Hard Ferrite (Ceramic) Magnets

Ceramic MagnetsHard Ferrite magnets are commonly known as Ceramic magnets due to the process used to produce them. Ferrite magnets are manufactured mainly of strontium or barium ferrites and iron oxide. Hard Ferrite (Ceramic) magnets are produced as Isotropic and Anisotropic types. Isotropic type magnets are produced without orientation and can be magnetized in any direction. On the other hand, Anisotropic magnets are exposed to an electromagnetic field during their process to achieve higher magnetic energy and properties. This is done by pressing dry powders or slurry into a desired die cavity with or without orientation. After the compaction into the dies the parts are exposed to a high temperature, a process known as sintering. This process allows them to hold the shape of the part and gives them mechanical and magnetic strength, and produces hard brittle parts. Because of their physical strength they should not be used as a structural part in any assembly. The grinding process using diamond grinding wheels allows for close dimensional tolerances. Ferrite (Ceramic) magnets have good resistance to demagnetization and with their high Curie temperature they have excellent high working temperatures and most of all they have excellent resistance to corrosion. Ferrite (Ceramic) magnets are excellent choices for many applications due to their economical low price and abundance of raw materials and they do not fluctuate much in price.They are the most widely used magnets in a wide range of applications. Ferrite (Ceramic) magnets come in a variety of shapes; round, square, rectangular, arc segments, triangle, rings and special shapes.

ceramic magnetsApplications:
Hard ferrite magnets have a wide variety of applications: Speaker Magnets, DC Motors, Sweepers, Magnetic Separators for ferrous materials, Automotive Sensors, MRI’s, Reed Switching, Hall Effect Devices, in Assemblies such as (separating, holding, lifting, retrieving, and latching), Refrigerator Magnets and Arts and Crafts as well as many other novelty applications.

Typical Magnetic Properties of Hard Ferrite (Ceramic) Magnets

Grade Max. Energy
Product - BHmax

MGOe - kJ/m³
Residual
Induction - Br
Gauss - mT
Coercive Force
Hc
Oersteds - kA/m
Intrinsic Coercive
Force – Hci
Oersteds      kA/m
Ceramic 1      (C1)    1.05    8.35    2300     230   1860    150 3250    260
Ceramic 5      (C5)    3.40    27.1    3800     380   2400    190 2500    200
Ceramic 7      (C7)    2.75    21.9    3400     340   3230    258 4000    318
Ceramic 8     (C8A)    3.50    27.8    3850     385   2950    235 3050    242
Ceramic 8     (C8B)    4.12    32.8    4200     420   2913    232 2960    236
Ceramic 9      (C9)    3.32    26.4    3800     380   3516    280 4010    320
Ceramic 10   (C10)    3.82    30.4    4000     400   3617    288 3510    280
Ceramic 11   (C11)    4.32    34.4    4300     430   2512    200 2560    204

Typical Physical & Thermal Properties of Hard Ferrite (Ceramic) Magnets

Material Properties Typical Values
Thermal Conductivity 0.018
cal/inch-sec• ⁰C
0.029
W/cm•C
Electrical Resistivity 10⁶ ohm•cm 10⁶ ohm•cm
Coefficient of thermal expansion (250⁰C – 450⁰C
Parallel to orientation  // to M
8 x 10⁻⁶
inch/inch • ⁰F
14 x 10⁻⁶
cm/cm • ⁰C
Perpendicular to orientation   ⊥ to M6 x 10⁻⁶
Inch/inch • ⁰F
10 x 10⁻⁶
Cm/cm • ⁰C
Modulus of elasticity 2.6 x 10⁷ psi 1.8 x 10¹¹ Pa
Compressive strength 130,000 psi 895 x 10⁶ Pa
Tensile strength 5,000 psi  34 x 10⁶ Pa
Hardness ( Mohs) 7 7
Flexural strength 9,000 psi 62 x 10 Pa
Curie Temperature 842-860 ⁰F 450-460 ⁰C
Recommended Max. Operating Temperature * 482⁰F 250⁰C
Density 0.177 -.184 lbs/in³ 4.9-5.1 g/cm³

*Temperature greater than 450⁰C will require re-magnetization

Note: The above data is compiled from industries and research sources and should only be used for reference only.

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