One-Step Aerosol Synthesis of SiO2-Coated FeNi Particles by Using Swirler Connector-Assisted Spray Pyrolysis

Abstract

Silica-coated soft magnetic particles are essential for some powder magnetic cores consisting of primary (coarse particles) and secondary (fine particles) soft magnetic particles in the advancement of electric devices. Herein, we report the first investigation on the direct synthesis of submicron-sized silica-coated FeNi (FeNi@SiO2) particles as the secondary particle using a connector-assisted spray pyrolysis route. Provided by computational fluid dynamics calculation in applying different connector types, i.e., T-shaped and swirler, we found that the mixing performance between FeNi and HMDSO vapor in the swirler connector played an important role in resulting heterogeneous nucleation, which is crucial for obtaining the higher coating ratio (CR) and fewer undesired nanoparticles than that of the T-shaped connector. The as-prepared submicron-sized FeNi@SiO2 particles (353 nm) with the highest CR (95.9%) demonstrated a remarkable DC bias characteristic (Isat) and eddy current loss values on a powder magnetic core, promising the practical application in manufacturing soft magnetic components.