Preparation of ferrite films for electrical insulation by ultrasound-enhanced ferrite plating

The ferrite plating with applying power ultrasound waves of 19.5 kHz and 600 W enabled us to encapsulate entirely MnZn ferrite cores for transformers with Ni/sub x/Zn/sub y/Fe/sub 3-x-y/O/sub 4/ coating. Supplying a NH/sub 4/OH solution during the plating broke the limit of the solubility of Ni ions to ferrite-plated films. The electrical resistance of the NiZn ferrite increased with increasing the Ni and Zn content, reaching 2.3/spl times/10/sup 5/ /spl Omega/ cm at the composition of Ni/sub 0.24/Zn/sub 0.30/Fe/sub 2.46/O/sub 4/. The saturation magnetization was 540 emu/cm/sup 3/. The MnZn ferrite cores were successfully encapsulated with NiZn ferrite coating, resulting in the increase of their surface resistance to over 100 k/spl Omega/.