GB/T 3217-1992 Magnetic test methods for permanent magnetic (hard magnetic) materials
Some standard content:
National Standard of the People's Republic of China
Methods for testing the magnetic properties of permanent magnetic (maguetically hurd) materials
Methods for testing the magnetic properties of permanent magnetic (maguetically hurd) materials 1 Subject content and scope of application
This standard specifies the magnetic test methods for permanent magnetic (maguetically hurd) materials: GB/T 3217-92
Replaces GE3217--·82
This standard applies to lead-nickel-cobalt permanent magnets, ferrite permanent magnets, iron-chromium-cobalt permanent magnets, rare earth permanent magnets and other permanent magnetic materials. 2 Reference standards
GB 2900.4 Electrical J Terminology Tungong. Alloy 3 Terminology
3.1 Demagnetization line demagnetization hysteresis loop The second or fourth quadrant of the saturation hysteresis loop, which is defined by the remanence 3 (3, J,) and the coercive force Hc or the internal coercive force He (see Figure 1).
3.2 Maximum energy product (BII) x
maxinium BH product
The maximum value of the product of the magnetic flux density (magnetic induction intensity) and the corresponding magnetic field intensity on the demagnetization curve. The coordinates of the (BII) point are represented by (BH) (see Figure 1).
3.3 Recoil line and recoil permeability The recoil line of water magnetic materials refers to the local hysteresis loop of a point on the demagnetization curve when it is in the recovery state. The ratio of the average slope of the recoil line to the magnetic constant is defined as the absolute complex permeability (see Figure 1). Find the recoil permeability and calculate it according to formula (1):
Approved by the State Administration of Technical Supervision on January 18, 1992
Figure 1 Demagnetization line and recoil line
Implementation on October 1, 1992
武: =4r×10--H/m;
GB/T3217-92
H——Difference in magnetic flux density between the two ends of the double line, T;H-\: Difference in magnetic field intensity between the two ends of the return line, A/m. 4 Unit system
Use the International System of Units (SI), see Appendix A for details. 5 Internal true coercivity Hc is less than or equal to 600 kA/m Measurement of permanent magnetic materials 5.1 Magnetization device
5.1.1 The magnetization device consists of a magnetic moment, a pole head and a magnetizing winding. The yoke, the pole head and the sample form a closed magnetic circuit (see Figure 2). 21
Figure 2 Magnetization device
[—Magnetizing winding; 2-Magnetic field detector + 3--Yoke + 4-B (or J measuring coil 5-Sample, 6-Pole head
5.1.2 The inductive yoke and the pole head should be made of soft magnetic materials with a coercive force not greater than 100A/m, and their structure should be symmetrical. In order to minimize the harm caused by the rapid change of inductive conduction, the yoke is recommended to be made of a sheet iron core, and the inter-pole distance is continuously adjustable within a certain range. The surface should be flat, the surface roughness parameter R, the value is 3.2m, and the two pole faces should be parallel and perpendicular to the direction of the magnetic field. 5. 1. 3 The magnetizing windings should be as close to the specimen as possible and symmetrical to each other, with their axes aligned with the pole head axis. 5.1.4 Magnetizing power supply: The magnetizing power supply should have sufficient capacitance. During measurement, the magnetizing power supply regulator should be able to continuously and smoothly change the magnetic field within the entire measurement range. The instability of the magnetizing current should not exceed 0.1%/min. 5.1.5 The magnetizing device should be able to generate a magnetizing field that magnetizes the specimen to saturation. Its value varies with the type of permanent magnetic material and is related to the grain defects. The selection of the saturation magnetizing field strength m is usually related to the intrinsic coercive force. That is, Har = The KHe
coefficient K varies according to the type of permanent magnetic material, and is generally between 3 and 5. The saturation magnetic field strength of some permanent magnetic materials is shown in Appendix B, where the saturation magnetic field strength H is obtained as follows: when the magnetic field strength increases by 50% from a certain value, the increase in B, H (or H) of the sample does not exceed 1%, and this magnetic field value is considered to be the minimum saturation magnetic field strength value of this permanent magnetic material. 5.1.6 The magnetic field of the two pole faces should be sufficiently uniform in the entire space occupied by the sample, B measurement line diagram and magnetic field detector. Therefore, the geometric dimensions of the pole face must meet the formula (2), (3): GB/T 3217-92
D 2d -- 1.2 f
D 2 2. 0 L
In the test, the diameter of the L-shaped pole face or the shortest side length of the rectangular pole face is m21.., and the pole spacing is m
d--the maximum dimension of the uniform area perpendicular to the field direction, m. .(2)
When working, the flux density in the pole head should be much lower than its saturation flux density to ensure that the pole face is close to the magnetic equipotential surface. In practice, the flux density of the electrical pure iron pole head should be less than 1T, and the flux density of the iron-cobalt alloy pole head containing 35%~50% cobalt should be less than 1.2T. When the above conditions are met, the change of the magnetic field intensity in the magnetic field uniformity area between the pole faces does not exceed 1%. 5.2 Test format
5.2.1 The sample is a cylinder with a rectangular (or circular) cross-section. In order to make the sample uniformly magnetized, its size is limited by 5.1.6, and the sample length should be greater than 5 mm.
