A co-precipitation-reduction-diffusion process for the preparation of neodymium-iron-boron permanent 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.