Koa Corporation

Jfe Mineral Company, Ltd.

Naomi Ishida

Kenichi Iguchi

Yoji Gomi

Etsurou Udagawa

Yoshimi Nakata

Yuko Echizenya

Focusing on zinc oxide itself, which is a main raw material for a zinc oxide varistor (laminated varistor), a predetermined amount of additive is added to a zinc oxide powder having crystallite size of 20 to 100 nm, particle diameter of 20 to 110 nm found using a specific area BET method, untamped density of 0.60 g/cmor greater, and tap density of 0.80 g/cmor greater. This allows a zinc oxide sintered body to secure uniformity, high density, and high electric conductivity, resulting in a zinc oxide varistor with high surge resistance, capable of downsizing and cost reduction. Moreover, addition of aluminum (Al), as a donor element, to the zinc oxide powder allows control of sintered grain size in conformity with the aluminum added amount and baking temperature, and also allows adjustment of varistor voltage, etc.

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Fuchu, Japan

Naomi Ishida