A Co-precipitation-reduction-diffusion Process for the Preparation of Neodymium-iron-boron Permanant Magnetic Alloys

摘要

A process is disclosed for the preparation of a Nd-Fe-B permanent magnetic alloy, which process comprises the steps of: (a) mixing an aqueous solution of a neodymium salt with an aqueous solution of a ferrous salt to yield a feed solution, which is then subjected a co-precipitation with a precipitant of an aqueous solution of ammonium hydroxide and ammonium carbonate containing a soluble boron compound to form a co-precipitate product; (b) introducing hydrogen into the co-precipitate product to remove part of the oxygen therefrom, with the hydrogen pre-reduction continuing until there is no moisture evolving in the tail gas and only oxygen is left over in the product apart from the alloy elements, so as to form a hydrogen pre-reduction product; (c) completely mixing the hydrogen pre-reduction product with metallic calcium or calcium hydride, to cause a calcium reduction-diffusion, and (d) rinsing and drying the reduction product, and manufacturing the alloy powder.