5.2.2 The two end faces of the specimen shall be ground to be parallel to each other, with parallelism not exceeding tolerance grade 9, the end faces being straight to the axis, and the verticality not exceeding tolerance grade 9. The surface roughness parameter R is 3.2 μm to reduce the air gap (see 5.4.2). 5.2.3 The cross-sectional area of the specimen shall remain consistent along the entire length, and its deviation shall not exceed 1% of its minimum transverse load. The measurement error of the specimen size shall not exceed 0.2%.
5.2.4 The specimen shall not have external and internal defects. For example: notches, edge loss, cracks, sand holes and pores. 5.2.5 For anisotropic permanent magnetic materials, when measuring their magnetic properties, the magnetic direction of the specimen shall be consistent with the easy magnetization direction of the material. 5.2.6 For materials with large temperature coefficients, such as ferrite hydromagnetic materials, the temperature change of the specimen during measurement shall not exceed ±3°C. 5. 2.7
The sample is placed in the uniform magnetic field area between the poles of the magnetizing device (see 5.1.6). The intended magnetization direction of the sample should be consistent with the direction of the magnetic field.
5.3 Measurement of magnetic flux density
5.3.1 The change in magnetic flux density is measured by connecting a measuring coil to an induced voltage time integrator. 5.3.2 The measuring coil is a uniform single layer, tightly attached to the middle of the sample and symmetrically connected to both ends of the sample. In order to eliminate the induced voltage generated by the leads of the measuring coil, the leads should be relatively close together. 5.3.3 The induced voltage time integrator can be a galvanometer, a fluxmeter, an electronic integrator or other dynamic devices. 5.3. 4 The change in magnetic flux density is calculated by formula (4): AB B -
Wherein: B,::t instantaneous magnetic flux density, T; B,-—, instantaneous magnetic flux density, T;
· test cross-sectional area, rn\;
N—number of measuring wires
dr· integral of the corresponding voltage.V·.
Taking into account the air flux included in the measuring coil, the change in magnetic flux density should be corrected. The corrected change in magnetic flux density △.m is calculated by formula (5):
(5 - 57
ABonNS!
-the change in magnetic field intensity that causes the change in magnetic flux density 4B, A/m Formula: A
S. Effective cross-sectional area of the measuring wire, m.
5.3.5 The measurement error of magnetic flux density should not exceed 2%.++++++++++++++++++++++( 5 )
5.4 Pre-measurement of magnetic field strength
GB/T 3217-92
5.4.1 The magnetic field strength is measured by a magnetic field detector with corresponding instruments, and the integrator or the Sear probe with an electric measuring instrument described in 5.3.1 is connected to the measuring coil for measurement. The sensor of the magnetic field detector should be pre-set and its lead wires twisted together. 5.4.2 In addition to the test specimens in accordance with the requirements of 5.2.7, in order to reduce the error of measuring magnetic field caused by air gap 8 (see Figure 3) (for other methods, see Appendix (), the test specimens should be tightened. 1
Field-avoiding detection type
Figure 3 Air gap
5.4.3 The magnetic field strength directly measured on the surface of the sample is equal to the magnetic field strength inside the sample only when the magnetic field strength on the surface of the sample is measured from the side of the sample. In order to obtain the magnetic field strength inside the sample, the position of the magnetic field detector must meet the requirements of 5.1.6, as close to the sample as possible and opposite to the two end surfaces of the sample, with its axis consistent with the magnetization direction of the sample. 5.4.4 The measurement error of the magnetic field strength should not exceed 2%. 5.5 Deformation function measurement
5.5.1 Measurement process with impulse galvanometer5.5.1.1 For the magnetization device with laminated yoke, place the sample in,Under the Hmx specified in Appendix B, magnetize to the saturation magnetic state Bau, and perform magnetic training to ensure the magnetic state of the test group is stable. Then, cut off the magnetizing current and measure the flux density change △B (see Figure 4a) according to Article 5.3.
