A method for measuring magnetic field strength based on potential measurement

Abstract

The present invention discloses a method for measuring magnetic field strength based on potential measurement. The method includes the preparation of an electrode system: a working electrode and a reference electrode form an electrode system; open-circuit potential measurement: under the condition of no magnetic field, the working electrode is immersed in a solution containing oxidant ions to make the open-circuit potential reach a stable state OCP(0T); determination of the open-circuit potential of the working electrode after applying different intensities of magnetic fields: gradually apply magnetic fields of 0.02T - 0.5T, and measure the open-circuit potential OCP(xT) of the working electrode under each magnetic field condition; plot a standard curve of the potential values corresponding to different magnetic field intensities; by measuring OCP(xT) or OCP(xT) - OCP(0T) of the working electrode in a certain system, and through the plotted standard curve, obtain the numerical value of the corresponding magnetic field strength. The present invention measures the magnetic field strength by measuring the change in the open-circuit potential of a metal in a solution containing charged oxidants caused by an applied magnetic field.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic field strength measurement, and particularly relates to a magnetic field strength test method based on potential measurement. Background Art

[0002] Magnetic fields play a very important role in nature and industrial fields. For example, in fields such as spatial positioning, industrial flaw detection, and medical imaging, the quantification of magnetic field strength plays a key role. Compared with the simple and easy measurement of electric field strength or potential, the measurement of magnetic field strength is relatively complex. Several existing magnetic field strength test methods, such as the fluxgate method, Hall effect method, magnetoresistance effect method, nuclear magnetic resonance method, superconducting effect method, magneto-optical effect method, etc., require special devices and instruments and are all based on physical effects. If a common instrument or meter, such as a voltmeter (potentiometer), can be used to measure the magnetic field strength, it will be more simple and convenient. The working principle of the present invention is based on magnetoelectrochemistry theory: the magnetic field affects the surface electrode reaction rate of a specific metal in an ionic oxidant solution by superimposing the Lorentz force effect, resulting in changes in the electrochemical state of the metal, such as the electrode potential. Therefore, by detecting the change in the metal electrode potential caused by an unknown magnetic field, the strength of the unknown magnetic field can be measured, and the magnetic field strength can be measured with a voltmeter. Summary of the Invention

[0003] In order to solve the problems of the existing technology, the purpose of the present invention is to develop a magnetic field strength test method based on potential measurement, and measure the magnetic field strength by measuring the change in the open-circuit potential of a metal in a charged oxidant caused by an externally applied magnetic field.

[0004] To achieve the above object of the invention, the present invention adopts the following technical solutions:

[0005] A magnetic field strength test method based on potential measurement, the method comprising the following steps:

[0006] Step 1: Preparation of the electrode system

[0007] Use a metal electrode as the working electrode and the reference electrode to form an electrode system, and connect it to an electrochemical workstation or a voltmeter;

[0008] Step 2: Measurement of the open-circuit potential

[0009] Immerse the working electrode of the electrode system in a solution containing oxidant ions, and record the open-circuit potential value OCP(0T) until it reaches a stable state;

[0010] Step 3: Measure the open-circuit potential of the working electrode after applying external magnetic fields of different intensities

[0011] After the open-circuit potential reaches stability under the 0T condition, apply a magnetic field with a given intensity. The magnetic field intensity ranges from 0.02T to 0.5T, and the magnetic field is applied gradually from small to large. Measure the open-circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open-circuit potential reaches a stable state before increasing the magnetic field intensity and waiting again until the open-circuit potential reaches a steady state. Record the open-circuit potential value OCP(xT) at each magnetic field intensity.

[0012] Step Four: Plot the standard curve of the open-circuit potential values corresponding to different magnetic field intensities

[0013] Based on the measured electrode potential values of the working electrode at different magnetic field intensities after reaching the steady state, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under the magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with the magnetic field and the electrode potential without the magnetic field (X-axis) ~ magnetic field intensity B (Y-axis) [OCP(xT) - OCP(0T)] ~ B.

