Method for measuring hydrogen diffusion coefficient and trap parameters of high hydrogen trap material

Abstract

The present application relates to the field of metal material performance testing and analysis, and provides a method for measuring hydrogen diffusion coefficient and trap parameters of high hydrogen trap material, which comprises the following steps: step 1: high-temperature double electrolytic cell hydrogen diffusion test; step 2: normal-temperature double electrolytic cell hydrogen diffusion test; step 3: normal-temperature double electrolytic cell secondary hydrogen diffusion test; step 4: calculation of real hydrogen diffusion coefficient D eff ; step 5: calculation of reversible hydrogen trap strength factor; and step 6: calculation of irreversible hydrogen trap saturated hydrogen content. Compared with the prior art, the method for measuring hydrogen diffusion coefficient and trap parameters of high hydrogen trap material solves the interference problem caused by the combined action of reversible hydrogen traps and irreversible hydrogen traps on hydrogen atoms during the diffusion process in the metal, realizes the simulation of the real internal hydrogen diffusion behavior state under the service state of the material, and greatly improves the test precision and accuracy.

Description

Technical Field

[0001] This invention relates to the field of performance testing and analysis of metallic materials, and more specifically, to a method for determining the hydrogen diffusion coefficient and trapping parameters of high-hydrogen-trap materials. Background Technology

[0002] Metallic materials are susceptible to hydrogen embrittlement in complex service environments such as humidity and electrochemical interference, severely impacting their safety and reliability. This has long been a common challenge in fields such as shipbuilding and marine engineering. Hydrogen embrittlement is essentially the result of the synergistic evolution of local hydrogen concentration and stress-strain state within the metal. When the dynamic changes in hydrogen concentration and the interaction of the local stress field at a specific location reach a critical state, the synergistic effect induces hydrogen-induced fracture. The hydrogen embrittlement process is controlled by hydrogen atom dynamics. Hydrogen atoms are strongly influenced by factors such as the internal chemical potential gradient, local stress field, and microstructural defects, causing them to diffuse and accumulate in specific regions within the metal lattice, thereby accelerating crack propagation and fracture. Therefore, studying the hydrogen diffusion mechanism and behavior in metals is crucial for assessing the hydrogen embrittlement susceptibility of materials and predicting their safe service life.

[0003] Currently, the main methods for studying hydrogen diffusion behavior include electrochemical permeation, thermal desorption, and gas-phase permeation. The basic principle of these methods is to drive hydrogen atoms to penetrate the matrix and diffuse by creating a hydrogen concentration gradient or chemical potential gradient at the material boundary.

[0004] Among these methods, electrochemical permeation is the most widely used. This method is based on a dual-electrolytic cell model. The metal to be tested is made into a thin sheet and placed between two unconnected electrolytic cells. One side of the sheet is a hydrogen-filled cell (cathode), where a cathode polarization current is applied or the sheet is immersed in a specific acidic solution to drive hydrogen atoms to be reduced and permeate into the substrate. The other side is an oxidation cell (anode), where a constant anodic potential is applied, causing hydrogen atoms in the substrate to diffuse and form hydrogen gas, which is then expelled. Hydrogen atoms that have permeated into the substrate diffuse towards the anode side under the drive of the concentration gradient, and upon reaching the surface of the oxidation cell, are rapidly oxidized into hydrogen ions, thus generating a current in the detection circuit. The change of the oxidation cell current over time is recorded, and using Fick's second law, the hydrogen diffusion coefficient and state parameters of the metal material are calculated based on the characteristic lag time corresponding to the current reaching its steady-state maximum value. Traditional electrochemical permeation has advantages such as high testing sensitivity and ease of operation.

[0005] Thermal desorption focuses on analyzing the characteristics of hydrogen traps within materials. It involves electrochemically or under high-pressure gas-phase hydrogen purging of the sample, causing hydrogen atoms to accumulate within the matrix. Subsequently, the sample is heated at a constant rate in a vacuum system, and the flow rate of escaping hydrogen at a specific temperature is monitored in real time using a mass spectrometer or thermal conductivity detector. This method offers high resolution and is suitable for studying low-concentration hydrogen and long-term diffusion behavior; however, it demands stringent instrument precision and is time-consuming.

