CN1514240A - A test method and special device for the change of electromagnetic properties of materials - Google Patents

Abstract

The invention belongs to the technical field of measurement, and relates to a test method for the change of electromagnetic properties of materials and a special device thereof; the test method includes steps such as sample preparation, magnetic circuit assembly, circuit connection and debugging, measurement and data recording. The special device based on the test method for the change of the electromagnetic properties of the above materials is composed of two differential coils using a C-shaped iron core and corresponding measuring instruments; the invention is low in cost, easy to use, and has a wide range of applications, especially for liquid metal electromagnetic The measurement of the property change can obtain the curve of the electromagnetic properties of the liquid metal changing with the temperature.

Description

A test method and special device for the change of electromagnetic properties of materials

technical field

The invention belongs to the field of measurement technology, and in particular relates to a testing method for the change of electromagnetic properties of materials and a special device thereof.

Background technique

At present, the main methods for measuring the magnetic properties of materials such as magnetic susceptibility include the force method and the induction method.

The magnetic method is to calculate the magnetic susceptibility of the sample by measuring the force of the sample in the magnetic field. The sample is subjected to a force F _z in a mixed magnetic field composed of a constant magnetic field H ₀ and a magnetic field with a gradient. The magnitude of this force is shown by the following formula,

$\stackrel{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; grad</span>}<span\; class="notranslate">\; (</span>\stackrel{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; ,</span>\stackrel{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; )</span>$

In actual work, we assume that the magnetization is uniform and control the magnitude and direction of the applied magnetic field, then the above formula is simplified as

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&chi;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; h</span>}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; z</span>}}$

Use a balance to precisely measure the magnitude of the force F _z , and then calculate the magnitude of the magnetic susceptibility of the sample. For example, Faraday Balance (Faraday Balance) is the specific application of Faraday method in measurement.

The electromagnetic induction method is to use the basic principle of electromagnetic induction to measure the current or voltage induced by the magnetic field in the induction coil, and then calculate the magnetic susceptibility of the sample. As shown in the following formula, if a sinusoidal alternating current is applied to both ends of the coil, and the induced electromotive force at both ends of the coil is measured, the change of the magnetic flux passing through the coil is calculated, and then the magnetic permeability of the sample is calculated.

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}{\mathrm{<span\; class="notranslate">\; \&omega;\&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\frac{\mathrm{<span\; class="notranslate">\; D</span>}}{\mathrm{<span\; class="notranslate">\; dH</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i\&omega;t</span>}}$

Devices such as vibrating sample magnetometer (VSM), AC Susceptometer, and SQUID magnetometers are examples of the application of this method. The methods and corresponding equipment mentioned above are mostly used in scientific experiments in laboratories. The instruments are precise, expensive, and have many restrictions in use.

Contents of the invention

The object of the present invention is to overcome above-mentioned deficiencies in the prior art, provide a kind of easy to use, low in cost, the test method and special-purpose device thereof of electromagnetic property change of the material of wide application range, especially suitable for the measurement of liquid metal electromagnetic property change.

The present invention is achieved in the following ways:

A test method for the change of electromagnetic properties of materials. According to the principle that the output signal of the entire magnetic circuit changes when the electromagnetic properties of the sample in the magnetic circuit change, by measuring the difference between the output signal of the reference coil and the measurement coil, And then know the change of the electromagnetic characteristic of sample itself; It is characterized in that comprising the following steps:

1) Sample preparation: clean and weigh the sample to be tested, and under the protection of an inert gas, heat the sample to be tested to melt, mix well, and then cool to room temperature;

2) Magnetic circuit assembly: use two C-shaped iron cores with the same material, number of turns, winding direction, and identical coils. Among them, the coil I composed of the primary coil I, the secondary coil I, and the iron core I is used as the measurement The coil is composed of primary coil II, secondary coil II and iron core II. Coil II is used as the reference coil. The sample to be tested is placed in the gap of the C-shaped iron core of the measuring coil, and the reference sample is placed in the C-shaped iron core of the reference coil. In the gap of the core, the magnetic circuit completely passes through the sample to be tested;

