Both the linear probe and the L-shaped probe rely on the probe shell 2 with the screw-on ear plate to move up and down in the center of the annular bracket 4 to control the detection depth and detection radius.

[0039] A rubber stopper is added to the outside of the injection hole. After the rubber stopper plugs the injection hole, the solution inside the annular columnar gel block 9 is drawn through the rust layer. A negative pressure is easily formed in the hollow tube interlayer, so the solution no longer flows downwards, but it remains connected to the annular columnar gel block 9. This state is suitable for rust layers that are relatively thin and have relatively smooth surfaces inside metal artifacts. By opening and closing the injection hole, the supply of electrolyte solution is regulated using the principle of atmospheric pressure balance to accommodate more rusted surfaces.

[0040] The annular columnar gel block 9 is designed in the form of a hollow circular column. The endoscope extends from the hollow circular column of the annular columnar gel block 9, which not only does not obstruct the observation and recording of the endoscope, but also avoids the phenomenon of poor adhesion of the air layer caused by the shape of the metal artifact when using a whole gel block.

[0041] Example 1: The purpose of this embodiment is to clarify the optimal range of the amount and concentration of Lota-carrageenan and calcium nitrate in the synthesis of the gel detection head. Considering the precious value of metal artifacts, secondary damage during the detection process should not be caused by externally introduced electrolytes, and effective electrochemical corrosion parameters must be clearly obtained. Taking both into account, the following experimental group with the following ratio was designed, and the corrosion resistance data of the simulated samples were obtained by electrochemical impedance spectroscopy, including corrosion characterization data such as the real part of impedance, the imaginary part of impedance, the impedance modulus, and the phase angle.

[0042] First, sample preparation: In order to achieve the uniformity and repeatability of the substrate in the simulation experiment, HT100 grade cast iron was selected and polished evenly with 1000-grit sandpaper. The oil stains attached to the metal surface were removed by cleaning with a mixture of acetone and ethanol. The entire sample was then uniformly coated with a 0.5 g / L sodium chloride (NaCl) solution and left to stand at room temperature for 24 hours. This process was repeated for 3 cycles until a rough surface with obvious granular rust was formed. Then the test could begin.

[0043] Second, prepare the gel head in advance using a mold. Pour 0.30-2.00g of lota-carrageenan powder into the mold, add water to 100ml, stir and heat at 60℃ until it becomes a paste, cool to room temperature, add 5-10ml of 0.50-0.20mol / L calcium nitrate aqueous solution, stir slowly in the mold, and a transparent gel will be formed in 1-2 minutes. Remove it from the mold and install it on the front end of the probe.

[0044] Third, inject the test solution: Use a disposable syringe to add 0.013-0.046 mol / L calcium nitrate aqueous solution to the injection hole at the top of the probe, filling it completely without overflowing. The added concentration should be consistent with the effective concentration of calcium nitrate in the gel.

[0045] Calculation formula: C=(C0·V2) / (V1+V2); where: C0 is the initial molar concentration of calcium nitrate aqueous solution, mol / L; V1 is the volume of lota-carrageenan sol, mL; V2 is the volume of added calcium nitrate aqueous solution, mL; C is the final molar concentration of calcium nitrate in the composite gel system, mol / L.

[0046] Third, connecting the metal artifact: use copper foil tape to firmly attach it to the thinner rusted local surface of the simulated sample block, press it firmly with alligator clips, and then connect it to the electrochemical workstation as a working electrode in preparation for testing.

[0047] Fourth, fix the testing bracket and press the probe against the test point of the cultural relic: Select a linear probe bracket and support the testing bracket directly above the simulated sample block. With the help of fine-tuning threads, slowly press the probe against the surface of the simulated sample block by rotating the ear plates on both sides of the probe top.

[0048] Fifth, endoscopic observation and recording: The endoscope at the center of the probe is illuminated, and the focus can be adjusted with the help of the fine-tuning thread. The rust layer structure of the test point on the surface of the simulated sample block is observed and recorded in real time through the display screen.

[0049] Sixth, connect the electrodes and start the test. For rough surfaces with significant undulations, open the injection port plug on the outer side of the upper end of the probe to balance the internal and external pressures and keep the gel head moist. For smoother surfaces, keep the injection port closed. After pressing and compacting the simulated sample, clamp the alligator clip with copper foil to the working electrode port of the electrochemical workstation, clamp the platinum mesh electrode to the auxiliary electrode port, and clamp the Ag / AgCl-saturated KCl electrode to the reference electrode port to start the electrochemical impedance spectroscopy test.

