Sintered Neodymium Magnets

Sagawa, Hadjipanayis, and Croat independently discovered Nd-Fe-B based rare earth permanent magnets almost simultaneously in 1984. The main phase of this material is Nd2Fe14B and its maximum energy products achieved 280kJ/m3 at that time. Besides the relatively lower Curie temperature, Nd2Fe14B is an ideal and promising permanent magnet material. The successful development of Neodymium magnets announced the birth of the third-generation rare earth permanent magnets. Sintered Neodymium magnets, also known as Neo magnets, offer the strongest magnetic power today. They are particularly suitable for high volume production in the variety of shapes and sizes. Precise dimensional control can be obtained in the machining processes. With these advantages, Neodymium magnets have been widely applied in lots of commercial fields, such as high-performance motors, brushless DC motors, magnetic separators, magnetic resonance imaging (MRI), sensors, loudspeakers, consumer electronics and green energy.

Sintered Neodymium Magnets-Main

Manufacturing Process of Sintered Neodymium Magnets

Sintered Neodymium Magnets-Manufacturing Process

Magnetic Properties of Sintered Neodymium Magnets

 
Grade

Remanence

Br

Coercivity

Hcb

Intrinsic Coercivity

Hcj

Max. Energy Product

(BH)max

Max. Working Temperature
TkGskA/mkOekA/mkOekJ/m3MGOe
N301.08-1.1310.8-11.3≥798≥10.0≥955≥12223-24728-3180
N331.13-1.1711.3-11.7≥836≥10.5≥955≥12247-27131-3480
N351.17-1.2211.7-12.2≥868≥10.9≥955≥12263-28733-3680
N381.22-1.2512.2-12.5≥899≥11.3≥955≥12287-31036-3980
N401.25-1.2812.5-12.8≥907≥11.4≥955≥12302-32638-4180
N421.28-1.3212.8-13.2≥915≥11.5≥955≥12318-34240-4380
N451.32-1.3813.2-13.8≥923≥11.6≥955≥12342-36643-4680
N481.38-1.4213.8-14.2≥923≥11.6≥955≥12366-39046-4980
N501.40-1.4514.0-14.5≥796≥10.0≥876≥11382-40648-5180
N521.43-1.4814.3-14.8≥796≥10.0≥876≥11398-42250-5380
N551.46-1.5214.6-15.2≥796≥10.0≥876≥11414-43052-5480
N35M1.17-1.2211.7-12.2≥868≥10.9≥1114≥14263-28733-36100
N38M1.22-1.2512.2-12.5≥899≥11.3≥1114≥14287-31036-39100
N40M1.25-1.2812.5-12.8≥923≥11.6≥1114≥14302-32638-41100
N42M1.28-1.3212.8-13.2≥955≥12.0≥1114≥14318-34240-43100
N45M1.32-1.3813.2-13.8≥995≥12.5≥1114≥14342-36643-46100
N48M1.37-1.4313.7-14.3≥1027≥12.9≥1114≥14366-39046-49100
N50M1.40-1.4514.0-14.5≥1033≥13.0≥1114≥14382-40648-51100
N52M1.43-1.4814.3-14.8≥1050≥13.2≥1114≥14398-42250-53100
N54M1.45-1.5014.5-15.0≥1051≥13.2≥1114≥14414-43852-55100
N35H1.17-1.2211.7-12.2≥868≥10.9≥1353≥17263-28733-36120
N38H1.22-1.2512.2-12.5≥899≥11.3≥1353≥17287-31036-39120
N40H1.25-1.2812.5-12.8≥923≥11.6≥1353≥17302-32638-41120
N42H1.28-1.3212.8-13.2≥955≥12.0≥1353≥17318-34240-43120
N45H1.32-1.3613.2-13.6≥963≥12.1≥1353≥17342-36643-46120
N48H1.37-1.4313.7-14.3≥995≥12.5≥1353≥17366-39046-49120
N50H1.40-1.4514.0-14.5≥1011≥12.7≥1353≥17382-40648-51120
N52H1.43-1.4814.3-14.8≥1027≥12.9≥1353≥17398-42250-53120
N35SH1.17-1.2211.7-12.2≥876≥11.0≥1592≥20263-28733-36150
N38SH1.22-1.2512.2-12.5≥907≥11.4≥1592≥20287-31036-39150
N40SH1.25-1.2812.5-12.8≥939≥11.8≥1592≥20302-32638-41150
N42SH1.28-1.3212.8-13.2≥987≥12.4≥1592≥20318-34240-43150
N45SH1.32-1.3813.2-13.8≥1003≥12.6≥1592≥20342-36643-46150
N48SH1.37-1.4313.7-14.3≥1027≥12.9≥1592≥20366-39046-49150
N50SH1.40-1.4514.0-14.5≥1003≥12.6≥1592≥20382-40648-51150
N28UH1.04-1.0810.4-10.8≥764≥9.6≥1990≥25207-23126-29180
N30UH1.08-1.1310.8-11.3≥812≥10.2≥1990≥25223-24728-31180
N33UH1.13-1.1711.3-11.7≥852≥10.7≥1990≥25247-27131-34180
N35UH1.17-1.2211.7-12.2≥860≥10.8≥1990≥25263-28733-36180
N38UH1.22-1.2512.2-12.5≥876≥11.0≥1990≥25287-31036-39180
N40UH1.25-1.2812.5-12.8≥899≥11.3≥1990≥25302-32638-41180
N42UH1.28-1.3212.8-13.2≥899≥11.3≥1990≥25318-34240-43180
N45UH1.32-1.3613.2-13.6≥908≥11.4≥1990≥25342-36643-46180
N48UH1.37-1.4313.7-14.3≥908≥11.4≥1990≥25366-39046-49180
N28EH1.04-1.0810.4-10.8≥780≥9.8≥2388≥30207-23126-29200
N30EH1.08-1.1310.8-11.3≥812≥10.2≥2388≥30223-24728-31200
N33EH1.13-1.1711.3-11.7≥836≥10.5≥2388≥30247-27131-34200
N35EH1.17-1.2211.7-12.2≥876≥11.0≥2388≥30263-28733-36200
N38EH1.22-1.2512.2-12.5≥899≥11.3≥2388≥30287-31036-39200
N40EH1.25-1.2812.5-12.8≥899≥11.3≥2388≥30302-32638-41200
N42EH1.28-1.3212.8-13.2≥899≥11.3≥2388≥30318-34240-43200
N45EH1.32-1.3613.2-13.6≥899≥11.3≥2388≥30342-36643-46200
N28AH1.04-1.0810.4-10.8≥787≥9.9≥2786≥35207-23126-29230
N30AH1.08-1.1310.8-11.3≥819≥10.3≥2786≥35223-24728-31230
N33AH1.13-1.1711.3-11.7≥843≥10.6≥2786≥35247-27131-34230
N35AH1.17-1.2211.7-12.2≥876≥11.0≥2786≥35263-28733-36230
N38AH1.22-1.2512.2-12.5≥899≥11.3≥2786≥35287-31036-39230
  • The above-mentioned data of magnetic properties and physical properties are given at room temperature.
  • The max working temperature of magnet is changeable due to length-diameter ratio, coating thickness and other environment factors.