3) Line connection and debugging: connect the circuit, put the reference sample into the reference coil, when the sample to be tested is put into the measuring coil, the measured value of the millivoltmeter is the measured value I, when the sample to be tested is not put into the measuring coil , the measured value of the millivolt meter is the measured value II, adjust the output frequency and output voltage of the signal generator, so that the difference between the measured value I and the measured value II reaches the maximum, so as to determine the frequency and voltage of the input signal; then, in When the sample to be tested is not placed in the notch of the C-shaped iron core of the measuring coil, adjust the position of the reference sample in the notch of the C-shaped iron core of the reference coil, so that the measured value of the millivoltmeter reaches a minimum value;

4) Measurement and data recording: cleaning, weighing the sample to be tested, preparing a high temperature resistant container, measuring its shape and size, putting the sample to be tested in the high temperature resistant container, and then using a high frequency induction furnace to heat the sample to be tested Until it is completely melted, put the molten sample to be tested into the gap of the C-shaped iron core of the measuring coil. The container and the iron core are insulated with heat-insulating and heat-insulating materials. A signal generator is used to generate a sinusoidal AC signal and input to the primary coil. , when the signal is output from the secondary coil, measure its magnitude with a millivoltmeter; the signal output from the millivoltmeter is amplified, rectified, filtered, and AD converted by a signal processing device, and then connected to a computer for storage; at the same time, measure and record Sample temperature, process data, output graphs.

The test method for the change of the electromagnetic properties of the above materials is also characterized in that the container containing the sample to be tested in step 4) is a quartz glass test tube, and the thermal insulation material is alumina thermal insulation brick or zirconia thermal insulation brick.

A special device based on the test method of the change of the electromagnetic properties of the above-mentioned materials: including a signal generator, a millivolt meter, a signal processing device, and a computer, and is characterized in that it also includes a primary coil I, a primary coil II, a secondary coil I, and a secondary coil. Primary coil II, C-shaped iron core I, C-shaped iron core II; primary coil I, secondary coil I, C-shaped iron core I form the measuring coil, primary coil II, secondary coil II, and C-shaped iron core II form the benchmark Coil; at the signal input end, the primary coil I and the primary coil II are connected in series, and at the signal output end, the secondary coil I and the secondary coil II are connected in parallel; the signal output end is connected to the input end of the millivolt meter, and the output port of the millivolt meter is connected to to the input end of the signal processing device, and the output end of the signal processing device is connected to the signal acquisition card of the computer.

The special device for the test method of the change of the electromagnetic properties of the above-mentioned materials is also characterized in that: when the coil is wound, the primary coil is inside, the secondary coil is outside, and the two coils are wound in the same direction; the number of turns of the secondary coil is greater than that of the primary coil.

Because the present invention adopts two identical differential coils and a C-shaped iron core, the present invention is low in cost, convenient to use, and wide in scope of application. The curves of the electromagnetic properties of the material as a function of temperature.

Description of drawings

Fig. 1 is the principle structure schematic diagram of the present invention,

Fig. 2 is a schematic diagram of the winding of the coil of the present invention.

In the figure: 1 primary coil I, 2 sample to be tested, 3 iron core I, 4 secondary coil I, 5 computer, 6 signal processing device, 7 millivolt meter, 8 resistor, 9 secondary coil II, 10 iron core II , 11 reference samples, 12 primary coil II, 13 signal generator.

Detailed ways:

Provide two specific embodiments of the present invention below:

Embodiment 1, using this method and special device to the measurement process and result of metal aluminum:

Measuring device:

◆The circuit and magnetic circuit are assembled in the following way: at the signal input end, primary coil I and primary coil II are connected in series, at the signal output end, secondary coil I and secondary coil II are connected in parallel; the signal output terminal of GFG8255A signal generator 13 is connected to The primary coil I and the primary coil II, the secondary coil I and the secondary coil II are connected to the input terminal of the HG2170 dual-channel millivolt meter 7, and the signal output port of the HG2170 dual-channel millivolt meter 7 is connected to the input terminal of the signal processing device 6 , the output terminal of the signal processing device 6 is then connected to the computer 5 for storage; when the coil is wound, the primary coil is inside, the secondary coil is outside, and the two coils are wound in the same direction, the primary coil is 100 turns, and the secondary coil is 400 turns; the inner diameter of the iron core 40mm, outer diameter 55mm, thickness 12.5mm, gap width 22mm.

