Abstract
The granulation of Nd-Fe-B powder was investigated by the spray-drying method, using poly (vinyl alcohol) as a binder to give it good flowability. The amount of oxygen and carbon in sintered magnets can be controlled below the upper limit by cooling the slurry and debinding green compacts in a hydrogen atmosphere. As the granulated Nd-Fe-B powder has good flowability, thin green compacts can be easily produced from it, and the sintered bodies are highly accurate in size. Micro-ring magnets with a thickness of 0.6 mm and thin-plate magnets with a thickness of 0.2 mm were successfully synthesized by spray-dried Nd-Fe-B powder without any serious damage to the surfaces by oxidation, which harms coercivity and the squareness of demagnetization curve.
