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%.
GB/T 13560-2017 The following standards are cited：