Measurement steps:

◆Sample preparation: cleaning and weighing the metal aluminum sample. Under the protection of argon, the metal aluminum sample is heated to melt, mixed evenly, and then cooled to room temperature;

◆Magnetic circuit assembly: place the metal aluminum sample to be tested in the gap of the C-shaped iron core of the measuring coil, and place the reference sample (amorphous alloy) in the gap of the C-shaped iron core of the reference coil, so that the magnetic circuit passes through completely Aluminum samples to be tested;

◆Line connection and debugging: connect the circuit, put the reference sample into the reference coil, when the metal aluminum sample is put into the measuring coil, the measured value of the millivolt meter is the measured value I, when the metal aluminum sample is not put into the measuring coil, The measured value of the millivoltmeter is the measured value II, adjust the output frequency and output voltage of the signal generator, so that the difference between the measured value I and the measured value II reaches the maximum, so as to determine that the input signal frequency is 200Hz; then, in the measurement coil When no sample is placed in the notch of the C-shaped iron core of the reference coil, adjust the position of the reference sample in the notch of the C-shaped iron core of the reference coil, so that the measured value of the millivoltmeter reaches a minimum value;

◆Measurement and data recording: Clean and weigh the metal aluminum sample, measure the diameter of the quartz glass test tube, put it in a high temperature resistant quartz glass test tube, and then use a high-frequency induction furnace to heat it until it is completely melted, and then put it Into the gap of the measuring coil, aluminum oxide insulation bricks and asbestos boards are used for heat insulation between the test tube and the iron core, and a 200Hz sinusoidal AC signal is generated by using a GFG8255A signal generator, which is input into the primary coil I and the primary coil II. When the signal is transmitted from the secondary coil After the output of I and secondary coil II, use the HG2170 dual-channel AC millivoltmeter to measure its size, and the output from the millivoltmeter is amplified, rectified, filtered, and AD converted by the signal processing device, and then connected to the computer for storage; at the same time, use Raynger3i Portable infrared temperature measuring instrument measures and records the temperature of metal aluminum samples; data processing, output charts.

Embodiment 2, use this method and corresponding device to the measurement process and result of lead-tin alloy:

Measuring device:

◆The circuit and magnetic circuit are assembled in the following way: at the signal input end, primary coil I and primary coil II are connected in series, at the signal output end, secondary coil I and secondary coil II are connected in parallel; the signal output terminal of GFG8255A signal generator 13 is connected to The primary coil I and the primary coil II, the secondary coil I and the secondary coil II are connected to the HG2170 dual-channel millivolt meter 7, and the signal output port of the HG2170 dual-channel millivolt meter 7 is connected to the input terminal of the signal processing device 6, and the signal processing The output terminal of the device 6 is connected to the computer 5 for storage; when the coil is wound, the primary coil is inside, the secondary coil is outside, and the two coils are wound in the same direction, the primary coil is 100 turns, and the secondary coil is 400 turns; the inner diameter of the iron core is 40mm, and the outer The diameter is 55mm, the thickness is 12.5mm, and the gap width is 22mm.

Measurement steps:

◆Sample preparation: cleaning and weighing the lead-tin alloy sample. Under the protection of argon, heat the lead-tin alloy sample to melt, mix well, and then cool to room temperature;

◆Magnetic circuit assembly: place the lead-tin alloy sample to be tested in the gap of the C-shaped iron core of the measuring coil, and place the reference sample (amorphous alloy) in the gap of the C-shaped iron core of the reference coil, so that the magnetic circuit is completely Pass the lead-tin alloy sample to be tested;

◆Line connection and debugging: connect the circuit, put the reference sample into the reference coil, when the lead-tin alloy sample is put into the measuring coil, the measured value of the millivolt meter is the measured value I, when the lead-tin alloy sample is not put into the measuring coil When , the measured value of the millivolt meter is the measured value II, adjust the output frequency and output voltage of the signal generator, so that the difference between the measured value I and the measured value II reaches the maximum, so as to determine the input signal frequency as 1000Hz; then, in When the lead-tin alloy sample is not placed in the notch of the C-shaped iron core of the measuring coil, adjust the position of the reference sample in the notch of the C-shaped iron core of the reference coil, so that the measured value of the millivolt meter reaches a minimum value;