Other Properties of Sintered Neodymium Magnets

ItemsParametersUnitReference Range
Other Magnetic PropertiesTemper. Coeff. of Br / α(Br)%/℃-0.08 ~ -0.13
Temper. Coeff. of Br / β(Hcj)%/℃-0.35 ~ -0.80
Curie Temperature / Tc310-380
Recoil Permeability / μrec1.05
Physical PropertiesDensity / ρg/cm37.40-7.80
Vickness Hardness / HV550-650
Electrical ResistivityμΩ·m1.4
Compressive StrengthMPa1050
Tensile StrengthMPa80
Bending StrengthMPa290
Thermal ConductivityW/(m·K)6-8
Coeff. of Thermal Expansion10-6/KC⊥: -1.5, C∥6.5.

Surface Treatment of Sintered Neodymium Magnets

Coating

Thickness

(μm)

Color

SST

(hrs)

PCT

(hrs)

Characteristics
BW-Zn4-15Bright blue≥24Secondly commonly used single layer coating. Poor anti-corrosion ability.
Color-Zn4-15Shining color≥48Anti-corrosion ability is better than BW-Zn.
Ni-Cu-Ni5-20Bright silver≥48≥48Most regular used multi-layer coating. Excellent humidity and salt spray resistance.
Chemical-Ni5-20Dark silver≥72≥48Excellent humidity and salt spray resistance with uniform appearance.
Black-Ni5-20Gloss black≥48≥48Excellent humidity and salt spray resistance with superior appearance and decoration.
Ni + Au5-20Golden≥72≥96Excellent electrical conductivity and decorative.
Ni + Ag5-20Silver≥72≥96Excellent electrical conductivity and decorative.
Ni-Cu-Ni-Sn5-20Silver≥72≥96Excellent humidity resistance.
Passivation/Phosphate1-3Dark greyTemporary protection.
Aluminum2-15Bright silver≥24≥24Noticeable coating.
Epoxy resin10-30Black/Grey≥72≥72Excellent humidity and salt spray resistance. Superir binding force.
Parylene5-20Colorless≥96Excellent humidity, salt spray, corrosive vapors, and solvents resistance. Free of pore.
Everlube10-15Golden yellow≥120≥72Excellent humidity resistance.
Teflon8-15Black≥24≥24High temperature and rub resistance. Self-lubricant and 100% water-proof.
Note: anti-corrosion capability of coating is also influenced by the shape and size of magnet.
Sintered Neodymium Magnets-surface treatment