[0014] Step Five: Determine the unknown magnetic field intensity

[0015] By measuring OCP(yT), or OCP(yT) - OCP(0T), with the same electrode system placed in a magnetic field of unknown intensity, and through the standard curve plotted in Step Four, the corresponding magnetic field intensity value can be obtained.

[0016] Preferably, the temperature of all processes of the magnetic field intensity test method based on potential measurement is the same temperature. Further preferably, the temperature of all processes is room temperature, and the room temperature is kept relatively constant by air conditioning with a fluctuation not exceeding 2°C.

[0017] Preferably, all processes of the magnetic field intensity test method based on potential measurement are repeated not less than 3 times, the fluctuation of the measured potential difference value at the used magnetic field intensity does not exceed 10%, and the deviation degree of the corresponding measured magnetic field intensity is not higher than 10%.

[0018] Preferably, in Step One, the working electrode is an industrial pure Fe electrode with a diameter of not less than 5 mm, and the electrode surface is polished to 1500 mesh with metallographic sandpaper; the reference electrode is a saturated calomel electrode.

[0019] Preferably, in Step Two, the oxidant ion is preferably ferric ion.

[0020] Preferably, in Step Two, the anion corresponding to the ferric ion oxidant is sulfate.

[0021] Preferably, in Step Two, the anion corresponding to the ferric ion oxidant is chloride.

[0022] Preferably, in the third step, the external magnetic field is in the horizontal direction, and the magnetic field direction is parallel to the surface of the working electrode.

[0023] Preferably, in the second step, the combination of the working electrode and the oxidant ions enables the electrode reaction rate at the open circuit potential to be controlled entirely or partially by the mass transfer process of the oxidant at the electrode interface.

[0024] In the third step, immerse the working electrode of the electrode system in a solution containing oxidant ions until the open circuit potential reaches a stable state; apply external magnetic fields of different intensities at different time intervals, and the time intervals are determined according to the time required for each condition to reach a steady state.

[0025] Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

[0026] 1. The present invention can measure the magnetic field strength through potential testing, and the testing method based on the electrochemical principle has substantive features.

[0027] 2. The testing method of the present invention has high precision, good repeatability, and the measurement process is easy to control;

[0028] 3. The method of the present invention is simple, easy to implement, low in cost, suitable for popularization and use, and has significant advantages. Description of the Drawings

[0029] Figure 1 It is the open circuit potential result diagram of Fe in 0.04 mol / L Fe2(SO4)3 solution in Example 1, (a): OCP(xT)~B, (b): [OCP(xT)-OCP(0T)]~B.

[0030] Figure 2 It is the open circuit potential result diagram of Fe in 0.08 mol / L Fe2(SO4)3 solution in Example 2 of the present invention, (a): OCP(xT)~B, (b): [OCP(xT)-OCP(0T)]~B.

[0031] Figure 3 It is the open circuit potential result diagram of Fe in 0.12 mol / L Fe2(SO4)3 solution in Example 3 of the present invention, (a): OCP(xT)~B, (b): [OCP(xT)-OCP(0T)]~B.

[0032] Figure 4 It is the open circuit potential result diagram of Fe in 0.16 mol / L Fe2(SO4)3 solution in Example 4 of the present invention, (a): OCP(xT)~B, (b): [OCP(xT)-OCP(0T)]~B.

[0033] Figure 5This is the open-circuit potential result graph of Fe in 0.08 mol / L FeCl3 solution in the fifth embodiment of the present invention. (a): OCP(xT) ~ B, (b): [OCP(xT) - OCP(0T)] ~ B.

[0034] Figure 6 This is the open-circuit potential result graph of Fe in 0.16 mol / L FeCl3 solution in the sixth embodiment of the present invention. (a): OCP(xT) ~ B, (b): [OCP(xT) - OCP(0T)] ~ B.

[0035] Figure 7 This is the open-circuit potential result graph of Fe in 0.24 mol / L FeCl3 solution in the seventh embodiment of the present invention. (a): OCP(xT) ~ B, (b): [OCP(xT) - OCP(0T)] ~ B.