◆Measurement and data recording: Clean and weigh the lead-tin alloy sample, measure the diameter of the quartz glass test tube, put it in a high-temperature resistant quartz glass test tube, and then use a high-frequency induction furnace to heat it until it is completely melted, and then put it Put it into the gap of the measuring coil, use alumina insulation bricks and asbestos boards for heat insulation between the test tube and the iron core, use the GFG8255A signal generator to generate a 1000Hz sinusoidal AC signal, input the primary coil I and primary coil II, when the signal is from the secondary After coil I and secondary coil II are output, use the HG2170 dual-channel AC millivoltmeter to measure their size, and the output from the millivoltmeter is amplified, rectified, filtered, and AD converted by the signal processing device, and then connected to the computer for storage; at the same time, use Raynger3i portable infrared temperature measuring instrument measures and records the temperature of lead-tin alloy samples; data processing and output charts.

Claims (4)

1. the method for testing that changes of a material electromagnetic property, according to when the sample in the magnetic circuit when the electromagnetic property of itself changes, the principle that the output signal of whole magnetic circuit changes, by the measuring basis coil with measure the difference of coil output signal, and then learn the variation of the electromagnetic property of sample own; It is characterized in that may further comprise the steps:

1) specimen preparation: cleaning, weighing testing sample, under the protection of inert gas, testing sample is heated to fusing, mix, be cooled to room temperature again;

2) magnetic circuit assembling: use two and all adopt C shape iron core, and material, the number of turn, around to, identical coil, wherein, form coil I as measuring coil by primary coil I, secondary coil I, iron core I, form coil II as reference coil by primary coil II, secondary coil II, iron core II, testing sample is placed the breach of the C shape iron core of measuring coil, authentic specimen is placed the breach of the C shape iron core of reference coil, make magnetic circuit pass through testing sample fully;

3) circuit connects and debugging: connect circuit, authentic specimen is put into reference coil, when testing sample is put into the measurement coil, the measured value of milivoltmeter is measured value I, when testing sample was not put into the measurement coil, the measured value of milivoltmeter was measured value II, the output frequency of conditioning signal generator and output voltage, make the difference of measured value I and measured value II reach maximum, determine the frequency and the voltage of input signal with this; Then, in the breach of the C shape iron core of measuring coil, do not put under the situation of testing sample, regulate the position of authentic specimen in the breach of the C of reference coil shape iron core, make the measured value of milivoltmeter reach minimal value;

4) measurement and data recording: clean, the weighing testing sample, prepare a resistant to elevated temperatures container, measure its geomery, testing sample is contained in the resistant to elevated temperatures container, use Efco-Northrup furnace that testing sample is heated to fusing fully then, again the testing sample of fusion is put into the breach of the C shape iron core of measuring coil, adopt insulation and heat-barrier material heat insulation between container and iron core, use signal generator generation sinusoidal ac signal, the input primary coil after signal is exported, is measured its size with milivoltmeter from secondary coil; Output signal is connected to Computer Storage again through signal processing apparatus amplification, rectification, filtering, AD conversion; Simultaneously, measure and the record sample temperature deal with data, output chart.

2. the method for testing that material electromagnetic property according to claim 1 changes is characterized in that the container of splendid attire testing sample is the quartz glass test tube in the step 4), and heat insulation insulation material is aluminium oxide insulating brick or zirconia insulating brick.

3. the isolated plant of a method of testing that changes based on claim 1,2 described material electromagnetic properties: comprise signal generator, milivoltmeter, signal processing apparatus, computing machine, it is characterized in that it also comprises primary coil I, primary coil II, secondary coil I, secondary coil II, C shape iron core I, C shape iron core II; Primary coil I, secondary coil I, C shape iron core I form the measurement coil, and primary coil II, secondary coil II, C shape iron core II form reference coil; At signal input part, primary coil I and primary coil II series connection, signal output part, secondary coil I and secondary coil II parallel connection; Signal output part is connected to the input end of milivoltmeter, and the output port of milivoltmeter is connected to the input end of signal processing apparatus, and the output terminal of signal processing apparatus is connected to the data acquisition card of computing machine.

4. the isolated plant of the method for testing that material electromagnetic property according to claim 3 changes is characterized in that: during coil winding, primary coil is interior, secondary coil outside, two coil winding-directions are identical; The secondary coil number of turn is greater than the number of turn of primary coil.

Images