Preparation of Fe@Fe3O4/ZnFe2O4 Powders and Their Consolidation via Hybrid Cold-Sintering/Spark Plasma-Sintering

• Published in: Nanomaterials (Basel, Switzerland) Vol. 14; no. 2; p. 149
• Main Authors: Mesaros, Amalia, Neamțu, Bogdan Viorel, Marinca, Traian Florin, Popa, Florin, Cupa, Gabriela, Vasile, Otilia Ruxandra, Chicinaș, Ionel
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-01-2024; MDPI
• Subjects: Alternating current; Caustic soda; Coercivity; Cold; Cold pressing; Cold sintering; cold-sintering/spark plasma-sintering; Current loss; Eddy currents; Electrical insulation; Fe@Fe3O4 core–shell powder; Fourier transforms; Graphite; Heat resistance; in situ oxidation; Iron oxides; Magnetic permeability; Magnetic properties; Methods; Nanoparticles; Nitrates; Oxidation; Particulate composites; Permeability; Plasma sintering; Sintering (powder metallurgy); soft magnetic composite; Spectrum analysis; Zinc ferrites; ZnFe2O4 nanoparticles; Germany
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano14020149

Our study is focused on optimizing the synthesis conditions for the in situ oxidation of Fe particles to produce Fe@Fe3O4 core–shell powder and preparation via co-precipitation of ZnFe2O4 nanoparticles to produce Fe@Fe3O4/ZnFe2O4 soft magnetic composites (SMC) through a hybrid cold-sintering/spark plasma-sintering technique. XRD and FTIR measurements confirmed the formation of a nanocrystalline oxide layer on the surface of Fe powder and the nanosized nature of ZnFe2O4 nanoparticles. SEM-EDX investigations revealed that the oxidic phase of our composite was distributed on the surface of the Fe particles, forming a quasi-continuous matrix. The DC magnetic characteristics of the composite compact revealed a saturation induction of 0.8 T, coercivity of 590 A/m, and maximum relative permeability of 156. AC magnetic characterization indicated that for frequencies higher than 1 kHz and induction of 0.1 T, interparticle eddy current losses dominated due to ineffective electrical insulation between neighboring particles in the composite compact. Nevertheless, the magnetic characteristics obtained in both DC and AC magnetization regimes were comparable to those reported for cold-sintered Fe-based SMCs.