[0006] The gas-phase permeation method introduces a high concentration of hydrogen gas onto the metal surface, allowing hydrogen atoms to permeate the metal matrix. By detecting the hydrogen content at different depths and locations within the metal, parameters of the metal's hydrogen diffusion behavior can be calculated. This method is applicable to most metallic materials, but its drawbacks include a long experimental cycle and the need for precise control of the hydrogen source and concentration. This is particularly challenging for thin materials or metals with high hydrogen diffusion rates.

[0007] In recent years, many scholars have made inventions and innovations on testing environments and equipment based on existing research and testing methods. These innovations mainly focus on testing equipment for metal materials of different shapes and sizes, changing the testing area to improve testing accuracy, or improving testing efficiency by designing the structure of the testing electrolytic cell. For example, patent CN119715349A discloses a device and method for testing the hydrogen diffusion coefficient of high-strength steel. It improves the electrolytic cell structure to create a novel electrolytic cell device for testing the hydrogen diffusion coefficient, reducing heavy metal pollution caused by electroplating on the surface of high-strength steel. Patent CN114563341A discloses a device, method, and application for measuring the hydrogen diffusion coefficient of a micro-region of a welded joint. It designs and invents a hydrogen diffusion electrolytic cell device for welded joints, testing the hydrogen diffusion coefficient by adjusting the through-hole structure. Patent CN108548736A discloses a device and method for testing the dynamic hydrogen embrittlement performance of metallic materials with equal strain amplitude. It designs and invents a device that applies stress to induce strain in the metallic material and simultaneously tests the hydrogen diffusion coefficient of the metal under stress-strain conditions. Patent CN112881117A discloses a method for testing the stress corrosion of high-strength steel materials, introducing a method for testing the material's performance degradation rate by pre-charging the metallic material with hydrogen and then stretching it.

[0008] Existing testing methods are suitable for materials with low hydrogen trap density, or for assessing hydrogen diffusion when hydrogen atoms in the material have reached a steady state. However, for materials with high hydrogen trap density, such as Cr-Ni-Mo and Cr-Mo systems, conventional testing methods have significant limitations. These alloys contain numerous trap sites in their microstructure that can capture hydrogen atoms: Mo readily forms stable carbides (such as M2C), and the phase transformation stress field at the interface between this precipitate and the matrix constitutes an efficient hydrogen trap; Cr effectively stabilizes martensite or bainite structures, introducing high-density dislocations and lattice distortion, forming hydrogen traps; in the Cr-Ni-Mo system, Ni promotes the formation of reverse-transformed austenite, which has high hydrogen solubility and can absorb a large number of hydrogen atoms.

[0009] Hydrogen traps are classified into reversible and irreversible hydrogen traps. Reversible traps have relatively low binding energies, and hydrogen atoms, after being captured during diffusion, easily absorb activation energy and undergo transitions to re-participate in diffusion. Irreversible traps have higher binding energies, and hydrogen atoms, once trapped at room temperature, are difficult to desorb using their own energy. Irreversible traps capture hydrogen atoms, increasing the total hydrogen content of the material and making it easier for local hydrogen atom aggregation to occur, thus increasing the risk of hydrogen-induced cracking.

[0010] In conventional electrochemical permeation tests of materials with high trap density, the combined effect of strong adsorption from irreversible traps and dynamic adsorption / desorption from reversible traps significantly alters diffusion kinetics. This results in a severe lag in the initial hydrogen permeation curve, exhibiting a pronounced "hydrogen diffusion delay" phenomenon. The actual diffusion behavior deviates significantly from the ideal Fick diffusion model. The apparent hydrogen diffusion parameters calculated based on such unsteady permeation curves cannot reflect the true diffusion behavior of hydrogen atoms within the metal lattice, rendering the test data invalid for engineering applications. In real-world service materials, which are subjected to complex environments such as stress, humidity, or electrochemical corrosion, irreversible hydrogen traps in the matrix are typically saturated, while hydrogen atoms in reversible hydrogen traps maintain a dynamic equilibrium within the environment. Therefore, conventional electrochemical permeation testing methods cannot accurately simulate the constitutive characteristics and true hydrogen diffusion behavior of materials under actual service conditions.

