烧结钕铁硼的烧结（Sintering of sintered NdFeB）.doc

烧结钕铁硼的烧结（Sintering of sintered NdFeB） Sintering of sintered ndfeb! Time: 2009 06 month 28 days to the original source: Author: beyond the mad views: The sintering NdFeB is that in order to further improve the performance and use of magnets, improve the contact properties between powder improved the strength and microstructure of the magnet with high performance, need to be green is heated to a temperature below the melting point of the powder matrix phase and insulation technology of a period of time. Sintering is a very important process, and all manufacturers and researchers pay great attention to it. The relative density of NdFeB powder compacts is generally 50% ~ 70%, and porosity is generally 30% ~ 50%. The bonding between particles is all mechanical and the strength of bonding is very low. If the molding pressure is very large, the particles that have come into contact with each other have already undergone elastic or plastic deformation, when the sample is easier to crack and its microstructure is not high enough to produce high magnetic properties. In the sintering process, there will be a series of physical and chemical changes. First of all, the gas adsorbed on the surface of the powder particles (including water vapor) excluded organic compounds (such as isostatic pressing may be coated with oil or added antioxidant and lubricant) evaporation and evaporation, eliminate stress, reducing the surface of the powder particles of oxide powder particles, deformation recovery and recrystallization. Secondly, atomic diffusion, material transfer, and the contact between particles are changed by mechanical contact into physical and chemical contact, forming the combination of metal bond and covalent bond. Finally, the contact surface between the powders is enlarged, and the sintered neck is produced. Then the sintered neck grows, the density increases, and the grain grows and so on. Green powder has high porosity, surface area is large, so the surface energy, but al