Determination of a quantitative relationship between deposition duration and magnetic performance of soft ferromagnetic composites via data-analysis and theoretical models

Abstract

The industrial production of soft ferromagnetic composites demands a quantitative description of process parameters and magnetic performance. Here, Fe–Si/SiO2 soft ferromagnetic composites were prepared via a two-step method combining chemical vapour deposition and hot-pressed sintering. Investigations of surface and section morphology, phase composition and crystal structure were undertaken to characterise the deposition duration-dependence of SiO2 insulation coating thickness in Fe–Si/SiO2 soft ferromagnetic composites. A vibrating sample magnetometer, a resistivity tester and a B–H analyser were used to study the magnetic behaviours of Fe–Si/SiO2 soft ferromagnetic composites. Based on curves of deposition duration-dependence of SiO2 insulation coating thickness and other theoretical models, quantitative relationships between deposition duration and magnetic performance were determined for Fe–Si/SiO2 soft ferromagnetic composites. These results demonstrate that the coating and crystallisation of SiO2 insulation coatings had no influence on the crystal structure of Fe–Si substrate particles and that SiO2 insulation coating thickness increased linearly with deposition duration. Total core loss of Fe–Si/SiO2 soft ferromagnetic composites was strongly predicted by SiO2 insulation coating thickness. A quantitative equation relating magnetisation intensity to Fe–Si/SiO2 soft ferromagnetic composite deposition duration was derived on the basis of experimental data and subsequent model selection. Additional quantitative equations relating electrical resistivity and eddy current loss to Fe–Si/SiO2 soft ferromagnetic composite deposition duration were determined according to electromagnetic theory. These results establish a precise adjustment mechanism for magnetic behaviour in Fe–Si/SiO2 soft ferromagnetic composites and promote the industrialisation of a new preparation process combining chemical vapour deposition and hot-pressed sintering.