AB B.ux - B'.
Figure a Saturation hysteresis loop
GB/T 3217-92
Due to the residual magnetism of the pole head and the yoke, although the magnetizing current is zero at this time, the residual magnetic field strength generated by the yoke and the pole head is 11, not equal to F0. Therefore, 8, not equal to the next B..H. measured according to Article 5.4. Then the magnetizing field jumps to Hm and measures AB2AB, = B, + Rma
From (6) and (7), we can get:
R*,1/2(AB,AB,)
When H, is equal to 0, B, is equal to B, when H, is not equal to 0, B, is obtained on the demagnetization curve.(7)
.(8)
When measuring B and H at any point on the demagnetization curve, the test piece should be magnetized to the saturation point (BH..), and magnetic training is carried out. The magnetizing current is cut off and the magnetic state is at point B,,H,. Then the magnetizing field jumps to the magnetizing field intensity of the measuring point. At the same time, the micro-density change AB is measured. The B(0) formula of the point is calculated:
R = B'.- AB
Repeat the above process. Measure the and H values of each point, and the demagnetization curve is given. （
5.5.1.2 For the magnetizing device with non-laminated yoke, in order to reduce the non-instantaneous error caused by eddy current and inductance, the following measurement procedure is adopted: the magnetizing current that generates Hmx is reversed to measure Bm (see Figure 4h). It should be noted that the error value of the magnetizing current in both directions should be less than 1. Calculate by formula (10); 3
Demagnetization excitation line positive point B and 1 are measured. First, the sample is magnetically conditioned under Hmx, and then the ignition current is adjusted to the corresponding value of the maximum magnetic field. According to Article 5.4, its magnetic field independence I is measured, so that the magnetizing current jumps to its maximum value (corresponding to point H). When the flux density changes by 43, the magnetic flux density at this point is calculated by formula (11): B -ARBmx
Measure the demagnetization curve of each point in turn so that it can be drawn. 5.5.2 Measurement process of the integrator
5.5.2.1 Place the empty 3 measuring coils and the magnetic field detector in a space where the residual field is less than 0.1kA/m and adjust the integrator and the magnetic field demagnetizer to the correct position. At this time, the XY recorder is placed at the origin. Then put the sample into the B measuring coil, connect it to the magnetizing cover in 5.4.2, and connect the magnetic field detector between the two plates in 5.1.3. Magnetize the sample with the values of the magnetizing field strength and magnetizing field strength specified in the appendix, and then reduce the magnetizing current monotonically to zero. The magnetizing device is about residual magnetism, and the general recorder is placed in the first quadrant. Then change the magnetizing current direction and slowly increase the magnetizing current to make the magnetizing curve pass GB/T 3217—92
or II point (see Figure 5). At this time, the XY recorder records the magnetic flux density value and the corresponding magnetic field strength value at each point on the demagnetization curve. [
Figure 5 Demagnetization line and return line captured by electronic integrator For materials with large hysteresis between magnetic flux density and magnetic field strength, the change speed of magnetic field strength should be slow enough. In order to ensure accurate integration, the time constant of the electronic integrator should be large enough and the zero drift should be small enough. 5. 5.2. 2 Remanence 3, Determination of: After drawing the demagnetization curve, take the magnetic flux density value at the intersection of the demagnetization curve and the B axis (see Figure 1). 5.5.2.3 Determination of coercive force Hcn or intrinsic coercive force Hcr: The magnetic field intensity value at the intersection of the demagnetization curve and the straight line B equals zero is Hrn: The magnetic field intensity value at the intersection of the straight line B equals II is H (see Figure 5). 5.5.2.4 The entire hysteresis line can also be drawn through automatic scanning of the magnetizing current. The symmetry center of the hysteresis line is the coordinate origin of the B(H) line, so that the remanence B and the coercive force II can be obtained. 5.6 Determination of the maximum magnetic energy product (BH) m
The maximum magnetic energy product (BH) m is determined by the maximum value of the product of B and II on the demagnetization curve, or: it is determined by the method of tangency between the demagnetization curve and the isotropic energy line.
