JP2016095264A - High magnetic field pulse excitation type magnetic characteristics measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high magnetic field pulse excitation type magnetic characteristics measuring device capable of applying a high magnetic field.SOLUTION: A high magnetic field pulse excitation type magnetic characteristics measuring device is a magnetic characteristics measuring device which applies magnetic fields to coils provided around a sample in a state to sandwich the sample between a pair of sample presser bars so as to measure magnetic characteristics of the sample. Heaters for heating the sample are built in the vicinity of at least faces contacting with the sample in the sample presser bars, and the coils are made by winding winding wires while applying adhesives to them. Cooling channels in which cooling mediums circulate are provided to inner walls and/or external walls of the coils.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a high magnetic field pulse excitation type magnetic characteristic measurement technique.

  Conventionally, as a magnetic characteristic measuring apparatus, a BH tracer, a pulse excitation type magnetic characteristic measuring apparatus (PFM), a vibrating sample type magnetometer, etc. are known, and all of them measure a single BH curve. At present, it is within the range and magnetic properties cannot be measured. Regarding magnetic properties, there is a device such as a magnetic torque meter using a single crystal.

  Patent Document 1 discloses an apparatus for applying a magnetic field generated by a coil to a sample and measuring the magnetic characteristics of the sample. In this document, it is possible to measure characteristics at a high temperature by providing an introduction port for introducing a high-temperature gas into a space where a sample is held and a discharge port for discharging the gas.

Japanese Patent Application Laid-Open No. 61-073076

  In the technique described in Patent Document 1, since heating is performed with gas, the entire fixing rod for fixing the sample is heated, and in order to bring the sample to a predetermined temperature, the vicinity of the gas inlet becomes abnormally high. Therefore, considering the temperature rise due to pressurization, there is a problem that the sample cannot be fixed with sufficient pressure.

  For this reason, when a magnetic field is applied in a direction perpendicular to the easy magnetization axis direction of the magnet, a force that rotates the magnet is generated, but the rotation cannot be suppressed, and there is a problem that it is difficult to apply a large magnetic field. It was.

  The evaluation of magnetic characteristics is generally measured by a BH tracer and a pulse excitation type magnetic characteristic measuring device (PFM).

  A BH tracer cannot generate a magnetic field of 2.5 T or more, and it is difficult to perform room temperature coercivity measurement of a neodymium sintered magnet having a coercive force higher than that.

  On the other hand, general PFM is dedicated to room temperature measurement, and high temperature measurement is difficult. Moreover, although the magnetic field of 12T or more is required in the measurement of the magnetization difficult direction, the maximum magnetic field is 12T, and the measurement of the magnetization difficult direction is difficult. A pulse excitation type magnetic characteristic measuring apparatus is also known, but measurement at a high temperature and a high magnetic field has been difficult.

  An object of the present invention is to provide a high magnetic field pulse excitation type magnetic property measuring apparatus capable of applying a high magnetic field at a high temperature.

  According to the present invention, there is provided a magnetic property measuring apparatus for measuring a magnetic property of a sample by applying a magnetic field to a coil provided around the sample while the sample is sandwiched between a pair of sample pressing rods. A heater for heating the sample is built in at least near the surface of the bar that contacts the sample, and the coil is wound with an adhesive applied to the winding, and the inner wall of the coil and / or the outer wall of the coil There is provided a high magnetic field pulse excitation type magnetic property measuring apparatus provided with a cooling passage through which a cooling medium flows.

  A reflux thyristor element may be provided in a path through which a large current flows from the capacitor bank to the coil in order to generate a high magnetic field.

  In addition to the signal integrator that integrates the measurement signal, a signal differentiator that differentiates the measurement signal to measure the anisotropic magnetic field Ha is provided, and further, the signal processing of the magnetization (J) measuring coil is performed with the signal integrator and the signal. In addition to a signal integrator that integrates a measurement signal having a changeover switch to be switched with a differentiator, a signal differentiator that differentiates the measurement signal to measure Ha in order to obtain an anisotropic magnetic field Ha measurement point is provided. It is preferable to have a selector switch for switching the coil signal processing between a signal integrator and a signal differentiator.

