Papers by Keyword: Bonded Magnet

Abstract: A bonded permanent magnet of Barium hexa Ferrite has been made using powder BaFe₁₂O₁₉ (commercial ferrite) and a polymer of bakelite powder as binder. The composition of bakelite was varried 5% wt. The preparation of sample was begun with mass weighing for each material, then mixed together using ball mill for 1, 6 and 12 hours and using aquades as milling media. The mixed powder is dried in an oven at 110 °C for 4 hours, then the particle size distribution was measured. After that, the dried sample powder was pressed to form a pellet at pressure 40 MPa and temperature about 160 °C for 20 minutes. The characterization of sample pellet was done such as measurement of bulk density, hardness , magnetic properties using VSM and anylisis of microstructure using SEM. The results of the characterization show that the density and magnetic properties tend to increase with increasing of milling time, where the highest density, hardness and highest magnetic properties are achieved at sample with milling time for 12 hours. The value of magnetic properties at this condition are flux magnetic of 530 Gauss, remenance of 3100 Gauss, coercivity of 1,10 kOe.

Abstract: Hybrid bonded magnet Ba-Ferrite/NdFeB with 5% wt Epoxy Resin (ER) as polymer binder hsa been developed with variations in BaFe₁₂O₁₉ to NdFeB weight ratio. The variation of the BaO6Fe₂O₃ : Nd-Fe-B weight ratio are 90%:10%; 80%:20%; 70%:30% and 60%:40%. The magnetic particle consist of Ba-Ferrite and NdFeB were mixed until homogenize and compacted by using hydraulic press machine with 8 Tonf force to form a disc shape sample. The disc sample was dried using vacuum dryer with 10 mm bar pressure at 80°C for one hour before being magnetized using impulse magnetizer. The best %wt composition ratio of Ba-Ferrite/NdFeB is 70%/30% and 60%/40%. The hybrid bonded magnetic properties at the best %wt composition ratio are: bulk density = 4.28-4.43 g/cm³, FM = 1057-1121 Gauss, Br = 3.46-3.70 kG, Hc = 3.25-3.70 kOe, and BHmax = 1.60-1.70 MGOe.

Abstract: The injection molding of magnetic powder could cost-effectively mass-produce net shape magnets. In order to prepare the injection molding bonded NdFeB permanent magnet material with better combined properties, the effect of binder on the magnetic property, mechanical property and fluidity of injection molding magnets and its mechanism microcosmically were investigated. The effect of additives such as silicone coupling agent, compound lubricants and antioxidant on the properties of injection molding magnets are discussed. The injection molding bonded magnets were prepared by using the MQP-B rapidly quenching NdFeB magnetic powder and polyamide 12. The magnetic properties are :Br=0.539T, Hcb=345.37kA/m, Hci=681.02kA/m, and (BH)max=47.37kJ/m3.

Abstract: The exchange spring magnetic powders of SmCo5/α-Fe were obtained by mechanical milling and annealing. SmCo5+20 wt% α-Fe powder milled for 8 h and annealed at about 550 °C was considered to be more appropriate for our purpose. The isotropic nanocomposite permanent magnets were obtained by bonding the magnet powder in a binder matrix. Several ratios from 0.5 to 1.5 wt % between binder and magnetic powder were used. The composite material was compacted in dies at pressure from 600 to 800 MPa. The heat treatments for polymerisation were performed at 180 °C for 1h. The density and the microstructure of the magnets are discussed in connection with the properties of the starting powder and processing conditions. Magnetic characteristics of Br, Hc and (BH)max were obtained from hysteresis curves in magnetic fields up to 10 T.

Abstract: The squareness factor γ used to evaluates for criterion allowing quick estimation of the quality of NdFeB melt-spun powders on Stoner–Wohlfarth model. For the powder compaction of 6.4 g/cm3 mass density, the measured value γ=0.48 serves the evidence of the Stoner – Wohlfarth behaviour of the powder grains and the preparation conditions are optimal for producing Stoner – Wohlfarth particles. For the powder compaction of given mass densities the calibration curve of the squareness factor γ is presented. We can observe one more thing that for the ideal, full dense compaction of NdFeB Stoner – Wohlfarth particle the squareness factor γ can not be large than 0.53.

Abstract: Two-phase nanocrystalline ribbons were prepared by melt-spun and subsequent heat treatment. Excellent magnetic properties of the bonded magnet were achieved as follows: Br = 0.67 T, JHc = 664.3 kA·m-1, (BH) max = 75.0 kJ·m-3. The mean grain size of the ribbons heat-treated at 710 °C/ 4 min is about 50 nm. After heat-treated the ribbons at 750 °C/ 4 min, the mean grain size is about 100 nm.