50results about How to "Lower nitriding temperature" patented technology

The invention discloses a low-temperature nitridation preparation method of iron-based rare earth permanent magnet powder. The method is characterized in comprising the steps that: (1) under Ar gas protection, Sm2Fe17 alloy is smelted by using pure samarium and pure iron in a vacuum induction furnace, such that an ingot is obtained; the ingot is subjected to a homogenization treatment, and is crushed into powdery particles with an average particle size smaller than 40mun; (2) a surfactant, grinding balls and the powdery particles are added into a ball milling tank; a ball milling medium is filled into the tank; and with the cooperation of the surfactant and high-energy ball milling, flaky powder with a nano-crystalline structure is obtained, wherein the surfactant is coated on the surface of the powder; (3) the powder is filtered, such that the ball milling medium is removed; and the powder is subjected to vacuum drying; and (4) the powder is subjected to a nitridation treatment under a low temperature of 300-400 DEG C. The microstructure of the obtained permanent magnet powder is nano-crystals with grain sizes of 8-20nm. The nano-sheet thickness is approximately 5-200nm, Hc is 5-14kOe, and (BH) max is 10-28MGOe. On the basis that an original structure and advantages are maintained, the nitridation temperature is greatly reduced. The nano-sheet powder can be prepared into a high-performance bonding magnet which can be used in fields such as motors and engines.

The invention discloses a preparation method of a samarium-iron-nitrogen series permanent magnet material. The method comprises the steps that metastable state samarium-iron alloy is subjected to severe plastic deformation and then is subjected to nitrogen treatment and annealing crystallization treatment, and therefore the samarium-iron-nitrogen series permanent magnet material can be obtained. In the method, when the deformed samarium-iron-nitrogen series permanent magnet material is subjected to nitrogen treatment, since the free volume 'defect' content in the metastable state alloy can beincreased through multiple shear bands produced in the severe plastic deformation process, entering and diffusion of nitrogen atoms are facilitated, and the nitriding amount and nitriding uniformity of the alloy can be remarkably improved; since the multiple shear bands are produced through the severe plastic deformation, the follow-up crystallization annealing temperature can also be reduced, andnitride is reduced or prevented from being produced; and generation of the metastable phase is restrained, grains are refined, and coercive force is improved. By means of the method, the nitriding speed can be improved, the nitriding temperature can be reduced, decomposition of a samarium-iron-nitrogen compound is restrained, the microstructure is refined, and the nitriding efficiency of samarium-iron alloy for preparing the samarium-iron-nitrogen magnetic material is improved.