  According to the present invention, a high magnetic field pulse excitation type magnetic property measuring apparatus can apply a high magnetic field at a high temperature.

It is a figure which shows one structural example of the rotation prevention mechanism and heating mechanism in the magnetic characteristic measurement of the perpendicular direction (magnetization difficulty direction) of the high magnetic field pulse excitation type | mold magnetic characteristic measuring apparatus by the 1st Embodiment of this invention. It is a functional block diagram which shows the example of whole structure of the high magnetic field pulse excitation type | mold magnetic characteristic measuring apparatus by this Embodiment. It is a figure which shows an example of the magnetization curve at the time of making it magnetize in the direction parallel to an orientation direction. It is a figure which shows an example of the magnetization curve at the time of making it magnetize in a perpendicular direction with an orientation direction. It is a figure which shows an example of the pulse strong magnetic field magnetic field generation circuit by this Embodiment, and is a figure which shows the detailed structure of the part shown by the code | symbol 3 of FIG. It is an image figure of general Ha measurement. It is a functional block diagram which shows one structural example of Ha measuring device by the measurement controller (computer) PC of FIG. It is an image figure of Ha measurement by this Embodiment. It is a figure which shows the example in the case of the Arrot-plot method. It is a figure which shows the example of a saturation magnetization measurement by a saturation asymptotic law method. It is a figure which shows the image of Suchksmith Thompson method. It is a Hcj-temperature T diagram. It is a Ms-temperature T diagram. It is a figure which shows the image of how to obtain | require (alpha) * Neff.

  Hereinafter, a high magnetic field pulse excitation type magnetic property measuring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. The present embodiment relates to an apparatus that can apply a high magnetic field, can repeatedly measure by an arbitrary magnetic field, and can change the applied magnetic field, as well as the general magnetic properties of magnetic materials, as well as anisotropic magnetic field and orientation. The present invention relates to an apparatus capable of evaluating magnetic properties such as degree.

(First embodiment)
FIG. 1 is a diagram showing a configuration example of an anti-rotation mechanism and a heating mechanism in the magnetic characteristic measurement in the vertical direction (difficult magnetization direction) of the high magnetic field pulse excitation type magnetic characteristic measuring apparatus according to the first embodiment of the present invention. is there. As shown in FIG. 1, the magnetic property measuring apparatus 1 is a ceramic sample holder that extends in the direction of the easy magnetization axis and presses the sample in order to resist rotational force by holding the sample 1-2 from both ends. Rods 1-1a, 1-1b, a pressure screw 1-4 for adjusting the pressure with which the sample pressing rods 1-1a, 1-1b push the sample, and a coil 1-8 for applying magnetism to the sample ( 1-8a to d). Further, a temperature measuring thermocouple 1-5 (1-5a, b) for measuring the temperature of the sample, a ceramic heater 1-3 (1-3a, b) for heating the sample, and a coil 1-8 In this embodiment, the cooling mechanism 1 is provided with a cooling heat insulating pipe 1-6 (inlet 1-6a, outlet 1-6b) and a sample positioning mechanism 1-12 that determines a sample position. The coil 1-8 is wound with an adhesive applied to the winding, and the cooling heat insulating pipe 1-6 is composed of an outer ceramic pipe and an inner inorganic glass cloth laminated pipe. A constant temperature controlled liquid is always passed through the gap between the heavy pipes, and the heat conduction from the heater to the magnetic field, the magnetization signal detection coil, and the magnetic field generation coil is cut off.

  In the above structure, the sample holding rod 1-1a and 1-1b including the ceramic heater 1-3 (1-3a and b) are fixed by sandwiching the sample 1-2. Heat can be directly conducted by conducting heat. Therefore, since it is not necessary to raise the sample pressing rods 1-1a and 1-1b to an unnecessarily high temperature, a mechanism for absorbing thermal expansion is unnecessary, and the sample 1-2 can be fixed with a large force. . In order to obtain the degree of orientation, it is necessary to measure the magnetic characteristics in the vertical direction of the sample. For this reason, a magnetic field is applied in a direction perpendicular to the orientation direction, and a rotational force is generated. Therefore, a ceramic sample presser bar is used to prevent rotation.

