| 摘要 |
PURPOSE:To obtain a sintered magnet whose corrosion-resistant property is excellent by a method wherein Si and Al are diffused within a prescribed range from the surface to the inside of a rare earth-based sintered magnet in such a way that they are thin at the inside and that they are dense on the surface. CONSTITUTION:Individual metals of Nd, Fe and B are melted at a high frequency; they are cart. Their ingot is crushed; fine powders are obtained; after that, the powders are filled into a metal mold; they are pressurized and molded. A powder molded body is obtained. Then, the powder molded body is buried in silicon powders; in aluminum oxide powders as a sintering-preventing agent and in lithium fluoride powders as a reaction-promoting agent; it is sintered; after that, it is cooled; an aging treatment is executed again in a sintering furnace; a sintered magnet which has a density grade within a range of 1 to 100mum from the surface to the inside is obtained. Thereby, Si and Al are oxidized in the air, an oxide layer which is dense and extremely stable is formed, and the sintered magnet whose corrosion-resistant property is excellent can be obtained. |
