Preparation of Nickel Thin Sheets with Nanosized Ferrites by Combustion Synthesis and Electroforming

概要

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Composite nickel sheets with nanosized nickel--zinc ferrite particles were prepared as electromagnetic shielding materials by electroforming in a modified nickel--sulfate bath with nickel--zinc ferrite particles. The nanosized nickel--zinc ferrites were prepared by combustion synthesis and mechanical milling. The combustion temperature and propagation rate were about 1150 °C and 8.9 mm/s, respectively. Neutron diffractometry revealed that the final nickel--zinc ferrites formed by combustion synthesis followed by mechanical milling were Ni0.42Zn0.58Fe2O4 with the crystal structure and lattice parameter of $Fd3m$ and 0.84124 nm, respectively. Microstructure observation and chemical analysis by transmission electron microscopy and energy-dispersive spectroscopy respectively showed that nanosized nickel--zinc ferrite particles with a diameter of about 20 nm exist in the thin composite nickel sheet. Maximum magnetization ($M_{\text{s}}$), residual magnetization ($M_{\text{r}}$), and coercive force (\text{i) were 7.75 Wb/m2/kg, 0.88 m3/kg, and 1297 A/m, respectively. The complex permeability decreases with an increase in frequency, and its real value ($\mu_{\text{r}}{}'$) has an maximum at about 0.65 GHz.
2011-01-25