Hitachi Metals, Ltd.

Tsukasa Mikamoto

Hisato Tokoro

Kimio Uchida

Kazuo Oda

A thin arc segment magnet made ofaan R--rare earth sintered magnet substantially comprising 28-33 weight % of R and 0.8-1.5 weight % of B, the balance being substantiallyFeT, wherein R is at least one rare earth element including Y, and T is Fe or Fe and Co, which has an oxygen content of 0.3 weight % or less, a density of 7.56 g/cmor more, a coercivity iHc of 1.1 MA/m (14 kOe) or more at room temperature, and an orientation Br/4&#x3c0;Iof 96% or more in an anisotropy-providing direction at room temperature can be produced by using a slurry mixture formed by introducing fine alloy powder of the above composition into a mixture liquid comprising 99.7-99.99 parts by weight of a mineral oil, a synthetic oil or a vegetable oil and 0.01-0.3 parts by weight of a nonionic surfactant and/or an anionic surfactant.

Arc segment magnet, ring magnet and method for producing such magnets

A thin arc segment magnet made of a rare earth sintered magnet substantially comprising 28-33 weight % of R and 0.8-1.5 weight % of B, the balance being substantially Fe, wherein R is at least one rare earth element including Y, and T is Fe or Fe and Co, which has an oxygen content of 0.3 weight % or less, a density of 7.56 g/cm,or more, a coercivity iHc of 1.1 MA/m (14 kOe) or more at room temperature, and an orientation Br/4&pgr;I,of 96% or more in an anisotropy-providing direction at room temperature can be produced by using a slurry mixture formed by introducing fine alloy powder of the above composition into a mixture liquid comprising 99.7-99.99 parts by weight of a mineral oil, a synthetic oil or a vegetable oil and 0.01-0.3 parts by weight of a nonionic surfactant and/or an anionic surfactant.

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Saitama-ken, Japan

Tsukasa Mikamoto