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Magnetic Bar , Magnetic Material , Magnetic Assemblies

Magnetic experts said that the difference of plumbum shape of magnet and spinal shape of magnet are "R block" where is unavailable for less-symmetrical hexahedron 2b crystal to spinal ferrite. Fe3+ has such a great interplay of anion around triangle particle fields that yields a anisotropic higher than cubic crystal. That is to say, Fe3+ supply a higher anisotropic in the 2b.

Magnetic experts said that the difference of plumbum shape of magnet and spinal shape of magnet are "R block" where is unavailable for less-symmetrical hexahedron 2b crystal to spinal ferrite. Fe3+ has such a great interplay of anion around triangle particle fields that yields a anisotropic higher than cubic crystal. That is to say, Fe3+ supply a higher anisotropic in the 2b. Besides 2b, 12k and Fe3+ on other positions make a good contribution to anisotropic. To advance the coercivity by mechanism, we have gained a certain progress. Magnetic resonance value Br has been very near to the theoretic value in industry production, while the value of coercivity are still 1/3 less than the theoretic value-616ka/m(Sr ferrite) at least. Following are common ways to advance coercivity in industrial manufacturing process Make the size of particle distributed on average at state of single domain, the particle size of single domain for permanent magnetic ferrite are around 0.9u normally. Under the condition of single domain, the magnet vector is enabled to rotate and Hcj is higher. In facts, the single domain and multi domain are co-existence under mass production. The core of anti-magnetization is still coming up and the magnet vector is also rotated. Analyzer is important for researching the manufacture machinery and the particle of single domain. Now people are using average particle size analyzer step by step to test particle size distribution, balling mill and grinder are used for making particle of single domain. Avoid using the vibrating mill as possible can prevent forming sheet shape particle. it is an important method to advance coercivity by adjusting the formula and manufacture technology. The formula value "n" has some effects on coercivity. When n6, change the formula additive and manufacturing technology, the coercivity can reach 400ka/m or above, and Br will also reach above 400mt. Under special condition, when rate of mol comes to 8 for Fe2O3 and SrCO3, which can lead both Br and Hcj to theoretic value. Herein comes a discussion on the change of coercivity value under n=6.1 when altering the additive: A. n=6.1, both first additive and second additive are: 0.4% CaCO3 and 0.4% kaolin Magnetic parameters: Br:390mT, HCB:180kA/m, HCJ:190ka/m, (BH)max:27.5kJ/m3 In A formula, when adding 0.7% Cr2O3 and 0.6% Al2O3 the second time, the magnetic performance becomes to: Bre380Mt, HCBe250ka/m, HCJe270ka/m, Al and Cr will replace Fe ion of crystal, coercivity is advanced, but Br will lower a little. In A formula, if second additive becomes to: 0.6% CaCO3, 0.8% SrSO4, 1.0% Cr2O3, 0.4% Al2O3, the magnetic parameter becomes to: 397mT Br, HCBe276kA/m, HCJe288kA/m, (BH)max:29kJ/m3; adding SrSO4 can increase the activity of magnetic material and advance the value of Br and HC. In A Formula, if the second additive changes to: 0.6% CaCO3, 0.8% SrSO4, 1.0% Cr2O3, 0.4% Al2O3, the magnetic performance parameter will change to: Bre390mT, HCJe310kA/m. B. if adding some SrCO3 in the second additive, it will help to generate M phase and complete growth of broken crystal particle, If SiO2 is added into the second additive, it will assemble on the ferrite crystal particles to strengthen the surface resistance and prevent the crystal from growing. When the adding rate exceeds 0.2%, the force of coervicity will increase. Surely, it is also favorable to advance coervicity by lowing the temperature of sintering or shortening the attemperation time on the artwork. The way to make high performance permanent ferrite Just as mentioned in many files, the efficiency of molding will be low and make it more complicated through milling the particle of permanent magnetic ferrite. It will decrease Br to improve coercivity through add oxid such as Al or Cr. If want to get coercivity up to 320kA/m(over 4000Oe), meanwhile to keep the value of Br below 400MT or less, it can be hit through ion replacement which is certificated feasible in results of research and practice by many experts. The property of mass production is as follow: Br:426mT, HCB:297.3kA/m, HCJ:371.7kA/m, (BH)max:34.3kJ/m3 Br:4260Gs, HCB:3735Oe, HCJ:4670Oe, (BH)max:4.31MGOe It is feasible to choose oxide of rare earth La and oxide of Co to replace hexangular crystal Sr ion and Fe ion of permanent magnetic ferrite, whose ionic radius is nearly the same. If keeping the number of ion the same in the replacing process, and balancing the compensate charge, it can advance the coervicity and Br greatly. By proving of testing, its property is best when the adding weight rate is within 0.5-5%, TDK have released FB9 series, some labs of our country have also produced the same grade of permanent magnetic ferrite with FB9, which is near the theoretic value of permanent magnetic ferrite. Innovation for old products should include heighten produce efficiency, lowing cost and creating new technical artwork besides improving parameters.

