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US 6,855,186 B2Granted
Process for the production of neodymium-iron-boron permanent magnet alloy powder
AssigneeCouncil of Scientific and Industrial Research
InventorsPatcha Ramachandra Rao, Venkatesh Rao, Arvind Singh
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Abstract
The present invention relates to an improved process for the production of neodymium-iron-boron permanent magnet alloy powder. The neodymium-iron-boron alloy prepared by the process of the present invention can be processed further to get anisotropic permanent magnets, bonded as well as sintered.
Claims13
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:
- Neodymium
- 10 to 40 wt %
- Iron
- 60 to 90 wt %
- Boron
- 1 to 10 wt %
- (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.
8 more elements
A process for the production of neodymium-iron-boron permanent magnet alloy powder which comprises the steps of:
- (i) providing a solution consisting essentially of neodymium salt in a strength of 0.25-2.0 M, a solution consisting of iron salt in a strength of 0.25-2 M and a solution of an alkali borohydride in a strength of 1-5 M;
- (ii) mixing the neodymium salt solution with the iron solution to obtain a mixed neodymium-iron salt solution and adjusting the pH of the mixed solution to a range of 1.5-2.5;
- (iii) adding the alkali borohydride solution to the mixed neodymium-iron salt solution slowly and continuously to form a resultant solution and maintaining the resultant solution at a temperature in a range of 5 to 15° C. with continuous stirring to form a black precipitate;
- (iv) recovering the precipitate;
- and
- (v) heat treating the precipitate in the presence of argon and hydrogen to form a two phase alloy powder of neodymium-iron-boron comprising 10 to 40 wt % neodymium, 60 to 90 wt % iron and 1 to 10 wt % boron.
3 more elements
Dependencies are inferred from the claim text.