[0050] like Figures 12-19 As shown in Tables 1 and 2, except for the first group, the real and imaginary parts of the Nyquist plot together form two sets of incomplete semicircles, indicating that the gel electrolyte at this ratio detects a consistent corrosion behavior pattern in the simulated sample. Furthermore, as the effective concentration of calcium nitrate increases, the radii of the two sets of semicircles gradually decrease. The impedance modulus of the Bode plot also decreases with increasing effective concentration, while the phase angle remains essentially stable within a uniform pattern.

[0051] In the first group, the content of carrageenan and calcium nitrate was the lowest, resulting in an equivalent circuit model that differed from other groups. An additional set of diffusion-suppressing electronic components was added, and the phase angle showed a peak in the mid-frequency range. This was mainly because the effective concentration of calcium nitrate was low, and the concentration of lota-carrageenan was low, resulting in a weak gel strength. It was difficult to stabilize on the rust layer, and slight shaking would cause slight displacement during the detection process. The detection surface area formed at the interface with the rust layer would change accordingly, leading to data deviation.

[0052] Therefore, under the condition of ensuring that no human interference or secondary damage is caused to the cultural relics, 0.60-2.00g of lota-carrageenan powder is poured into the mold, water is added to 100ml, and the mixture is stirred and heated at 60℃ until it becomes a paste. After cooling to room temperature, 7-10ml of 0.50-0.20mol / L calcium nitrate aqueous solution is added. The resulting transparent gel is basically the most suitable ratio for testing.

[0053] Table 1. Proportions for Gel Electrolyte Synthesis

[0054] Table 2. Impedance fitting data of simulated samples with different gel electrolyte ratios.

[0055] Example 2: This embodiment tests two areas: the internal and external sidewalls of a bronze vessel unearthed from an archaeological site. After excavation, organic liquid was found inside the bronze vessel. The purpose is to demonstrate that this invention can obtain the internal corrosion state of bronze artifacts with organic residue, and the external corrosion state under soil burial conditions. The study investigates the differences in the impact of the organic liquid environment inside the bronze vessel and the external soil environment on bronze corrosion under thousands of years of burial conditions.

[0056] Testing process: First, pre-preparing the gel head: Use a mold to pre-prepare the gel head. Pour 2.00g of lota-carrageenan powder into the mold, add water to 100ml, stir and heat at 60℃ until it becomes a paste, cool to room temperature, add 10ml of 0.50mol / L calcium nitrate aqueous solution, and slowly stir in the mold to form a transparent gel. Remove it from the mold and install it at the front end of the probe.

[0057] Second, inject the test solution: Use a disposable syringe to add 0.046 mol / L calcium nitrate aqueous solution to the injection hole at the top of the probe until the hole is full without overflowing.

[0058] Third, connecting metal artifacts: use copper foil tape to firmly attach to the thinner rusted area on the bottom of the bronze pot, press it firmly with alligator clips, and then connect it to the electrochemical workstation as a working electrode for testing.

[0059] Fourth, fix the testing bracket: Select an L-shaped testing probe bracket. Place the testing bracket directly above the bronze pot, with the center probe inserted into the pot. Adjust the fine-tuning screws on the three support feet to make the bracket level and stable.

[0060] Fifth, press the probe against the inner side wall of the bronze pot. Slowly move the gel tip to the same horizontal plane as the point to be measured on the inner side wall of the bronze pot, and then slowly press the probe against the side of the point to be measured by rotating the ear plates on both sides of the probe tip.

[0061] Sixth, endoscopic observation and recording: The endoscope in the center of the probe is illuminated, and the focus can be adjusted with the help of the fine-tuning thread. The rust layer structure of the test point inside the bronze pot can be observed and recorded in real time through the display screen.

[0062] Seventh, connect the electrodes and begin the test. The inside of the container is thickly corroded, rough, and has a large surface undulation. Open the liquid injection hole plug on the outer side of the upper end of the probe to balance the internal and external pressures and keep the solution moist on the gel head. Attach the alligator clip with copper foil to the working electrode port of the electrochemical workstation, attach the platinum mesh electrode to the auxiliary electrode port, and attach the Ag / AgCl-saturated KCl electrode to the reference electrode port to begin open circuit potential, electrochemical impedance, and potentiodynamic scanning tests.

[0063] Eighth, after the internal test is completed, extract the probe and repeat steps four through seven above to test the external sidewalls of the corresponding points.

