Ngk Spark Plug Company, Limited

Takayoshi Morishita

Tetsuji Yogo

Keiji Suzuki

Hironobu Ishikawa

A ceramic dynamic pressure bearing comprising a first member and a second member, wherein the first member and the second member define a dynamic pressure gap therebetween, the first member and the second member relatively rotate around an axis of rotation, the relative rotation generates a fluid dynamic pressure in the dynamic pressure gap, the first member has a first surface directing to the dynamic pressure gap and the second member has a second surface directing to the dynamic pressure gap, and at least one of the first and second surfaces comprises ceramic, the ceramic comprises: a ceramic matrix that is selected from alumina ceramic, zirconia ceramic and silicon nitride ceramic; and 15 vol % to 70 vol % of an electrically-conductive inorganic compound phase based on the total amount of the ceramic, the phase is dispersed in the ceramic matrix, the phase comprises at least one compound selected from tungsten carbide, silicon carbide, conductive oxide, metallic nitride, metallic carbide, metallic boride, and metallic carbon nitride, and the metallic nitride, the metallic carbide, the metallic boride, and the metallic carbon nitride each independently comprises at least one of Hf, Mo, Ti, Zr, Nb, and Ta.

Ceramic dynamic pressure bearing, motor with bearing, hard disc apparatus and polygon scanner

A sintered ceramic body which can be worked by electrical discharge machining, has high mechanical strength, and can be worked into sintered ceramic tools which have long life is disclosed. Further, sintered ceramic tools which have long life and scarcely cause flaws in work pieces are provided. The sintered ceramic body comprises ceramic particles having specific particle diameter and particle distribution.

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Kanagawa-ken, Japan

Takayoshi Morishita