[0011] In summary, when testing hydrogen diffusion process parameters of alloy materials containing high hydrogen trap density, such as Cr-Ni-Mo and Cr-Mo systems, the effects of hydrogen traps on hydrogen atom capture, adsorption / desorption severely affect the test results, making it impossible to accurately characterize the true hydrogen diffusion behavior of high hydrogen trap materials.

[0012] In view of this, the present invention is hereby proposed. Summary of the Invention

[0013] The purpose of this invention is to propose a method for determining the hydrogen diffusion coefficient and trapping parameters of high hydrogen trapping materials, in order to solve the problem in the prior art that when testing the hydrogen diffusion process parameters of alloy materials containing high hydrogen trapping density such as Cr-Ni-Mo and Cr-Mo systems, the hydrogen trapping effect on hydrogen atom capture and adsorption / desorption seriously affects the test results, and cannot accurately characterize the true hydrogen diffusion behavior of high hydrogen trapping materials.

[0014] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0015] A method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material, the method comprising the following steps:

[0016] Step 1: High-temperature dual-electrolysis cell hydrogen diffusion test: Select a thin metal sheet sample with a thickness of l that has not been filled with hydrogen and place it into the electrochemical dual-electrolysis cell with a contact area of ​​A0. Turn on the heating device and raise the temperature of the molten salt to the first test temperature T.H The first test temperature T H Above room temperature, the temperature of the thin metal sheet sample at the first test temperature T is calculated. H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H Then, using Arrhenius's thermal activation law, the first test temperature T was... H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H Extrapolation yields the target ambient temperature T. R The hydrogen diffusion coefficient D of the reference lattice at room temperature L (T R ) and the solubility of hydrogen in the room-temperature lattice S L (T R );

[0017] Step 2: Room temperature dual-electrolysis cell hydrogen diffusion test: Select a brand new, untested metal sheet sample of thickness l from the same batch, and test it at the target room temperature T. R The first hydrogen permeation test was conducted until the permeation current reached the first steady-state value. And record the initial penetration hysteresis time. At this point, the irreversible hydrogen traps in the metal sheet sample have been completely filled with hydrogen atoms and have reached a physical saturation state; subsequently, the hydrogen charging of the sample is stopped and degassing is performed until the anodic current falls back to the background baseline.

[0018] Step 3: Secondary hydrogen diffusion test in a dual-electrolysis cell at room temperature: The sample treated in Step 2 is subjected to a second electrochemical permeation test under the same test conditions as in Step 2, and the secondary permeation hysteresis time is recorded. ;

[0019] Step 4: Calculate the true hydrogen diffusion coefficient D eff ;

[0020] Step 5: Calculate the reversible hydrogen trap strength factor ;

[0021] Step 6: Calculate the saturation hydrogen content of the irreversible hydrogen trap. .

[0022] Furthermore, in step 1, the first test temperature T H When the condition is met, the thermal activation energy of hydrogen atoms in the metal sheet sample is greater than the binding energy of their hydrogen traps.

[0023] Furthermore, in step 1, the metal sheet sample is subjected to a first test temperature T. H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H The calculation formula for ) is as follows:

[0024] ;

[0025] ;

[0026] Wherein, l is the thickness of the metal sheet sample. To be at the first test temperature T H Steady-state current during the test To be at the first test temperature T H The hysteresis time when the permeation current reaches 63% of the steady-state current value during the test, where F is the Faraday constant.

[0027] Furthermore, in step 1, the room-temperature reference lattice hydrogen diffusion coefficient D L (T R ) and the solubility of hydrogen in the room-temperature lattice S L (T R The calculation formula for ) is as follows:

[0028] ;

[0029] ;

[0030] Where E is the activation energy, R is the gas constant, and ΔH is the heat of lattice dissolution.