  Furthermore, since the coil 1-8 is fixed with an adhesive and the cooling medium passage is provided to cool the coil, even if an electric current is passed through the coil for applying a large magnetic field, the coil temperature hardly rises. Is difficult to loosen. Therefore, a large current can flow.

  As described above, it is easy to measure magnetic characteristics in a strong magnetic field at a high temperature, and in particular, it is possible to perform measurement in a state where a magnetic field is applied in the direction perpendicular to the easy axis of magnetization.

f ₁ = M _r‖ / M _s (1)

f ₂ = cosφ φ = arctan [2M _r⊥ / M _r‖ ] (2)

f ₃ = (M _s -M _r‖ ) / M _s (3)

_{Here, f 1, f 2, f} 3 is the degree of orientation, M _R⊥ the vertical direction of the remanent magnetization to the orientation direction, the residual magnetization in the direction parallel to the M _R‖ orientation direction, M _s is the saturation magnetization It is.

By the above formulas (1), (2) and (3), the orientation degrees f ₁ , f ₂ and f ₃ of the magnet can be defined, and the orientation degrees f ₁ , f ₂ and f ₃ can be measured. When measuring a strong magnet that requires application of a high magnetic field with a conventional device, only f ₁ can be measured, but the measured value of Js (saturation magnetization), which will be described later, cannot be obtained in the saturation region. Only a low value of can be obtained.

  FIG. 2 is a functional block diagram showing an example of the overall configuration of the high magnetic field pulse excitation type magnetic property measuring apparatus according to the present embodiment.

  As shown in FIG. 2, the high magnetic field pulse excitation type magnetic property measuring device includes a measuring device 1, a control device 3, a computer interface unit 4, a signal waveform storage unit 5, and a capacitor bank control unit 6. doing.

  In addition to the structure shown in FIG. 1, the measuring device 1 has a sample loading / unloading port 1-7 for loading and unloading a sample by an upper holding rod 1-1a for holding the sample 1-2. The sample 1-2 is held at the center position of the exciting coil section 1-8 together with the lower pressing rod 1-1b to be supported.

  The ceramic heater for controlling the temperature of the sample and the thermocouple for detecting the sample temperature are respectively provided with 1-3a and 1-5a on the upper surface and 1-3b and 1-5b on the lower surface. The temperature of the upper surface portion of the sample is composed of a thermocouple for detecting the upper surface temperature and a power source for the upper surface heating ceramic heater having a PID control function. The temperature of the lower surface of the sample is composed of a thermocouple for detecting the lower surface temperature and a ceramic heater power source for heating the lower surface having a PID control function. The sample upper surface portion and the lower surface portion perform automatic temperature control independently with respect to the same sample temperature setting value, so that the temperature distribution difference in the sample can be reduced.

  Further, the measuring apparatus 1 includes a measurement signal detection unit 1-11 for detecting a measured signal, and a manual sample position setting unit (sample positioning mechanism unit) 1− for setting a sample position in the lower holding rod 1-1b. 12 and an exciting coil cooling unit temperature control unit 1-10 for controlling the cooling unit temperature of the exciting coil unit 1-8 provided in the exciting coil cooling case (cooling pipe) 1-6. . The control device 3 includes a charge voltage detection control unit that detects and controls a charge voltage, a security control unit that protects the device, a first function unit 3-1 that includes a switch operation unit that is a switch for operation, and the like. A magnetic field generation control unit 3-2 that controls the magnetic field of the coil unit 1-8; a control unit (second function unit) 3-3 that controls power reception and charging; and a capacitor bank unit 3-4. ing. The capacitor bank unit 3-4 is controlled by a capacitor bank control unit 6 having a measurement controller unit.

  FIG. 3 is a diagram showing an example of a magnetization curve when magnetized in a direction parallel to the orientation direction, and FIG. 4 is a diagram showing an example of a magnetization curve when magnetized in a direction perpendicular to the orientation direction.

