Kyocera Corporation

Tetsuzi Hayasaki

Masahiro Okumura

Hiroshi Aida

Shunichi Murakawa

Yumiko Itoh

Katsumi Nakamura

A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiOand a secondary phase of at least one of MgFeO, FeO, and FeO. The ceramic sinter can be produced by a process including: sintering a ceramic sinter from a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt and chromium; machining the sinter into a desired shape of a member of supporting a magnetic disc substrate, and annealing the sinter such that the ceramic sinter has conductive aggregation deposited on its peripheral surface, wherein in the annealing step, the member is heated at a temperature in between a glass transition temperature of the sinter minus 500&#xb0; C. and a softening temperature of the sinter plus 600&#xb0; C.

Member for supporting magnetic disc substrates, process of producing the same, and magnetic disc device using the same

A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiOand a secondary phase of at least one of MgFeO, FeOand FeO. The ceramic sinter can be produced by a process including: sintering a ceramic sinter from a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt and chromium; machining the sinter into a desired shape of a member of supporting a magnetic disc substrate, and annealing the sinter such that the ceramic sinter has conductive aggregation deposited on its peripheral surface, wherein in the annealing step, the member is heated at a temperature in between a glass transition temperature of the sinter minus 500&#xb0; C. and a softening temperature of the sinter plus 600&#xb0; C.

A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BClor Clis formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3YO.5AlO, 2YO.AlO, YO.AlOor disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 &#x3bc;m or less in center line average roughness Ra is utilized.

Ceramic material resistant to halogen plasma and member utilizing the same

A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BCl or Cl is formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3Y O &middot;5Al O , 2Y O &middot;Al O , Y O &middot;Al O or disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 &mgr;m or less in center line average roughness Ra is utilized.

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Kokubu, Japan

Tetsuzi Hayasaki