Patent ID: 6855186
Filing Date: 2005-02-15
Classification: H01F

Abstract:
1. A process for the production of neodymium-iron-boron permanent magnet alloy powder which comprises the following steps: (i) preparing a neodymium salt solution with a strength in the range of 0.25-2.0 M, an iron salt solution with a strength in the range of 0.25-2 M and a alkali borohydride solution with a strength in the range of 1-5 M, (ii) mixing the neodymium salt and iron salt solutions using argon or hydrogen to form a mixed neodymium-iron salt solution and adjusting the pH of the mixed solution in the range of 1.5-2.5, (iii) adding the alkali borohydride solution slowly and continuously to the neodymium-iron salt solution of step (ii) in inert atmosphere and maintaining at a temperature in the range of 5 to 15° C. with continuous stirring to get a black precipitate having a composition comprising: (iv) filtering and washing the precipitate with water and an organic solvent, and (v) heat treating the precipitate at a temperature in the range of 500 to 750° C. to obtain the alloy of Nd—Fe—B.