As a method for measuring the degree of orientation, Jr‖ / Jr‖ is measured, and the degree of orientation f ₂ is further calculated by the formula of degree of orientation f ₂ = cosφ and φ = arctan (2M _r⊥ / M _r‖ ). The magnetic field required for Jr⊥ measurement is 12T or more. However, in the case of measuring a strong magnet that requires a high magnetic field as shown in FIG. In addition to the measurement in the region where the value of ⊥ is not saturated, the measurement at a high temperature is difficult because there is no heating method inside the high magnetic field generating coil. As a factor on the coil side, it was necessary to increase the large current and the number of coil turns as much as possible in order to generate a high magnetic field. On the other hand, when such a coil design is adopted, the space inside the coil is limited, and there is no structure that enables heating in a narrow space and detection of magnetic flux density. Further, when the sample temperature is heated, if the heat is transmitted to the coil, the coil is overheated, the insulation between the windings is lowered, and a short circuit may occur, resulting in a coil burst.

  FIG. 5 is a diagram showing an example of a pulsed strong magnetic field generating circuit according to the present embodiment, and is a diagram showing a detailed configuration of a portion indicated by reference numeral 3 in FIG.

  As shown in FIG. 5, the pulse strong magnetic field generation circuit according to this embodiment is provided with means for generating a high magnetic field and ensuring the safety of the coil. That is, in order to generate a high magnetic field, the capacitor bank capacity is changed from 16 mF to 4 times 64 mF (0.5 mF × 128 pieces). 8 is provided with reflux SCRs (thyristors) 26 and 27 for controlling discharge when energizing a large current, and a magnetic field generating coil 1-8 capable of withstanding a high voltage and a large current. In addition, a charging voltage detection unit 29a is provided between both terminals of the capacitor bank unit 3-4 and the coil 1-8, and bank switching vacuum switches 23a to 23d are provided.

  Thereby, the electric current for generating a strong magnetic field can be sent from the conventional maximum magnetic field 8T to the maximum magnetic field 15T.

  Since a large current flows when a high magnetic field is generated, a large tension is applied to the copper wire, causing a short circuit when the winding is loosened. Therefore, with respect to the winding method, the winding coil was fixed so as not to loosen while applying a high thermal conductive adhesive while applying back tension. As a countermeasure against heat generation of the coil, a large current is applied when a high magnetic field is generated. At that time, Joule heat is generated, and when the temperature becomes high, the coil adhesive fixing force decreases, and there is a risk of short circuit. In view of this, a cooling method is provided by adopting a winding method in which a cooling oil circulation oil passage member is wound around the inside of the coil bobbin and the outer periphery of the multilayer winding coil to efficiently cool the oil. As a cooling mechanism, a plurality of cooling passage holes extending in the vertical direction are arranged on the inner and outer peripheral walls of the coil along the periphery of the coil.

  FIG. 6 is an image diagram of general Ha measurement. Ha is obtained from the JH curve in the first quadrant.

As shown in FIG. 8, the anisotropic magnetic field Ha is defined as H at which d ² J / dH ² is minimized for the second time in the first quadrant of the JH curve in which the magnetic field is applied in the direction perpendicular to the orientation direction. .

The conventional apparatus only measures the JH curve, and mainly measures the BH curve in the second quadrant, and has no Ha measurement function.
In the present embodiment, an anisotropic magnetic field Ha, which is one of material properties, can also be measured.

  FIG. 7 is a functional block diagram showing an example of the configuration of the Ha measuring device by the measurement controller unit (computer) PC of FIG. As shown in FIG. 7, the Ha measuring device PC includes a J coil 21a, an H coil 21b, a signal integrator 23, a signal differentiator 24, a signal waveform storage device 25, a waveform signal storage unit 5 of the PC body, And a switch 28 for switching between the signal differentiator 24 and the signal integrator 23 is newly provided.

FIG. 8 is an image diagram of Ha measurement according to the present embodiment. The anisotropic magnetic field Ha is a coercive force index of the material and can be obtained as the second minimum value of d ² J / dH ² .

  In order to measure Ha of a strong magnet such as a rare earth magnet, a strong magnetic field having a maximum magnetic field of 12T or more is required, and the maximum magnetic field of 8T is insufficient. Conventionally, since the number of measurement points and the like is not sufficiently optimized, the secondary differential value varies, and the detection position of the second-order secondary differential minimum value in the demagnetization process varies.

In the present embodiment, noise is reduced by the signal differentiator 24 in FIG. 7 in the first quadrant in the vertical direction in FIG. 8, and d ² J / dH ² can be accurately measured.