[0036] Figure 8 This is the open-circuit potential result graph of Fe in 0.32 mol / L FeCl3 solution in the eighth embodiment of the present invention. (a): OCP(xT) ~ B, (b): [OCP(xT) - OCP(0T)] ~ B. Detailed implementation manners

[0037] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings through specific implementation manners. However, it is not limited thereto. Any technical solutions obtained by modifying the technical solutions of the present invention or adopting equivalent replacements or equivalent changes fall within the protection scope of the present invention.

[0038] The above solutions will be further described below in conjunction with specific embodiments. The preferred embodiments of the present invention are described in detail as follows:

[0039] Embodiment 1:

[0040] In this embodiment, a method for measuring magnetic field strength based on potential measurement includes the following steps under room temperature conditions:

[0041] Step 1: Preparation of electrode system

[0042] A metal working electrode and a reference electrode form a measurement electrode system and are connected to an electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0043] Step 2: Open-circuit potential measurement

[0044] Immerse the working electrode Fe of the electrode system in 0.04 mol / L Fe2(SO4)3 solution for 3 h until the open-circuit potential reaches a stable state, record its value, and mark it as OCP(0T);

[0045] Step 3: Measure the open-circuit potential of the working electrode after applying magnetic fields of different intensities

[0046] After the open-circuit potential under 0T condition reaches stability, apply a magnetic field with a given intensity. The applied magnetic field is in the horizontal direction, and the magnetic field direction is parallel to the surface of the working electrode. The magnetic field intensity ranges from 0.02T to 0.5T, and the magnetic field is applied gradually from small to large. Measure the open-circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open-circuit potential of the working electrode reaches a stable state and then increase the magnetic field intensity and continue to wait until the open-circuit potential reaches a steady state again. Immerse for 5 minutes under each magnetic field condition to make the open-circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open-circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open-circuit potential value OCP(xT) at each magnetic field intensity.

[0047] Step 4: Plot the standard curve of the potential values corresponding to different magnetic field intensities

[0048] According to the measured electrode potential values of the working electrode after reaching a steady state under different magnetic field intensities, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under a magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field (X-axis) ~ magnetic field intensity B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 1 shown; the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field measured experimentally is the largest under the 0.5T magnetic field state, and the potential difference is in the range of 16.5 to 18, and its deviation is 8.8%, less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation of the potential difference is 8.8%, the corresponding deviation of the measured magnetic field intensity is 7.58%, less than 10%.

[0049] Step 5: Determine the unknown magnetic field intensity

[0050] By using the same electrode system placed in a magnetic field with an unknown magnetic field intensity to measure OCP(yT), or OCP(yT) - OCP(0T), through the standard curve plotted in Step 4, the corresponding magnetic field intensity value can be obtained.

[0051] Example 2

[0052] This example is basically the same as Example 1, with the special feature being:

[0053] In this example, a method for measuring magnetic field intensity based on potential measurement, under room temperature conditions, the method includes the following steps:

[0054] Step 1: Prepare the electrode system

[0055] A metal working electrode and a reference electrode form an electrode system, which is connected to an electrochemical workstation. The working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode.

[0056] Step 2: Open-circuit potential measurement

[0057] Immerse the working electrode Fe of the electrode system in a 0.08 mol / L Fe2(SO4)3 solution for 2.5 h until the open-circuit potential reaches a stable state, record its value, and mark it as OCP(0T).

[0058] Step 3: Measure the open-circuit potential of the working electrode after applying magnetic fields of different intensities

[0059] After the open-circuit potential under the 0T condition reaches stability, apply a magnetic field of a given intensity. The applied magnetic field is in the horizontal direction, the magnetic field direction is parallel to the surface of the working electrode, and the magnetic field intensity is 0.02T - 0.5T. The magnetic field is applied gradually from small to large. Measure the open-circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open-circuit potential of the working electrode reaches a stable state and then increase the magnetic field intensity and continue to wait until the open-circuit potential reaches a steady state again. Immerse for 5 min under each magnetic field condition to make the open-circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open-circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open-circuit potential value OCP(xT) at each magnetic field intensity.