[0064] like Figures 20-23 As shown in Tables 3 and 4, the open-circuit potential of the inner sidewall of the bronze vessel decreased rapidly in the initial stage of the test, and then gradually stabilized, with a stable value of approximately -0.45V. This is significantly lower than that of the outer sidewall in contact with the soil environment, indicating that the internal corrosion stability is poor and the corrosion resistance is low. The electrochemical impedance spectroscopy shows an incomplete semi-circular arc at low and mid-frequency frequencies, transitioning to a diffusion suppression mode at mid and high frequencies. The corrosion modes of the inner and outer potentials are similar. Plotting the corresponding equivalent circuits reveals that the internal impedance modulus is lower, the double-layer capacitance is higher, and the corrosion resistance is lower. In the fitted data obtained from the potentiodynamic scanning curves, the polarization resistance of the inner sidewall is lower, the corrosion current is larger, and the corrosion rate is faster. This indicates that the organic environment is more corrosive to bronze under long-term burial conditions than the soil environment.

[0065] As can be seen from this embodiment, this patent can be combined with a variety of electrochemical detection technologies to effectively assess the corrosion differences between the inside and outside of the bronze pot at the excavation site, proving that the interior of the bronze pot with organic residue has poor corrosion resistance. After extracting the residue, the interior of the object needs to be carefully protected.

[0066] Table 3. Fitting data of corrosion electrochemical impedance curves of the internal and external sidewalls of the bronze pot.

[0067] Table 4. Fitting data of corrosion potential kinetic scan curves of the internal and external sidewalls of the bronze pot.

[0068] Example 3: This embodiment tests two areas: the inner sidewall and the bottom of a silver vial unearthed from an archaeological site. The bottom of the vial contains trace amounts of lumps, suspected to be remnants of ancient spices. The purpose of this embodiment is to demonstrate that the invention can obtain the internal corrosion state of a silver vial containing ancient spice residue, and whether there is any organic matter protecting the silver material.

[0069] Testing process: First, prepare the gel head: Use a mold to prepare the gel head in advance. Pour 1.15g of lota-carrageenan powder into the mold, add water to 100ml, stir and heat at 60℃ until it becomes a paste, cool to room temperature, add 7.5ml of 0.35mol / L calcium nitrate aqueous solution, and slowly stir in the mold to form a transparent gel. Take it out of the mold and install it on the front end of the probe.

[0070] Second, inject the test solution: Use a disposable syringe to add 0.025 mol / L calcium nitrate aqueous solution to the injection hole at the top of the probe until the hole is full without overflowing.

[0071] Third, connecting metal artifacts: use copper foil tape to firmly attach to the thinner rusted area at the bottom of the silver vial, press it firmly with alligator clips, and then connect it to the electrochemical workstation as a working electrode for testing.

[0072] Fourth, fix the testing bracket, with the probe against the inner side wall and bottom of the bronze vessel: First, select an L-shaped probe bracket and support it directly above the silver vial. Insert the center probe into the vessel and adjust the fine-tuning screws on the three support feet to make the bracket horizontal and stable. The probe should then touch the inner side wall of the bronze vessel. Slowly move the gel tip to the same horizontal plane as the test point on the inner side wall of the silver vial, and then slowly press the probe against the test point by rotating the ear plates on both sides of the probe tip.

[0073] Fifth, endoscopic observation and recording: The endoscope at the center of the probe is illuminated, and the focus can be adjusted with the help of the fine-tuning thread. The rust layer structure of the test point inside the silver vial can be observed and recorded in real time through the display screen.

[0074] Sixth, connect the electrodes and begin testing. The corrosion inside the vessel is thin but dense, so there's no need to open the top injection port; simply place the probe directly against the silver surface to begin testing. Attach the alligator clip with copper foil to the working electrode port of the electrochemical workstation, attach the platinum mesh electrode to the auxiliary electrode port, and attach the Ag / AgCl-saturated KCl electrode to the reference electrode port to begin open-circuit potential, electrochemical impedance, and potentiodynamic scanning tests.

[0075] Seventh, after the internal testing is completed, remove the probe and replace it with a linear probe holder. Place the testing holder directly above the simulated sample block. By screwing the lugs on both sides of the probe tip, and with the assistance of the fine-tuning threads, slowly press the probe against the surface of the simulated sample block to test the corrosion points at the bottom of the silver vial. Repeat steps five through seven above to test the bottom of the inside of the silver vial.