Besides 2b, 12k and Fe3+ on other positions make a good contribution to anisotropic. To advance the coercivity by mechanism, we have gained a certain progress. Magnetic resonance value Br has been very near to the theoretic value in industry production, while the value of coercivity are still 1/3 less than the theoretic value-616ka/m(Sr ferrite) at least.

Following are common ways to advance coercivity in industrial manufacturing process

Make the size of particle distributed on average at state of single domain, the particle size of single domain for permanent magnetic ferrite are around 0.9u normally. Under the condition of single domain, the magnet vector is enabled to rotate and Hcj is higher. In facts, the single domain and multi domain are co-existence under mass production. The core of anti-magnetization is still coming up and the magnet vector is also rotated. Analyzer is important for researching the manufacture machinery and the particle of single domain. Now people are using average particle size analyzer step by step to test particle size distribution, balling mill and grinder are used for making particle of single domain.

Avoid using the vibrating mill as possible can prevent forming sheet shape particle. it is an important method to advance coercivity by adjusting the formula and manufacture technology. The formula value "n" has some effects on coercivity. When n6, change the formula additive and manufacturing technology, the coercivity can reach 400ka/m or above, and Br will also reach above 400mt. Under special condition, when rate of mol comes to 8 for Fe2O3 and SrCO3, which can lead both Br and Hcj to theoretic value. Herein comes a discussion on the change of coercivity value under n=6.1 when altering the additive:

A. n=6.1, both first additive and second additive are: 0.4% CaCO3 and 0.4% kaolin

Magnetic parameters: Br:390mT, HCB:180kA/m, HCJ:190ka/m, (BH)max:27.5kJ/m3

In A formula, when adding 0.7% Cr2O3 and 0.6% Al2O3 the second time, the magnetic performance becomes to: Bre380Mt, HCBe250ka/m, HCJe270ka/m, Al and Cr will replace Fe ion of crystal, coercivity is advanced, but Br will lower a little.

In A formula, if second additive becomes to: 0.6% CaCO3, 0.8% SrSO4, 1.0% Cr2O3, 0.4% Al2O3, the magnetic parameter becomes to: 397mT Br, HCBe276kA/m, HCJe288kA/m, (BH)max:29kJ/m3; adding SrSO4 can increase the activity of magnetic material and advance the value of Br and HC.

In A Formula, if the second additive changes to: 0.6% CaCO3, 0.8% SrSO4, 1.0% Cr2O3, 0.4% Al2O3, the magnetic performance parameter will change to: Bre390mT, HCJe310kA/m.

B. if adding some SrCO3 in the second additive, it will help to generate M phase and complete growth of broken crystal particle, If SiO2 is added into the second additive, it will assemble on the ferrite crystal particles to strengthen the surface resistance and prevent the crystal from growing. When the adding rate exceeds 0.2%, the force of coervicity will increase. Surely, it is also favorable to advance coervicity by lowing the temperature of sintering or shortening the attemperation time on the artwork.

The way to make high performance permanent ferrite Just as mentioned in many files, the efficiency of molding will be low and make it more complicated through milling the particle of permanent magnetic ferrite. It will decrease Br to improve coercivity through add oxid such as Al or Cr. If want to get coercivity up to 320kA/m(over 4000Oe), meanwhile to keep the value of Br below 400MT or less, it can be hit through ion replacement which is certificated feasible in results of research and practice by many experts. The property of mass production is as follow:

Br:426mT, HCB:297.3kA/m, HCJ:371.7kA/m, (BH)max:34.3kJ/m3 Br:4260Gs, HCB:3735Oe, HCJ:4670Oe, (BH)max:4.31MGOe It is feasible to choose oxide of rare earth La and oxide of Co to replace hexangular crystal Sr ion and Fe ion of permanent magnetic ferrite, whose ionic radius is nearly the same. If keeping the number of ion the same in the replacing process, and balancing the compensate charge, it can advance the coervicity and Br greatly. By proving of testing, its property is best when the adding weight rate is within 0.5-5%,

TDK have released FB9 series, some labs of our country have also produced the same grade of permanent magnetic ferrite with FB9, which is near the theoretic value of permanent magnetic ferrite. Innovation for old products should include heighten produce efficiency, lowing cost and creating new technical artwork besides improving parameters.