[0060] Step 4: Plot the standard curve of the potential values corresponding to different magnetic field intensities

[0061] According to the measured electrode potential values of the working electrode after reaching a steady state at different magnetic field intensities, plot the standard curve of electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under a magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field (X-axis) ~ magnetic field intensity B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 2 shown; the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field measured experimentally is the largest under the 0.5T magnetic field state, and the potential difference is in the range of 14.47 to 15.97 mV, and its deviation is 9.8%, less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation of the potential difference is 9.8%, the corresponding deviation of the measured magnetic field intensity is 9.21%, less than 10%.

[0062] Step 5: Determination of the unknown magnetic field intensity

[0063] By placing the same electrode system in a magnetic field of unknown magnetic field strength, OCP(yT) or OCP(yT)-OCP(0T) can be measured, and the corresponding magnetic field strength value can be obtained through the standard curve drawn in step 4.

[0064] Embodiment 3

[0065] This embodiment is basically the same as the first embodiment, except that:

[0066] In this embodiment, a magnetic field strength test method based on potential measurement is provided. Under room temperature conditions, the method comprises the following steps:

[0067] Step 1: Electrode system preparation

[0068] The metal working electrode and the reference electrode constitute a three-electrode system and are connected to the electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0069] Step 2: Open circuit potential measurement

[0070] The working electrode Fe of the electrode system was immersed in a 0.12 mol / L Fe2(SO4)3 solution for 1.5 h until the open circuit potential reached a stable state, and its value was recorded and marked as OCP (0T);

[0071] Step 3: Determine the open circuit potential of the working electrode after applying magnetic fields of different strengths

[0072] After the open circuit potential reaches stability under 0T conditions, a magnetic field of a given strength is applied. The applied magnetic field is horizontal, parallel to the surface of the working electrode, and the magnetic field strength is 0.02T-0.5T. The magnetic field is applied gradually from small to large, and the open circuit potential of the working electrode at each magnetic field strength is measured. At each magnetic field strength, the open circuit potential of the working electrode is increased until it reaches a stable state, and then the magnetic field strength is increased until the open circuit potential reaches a steady state again. Under each magnetic field condition, the open circuit potential of Fe under the magnetic field condition is soaked for 5 minutes to reach a stable value. The determination of the open circuit potential under any magnetic field strength is repeated more than 3 times to ensure the reproducibility of the experimental results; the open circuit potential value OCP (xT) under each magnetic field strength is recorded.

[0073] Step 4: Draw the standard curve of potential values corresponding to different magnetic field strengths

[0074] According to the electrode potential values of the working electrode after reaching the steady state under different magnetic field strengths, a standard curve of electrode potential E (X axis) under magnetic field and magnetic field strength B (Y axis) is drawn, OCP (xT) ~ B, or a standard curve of the difference between the electrode potential with magnetic field and the electrode potential without magnetic field ΔE (X axis) ~ magnetic field strength B (Y axis), [OCP (xT) - OCP (0T)] ~ B, such asFigure 3 As shown in the figure; the difference ΔE between the electrode potential measured experimentally with a magnetic field and the electrode potential without a magnetic field is the largest under a 0.5T magnetic field. The potential difference ranges from 15.63 to 16.56 mV, and its deviation is 5.6%, which is less than 10%. Fitting [OCP(xT)-OCP(0T)]~B, when the deviation of the potential difference is 5.6%, the deviation of the corresponding measured magnetic field strength is 9.6%, which is less than 10%.

[0075] Step Five: Determination of the unknown magnetic field strength

[0076] By placing the same electrode system in a magnetic field with an unknown magnetic field strength to measure OCP(yT), or OCP(yT)-OCP(0T), and through the standard curve drawn in Step Four, the corresponding magnetic field strength value can be obtained.