  The anisotropic magnetic field has been measured with a device capable of generating a high magnetic field (such as a superconducting magnet), but can be easily measured without using such a special mechanism.

  As described above, according to the present embodiment, it is possible to fix the sample with a sufficient pressure even in consideration of a temperature increase due to heating.

  In addition, when a magnetic field is applied in a direction perpendicular to the easy axis of magnetization of the magnet, the rotating force of the magnet can be suppressed and a large magnetic field of 12 T or more can be applied.

  As shown in Table 1, in the conventional magnetic property measuring apparatus, it was difficult to measure and evaluate the degree of magnet orientation, Ha, α & Neff, K1, K2, etc., as in the apparatus according to the present embodiment.

  That is, as shown in Table 1, with the current magnetic property evaluation apparatus, only one BH curve measurement can be performed, and the degree of orientation, Ha (anisotropic magnetic field), α (coercivity degradation index with respect to ideal Ha), Neff (demagnetizing factor of material grain shape) and K1 & K2 (crystalline magnetic anisotropy constant) cannot be measured.

The major issues are as follows.
1. It is difficult to generate a high magnetic field for safety reasons.
2. Does not have magnetic field detection / differential calculation function.
3. There is no post processing system for analysis.

  In general, the performance of a magnet can be evaluated by measuring the BH curve by measuring only Br (Jr): residual magnetic flux density (residual magnetic polarization, Hcj: coercive force, BHmax: maximum energy product, etc.) Therefore, in the conventional apparatus, it was sufficient to obtain only the data by measuring the BH curve, and in order to evaluate other magnetic characteristics, it is necessary to calculate separately from the obtained BH curve data. there were.

  In this embodiment, in order to clarify how the process affects the magnet performance in order to improve the influence of the process on magnet manufacture and the coercive force of the magnet, The purpose is to be able to measure all the series of magnetic properties with the device.

The issues in measuring each characteristic item are summarized below.
α & Neff measurement: This measurement requires data of saturation magnetization Js and its temperature characteristics, anisotropic magnetic field Ha and its temperature characteristics, but 12T for measurement of Js and Ha of strong magnets such as rare earth magnets. Measurement with the above high magnetic field is necessary, and measurement with a general magnetic property measuring apparatus is difficult. In addition, it is more difficult to measure the characteristics at high temperatures.

  As described above, the conventional measuring device has not been able to develop an analysis method according to the physical law with a low maximum magnetic field, a narrow magnetic field application speed variable range, but as described below, the technique according to the present embodiment has not been developed. As shown in Table 1, it is possible to evaluate general performance evaluation, degree of orientation, special performance evaluation, and magnetocrystalline anisotropy, and the measurement temperature also covers a range from room temperature to about 200 ° C. I was able to do it.

  According to the present embodiment, an apparatus capable of measuring the degree of orientation, in magnetic crystallography, the residual magnetization Jr in the direction parallel to and perpendicular to the orientation direction as shown in FIGS. In the vertical direction, it is necessary to saturate particularly in the first quadrant, and a magnetic field of about 9600 kA / m (12 T) required for Jr⊥ measurement can be obtained. Moreover, according to this Embodiment, this performance can be measured safely.

(Summary)
(1) Points for preventing sample rotation In the prior art, temperature control was performed by spraying high-temperature nitrogen gas on the sample. The gas spraying method has an advantage that the gas flows on the five surfaces (bottom surface, front, rear, left and right surfaces) of the sample, and the temperature distribution in the sample can be reduced. However, because the high-temperature gas flows through the φ6mm space of the sample fixing rod (tube shape: outer diameter φ10mm, inner diameter φ6mm) in the variable temperature part, the entire upper and lower sample fixing rods are heated and reach 500 ° C in the high temperature part In order to prevent the sample rod from being damaged by the thermal expansion of the rod, the sample was fixed by applying pressure with a spring.

  Therefore, the measurement direction of the sample is only the easy magnetization axis. In the measurement in the hard magnetization axis direction, the sample rotates and the inner wall of the sample is damaged.

