Patent ID: 9415445
Filing Date: 2016-08-16
CPC Classification: B22F,C22C,H01F

Claim Text:
1. A method for producing neodymium-iron-boron rare earth permanent magnetic material, comprising steps of: alloy smelting; pulverization; milling; magnetic compaction; vacuum sintering; and aging; wherein a particle size obtained by the step of pulverization is larger than that of the step of milling, and the step of milling comprises: firstly, evenly mixing the powder obtained by pulverization with one or more nano-sized powder selected from the group consisting of praseodymium oxide, neodymium oxide, aluminum oxide and zirconia, to obtain a mixture; and secondly, milling the mixture by a jet mill; wherein in the step of milling the mixture by the jet mill, the jet mill is a jet air flow mill; a particle size of the powder is controlled by a size sorting wheel; the powder is collected by a cyclone collector; powder with a grain diameter less than 1 μm discharged by gas exhaust pipes of the cyclone collector is collected by a filter; then the powder with the grain diameter less than 1 μm collected by the filter and the powder collected by the cyclone collector are mixed under a protection of nitrogen; and an oxygen content of the atmosphere in the jet mill is less than 50 ppm.