[0077] Example Four

[0078] This example is basically the same as Example One, with the special feature that:

[0079] In this example, a method for testing the magnetic field strength based on potential measurement, under room temperature conditions, the method includes the following steps:

[0080] Step One: Preparation of the electrode system

[0081] A metal working electrode and a reference electrode electrode system, and connect it to an electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0082] Step Two: Open circuit potential measurement

[0083] Immerse the working electrode Fe of the electrode system in a 0.16 mol / L Fe2(SO4)3 solution for 1 h until the open circuit potential reaches a stable state, record its value, and mark it as OCP(0T);

[0084] Step Three: Measure the open circuit potential of the working electrode after applying different intensities of magnetic fields

[0085] After the open circuit potential reaches stability under the condition of 0T, a magnetic field with a given intensity is applied externally. The externally applied magnetic field is in the horizontal direction, the magnetic field direction is parallel to the surface of the working electrode, the magnetic field intensity is 0.02T - 0.5T, and the magnetic field is applied gradually from small to large. The open circuit potential of the working electrode is measured at each magnetic field intensity. At each magnetic field intensity, wait until the open circuit potential of the working electrode reaches a stable state and then increase the magnetic field intensity and continue to wait until the open circuit potential reaches a steady state again. Immerse for 5 minutes under each magnetic field condition to make the open circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open circuit potential value OCP(xT) at each magnetic field intensity.

[0086] Step 4: Plotting the standard curve of the potential values corresponding to different magnetic field intensities

[0087] According to the measured electrode potential values of the working electrode after reaching a steady state at different magnetic field intensities, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under the magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with the magnetic field and the electrode potential without the magnetic field (X-axis) ~ magnetic field intensity B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 4 shown; the difference ΔE between the electrode potential with the magnetic field and the electrode potential without the magnetic field measured experimentally is the largest under the magnetic field state of 0.5T. The potential difference is in the range of 15.7 to 16.5 mV, and its deviation degree is 5.59%, less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation degree of the potential difference is 5.59%, the corresponding deviation degree of the measured magnetic field intensity is 9.07%, less than 10%.

[0088] Step 5: Determination of the unknown magnetic field intensity

[0089] By measuring OCP(yT), or OCP(yT) - OCP(0T), by using the same electrode system placed in a magnetic field with an unknown magnetic field intensity, the corresponding magnetic field intensity value can be obtained through the standard curve plotted in Step 4.

[0090] Example 5

[0091] This example is basically the same as Example 1, with the special feature that:

[0092] In this example, a method for testing the magnetic field intensity based on potential measurement, under room temperature conditions, the method includes the following steps:

[0093] Step 1: Preparation of the electrode system

[0094] A metal working electrode and a reference electrode form an electrode system, which is connected to an electrochemical workstation or a potentiometer; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0095] Step 2: Open-circuit potential measurement

[0096] Immerse the working electrode Fe of the electrode system in a 0.08 mol / L FeCl3 solution for 3 h until the open-circuit potential reaches a stable state, record its value, and mark it as OCP(0T);

[0097] Step 3: Measure the open-circuit potential of the working electrode after applying magnetic fields of different intensities

[0098] After the open-circuit potential under the 0T condition reaches stability, apply a magnetic field with a given intensity. The applied magnetic field is in the horizontal direction, and the magnetic field direction is parallel to the surface of the working electrode. The magnetic field intensity is 0.02T - 0.5T. The magnetic field is applied gradually from small to large. Measure the open-circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open-circuit potential of the working electrode reaches a stable state and then increase the magnetic field intensity and continue to wait until the open-circuit potential reaches a steady state again. Immerse for 5 min under each magnetic field condition to make the open-circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open-circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open-circuit potential value OCP(xT) at each magnetic field intensity.