  Since the apparatus according to the present embodiment requires an anisotropic magnetic field measurement at a high temperature, the sample temperature variable method using a high temperature gas is not used, and the heat generation response due to the control current is fast on and under the sample fixing rod. A pair of ceramic heaters were installed above and below, respectively, and the heat of the heaters was conducted to the sample through a resin with good thermal conductivity. The part that reaches the maximum temperature of 500 ° C by the above-mentioned nitrogen gas heating is reduced to about 300 ° C by the ceramic heater method. The expansion need not be relaxed by the spring pressure as in the high-temperature nitrogen gas method, and sufficient pressurization to suppress the sample rotation during measurement of the hard axis is possible.

(2) Points of the heating method The main point of the heating method is how to suppress the thermal expansion of the sample fixing rod. The main point is that by using the ceramic heater and the high thermal conductive resin (non-magnetic material) and their arrangement, the heat source temperature required for controlling the sample temperature (up to 200 ° C) is reduced from 500 ° C in the nitrogen gas blowing method to 300 ° C. This is the point where the thermal expansion of the upper and lower sample fixing rods (total length approximately 450mm, φ10mm) is minimized. As a result, it was possible to measure the anisotropic magnetic field of the sample at a high temperature.

  Hereinafter, an application example of the high magnetic field pulse excitation type magnetic property measuring apparatus according to the embodiment of the present invention will be described in detail.

(Example 1)
Example 1 relates to a technique for measuring saturation magnetization Ms (Js) using the above-described high magnetic field pulse excitation type magnetic characteristic measuring apparatus.

  FIG. 9 is a diagram showing an example in the case of the Arrott-plot method, and is based on the following equation.

Here, M (H, T) is an arbitrary magnetic field H, T is a magnetic flux density at an arbitrary temperature, M (0, 0) is a magnetic flux density at a magnetic field H = 0 and a temperature T = 0K, and T is an arbitrary magnetic field. Tc is the Curie temperature, χ ₀ is the initial magnetic susceptibility, a (T) is the first term coefficient, and b is the second term coefficient.

As described above, M (H, T) is plotted with H being variable under constant temperature, and Ms (Js) = Mspo at H = 0, that is, saturation magnetization Ms (Mspo) by the Arrott-plot method is obtained. be able to.
FIG. 10 is a diagram illustrating an example in the case of the saturation asymptotic rule, which is based on the following equation.

Here, M (H) is the magnetization in an arbitrary magnetic field H, χ _hf is the magnetic susceptibility in an arbitrary magnetic field, and a ₁ and a ₂ are coefficients. From this equation, the saturation magnetization Ms (Msat) by the saturation asymptotic law method can be obtained.

  Conventionally, the saturation magnetization Js is regarded as the value of maximum magnetization in the range of the maximum magnetic field that can be applied in the apparatus as Js, or the Ms is obtained from the MH loop. It was difficult to ask for Ms.

  If the magnetic characteristics are measured using this apparatus, the saturation magnetization Ms can be obtained by performing analysis processing including data smoothing processing as shown in FIGS. 9 and 10 from the first quadrant data in the parallel direction.

(Example 2)
The second embodiment relates to a technique for measuring the magnetocrystalline anisotropy constants K1 and K2 using the above-described high magnetic field pulse excitation type magnetic property measuring apparatus. FIG. 11 is a diagram showing an image of the Sucksmith-Thompson method.

  Conventionally, the magnetocrystalline anisotropy has been measured by using a magnetic torque meter after preparing a single crystal sample. However, due to the difficulty of sample preparation and variations in measurement data, when drawing as shown in FIG. In addition, there are cases where plots of data vary and it is difficult to derive K1 and K2.

The second embodiment is an analysis process including the data smoothing process as shown in FIG. 11 based on the vertical first quadrant data of FIG. 6 and the Ms data of FIGS. 9 and 10. The characteristics K1 and K2 can be obtained. K1 is a primary magnetocrystalline anisotropy constant, and K2 is a secondary magnetocrystalline anisotropy constant.
In the second embodiment, as shown in FIG. 11, K1 and K2 can be obtained with high accuracy.

