Jet mill

About: Jet mill is a research topic. Over the lifetime, 803 publications have been published within this topic receiving 5686 citations.

Manufacturing method of sintered rare-earth magnet

Abstract: PROBLEM TO BE SOLVED: To improve molded body strength by means of molding in a magnetic field by suppressing the degradation in magnetic characteristics. SOLUTION: This method comprises: a step of coarse crushing a raw material alloy of an Nd-Fe-B-based sintered magnet; a step of pulverizing the coarse-crushed powder obtained in the coarse crushing step by a jet mill; a step of pressure molding the pulverized powder obtained in the pulverizing step while applying a magnetic field to the powder; and a step of sintering the molded body obtained in the pressure molding step. In the pulverizing step, an impingement jet mill is used and the amount of oxygen of its pulverization atmosphere is specified to 8,000 to l5,000 ppm. The pulverized powder preferably satisfies the conditions of an average grain size D50=3.0 to 6.0 μm, D10/D50=0.35 to 0.55, D90/D50=1.80 to 2.05. COPYRIGHT: (C)2008,JPO&INPIT

Method for preparing high coercive force magnet

Abstract: PROBLEM TO BE SOLVED: To provide a method for preparing a high coercive force magnet, capable of optimizing a process of containing a heavy rare earth powder in a permanent magnet using a jet mill without ejecting an ultrafine powder to improve production efficiency and reduce cost.SOLUTION: A method for preparing a high coercive force magnet comprises the steps of: 1) mixing a R-Fe-B-M alloy powder with a heavy rare earth powder Ror a heavy rare earth powder RX; 2) polishing the mixed powder by a new jet mill 8; 3) mixing and pressing the polished magnetic powder into a block to be preliminarily sintered; 4) performing autoclave treatment; and 5) obtaining a high coercive force magnet by aging treatment. The collection of an ultrafine powder by a filter 14 is achieved when the magnetic powder including the R-Fe-B-M alloy powder and the heavy rare earth is simultaneously polished by the new jet mill improved not so as to eject an ultrafine powder.

Production of ultra-magnetostrictive alloy

Abstract: PURPOSE: To easily produce an untra-magnetostrictive alloy having oriented crystal or single crystal, etc., by sintering and integrating an alloy powder having a (near-) stoichiometric composition of an intermetallic compound of rare earth element and transition metal element. CONSTITUTION: An ingot having an alloy composition of (Tb 0.5 Dy 0.5 )(Fe 0.9 Mn 0.1 ) 1.999 by atomic ratio as a stoichimetric composition of an intermetallic compound of Laves type, etc., of rare earth element, such as Tb and Dy, and transition metal element, such as Fe and Mn, or a composition in the vicinity of the above is prepared. This ingot is crushed in an Ar gas flow and subjected to jet mill crushing in a nitrogen jet stream, and the resulting pulverized powder is formed into a green compact by using dies and punches made of stainless steel while applying the prescribed magnetic field. This green compact is sintered in an Ar atmosphere at about 1210°C for about 1hr, by which the ultra- magnetostrictive alloy having a polycrystal oriented structure with uniform crystal orientation can be produced. Further, by controlling the conditions, a single crystal or macrocrystalline grain close to the single crystal can be obtained. COPYRIGHT: (C)1992,JPO&Japio

Sinterable Si3N4 powder and a process for its preparation

Abstract: Sinterable Si3N4 powder having an average particle size of less than 1 mu m, wherein no individual particle has a diameter greater than 100 mu m, the total content of metallic impurities of the powder is less than 1000 ppm and the iron content is less than 200 ppm is produced by grinding agglomerated Si3N4 in a spiral jet mill.