[0031] Furthermore, in step 4, the true effective hydrogen diffusion coefficient D eff The calculation formula is:

[0032] ;

[0033] Wherein, l is the thickness of the metal sheet sample. This is the hysteresis time of the second penetration.

[0034] Furthermore, in step 5, the reversible hydrogen trap strength factor The calculation formula is as follows:

[0035] .

[0036] Furthermore, in step 6, the irreversible hydrogen trap is saturated with hydrogen content. The calculation formula is as follows:

[0037] .

[0038] Furthermore, in step 1, the electrochemical permeation test employs a dual-electrolysis cell system, wherein the electrolyte used in both the hydrogen charging cell and the oxidation cell of the dual-electrolysis cell is a mixed solution of NaHSO4, KHSO4, and Na2SO4.

[0039] Furthermore, in steps 2 and 3, the electrochemical permeation test employs a dual-electrolysis cell system. The electrolyte used in the hydrogen charging cell of the dual-electrolysis cell is an aqueous solution of H2SO4 and NH4SCN, and the electrolyte used in the oxidation cell of the dual-electrolysis cell is an aqueous solution of NaOH.

[0040] Furthermore, the high-hydrogen trap material is a metallic material of the Cr-Mo system or the Cr-Ni-Mo system.

[0041] Compared with existing technologies, the method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material described in this invention has the following advantages:

[0042] 1) This invention solves the problem of interference caused by the combined effect of reversible and irreversible hydrogen traps during the diffusion of hydrogen atoms inside the metal by testing the hydrogen diffusion behavior of Cr-Ni-Mo and Cr-Mo system metal materials under different test environments. It realizes the simulation of the real internal hydrogen diffusion behavior of materials under service conditions, and greatly improves the precision and accuracy of the test.

[0043] 2) The present invention provides a method for determining the hydrogen diffusion coefficient and trapping parameters of high-hydrogen-trap materials. This invention identifies and distinguishes the sites of hydrogen atoms within metallic materials, thereby expressing the true hydrogen diffusion behavior in high-hydrogen-trap materials. Through this method, the true hydrogen diffusion coefficient, reversible hydrogen trapping intensity factor, and irreversible hydrogen trapping saturation hydrogen content are obtained. These core parameters provide a scientific basis for the analysis and evaluation of hydrogen embrittlement behavior in metallic materials. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material according to an embodiment of the present invention. Detailed Implementation

[0045] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0046] It should be noted that in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] Example 1

[0049] Based on the diffusion model of a dual electrolytic cell in electrochemical testing, this invention analyzes and identifies the distribution characteristics of hydrogen atoms within high-hydrogen-trap materials. Hydrogen atom sites are categorized into: free hydrogen atoms, hydrogen atoms in reversible hydrogen traps, and hydrogen atoms trapped in irreversible hydrogen traps. By changing the testing environment, the states of hydrogen atoms at these three sites are controlled, simulating the internal hydrogen atom distribution characteristics of metals under service conditions. Mathematical analysis yields the formulas for calculating the true hydrogen diffusion coefficient and trap parameters, which characterize the hydrogen diffusion behavior of high-hydrogen-trap materials.

[0050] Specifically, this embodiment proposes a method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen-trap material, wherein the high-hydrogen-trap material is a Cr-Mo system or a Cr-Ni-Mo system metallic material, such as... Figure 1 As shown, the measurement method includes the following steps:

[0051] Step 1: High-Temperature Dual Electrolytic Cell Hydrogen Diffusion Test: A thin metal sheet sample with a thickness of l and no hydrogen charge is placed in an electrochemical dual electrolytic cell with a contact area of ​​A0. The electrochemical permeation test uses a dual electrolytic cell system. The electrolyte used in both the hydrogen charging cell and the oxidation cell of the dual electrolytic cell is a mixed solution of NaHSO4, KHSO4, and Na2SO4. The heating device is turned on to raise the temperature of the molten salt to the first test temperature T. H The first test temperature T H Above room temperature, the first test temperature T H When the condition is met, the thermal activation energy of hydrogen atoms in the metal sheet sample is greater than the binding energy of their hydrogen traps, thus inactivating the hydrogen trapping effect inside the metal using the thermal activation energy. The metal sheet sample is charged with hydrogen in a hydrogen-filled cell, and a constant anolyte potential is applied to the oxidation cell. The oxidation current versus time curve is recorded. When the current reaches a steady state... At that time, the lag time of 63% of the steady-state current is utilized. The metal sheet sample was calculated at the first test temperature T. HThe hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H The metal sheet sample was tested at a first test temperature T. H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H The calculation formula for ) is as follows:

[0052] ;

[0053] ;

[0054] Wherein, l is the thickness of the metal sheet sample. To be at the first test temperature T H Steady-state current during the test To be at the first test temperature T H The hysteresis time when the permeation current reaches 63% of the steady-state current value during the test, where F is the Faraday constant.

[0055] Then, using Arrhenius's thermal activation law, the first test temperature T is... H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H Extrapolation yields the target ambient temperature T. R The hydrogen diffusion coefficient D of the reference lattice at room temperature L (T R ) and the solubility of hydrogen in the room-temperature lattice S L (T R The room-temperature reference lattice hydrogen diffusion coefficient D L (T R ) and the solubility of hydrogen in the room-temperature lattice S L (T R The calculation formula for ) is as follows:

[0056] ;

[0057] ;

[0058] Where E is the activation energy, which can be obtained by fitting multiple measurements at high temperature; R is the gas constant, and ΔH is the lattice dissolution heat, which can be obtained by fitting multiple experiments.

[0059] Step 2: Room temperature dual-electrolysis cell hydrogen diffusion test: Select a brand new, untested metal sheet sample of thickness l from the same batch, and test it at the target room temperature T. R The first hydrogen permeation test was conducted using a dual-electrolysis cell system. The hydrogen-filling cell used an aqueous solution of H₂SO₄ and NH₄SCN, while the oxidation cell used an aqueous solution of NaOH. The experimental environment temperature was controlled at room temperature T. R (Room temperature). The sample undergoes its first hydrogen permeation test. During this test, lattice diffusion, reversible trap dynamic adsorption, and irreversible trap capture of hydrogen atoms occur simultaneously until the oxidation cell is completely oxidized and the first steady-state current value is reached. The total penetration time is t1, and the initial penetration lag time is recorded. At this point, the irreversible hydrogen traps within the metal sheet sample are completely filled with hydrogen atoms and reach a physical saturation state. Subsequently, hydrogen charging of the sample is stopped and degassing is performed. The anodic oxidation potential is kept constant, and the anodic current decay curve is monitored until the anodic current completely falls back to the initial environmental background baseline, causing the reversible hydrogen traps and free hydrogen in the lattice within the sample to escape, while the irreversible hydrogen traps remain in a saturated state filled with hydrogen atoms.

[0060] Step 3: Secondary hydrogen diffusion test in a dual-electrolysis cell at room temperature: The sample treated in Step 2 is subjected to a second electrochemical permeation test under the same test conditions as in Step 2, and the secondary permeation current curve is recorded until the second steady-state current value is reached. Record the secondary osmosis hysteresis time Since the irreversible traps are filled with hydrogen atoms at this time, the rate of change of the irreversible hydrogen trap concentration in the sample is zero. This curve only reflects the dynamic equilibrium diffusion state between pure lattice diffusion and reversible trap diffusion.

[0061] Step 4: Calculate the true hydrogen diffusion coefficient D eff .

[0062] The true hydrogen diffusion coefficient expresses the material's actual hydrogen diffusion penetration capability under service conditions. In secondary permeation tests, since the irreversible traps are completely saturated, the concentration change rate is zero. The secondary permeation hysteresis time is used to... Using classic Fick's law, the true effective hydrogen diffusion coefficient D after eliminating irreversible trap interference was calculated. eff The true effective hydrogen diffusion coefficient D eff The calculation formula is:

[0063] ;

[0064] Wherein, l is the thickness of the metal sheet sample. This is the hysteresis time of the second penetration.