Example 3
The third embodiment relates to an α · Neff measurement technique using the high magnetic field pulse excitation type magnetic characteristic measuring apparatus. 12 is an Hcj-temperature T diagram, FIG. 13 is an Ms-temperature T diagram, and FIG. 14 is a diagram showing an image of how to obtain α · Neff.
The coercive force Hcj is expressed by the following Kronmuller equation.

  Hcj (T) = α · Ha (T) −Neff · Ms (T) (8)

Here, μ ₀ Ms = Js: magnetization, α is a degradation coefficient from an anisotropic magnetic field that is an ideal coercive force, and Neff is interpreted as a demagnetizing field inside the crystal.

  Α and Neff can be obtained by measuring the temperature dependence of the coercive force / saturation magnetization as shown in FIGS. 12 and 13 and plotting it as shown in FIG.

  Hcj (T) / Ms (T) = α × Ha (T) / Ms (T) −Neff (9)

  Conventionally, there is no technology that can automatically measure the temperature dependence of Hcj (T), Ms (T), and Ha (T), and if it is limited to about 2T with a BH tracer, only Hcj (T) can be measured. It was difficult to measure Ha (T) and Ms (T).

  The third embodiment is a device that can set α and Neff in the second embodiment by setting the specified temperature and measuring the temperature dependence of Hcj and Ms automatically and continuously.

  Conventionally, in examining the influence of the manufacturing process on the coercive force Hcj in the development of a magnet, there was only a means for directly determining the influence on the Hcj as a final result.

  As α and Neff measurements are possible as in this example, it is possible to estimate whether the influence of internal grain size, grain shape, etc. on the produced magnet and the influence of the grain boundary structure are large. It becomes easy to do.

  This is because α is strongly influenced by the grain boundary structure, whereas Neff is easily influenced by the grain shape. The performance as a magnet is better when α is larger and Neff is smaller.

  In the above-described embodiment, the configuration and the like illustrated in the accompanying drawings are not limited to these, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  Each component of the present invention can be arbitrarily selected, and an invention having a selected configuration is also included in the present invention.

  The present invention is applicable to a high magnetic field pulse excitation type magnetic characteristic measuring apparatus.

DESCRIPTION OF SYMBOLS 1 ... Magnetic characteristic measuring mechanism (measuring device) 1-2 ... Sample 1-1a, 1-1b ... Sample pressing rod 1-4 ... Pressure screw, 1-5 (1-5a, 1-5b) Temperature measurement thermocouple, 1-6 ... cooling pipe, 1-7 ... sample inlet / outlet, 1-8 (1-8a to 1-8d) ... coil (excitation coil part), 1-10 ... excitation coil cooling part temperature control 1-11... Measurement signal detection unit, 1-12... Sample positioning mechanism unit (manual sample position setting unit), 3... Control device, 3-1 1st function unit, 3-2. 3-3 ... 2nd functional part, 3-4 ... capacitor bank part, 5 ... waveform storage part (signal waveform storage part) of PC main body, 6 ... capacitor bank control part, 23a-23d ... vacuum switch, 26, 27 ... Reflux SCR (thyristor), 21 ... J coil, 22 ... H coil, 23 ... signal integrator, 25 ... signal Type storage device.

Claims (3)

A magnetic property measuring apparatus that measures a magnetic property of a sample by applying a magnetic field to a coil provided around the sample in a state where the sample is sandwiched between a pair of sample pressing rods,
A heater for heating the sample is built in the vicinity of at least the surface of the sample pressing bar that contacts the sample, and the coil is wound while applying an adhesive to the winding, and the coil inner wall and / or the outer wall of the coil Includes a high magnetic field pulse excitation type magnetic property measuring apparatus provided with a cooling passage through which a cooling medium flows.   2. The high magnetic field pulse excitation type magnetic characteristic measuring apparatus according to claim 1, wherein a reflux thyristor element is provided in a path through which a large current flows from the capacitor bank to the coil in order to generate a high magnetic field. In addition to the signal integrator for integrating the measurement signal, a signal differentiator for differentiating the measurement signal to measure the anisotropic magnetic field Ha is provided.
The high magnetic field pulse excitation type magnetic property measuring apparatus according to claim 1, further comprising a changeover switch for switching the signal processing of the magnetization (J) measuring coil between a signal integrator and a signal differentiator.

Images