Hot-pressed ferrites for magnetic recording heads

Abstract

Hot-press ferrites in both Mn-Zn ferrite and Ni-Zn ferrite composition are reviewed. They are used as magnetic head cores.Production methods and the properties of hot-press ferrites are presented. Head performance, i.e., wear resistance, surface crumbling, and signal output scattering, etc., depends upon the magnetic properties and the microstructures of the sintered ferrite. To make these heads perform better, grain oriented Mn-Zn hot-press ferrites were developed, with either (111) or (110) axes, or both grain axes oriented. Also, some newly developed Mn-Zn hot-press ferrites are shown. One has a small grain size (~1 0 pm) to meet the demand for the narrow track width head with high recording density. Another consists of small grains (~1 0 pm) and grain boundaries with improved mechanical strength. It can withstand the severe machining process of the head fabrication. A third Mn-Zn hot-press ferrite has high saturation magnetization (Bt ~580 mT).