[0065] Step 5: Calculate the reversible hydrogen trap strength factor .

[0066] The reversible hydrogen trap strength factor expresses the hindering effect of reversible hydrogen traps on hydrogen atom diffusion. It represents the ratio of hydrogen atoms under the adsorption and desorption of reversible hydrogen traps to free hydrogen atoms. The larger the strength factor, the greater the content of reversible hydrogen traps inside the material. According to the theoretical model, when local thermodynamic equilibrium is established in the later stage of secondary infiltration, the partial derivatives of the concentrations of lattice-free hydrogen and reversible trapped hydrogen satisfy the following direct proportional relationship, where a represents free hydrogen and b represents hydrogen trapped by reversible traps:

[0067]

[0068] Substituting into the simplified diffusion equation, the effective diffusion coefficient D can be derived. eff Compared with the room temperature reference lattice diffusion coefficient D L (T) R The relationship between )

[0069] ;

[0070] D will be obtained through experiments. eff D was obtained by extrapolation from high temperature. L (T) R Substituting into the above equation and transforming it, we can obtain the reversible hydrogen trap intensity factor, which characterizes the reversible hydrogen trap distribution density inside the material. The reversible hydrogen trap strength factor The calculation formula is as follows:

[0071] .

[0072] Step 6: Calculate the saturation hydrogen content of the irreversible hydrogen trap. .

[0073] The saturation hydrogen content of irreversible hydrogen traps expresses the amount of hydrogen atoms captured by irreversible hydrogen traps within the metal. During the first room-temperature permeation process, when the irreversible traps are fully saturated, a large number of hydrogen atoms are captured. This is macroscopically manifested as a time-lag shift in the first permeation curve relative to the second permeation curve.

[0074] According to the integral flux comparison theory, the difference in integral flux between the two permeation curves during the steady-state process is completely equivalent to the number of hydrogen atoms absorbed by the irreversible trap. The lag time difference is defined. .

[0075] The saturated hydrogen content of the irreversible hydrogen trap per unit volume of material The calculation formula is as follows:

[0076] .

[0077] Specifically, in this embodiment, the high-hydrogen trap material is a Cr-Ni-Mo system metallic material, and its specific chemical composition is shown in Table 1. After heat treatment, the high-hydrogen trap material is divided into 20×20mm metal sheet samples with a thickness of 1mm, and the surface is ground to a smooth state.

[0078] Table 1 Chemical composition of materials used in the experiment

[0079]

[0080] Specifically, in this embodiment, the measurement method includes the following steps:

[0081] Step 1: High-temperature dual electrolytic cell hydrogen diffusion test: A thin metal sheet sample with a thickness of l and no hydrogen charge is placed in the electrochemical dual electrolytic cell. The contact area between the metal sheet sample and the electrolytic cell is A0, which is 2 cm². 2 Turn on the heating device to raise the temperature of the molten salt to the first test temperature T. H T H The temperature is 350℃. The hysteresis time is when the oxidation current reaches steady state. The value is 66.7 s. The diffusion coefficient D of the pure lattice at high temperature is obtained according to the calculation formula. L (T) H ) is 2.5×10 -5 cm 2 / s, steady-state current The solubility of hydrogen in the crystal lattice at high temperature is 0.603 mA. L (T H The value is 1.25 × 10 -5 mol / cm 3 Using Arrhenius's thermal activation law, the room-temperature reference lattice hydrogen diffusion coefficient D is derived from parameters calculated at high temperatures. L (T R ) is 2.0 × 10 -6 cm 2 / s, the lattice hydrogen solubility at room temperature is 1.25 × 10⁻⁶. -5 mol / cm 3 .