[0076] like Figures 24-29 As shown in Tables 5 and 6, the open-circuit potential at the bottom of the silver vial remained consistently higher than that of the inner sidewalls during the 3000-second test cycle, indicating a more pronounced surface passivation at the bottom. The electrochemical impedance spectroscopy (EIS) Nyquist plot clearly shows three sets of incomplete semicircles. Correspondingly, equivalent circuits were plotted. From the fitted data and Bode plot, the impedance modulus at the bottom was higher, and the phase angle was further away from the X-axis, indicating similar point corrosion patterns at the bottom and sidewalls. The organic film layer, substrate corrosion layer, and silver substrate interface can be distinguished sequentially. It is speculated that the bottom has a more pronounced organic protective layer, while the protective layer on the sidewalls is thinner. In the fitted data obtained from the potentiodynamic scanning curves, the polarization resistance of the inner sidewalls was lower, the corrosion current was higher, and the corrosion rate was faster, while the polarization resistance of the bottom was higher, the corrosion current was lower, and the corrosion rate was slower.

[0077] This embodiment demonstrates that the present invention can be combined with various electrochemical detection techniques to effectively assess the corrosion differences between the bottom and sidewalls of the interior of a silver vial containing ancient spice residues unearthed at the excavation site. It proves that the invention can provide stable detection over a long period and clearly display the interface effects inside the silver vial, with reasonable and stable data trends. It demonstrates that the bottom of the silver vial exhibits better corrosion resistance than the inner sidewalls after organic spice storage. After extracting the residues, the composition of the protective film at the bottom can be studied in detail, and the inner sidewalls of the artifact should be closely monitored during the preservation process.

[0078] Table 5. Electrochemical impedance fitting data for the bottom and sidewalls inside the silver vial.

[0079] Table 6. Potential motion scanning fitting data of the bottom and sidewalls inside the silver vial.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container, characterized in that: The device includes a wired endoscope, a probe housing with a rotating lug, a ring support, a fine-tuning rod, and a ring-shaped gel block. The bottom of the probe housing with the rotating lug has an external thread, and the center of the ring support has an internal thread. The bottom of the probe housing with the rotating lug is threadedly connected to the center of the ring support. Three sleeves are evenly fixed to the bottom of the ring support, and three fine-tuning rods are inserted into the sleeves and threadedly connected. The bottom of the fine-tuning rods rests on the ground. Inside the probe housing with the rotating lug, there is a wired endoscope, a C-type reference electrode with a gold-plated copper connector, and a C-type auxiliary electrode with a gold-plated copper connector.

2. The electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 1, characterized in that: The probe housing with the screw-on lugs has a hollow column in the inner ring and a hollow column in the outer ring; the wired endoscope extends into the hollow column in the inner ring. The C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector are both semi-circular fan-shaped and located inside the hollow column of the outer ring. The upper outer ends of the C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector expose the conductive metal contacts and are sealed and waterproofed by sealing rubber rings.

3. The electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 2, characterized in that: The C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector are symmetrically arranged; the arc angle of the C-type reference electrode with gold-plated copper connector and the C-type auxiliary electrode with gold-plated copper connector is 30°-150°.

4. The electrochemical probe for endoscopic detection of corrosion state inside a metal artifact container according to claim 3, characterized in that: The outer wall of the probe housing with the screw-on lugs is provided with a liquid injection hole and a rubber stopper. The liquid injection hole is connected to the outer wall of the probe housing with the screw-on lugs. Electrolyte is injected into the hollow column located on the outer ring through the liquid injection hole. The C-type reference electrode with gold-plated copper connecting end and the C-type auxiliary electrode with gold-plated copper connecting end are completely immersed in the liquid electrolyte.

5. The electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 4, characterized in that: The hollow column inside the probe housing with the screw-on ear plate has a uniform thickness in the outer ring, which narrows at the bottom of the hollow column and forms a narrower annular inner cavity sandwich structure of 0.3mm-1.0mm at the interface with the annular columnar gel, through which the solution is continuously supplied to the annular columnar gel.

6. The electrochemical probe for endoscopic detection of corrosion state inside a metal artifact container according to claim 5, characterized in that: The diameter of the injection hole is in the range of 0.1mm-0.3mm. The electrolyte solution is injected through the injection hole using a disposable syringe and flows slowly down the inner cavity of the hollow column on the outer ring until it contacts the annular columnar gel block. Keeping the injection hole open and the internal and external air pressure are consistent, the annular columnar gel block is kept moist for a long time, which is suitable for the rough rust layer inside the metal artifact and the poor surface smoothness.

7. The electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 6, characterized in that: The bottom of the probe housing with the screw-on lug is configured as a linear probe or an L-shaped probe. The linear probe is located on the same central axis from the top to the annular columnar gel block, focusing on acquiring the rust morphology and corrosion electrochemical signals of the bottom surface inside the metal artifact; The top of the L-shaped probe and the annular columnar gel block are in a mutually perpendicular state, focusing on acquiring the rust morphology and corrosion electrochemical signals of the inner side of the metal artifact. Both the linear probe and the L-shaped probe rely on the probe shell with the screw-on ear plate to move up and down in the center of the annular support to control the detection depth and detection radius.