[0099] Step 4: Plot the standard curve of the potential values corresponding to different magnetic field intensities

[0100] According to the measured electrode potential values of the working electrode after reaching the steady state at different magnetic field intensities, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under the magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with the magnetic field and the electrode potential without the magnetic field (X-axis) ~ magnetic field intensity B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 5 shown; the difference ΔE between the electrode potential with the magnetic field and the electrode potential without the magnetic field measured experimentally is the largest under the 0.5T magnetic field state, and the potential difference is in the range of 11.43 to 12.18 mV, and its deviation degree is 6.37%, which is less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation degree of the potential difference is 6.37%, the corresponding deviation degree of the measured magnetic field intensity is 8.71%, which is less than 10%.

[0101] Step 5: Determination of the unknown magnetic field intensity

[0102] By using the same electrode system placed in a magnetic field with an unknown magnetic field strength to measure OCP (yT), or OCP (yT) - OCP (0T), and through the standard curve drawn in Step 4, the corresponding magnetic field strength value can be obtained.

[0103] Example Six

[0104] This example is basically the same as Example One, with the special feature being:

[0105] In this example, a method for testing magnetic field strength based on potential measurement, under room temperature conditions, the method includes the following steps:

[0106] Step One: Preparation of the Electrode System

[0107] A metal working electrode and a reference electrode form an electrode system and are connected to an electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0108] Step Two: Open Circuit Potential Measurement

[0109] Immerse the working electrode Fe of the electrode system in a 0.16 mol / L FeCl3 solution for 2.5 h until the open circuit potential reaches a stable state, record its value, and mark it as OCP (0T);

[0110] Step Three: Measure the Open Circuit Potential of the Working Electrode after Applying Different Intensities of External Magnetic Fields

[0111] After the open circuit potential under 0T conditions reaches stability, apply a given intensity of magnetic field. The external magnetic field is in the horizontal direction, the magnetic field direction is parallel to the surface of the working electrode, the magnetic field intensity is 0.02 T - 0.5 T, and the magnetic field is applied gradually from small to large. Measure the open circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open circuit potential of the working electrode reaches a stable state before increasing the magnetic field intensity and continuing to wait until the open circuit potential reaches a steady state again. Immerse for 5 min under each magnetic field condition to make the open circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open circuit potential value OCP (xT) at each magnetic field intensity.

[0112] Step Four: Plot the Standard Curve of the Potential Values Corresponding to Different Magnetic Field Intensities

[0113] Based on the measured electrode potential values of the working electrode after reaching a steady state at different magnetic field intensities, plot a standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under a magnetic field, OCP (xT) ~ B, or a standard curve of the difference ΔE (X-axis) between the electrode potential with a magnetic field and the electrode potential without a magnetic field ~ magnetic field intensity B (Y-axis), [OCP (xT) - OCP (0T)] ~ B, as Figure 6As shown; the difference ΔE between the electrode potential measured experimentally with a magnetic field and the electrode potential without a magnetic field is the largest in the magnetic field state of 0.5T. The potential difference is in the range of 10.2 to 11.0 mV, and its deviation degree is 8.0%, which is less than 10%. Fitting [OCP(xT) - OCP(0T)] ~ B obtained, when the deviation degree of the potential difference is 8.0%, the deviation degree of the corresponding measured magnetic field intensity is 8.83%, which is less than 10%.

[0114] Step Five: Determination of the unknown magnetic field intensity

[0115] By placing the same electrode system in a magnetic field with an unknown magnetic field intensity to measure OCP(yT), or OCP(yT) - OCP(0T), and through the standard curve drawn in Step Four, the corresponding magnetic field intensity value can be obtained.

