Preparation of anisotropic Sm-Co particles using calcination process and addition of Ca(ac)2∙H2O

Abstract

Mechanochemical processes, including mechanical alloying by high-energy ball milling and subsequent reduction diffusion (RD) steps, have been widely used to fabricate particles with rare earth-transition metal compounds. However, a new process is required to synthesize magnetically alignable particles for enhancing the anisotropic properties of rare earth-transition metal hard magnetic compounds. In this study, commercial Sm2O3 and CoO powders were used as precursors to obtain Sm2Co17 or SmCo5 phases, and Ca(ac)2∙H2O powders were added for inhibition of particle growth and enhancement of particle distribution. In addition, pre-treatment conditions before the RD process have been investigated to obtain alignable particles. As a result, the average size of Sm-Co particles was able to be reduced to 300 nm according to the amount of the Ca(ac)2∙H2O powders and SmCo5 particles showed a maximum energy product of 18 MGOe with a squareness of 0.99. IEEE