NdFeB permanent magnet materials bonded manufacturing principles and techniques

NdFeB permanent magnet materials bonded manufacturing principles and techniques

Bonded NdFeB in magnetism, metallurgy, composite materials, powder metallurgy, chemical industry and other subjects developed on the basis of knowledge - the kind of novel functional composite materials, sintered magnets has many features do not have attracted researchers and business attention. After nearly two decades of research and development, it became the permanent magnet material in the family - a new favorite, increasingly wide range of applications.
Bonded NdFeB theories and technologies include high-performance magnetic preparation ¢Ù, ¢Ú co-premixed powder and binder material preparation technologies, ¢Û magnet molding technology, ¢Ü magnet post-processing techniques. In order to adapt to evolving technologies and application requirements, the content of these studies systematically summarized and it is very necessary. Of bonded NdFeB magnets focus on design theory, high-performance two-phase exchange coupling magnetic nanoparticles, bonded NdFeB magnets with a binder and additives, preparation of bonded NdFeB magnets, bonded NdFeB magnet hybrid, were studied prepared with different characteristics bonded NdFeB-based magnets.
Firstly, the design of bonded NdFeB studies, presented two types of compression molding and injection molding bonded NdFeB magnetic powder stacking model to calculate the basic two types of magnets binder demand, namely: 2.42wt % and 5.18wt%; in the analysis of the performance of bonded NdFeB is proposed based on its design process.
Research summarized in the analysis, based on the study of the Nd (Pr)-Fe-B-Ti-c system coupling two-phase nano-magnets, by arc melting, rapid quenching melt spinning 14 ingredients prepared Nd (Pr) ZFe14B/a-Fe alloy, the use of VSM testing and analysis of their magnetic, TEM and XRD analysis of the structure and composition, and affect the material structure and properties of factors are analyzed, results showed that: the right amount of carbon added to the Chin and Nd (Pr)-Fe-B-based Nanocomposite permanent magnet, changing the alloy annealed in the process of cooling and crystallization sequence of phase precipitation, the 2-14-1 phase as the first precipitated phase, inhibits the precipitation of a-Fe and grain growth, crystallization by rapid quenching and annealing, the formation of small uniform NdZFe14B nanocrystals (20-30nm) is the grain boundary area to a-Fe-based soft magnetic phase separated microstructure; when Re content of 7-9.5at%, Ti and 2-14-l relative to the molar ratio l: l, TIC and TIB2 molar ratio l: 2 ʱ, Re-Fe-B-Ti-e alloy, the average energy product of about To 15MGoe (119.4KJ/m3), which reached 9at% rare earth content, the nano-exchange coupling permanent magnet coercivity up to 950KA / m or more.
Prepared by different binders bond the magnetic properties of NdFeB magnets, magnets prepared by mechanical properties and process performance comparison and comprehensive analysis of experiments to determine the compression bonded NdFeB magnets prepared epoxy value should be chosen high, lubrication, strong, uniform package of solid resin powder as the main component of the binder, in which F48 and E-20 resin is the ideal resin; experimental study of the batch is stored at different times after the preparation of the magnetic properties and mechanical properties, found that the performance is mainly affected by aging epoxy curing agent and the ease of reaction, high temperature curing agent and for preparation of latent curing agent with the material, which dicyandiamide / epoxy resin system prepared with the overall performance was better than expected maleic acid with / epoxy system. With the material system (HQP-ZG + F-48 + DICY) spent 62 days compressive strength of the magnet made to maintain more than 180MPa; by adjusting the nylon and MQP-D powder ratio, mixing the different ratios of nylon wear QP-D powder, hot pressing made of magnets, the magnets of the density of the test results showed that: 78% of the volume fraction of magnetic powder and nylon mixing, when the molding pressure reached 120MPa, the density of the magnet reached 5.9g/cm3 , can be prepared for low pressure molding of high density magnets; using F44 resin and hardener m-phenylenediamine at 180 ¡æ bonded NdFeB magnets can be achieved when the strength of 110MPa or more, at high temperatures can be used normally.
This paper also bonded NdFeB magnets prepared key technology research, the main contents and results:
(1) obtained by means of ball milling the powder with different particle size, measured after bonded magnets made from magnetic properties, and calculate the magnetic performance. The results show that the smaller the magnetic grain size, magnetic properties of magnets and magnetic powder for the worse, and the fundamental reason is that magnetic particle size decreases, the internal magnetic field and magnetic particles increase the lead back between the magnetic variation, if the magnetic refinement process caused partial oxidation of powder can lead to a decline in magnetic properties. Small size of the magnet made of bonded magnets, due to the magnets can also cause a decline in density of magnetic properties of the progress - steps down;
(2) experiment with a different agent, different dosage, and different treatment methods on magnetic pretreatment, by measuring, comparing the mechanical properties of bonded magnet prepared with the magnetic properties, that the coupling agent solution on the powder through the pre- treatment can significantly improve the magnetic properties of magnetic and mechanical properties, of which the best silane and the amount of vinegar Chin lwt% and 0.lwt%;
(3) Study of mixed plastic granulation process with adding different materials on the flow of lubricant and formability, and found that 0.2% of zinc stearate and polyvinyl butyral (mass ratio between 1 : 1) mixing lubricants can significantly improve both the material with the mobility of bonded magnets can guarantee the mechanical and magnetic properties; Yan) with different binder content on the magnetic properties of bonded magnets and mechanical performance measurement analysis, found that the amount of binder is about 2-3wt% can get the best overall performance;

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(4) experiment by measuring the magnetic particle size under different pressures and the corresponding changes in magnetic properties of bonded magnets, with: magnet fracture analysis, that the molding pressure of 900MPa is appropriate, the molding pressure is not high density of small magnets, magnetic low; Although you can enter too - further improve the magnetic density, but the magnetic crush of serious, an increase of the demagnetization field inside the magnet, the magnetic properties are not significantly increased, while mold brought back to a severe test;
(5) Experimental study of the different molding temperatures, the density of bonded magnets and magnetic results show that the resin temperature near the softening point above the molding temperature and pressure can increase the density and magnetic properties of magnets;
(6) experimental studies using XRD NdFe12Nx anisotropic bonded magnets affect the degree of orientation factors, found that pretreatment by solvent and can damage the magnetic strong magnetic field exists between the static magnetic effect as a result of the reunion, and then through the magnetic field mixed gel drying, granulation field after the molding, curing can be oriented to the magnets with high maximum energy product achieved 6.44MGOe;
(7) experiments were prepared by high energy product for the 94KJ/m3, (11.8MG0e) thermosetting NdFeB magnet, and the density of 5.9g/cm3, energy product is 62.0 KJ/m3 (7.79MGOe) the outer diameter of 220mm magnet. Finally, experimental studies of the isotropic and anisotropic NdFeB silver ferrite, anisotropic Sm2Co17: two systems of hybrid bonded magnets, measuring the proportion of different hybrid magnetic properties of bonded magnets, the results show that the NdFeB / ferrite magnets in the gills of silver mixed ferrite content of 50% or less coercive force when the phenomenon of absolute increase, while in the NdFeB / anisotropic Sm2Co17,: hybrid magnet Sm2Co17: 10% content of residual magnetism when enhancement, its energy product achieved 1l.3MG0e (89.95kJ/m3), Henkel curves show that the isotropic NdFeB / anisotropic Sm2Co17: hybrid bonded magnets in the presence of nano-phase permanent magnet coupling exchange interaction in a similar . Hybrid magnet at the same time showing a more single - Preparation of the bonded magnet powder and better temperature stability.

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Tags: neodymium magnets NdFeB permanent magnet materials Smco magnets