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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 13560-2009 Materials for sintered neodymium iron boron permanent magnets.
In addition to editorial changes, the following technical changes have been made with respect to GB/T 13560-2009:
—Normative references are added, including GB/T 15676 Terms for rare earths, GB/T 24270 Method of measurement of temperature coefficient of magnetic properties of permanent magnetic materials, GB/T 29628 Guides for methods of measurement of the magnetic properties of permanent (magnetically hard) materials by pulsed field magnetometry and GB/T 34491 Coatings for sintered neodymium iron boron permanent magnets (see chapter 2);
—the terms and definitions of "irreversible flux losses" and "maximum operating temperature" are added (see 3.3 and 3.4);
—Character designations and examples are added (see 4.3);
—Some designations of materials are added, the magnetic parameters of some designations are modified and squareness parameters are added (see Table 1);
—Test methods are modified as follows: The test methods of principal magnetic properties of N, M, H, SH and UH materials are subject to the requirements of GB/T 3217, and EH and TH materials subject to the requirements of GB/T 29628 (see 6.1);
—New test methods are added. In 6.2, the test methods of temperature coefficient of remanence and intrinsic coercivity of materials are subject to the requirements of GB/T 24270 (see 6.2);
—Dimensional deviations in Table A.1 of Annex A are modified (see Table A.1);
—Annex B is modified as follows: Table B.1 is split into Table B.1 "Additional magnetic properties of sintered neodymium iron boron permanent magnets" and Table B.2 "Mechanical and physical properties of sintered neodymium iron boron permanent magnets"; some parameters are modified and the parameters of bending strength and maximum operating temperature are added (see Table B.1 and Table B.2);
—Chemical composition of sintered neodymium iron boron permanent magnets is added to Annex C (see Table C.1);
—Table of the system of unit and conversion of magnetic property and table of correspondence between designation and magnetic property, for sintered neodymium iron boron permanent magnets are added to Annex D (see Table D.1 and Table D.2);
This standard was proposed by and is under the jurisdiction of the National Technical Committee on Rare Earth of Standardization Administration of China (SAC/TC 229);
The previous editions of the standard replaced by this standard are as follows:
—GB/T 13560-1992, GB/T 13560-2000 and GB/T 13560-2009.
Sintered neodymium iron boron permanent magnets
1 Scope
This standard specifies the requirements, test methods, inspection rules, marking, packaging, transport, storage, quality certificate for sintered neodymium iron boron permanent magnets.
This standard is applicable to sintered neodymium iron boron permanent magnets produced by powder metallurgy process.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2828.1-2012 Sampling procedures for inspection by attributes—Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
GB/T 3217 Permanent magnet (magnetically hard) materials—Methods of measurement of magnetic properties
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 9637 Electrotechnical terminology—Magnetic materials and components
GB/T 15676 Terms for rare earths
GB/T 24270 Method of measurement of temperature coefficient of magnetic properties of permanent magnetic materials
GB/T 29628 Guides for methods of measurement of the magnetic properties of permanent (magnetically hard) materials by pulsed field magnetometry
GB/T 34491 Coatings for sintered neodymium iron boron permanent magnets
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 9637 and GB/T 15676, as well as the following, apply.
3.1
principal magnetic properties
The properties mainly include remanence Br, coercive force of magnetic polarization (intrinsic coercivity) HcJ, magnetic induction intensity coercivity HcB and maximum magnetic energy product (BH) max of permanent magnet.
3.2
additional magnetic properties
The properties mainly include relative recoil permeability μrec, temperature coefficient of remanence α (Br), temperature coefficient of coercive force of magnetic polarization (intrinsic coercive force) α (HcJ) and Curie temperature Tc of permanent magnet.
3.3
irreversible flux losses
irreversible relative variation of permanent magnetic flux generated due to temperature rise, under open-circuit conditions. It is calculated by Formula (1).
(1)
Where,
hirr—irreversible flux losses, %;
Ф(T0)—flux of magnet at temperature T0 under initial open-circuit conditions (Wb);
Ф(T1)—open-cirtuit flux of magnet with temperature changing from T0 to T1 and then reversing to T0 (Wb).
3.4
maximum operating temperature
The maximum holding temperature of a cylindrical sample of permanent magnet (with a diameter of D and a height of L, and L/D=0.7) in thermal demagnetization state, which, after saturation magnetization, is heated from room temperature to a certain constant temperature and, after 2 hours holding period, is then cooled to room temperature, with open irreversible flux losses not greater than 5%.
4 Classification and designation of material
4.1 Classification
Sintered neodymium iron boron permanent magnets, by the size of intrinsic coercivity, are classified into seven types—low coercivity N, medium coercivity M, high coercivity H, extra high coercivity SH, super high coercivity UH, extreme high EH and ultra high TH.
4.2 Designation
Each type, by maximum magnetic energy product, are classified into several designations. Materials on each designation may be processes into permanent magnet parts of a variety of shapes and specifications, including discs, cylinders, rings and pads.
4.3 Expression of character designation
Designations of sintered neodymium iron boron permanent magnets consist of the manufacturing characteristics, main description and magnetic properties of material. The first part, the letter "S", denotes the manufacturing characteristics of materials, i.e. the sintered materials produced by powder metallurgy sintering process; the second part, NdFeB, i.e. the element symbols of neodymium, iron and boron, denotes the main description of materials; the third part, the number before solidus, denotes the nominal value (kJ/m3) of maximum magnetic energy product (BH)max of sintered neodymium iron boron; the forth part, the number after solidus, denotes one tenth of the minimum intrinsic coercivity HcJ (kA/m) rounded to the nearest integer.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and designation of material
5 Requirements
6 Test methods
7 Inspection rules
8 Marking, packaging, transport, storage and quality certificate
Annex A (Normative) Geometric deviations of sintered neodymium iron boron permanent magnet
Annex B (Informative) Additional magnetic properties, and principal mechanical and physical properties of sintered neodymium iron boron permanent magnet
Annex C (Informative) Chemical composition, manufacturing process and application of sintered neodymium iron boron permanent magnet
Annex D (Informative) Table of the system of unit and conversion of magnetic property and table of correspondence between designation and magnetic property, for sintered neodymium iron boron permanent magnets