[0082] Step 2: Room temperature dual-electrolysis cell hydrogen diffusion test: Select a brand new, untested metal sheet sample of thickness l from the same batch, and test it at the target room temperature T. R The first hydrogen permeation test was conducted using a dual-electrolysis cell system. The hydrogen-filling cell used an aqueous solution of H₂SO₄ and NH₄SCN, while the oxidation cell used an aqueous solution of NaOH. The experimental environment temperature was controlled at room temperature T.R (Room temperature), the room temperature is constant at 25℃, i.e., T R The temperature was 25℃. The initial penetration hysteresis time was measured when the oxidation current reached steady state at room temperature. The time was 7616 seconds. The hydrogen charging current in the hydrogen charging cell was then turned off, and the oxidation current was monitored to return to baseline.

[0083] Step 3: Secondary Hydrogen Diffusion Test in a Room Temperature Dual Electrolyzer: The sample treated in Step 2 is subjected to a second electrochemical permeation test under the same test conditions as in Step 2. The hydrogen lag time is measured when the oxidation current reaches steady state. It is 1528s.

[0084] Step 4: Calculate the true hydrogen diffusion coefficient: Based on the true effective hydrogen diffusion coefficient D eff The calculation formula yields a true hydrogen diffusion coefficient of 1.11 × 10⁻⁶. -6 cm 2 / s.

[0085] Step 5: Calculate the reversible hydrogen trap strength factor Based on the reversible hydrogen trap strength factor The calculation formula yields a reversible hydrogen trap strength factor of 0.80 for this material.

[0086] Step 6: Calculate the saturation hydrogen content of the irreversible hydrogen trap. Based on the saturation hydrogen content of irreversible hydrogen traps The calculation formula yields the saturated hydrogen content of the irreversible hydrogen trap in this material. It is 9.174×10 -5 mol / cm 3 After conversion, it can be seen that the irreversible hydrogen trapping hydrogen content in the material is 11.78 ppm.

[0087] Comparative Example 1

[0088] Unlike Example 1, the room-temperature reference lattice hydrogen diffusion coefficient of the material was determined using a conventional electrochemical testing method.

[0089] The measured room-temperature reference lattice hydrogen diffusion coefficient of the material is 2.23 × 10⁻⁶. -7 cm 2 / s, approximately 20% of the true hydrogen diffusion coefficient in the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in Example 1.

[0090] It is evident that the hydrogen diffusion coefficient of the material measured by the traditional electrochemical testing method at room temperature reference lattice differs significantly from the actual hydrogen diffusion coefficient in the method for measuring the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in Example 1, indicating that the traditional electrochemical testing method has low accuracy.

[0091] Comparative Example 2

[0092] Unlike Example 1, this method uses a metal material that has been in service for a long time and tests its room-temperature reference lattice hydrogen diffusion coefficient and irreversible hydrogen trap saturation hydrogen content using conventional electrochemical testing methods. .

[0093] The room-temperature reference lattice hydrogen diffusion coefficient of the metallic material after long-term service was measured to be 1.08 × 10⁻⁶. -6 cm 2 / s represents 97% of the true hydrogen diffusion coefficient in the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in Example 1.

[0094] After long-term service, the saturation of irreversible hydrogen traps inside metallic materials results in a high hydrogen content. The measured value was 12.02 ppm, which is consistent with the irreversible hydrogen trap saturation hydrogen content described in Example 1, which is used in the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material. The difference is 2%.

[0095] Therefore, the room-temperature reference lattice hydrogen diffusion coefficient of the metal material obtained by conventional electrochemical testing methods after long-term service is basically consistent with the true hydrogen diffusion coefficient obtained by the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in Example 1; the irreversible hydrogen trap saturation hydrogen content of the metal material obtained by conventional electrochemical testing methods after long-term service is also consistent. The irreversible hydrogen trap saturation hydrogen content obtained by testing the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material as described in Example 1 The results are basically consistent; therefore, it can be seen that the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in Example 1 is highly accurate.

[0096] In summary, the method for determining the hydrogen diffusion coefficient and trap parameters of a high-hydrogen trap material described in this invention can accurately and effectively improve the accuracy of the test of the hydrogen diffusion coefficient and trap parameters of the material, and has certain engineering experimental significance.