[0116] Example Seven

[0117] This example is basically the same as Example One, with the special feature being that:

[0118] In this example, a method for testing the magnetic field intensity based on potential measurement, under room temperature conditions, the method includes the following steps:

[0119] Step One: Preparation of the electrode system

[0120] A metal working electrode and a reference electrode form a three - electrode system and are connected to an electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0121] Step Two: Measurement of the open - circuit potential

[0122] Immerse the working electrode Fe of the electrode system in a 0.24 mol / L FeCl3 solution for 1.5 h until the open - circuit potential reaches a stable state, record its value, and mark it as OCP(0T);

[0123] Step Three: Measurement of the open - circuit potential of the working electrode after applying different intensities of external magnetic fields:

[0124] After the open - circuit potential under the 0T condition reaches stability, apply an external magnetic field with a given intensity. The external magnetic field is in the horizontal direction, the magnetic field direction is parallel to the surface of the working electrode, the magnetic field intensity is from 0.02T to 0.5T, and the magnetic field is applied gradually from small to large. Measure the open - circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open - circuit potential of the working electrode reaches a stable state and then increase the magnetic field intensity and continue to wait until the open - circuit potential reaches a steady state again. Immerse for 5 min under each magnetic field condition to make the open - circuit potential of Fe reach a stable value under this magnetic field condition. The measurement of the open - circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open - circuit potential value OCP(xT) at each magnetic field intensity.

[0125] Step 4: Plotting the standard curve of potential values corresponding to different magnetic field strengths

[0126] Based on the measured electrode potential values of the working electrode after reaching a steady state under different magnetic field strengths, plot the standard curve of electrode potential E (X-axis) ~ magnetic field strength B (Y-axis), OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with magnetic field and the electrode potential without magnetic field (X-axis) ~ magnetic field strength B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 7 shown; the difference ΔE between the electrode potential with magnetic field and the electrode potential without magnetic field measured experimentally is the largest under the magnetic field state of 0.5T, and the potential difference is in the range of 9.68 to 10.37 mV, and its deviation is 6.89%, less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation of the potential difference is 6.89%, the corresponding deviation of the measured magnetic field strength is 9.02%, less than 10%.

[0127] Step 5: Determination of unknown magnetic field strength

[0128] By placing the same electrode system in a magnetic field with an unknown magnetic field strength to measure OCP(yT), or OCP(yT) - OCP(0T), the corresponding magnetic field strength value can be obtained through the standard curve plotted in Step 4.

[0129] Example 8

[0130] This example is basically the same as Example 1, with the special feature that:

[0131] In this example, a method for measuring magnetic field strength based on potential measurement includes the following steps at room temperature:

[0132] Step 1: Preparation of electrode system

[0133] A metal working electrode and a reference electrode form an electrode system and are connected to an electrochemical workstation; the working electrode is industrial pure Fe with a diameter of 5 mm, and the reference electrode is a saturated calomel electrode;

[0134] Step 2: Open-circuit potential measurement

[0135] Immerse the working electrode Fe of the electrode system in a 0.32 mol / L FeCl3 solution for 1 h until the open-circuit potential reaches a stable state, record its value, and mark it as OCP(0T);

[0136] Step 3: Measuring the open-circuit potential of the working electrode after applying different intensities of external magnetic fields

[0137] After the open-circuit potential reaches stability under 0T conditions, apply a magnetic field of a given intensity. The applied magnetic field is horizontal and its direction is parallel to the surface of the working electrode. The magnetic field intensity ranges from 0.02T to 0.5T. Apply the magnetic field gradually from small to large, and measure the open-circuit potential of the working electrode at each magnetic field intensity. At each magnetic field intensity, wait until the open-circuit potential of the working electrode reaches a stable state before increasing the magnetic field intensity and continue to wait until the open-circuit potential reaches a steady state again. Immerse for 5 minutes under each magnetic field condition to make the open-circuit potential of Fe reach a stable value under that magnetic field condition. The measurement of the open-circuit potential at any magnetic field intensity is repeated more than 3 times to ensure the reproducibility of the experimental results; record the open-circuit potential value OCP(xT) at each magnetic field intensity.

