The role of magnetic powder in neodymium iron boron

Magnetic powder is the abbreviation for magnetic powder body, which is a collection of a large number of basic material particles and gaps between particles. Powder is a substance that lies between a solid and a colloid. Below 0.1 μ The solid of m is called a colloid, while it is higher than 0.1 μ The solid of m is called a block or solid. There are many small pores between the particles in neodymium magnetic powder, and the bonding surface is very small. The atoms on the surface cannot form strong binding forces. Therefore, powder bodies do not have a fixed shape like dense bodies, but exhibit flowability similar to liquids. There are no macroscopic pores in the dense body, which are connected by the binding force of atoms. Powder metallurgy is commonly used in the preparation process of rare earth magnet alloys. Alloy ingots are produced by this method. Neodymium magnet powder is divided into three processes: coarse, medium, and fine, with a powder size requirement of 3-5 μ M. Rare earth magnet metals are prone to oxidation, for example, producing SMZ03 and ND203. These oxide fine powders will spontaneously ignite in the air at higher temperatures and become secondary powder particles through magnetic interactions, that is, a group of small particles gathered together by van der Waals forces, London forces, and magnetic interactions between the powders. Therefore, the poor flowability of the above-mentioned rare earth permanent magnet alloy powder in the main air results in certain difficulties in the next step of directional molding in the magnetic field.