5. 7 Determination of the recovery magnetic permeability K
5.7.1 Measurement process of impact current meter: According to the need, take a point P of the demagnetization curve as the base point of the recovery line (see Figure 1), then select the magnetic field strength value that is smaller than the absolute value of point P by AH, and change the magnetic field around AH to stabilize the magnetic state. Then measure the △B value and the corresponding △1 value according to Articles 5.3 and 5.4 respectively, and calculate according to formula (1). 5.7.2 Measurement process using electric integrator: According to Article 5.2.2, when the recording pen reaches the required point 1, change the direction of the magnetization field so that the change amount is H, and then return the recording pen to point P, and the recovery line is obtained. From the average slope of the recovery line, the recovery magnetic permeability is obtained (see Figure 5)
-Generally, it is not a constant along the demagnetization curve, so the corresponding II,, B, and △H values should be marked. 5.8 Calibration of test device
5.8.1 The test device should be calibrated regularly. The current transformer, standard mutual inductance coil, magnetic detector, J measuring coil, etc. used in the test device shall be sent to the measurement department for calibration regularly.
5.8.2 In order to ensure the accuracy and consistency of the magnetic parameter measurement of permanent magnetic materials, the standard samples calibrated by the national measurement department shall be used to compare the measurement results of various magnetic parameters. Standard samples shall be sent to the measurement department for calibration regularly. 5.9 Test report
The test report may include the following contents as required: Brand and geometrical dimensions of the sample material:
Type of instrument used:
Saturation magnetic field intensity Hm;
Corrective force ce or internal cumulative coercive force H
GB/T 3217-92
Maximum magnetic energy product (BII) value and coordinate BI value and H value: Reverse permeability value and H, B, AH value;
Uncertainty of measurement parameters
Ambient temperature during measurement;bzxZ.net
For magnetically anisotropic samples, indicate the magnetization direction. 6 Measurement of internal coercive force He greater than 600kA/m for permanent magnetic materials 6.1 Magnetization field
For samples with large internal coercive force! A 600kA/m dilute 1 permanent magnet sample can be magnetized to near saturation from the original magnetic state with a magnetic soup of H,1~1.5Hc. To measure the demagnetization curve, obtain the data of the first quadrant and re-magnetize to the original polarity, the device needs a magnetic field value of 11,~1.aHcr. To fully characterize the truly symmetrical magnetization state, a higher magnetic field value of I,3~5He is required. 6.2 Coil
, the coil uses well-insulated fine and soft copper wire, evenly wound on a non-magnetic ceramic skeleton. The flux measurement coil and the magnetic field compensation coil should be connected in reverse connection. According to the size of the electromagnet pole surface and the size of the sample, a concentric or double heart shape can be used (see Figure 6). The flux measurement coil and the collision field compensation coil should satisfy the following relationship: Where: N——Function of the flux measurement coil: N,A, - NA -- 0
A, a cross-sectional area of the flux measurement coil, m\;N. =Number of turns of magnetic field compensation coil;
A Transverse area of magnetic field compensation coil, m\. If the above relationship is not satisfied, it can be corrected by calculation. Field compensation line
Concentric
Figure 6J Measurement line diagram
6.3 Measurement method
Double heart
Pipe discharge
+ 12 )
Except for the following contents, the contents in Chapter 5 are generally still valid. 6.3.1 Before measurement, the test sample shall be magnetized by a pulse magnetizer or superconducting solenoid, and the maximum magnetic field strength shall be at least 3 to 5 times the internal magnetic field strength of the material. The pole of the magnetizer used for measurement shall have a locking mechanism to prevent the mechanical force generated under high magnetic field from squeezing the sample. 6.3.2 Place the empty measuring coil and magnetic field detector in a space with a stray field less than 0.1 kA/m. Carefully adjust the drift of the measuring device. After the test device is stable, put down the pen of the XY recorder and determine the coordinate origin (0) of the J(H) line. Then, put the sample into the test line diagram, pay attention to the magnetization direction of the test device, which should be consistent with the magnetization direction during measurement. According to 5.4.2, tighten the magnetization device in the center of the magnetization device. Attach the magnetic field detector to 5.1.3 and place it between the two poles. 6.3.3 According to Figure 7, set the magnetic state of the magnetic sample to point R, put the sample between the two poles, and set the magnetic state after tightening to point Q. Then turn on the magnetization power supply and magnetize the sample. Its magnetization state reaches point A, which is the starting point for recording. Usually the magnetic field at point A is more than 200 kA/n. Measurement sequence of magnetic field avoidance line