[0097] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material, characterized in that, The determination method includes the following steps: Step 1: High-temperature dual-electrolysis cell hydrogen diffusion test: Select a thin metal sheet sample with a thickness of l that has not been filled with hydrogen and place it into the electrochemical dual-electrolysis cell with a contact area of ​​A0. Turn on the heating device and raise the temperature of the molten salt to the first test temperature T. H The first test temperature T H Above room temperature, the temperature of the thin metal sheet sample at the first test temperature T is calculated. H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H Then, using Arrhenius's thermal activation law, the first test temperature T was... H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H Extrapolation yields the target ambient temperature T. R The hydrogen diffusion coefficient D of the reference lattice at room temperature L (T R ) and room temperature lattice hydrogen solubility S L (T R ); Step 2: Room temperature dual-electrolysis cell hydrogen diffusion test: Select a brand new, untested metal sheet sample of thickness l from the same batch, and test it at the target room temperature T. R The first hydrogen permeation test was conducted until the permeation current reached the first steady-state value. And record the initial penetration hysteresis time. At this point, the irreversible hydrogen traps in the metal sheet sample have been completely filled with hydrogen atoms and have reached a physical saturation state; subsequently, the hydrogen charging of the sample is stopped and degassing is performed until the anodic current falls back to the background baseline. Step 3: Secondary hydrogen diffusion test in a dual-electrolysis cell at room temperature: The sample treated in Step 2 is subjected to a second electrochemical permeation test under the same test conditions as in Step 2, and the secondary permeation hysteresis time is recorded. ; Step 4: Calculate the true hydrogen diffusion coefficient D eff ; Step 5: Calculate the reversible hydrogen trap strength factor ; Step 6: Calculate the saturation hydrogen content of the irreversible hydrogen trap. .

2. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In step 1, the first test temperature T H When the condition is met, the thermal activation energy of hydrogen atoms in the metal sheet sample is greater than the binding energy of their hydrogen traps.

3. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In step 1, the metal sheet sample is subjected to a first test temperature T. H The hydrogen diffusion coefficient D of the pure lattice is below L (T) H ) and lattice hydrogen solubility S L (T H The calculation formula for ) is as follows: ； ； Wherein, l is the thickness of the metal sheet sample. To be at the first test temperature T H Steady-state current during the test To be at the first test temperature T H The hysteresis time when the permeation current reaches 63% of the steady-state current value during the test, where F is the Faraday constant.

4. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 3, characterized in that, In step 1, the room-temperature reference lattice hydrogen diffusion coefficient D L (T R ) and the solubility of hydrogen in the room-temperature lattice S L (T R The calculation formula for ) is as follows: ； ； Where E is the activation energy, R is the gas constant, and ΔH is the heat of lattice dissolution.

5. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In step 4, the true effective hydrogen diffusion coefficient D eff The calculation formula is: ； Wherein, l is the thickness of the metal sheet sample. This is the hysteresis time of the second penetration.

6. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In step 5, the reversible hydrogen trap strength factor The calculation formula is as follows: 。 7. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 6, characterized in that, In step 6, the irreversible hydrogen trap is saturated with hydrogen content. The calculation formula is as follows: 。 8. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In step 1, the electrochemical permeation test uses a dual electrolysis cell system, and the electrolyte used in the hydrogen charging cell and the oxidation cell of the dual electrolysis cell is a mixed solution of NaHSO4, KHSO4 and Na2SO4.

9. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, In steps 2 and 3, the electrochemical permeation test uses a dual-electrolysis cell system. The electrolyte used in the hydrogen charging cell of the dual-electrolysis cell is an aqueous solution of H2SO4 and NH4SCN, and the electrolyte used in the oxidation cell of the dual-electrolysis cell is an aqueous solution of NaOH.

10. The method for determining the hydrogen diffusion coefficient and trapping parameters of a high-hydrogen trapping material according to claim 1, characterized in that, The high-hydrogen trap material is a metallic material of the Cr-Mo system or the Cr-Ni-Mo system.

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