In fact, it is expected that a combination of the highest magnetic characteristics can be obtained by exchanging the spring magnet. Currently, the same magnetic body in which the Nd2Fe14B phase is a hard magnetic phase and A-Fe or Fe3B is a soft magnetic phase is mainly studied. In order to obtain the nano-grain structure peculiar to such an exchange spring magnet, the most common method currently used is to obtain an amorphous ribbon by melt quenching, and then crystallize by heat treatment at 650700e.
The Materials Research Institute of Nissan Motor Co., Ltd. studied Nd11Fe72Co8V115B715 and Nd9Fe76Co8V1B6 alloys, and the density of the quenched ribbon or raw material ingot was 716Mg/m3, while the density of bonded magnet was only 612Mg/m3, only about 80% of the raw material ingot. A high performance magnet must further increase the density of the magnet. In order to achieve full densification of the magnet, it is difficult to achieve a typical sintering process of about 1100e. For this purpose, a spark plasma sintering method (SPS) method has been studied. The SPS method is a pressure sintering method using pulse current heating. Compared with the conventional hot pressing method, the sintering temperature is low and the sintering time is fast, and a dense magnet can be obtained. The magnetic properties of the prepared Nd9Fe76Co8V1B6 magnet were also investigated.
The results show that: (1) The sintered body exhibits a rebound phenomenon, and the obtained magnet is an exchange spring magnet composed of fine Nd2Fe14B type and A-Fe type crystal. (2) The obtained bulk exchange spring magnet is substantially isotropic and is independent of the direction of pressurization during sintering. (3) The particle size growth between the raw material powder particles was not observed even in the densified state, but fine grain growth was observed inside the powder. (4) Production conditions and characteristics of representative bulk exchange spring magnets: the roll speed of the amorphous ribbon is VS=20m/s; the alloy SPS condition is 675e@5min, the pressure is 490MPa; Br=0199T, HCJ= 415kA/m, (BH)max=10718kJ/m3, Hk/HCJ@100=23%, D=7159Mg/m3, rebound ratio=40%. (Qiming is taken from 5 powder hS powder metallurgy 6,2000,47 (6): 667) Nd-Fe-Co-Cu-Nb-B-based exchange spring magnets with Pr instead of a part of Nd are rapidly quenched and thinned with Nd-Fe-Co-Cu-Nb-B alloy. Magnetic properties, if a part of Nd in the alloy is further replaced by Pr, a large coercive force can be obtained because the formed Pr2Fe14B type crystal phase has a high anisotropic magnetic field. Therefore, in order to produce a high-performance A-Fe/(Nd,Pr)2Fe14B exchange spring magnet, the Institute of Science and Technology of Mingye University in Japan used Pr to replace a part of Nd with different components of Nd-Pr-Fe-Co-Cu-Nb-B. The thin strip prepared by single-roller quenching method was used to study the effects of the peripheral speed of the cooling roll and the heat treatment of the amorphous ribbon on the magnetic properties and physical properties of the thin-band magnet.
The raw materials used in this test are ruthenium, osmium, iron, cobalt, copper, ruthenium and boron metals. The melt component used for the spray-spinning strip is (Nd1-xPrx)9Fe7515Co8Cu015Nb1B6, the amount of Pr is x=010, 013, 015, 017, 110. The spin-bending ribbon is sprayed on the alloy melt in a high-purity hydrogen atmosphere. The surface of the single roll having a roll speed of 1015 m/s, the obtained amorphous ribbon was crystallized at 625700e in a high purity argon atmosphere for 010 min. After the thin strip sample was magnetized by 418 MA/m pulse, the magnetic properties, Curie temperature and temperature characteristics were measured using a vibrating sample magnetometer. The crystal structure of the ribbon sample was analyzed by powder X-ray diffraction, and the crystallization temperature of the amorphous ribbon was measured by a differential thermal analyzer. The results show that the Pr-rich amorphous Nd217Pr613Fe7515Co8Cu015Nb1B6 alloy ribbon obtained by single-roller quenching with a roll speed of 1215m/s is obtained by the optimal crystallization treatment of 675e. The obtained nanocrystalline (average particle size: 37nm) exchange spring magnet (BH) The max is 156116 kJ/m3, and the temperature coefficients of Jr and HCJ are A, respectively.
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Galvanized Square Steel Tube
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