8. The electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 7, characterized in that: A rubber stopper is added to the outside of the injection hole. After the rubber stopper plugs the injection hole, the solution inside the annular columnar gel block is drawn through the rust layer. A negative pressure is easily formed in the hollow tube interlayer, so the solution no longer flows downward, but the solution is still connected to the annular columnar gel block. This state is suitable for the rust layer inside metal artifacts that is relatively thin and has a relatively flat surface. By opening and closing the injection hole, the supply of electrolyte solution is regulated by the principle of atmospheric pressure balance to accommodate more rusted surfaces.

9. An electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container according to claim 8, characterized in that: The annular columnar gel block is designed in the form of a hollow circular column. The endoscope extends from the hollow circular column of the annular columnar gel block, which not only does not obstruct the observation and recording of the endoscope, but also avoids the phenomenon of loose air layer adhesion caused by using a whole gel block inside the metal artifact.

10. The working method of an electrochemical probe for endoscopic and detection of corrosion state inside a metal artifact container as described in any one of claims 1-9, characterized in that: Includes the following steps: Step 1: Pre-preparing the gel head: Before each test, prepare the gel head in advance using a mold. Pour 0.60g-2.00g of lota-carrageenan powder into the mold, add water to 100ml, stir and heat at 60℃ until it becomes a paste, cool to room temperature, add 7-10ml of 0.50-0.20mol / L calcium nitrate aqueous solution, stir slowly in the mold, and a transparent gel will be formed in 1-2 minutes. Remove it from the mold and install it on the front end of the probe. Step 2: Inject the test solution: Using a disposable syringe, add 0.013-0.046 mol / L calcium nitrate aqueous solution to the injection hole at the top of the probe, filling it completely without overflowing; the added concentration must be consistent with the effective concentration of calcium nitrate in the gel; calculation formula: C = (C0·V2) / (V1+V2); In the formula: C0 is the initial molar concentration of calcium nitrate aqueous solution, in mol / L; V1 is the volume of lota-carrageenan sol, in mL; V2 is the volume of added calcium nitrate aqueous solution, in mL; C is the final molar concentration of calcium nitrate in the composite gel system, in mol / L; Step 3, Connecting the metal artifact: Use copper foil tape to firmly attach it to the thinner rusted area of ​​the metal artifact, press it firmly with alligator clips, and then connect it to the electrochemical workstation as a working electrode for testing. Step 4, Fix the testing bracket: Select a linear probe or an L-shaped probe bracket according to the part of the metal artifact to be tested, including the inner bottom and inner sidewalls; support the testing bracket directly above the metal artifact to be tested, with the central probe inserted into the metal artifact, and adjust the three fine-tuning rods according to the height of the soil platform around the metal artifact to make the ring bracket horizontal and stable; adjust the probe insertion depth according to the depth of the metal artifact to avoid directly hitting the bottom of the artifact. Step 5: The probe is brought into contact with the test point on the artifact. This can be divided into testing the bottom surface of the metal artifact and testing the internal sidewalls. Testing the bottom surface of the metal artifact: Select the test point on the bottom of the metal artifact, and with the assistance of the fine-tuning threads, slowly press the probe against the test point on the bottom surface by rotating the ear plates on both sides of the probe tip. Testing the internal sidewalls of the metal artifact: Select the test point on the internal sidewall of the metal artifact, and slowly move the annular cylindrical gel block to the same horizontal plane as the test point by adjusting the three fine-tuning rods. Then, slowly press the probe against the test point on the side by rotating the ear plates on both sides of the probe tip. Step 6, Endoscopic observation and recording: The endoscope at the center of the probe is illuminated, and focusing can be assisted by the fine-tuning screw. The rust layer structure of the test point inside the metal artifact is observed and recorded in real time through the display screen. Step 7: Connect the electrodes and start the test: For rough surfaces with large surface undulations, the injection hole on the outer side of the upper end of the probe needs to be opened to balance the internal and external pressures and keep the gel head moist. For smoother surfaces, the injection hole can be kept closed. After pressing the metal artifact into the ground, clamp the alligator clip with copper foil to the working electrode port of the electrochemical workstation, clamp the platinum mesh electrode to the auxiliary electrode port, and clamp the Ag / AgCl-saturated KCl electrode to the reference electrode port before starting the test.

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