Effect of sintering enclosures and sintering parameters on the magnetic properties of a high permeability manganese-zinc ferrite

Citation
Ip. Kilbride et R. Freer, Effect of sintering enclosures and sintering parameters on the magnetic properties of a high permeability manganese-zinc ferrite, IEEE MAGNET, 36(1), 2000, pp. 375-380
Citations number
11
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
IEEE TRANSACTIONS ON MAGNETICS
ISSN journal
00189464 → ACNP
Volume
36
Issue
1
Year of publication
2000
Part
2
Pages
375 - 380
Database
ISI
SICI code
0018-9464(200001)36:1<375:EOSEAS>2.0.ZU;2-K
Abstract
Manganese-zinc ferrite (Mn0.52Zn0.41Fe2.07O4) has been prepared by the mixe d-oxide route. Specimens were in the form of toroids, pressed in the green state to 11.9 mm outside diameter and 5.9 mm inside diameter. To assess the effect of zinc loss, a variety of circular local sintering enclosures were employed. All specimens were initially sintered in air at 1390 degrees C f or times of 7.5-16 h, After cooling to 1200 degrees C they were held for 4 h in atmospheres containing 0.0125-0.05% oxygen, Sintered products were sin gle-phase, with density greater than or equal to 95% theoretical and a grai n size of about 20 mu m. Use of a partial sintering enclosure led to a 45% increase in initial permeability mu(i), but use of a full enclosure led to a reduction in mu(i), Firing the samples at 1200 degrees C in an atmosphere containing 0.025% oxygen yielded near-stoichiometric samples, in which the initial permeability was maximized (about 10 200) over a wide range of tem peratures 25-90 degrees C. The eddy current losses in such samples were twi ce as high as for samples sintered in an oxygen atmosphere containing 0.05 % oxygen.