Kawasaki Steel Corporation

Masakatsu Yamazaki

Tetsu Narutani

Hideaki Kobiki

Fumiaki Yoshikawa

Keizou Okuno

Hidekaku Yoshimatsu

Kouzou Fujiwara

Katsunobu Okutani

Masao Tsuzaki

Katashi Takaki

A method for sintering Mn--Zn ferrite green compacts is provided which includes a first heating step of raising the temperature from room temperature to 600.degree. C. within a period from 30 minutes to 5 hours, a second heating step of raising the temperature from 600.degree. C. to the sintering temperature and holding the sintering temperature until the start of cooling within a period shorter than 10 hours, and a cooling step of lowering the temperature to 150.degree. C. within a period longer than 3 hours, with the total period of the three steps being shorter than 20 hours. This method permits the efficient production in a short time of Mn--Zn ferrites having good magnetic properties.

Method for producing Mn-Zn ferrites

A low power loss Mn-Zn ferrite consists essentially of Fe.sub.2 O.sub.3, MnO and ZnO at a given mole ratio and contains given amounts of SiO.sub.2, CaO, niobium oxide and titanium oxide or antimony oxide as trace additives. This ferrite is suitable as a transformer material for switched mode power supply.

Low power loss Mn-Zn ferrites

A method for producing an oxide useful as a starting material for making soft ferrites comprised mainly of iron, zinc and at least one metal selected from manganese, magnesium, nickel and copper is described. In the method, while chlorides of metals other than zinc are roasted for oxidation to produce a composite oxide, zinc oxide is added during the roasting. This method ensures addition of zinc oxide at high yield without use of zinc chloride having a high vapor pressure. The resultant oxide for ferrites has desired ratios of metal constituents and contains spinel ferrites which are intermediate products with zinc oxide being uniformly dispersed. The use of the starting oxide leads to omission of a calcination step and a powder mixing step in the production process of ferrites. Ferrites with good quality can be obtained by direct sintering. An alternative method using zinc chloride instead of zinc oxide is also described which can provide an equivalent oxide for making ferrites.

Method producing composite oxides for use as starting materials for

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Chiba, Japan

Masakatsu Yamazaki