6.3.4 Continue to change the magnetic field monotonically according to the order of ACEF:, and the XY recorder will draw the demagnetization curve. 6.3.5 After drawing the demagnetization curve, pick up the pen of the XY recorder, adjust the magnetizing power supply, make the field zero, and take the period from the measuring coil. 6.3.6 You can also use the measurement process of determining the coordinate origin after the demagnetization curve is drawn, that is, after drawing the demagnetization curve, move the magnetic field detector to a space where the stray field is less than (.1kA/n), and at the same time move the J measuring coil to a space where the stray field is less than 0.1kA/m and take out the sample from the towel. At this time, the X recorder will be fixed to the mark origin (0,0) of the J (residual magnetism) line. 6.3.7 Determination of residual magnetism J: After drawing the demagnetization curve, the value of the remanent polarization intensity at the intersection of the demagnetization line and the coordinate axis is 6.3.8 Determination of coercive force H and internal coercive force He; take the demagnetization spider line The magnetic field intensity value at the intersection with the II coordinate axis is Ha, and the magnetic field intensity value at the intersection with the J-H first line is Hca (see Figure 7). 6.4 In actual operation, if the B(H) curve is needed, the J(Ff) curve can be converted into the B(H) curve according to the formula B=J+HI, or the J measurement line diagram can be replaced with the B measurement line diagram, and the B(H) curve can be drawn according to the above method. However, the gap between the sample and the B measurement coil should be small enough to reduce the measurement error. 6.5 Test report
Refer to Section 5.9,
Drive ()
Magnetic gradient
Flux density
Energy product
Magnetic permeability
GB/T 3217--92
Appendix A
SI of relevant magnetic quantities Unit
(Supplement)
Ampere! Shulai
Tesla (per cubic meter)
Jollai
Henrilai
The conversion relationship between the International System of Units (SI) and the Electromagnetic System of Units (CGSM) is: 1Wh=10'Mx
IT=10'Gs
1A/m-4rX10:(0e
1J/m=4X10Gs·Qe
Appendix B||tt ||Minimum saturation magnetic field strength of some permanent magnetic materials (supplement)
Material brand or type
LNGF56
LNGI72
Natural oxygen water chain
FrCrCo
SmCo1?
P-SmiCu5
Cu(CuCule)5
Sn2(CoCuFeZri1?
Nd-Fe-B
If... (kA/m)
T(Wb/m)
Initial bubble and field
Initial magnetic field
Initial magnetic field
Initial dynamic field
GB/T 3217-.92
Appendix C
Influence of air gap on measurement error
(Supplement)
The air gap between the sample and the pole surface should be as small as possible. The maximum relative error of the measured magnetic field caused by the air gap can be estimated according to the formula (C1) AH
Where: B—magnetic flux density at a given point on the demagnetization curve, T: I1.--magnetic field intensity at a given point on the demagnetization curve, A/m; —sample length, n:
—air gap between the sample and the pole surface, m
4 yuan×10-[1/m.
When the magnetic field measurement error H/H near the (HII) point is not greater than 1, the maximum air gap of various materials is: AlNiCo permanent magnet
Ferrite permanent magnet
Rare earth permanent magnet
..0. 000 25 L
=0. 005 L
When the above air gap requirements cannot be met, the magnetic field detector should be as close to the sample surface as possible, and its size should be as small as possible. Generally, the length of the magnetic field detector is not more than one-third of the length of the sample, and the thickness does not exceed 3. In this case, the standard can be appropriately relaxed. Additional remarks:
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China, and this standard was drafted by the Ministry of Machinery and Electronics Industry's Jialin Electric Science Research Institute. This standard was drafted by the Ministry of Machinery and Electronics Industry's Jialin Electric Science Research Institute. The main drafters of this standard are Li Guangwu and Zhang Fumin
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