[0138] Step 4: Plot the standard curve of the potential values corresponding to different magnetic field intensities

[0139] Based on the measured electrode potential values of the working electrode after reaching a steady state at different magnetic field intensities, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under a magnetic field, OCP(xT) ~ B, or the standard curve of the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field (X-axis) ~ magnetic field intensity B (Y-axis), [OCP(xT) - OCP(0T)] ~ B, as Figure 8 shown; the difference ΔE between the electrode potential with a magnetic field and the electrode potential without a magnetic field measured experimentally is the largest under a 0.5T magnetic field state. The potential difference ranges from 9.81 to 10.59 mV, and its deviation is 7.7%, less than 10%. Fit the obtained [OCP(xT) - OCP(0T)] ~ B. When the deviation of the potential difference is 7.7%, the corresponding deviation of the measured magnetic field intensity is 9.26%, less than 10%.

[0140] Step 5: Determine the unknown magnetic field intensity

[0141] By measuring OCP(yT), or OCP(yT) - OCP(0T), with the same electrode system placed in a magnetic field of unknown magnetic field intensity, the corresponding magnetic field intensity value can be obtained through the standard curve plotted in Step 4.

[0142] In summary, the above-mentioned embodiment of the magnetic field intensity measurement method based on potential measurement belongs to the technical field of magnetic field intensity measurement, and at the same time uses the electrochemical principle different from the physical principle measurement for measurement. This method includes: electrode system design and preparation, and measuring the open-circuit potential of the electrochemical system under magnetic field-free or magnetic field-applied conditions; the magnetic field is a horizontal magnetic field and is parallel to the electrode surface; the magnetic field intensity is 0.02 - 0.5T.

Claims

1. A method for measuring magnetic field strength based on potential measurement, characterized in that: The method includes the following steps: Step 1: Preparation of the electrode system A metal electrode is used as the working electrode and the reference electrode to form an electrode system, which is connected to an electrochemical workstation or a voltmeter; the working electrode is an industrial pure Fe electrode with a diameter of not less than 5 mm, and the reference electrode is a saturated calomel electrode; Step 2: Measurement of the open circuit potential The working electrode of the electrode system is immersed in a solution containing oxidant ions, and the open circuit potential value OCP(0T) is recorded until it reaches a stable state; the oxidant ions are ferric ions, and the anions corresponding to the ferric ions are sulfate or chloride ions; the combination of the working electrode and the oxidant ions makes the electrode reaction rate at the open circuit potential be controlled entirely or partially by the mass transfer process of the oxidant at the electrode interface; Step 3: Measurement of the open circuit potential of the working electrode after applying magnetic fields of different intensities After the open circuit potential under the 0T condition reaches stability, a magnetic field is applied, and the magnetic field intensity is 0.02T - 0.5T. The magnetic field is applied gradually from small to large. The open circuit potential of the working electrode at each magnetic field intensity is measured. At each magnetic field intensity, wait until the open circuit potential reaches a stable state and then increase the magnetic field intensity and continue to wait until the open circuit potential reaches a steady state again; Record the open circuit potential value OCP(xT) at each magnetic field intensity; Step 4: Plotting of the standard curve of the potential values corresponding to different magnetic field intensities According to the measured electrode potential values of the working electrode after reaching a steady state at different magnetic field intensities, plot the standard curve of the electrode potential E (X-axis) ~ magnetic field intensity B (Y-axis) under the magnetic field, OCP(xT) ~ B, or the standard curve of the difference between the electrode potential with the magnetic field and the electrode potential without the magnetic field ΔE (X-axis) ~ magnetic field intensity B (Y-axis) [OCP(xT) - OCP(0T)] ~ B; Step 5: Determination of the unknown magnetic field intensity By measuring OCP(yT), or OCP(yT) - OCP(0T) by using the same electrode system placed in a magnetic field with an unknown magnetic field intensity, the corresponding magnetic field intensity value can be obtained through the standard curve plotted in Step 4.

2. The magnetic field strength test method based on potential measurement according to claim 1, characterized in that: The test temperatures used in the above steps are the same or approximate.

3. The magnetic field strength testing method based on potential measurement according to claim 1, characterized in that: In Step 3, the applied magnetic field is in the horizontal direction, and the magnetic field direction is parallel to the surface of the working electrode.

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