Spang Industries, Inc.

Alex Goldman

Alfred M Laing

Bu-Fan B Yu

The present invention improves the processing and products of coprecipitation of Fe and other metals selected from Mn, Zn, Ni, and Mg as carbonates and hydroxides in the manufacture of magnetically soft ferrites. Teachings are provided which enable control of the characteristics, especially the particle shape of coprecipitated metal carbonates and hydroxides, to bring about significant advantages in further processing such as relief of critical sintering requirements to meet commercial specifications, improved intermediate products which can be more easily handled during processing, and improved quality magnetically-soft, compacted, ferrite components. In the manufacture of MnZn ferrites, sintering furnace temperatures encountered by components from the same batch can vary as much as 100.degree. C. while maintaining specifications of permeability and loss factor whereas, with prior ferrite materials, a variation of as little as 5.degree. C. to 10.degree. C. can make the difference between acceptable and non-acceptable product.

Carbonate/hydroxide coprecipitation process

Manufacturing process for ferrimagnetic materials and pressure compacted soft ferrite components utilizing a 'wet' process for compositional preparation of materials in which metal carbonates and metal hydroxides are coprecipitated in controllably selected ratios. An aqueous solution of metal ions is formed by dissolving pure metals in acid. This aqueous metal ion solution is added to a predetermined solution of carbonate ions and hydroxide ions. Concentrations, temperature, and rates of addition are controlled to select the ratio of carbonate groups to hydroxide groups in the coprecipitated particles and the size of such particles. The controllably selected ratio of carbonate groups to hydroxide groups facilitates separation of the coprecipitation particles and maintains residual hydroxide groups in the material so as to extend solid-state reactivity of the coprecipitated particles for grain growth and densification purposes until the final heat treatment in which the pressure compacted articles are sintered. The intermediate materials can be processed in conventional dry processing equipment and the ferrimagnetic powders can be compacted in dies used for dry process ferrites because of matched shrinking ratios. High toroidal permeability and low loss factors are combined in components for telecommunications and higher frequency uses; e.g. manganese-zinc ferrites suitable for filter core and like uses have toroidal permeabilities above 2000 and loss factors in the range of 0.8 .times. 10.sup.-6 to 1.5 .times. 10.sup.-6 at 100 kHz. Other cores include NiZn ferrites and MgMn ferrites.

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Pittsburgh, PA, United States of America

Alex Goldman