Improving the Soft Magnetic Properties of Iron Powder by Lubricant Milling Treatment and the Mechanochemical Formation of an Iron/Graphite Lubricant Interface

Abstract

Milling iron particles with a lubricant such as graphite deforms them into a platelet shape, and in the process, the (001) plane is oriented parallel to the platelet face. The (001) plane contains the <001> axis, which has excellent magnetic properties, making the particles ideal candidates for use as magnetic cores in motors. The effect of the graphite lubricant on the iron particles, i.e., the lubricity, depends on the milling atmosphere. X-ray absorption near edge structure (XANES) and transmission electron microscopy (TEM) observations reveal that this dependency is due to the difference in the orientation of the basal plane of graphite, where mechanochemically formed iron oxide at the graphite/iron interface most likely plays an important role in the orientation of the basal plane.