Ngk Spark Plug Company, Limited

Tomonori Niwa

Tetsuji Yogo

Yusuke Makino

Kaname Miwa

Jun Kurano

A ceramic member, in a carrier device, including: a plurality of ceramic layers; a clamping electrode formed on a first ceramic layer among the plurality of ceramic layers and inside of the plurality of ceramic layers, and configured to attract a dielectric material by electrostatic force; an electric heating element formed on a second ceramic layer, which is more distant from a side holding a carried object than the first ceramic layer among the plurality of ceramic layers, and configured to generate heat using electric power; a power feed port; a land formed on a third ceramic layer among the plurality of ceramic layers, and configured to receive electric power through the power feed port; and a via arranged to pass through at least one of the plurality of ceramic layers and provided as a conductive material to electrically connect the electric heating element with the land.

Carrier device and ceramic member

A ceramic member, in a carrier device, includes: a plurality of ceramic layers that have insulating properties and are integrally sintered; a clamping electrode formed on a first ceramic layer among the plurality of ceramic layers and inside of the plurality of ceramic layers, and configured to attract a dielectric material by electrostatic force; a power feed port configured to receive a supply of electric power to the clamping electrode from outside of the ceramic member; a land formed on a second ceramic layer, which is different from the first ceramic layer among the plurality of ceramic layers, and configured to receive electric power through the power feed port; and a via arranged to pass through at least one of the plurality of ceramic layers and provided as a conductive material to electrically connect the clamping electrode with the land.

A method for manufacturing ceramic balls useful as ball bearings is described, wherein spherical green bodies are formed into ceramic balls having few pores and substantially uniform strength distribution, using a rubber die having a hardness not higher than 65.

Ceramic ball, ball bearing, motor having bearing, hard disk drive, polygon scanner, and method for manufacturing ceramic ball

A zirconia containing ceramic ball is formed of a zirconia containing ceramic material which contains in an amount of not less than 10% by volume the zirconia ceramic phase composed predominantly of zirconium oxide. The size of the largest pore among pores present in a region extending radially from the surface of the ball to a depth of 50 &mgr;m as observed on a polished cross section of the ball taken substantially across the center of the ball is not greater than 3 &mgr;m. The ceramic ball can be manufactured through firing a green body whose relative density is enhanced to not lower than 61% by use of rolling granulation.

Zirconia containing ceramic ball, method for manufacturing same, ceramic ball bearing and check valve

A ceramic bearing ball in which at least a portion of a constituent ceramic is formed of an electrically conductive inorganic compound phase, whereby a proper electrical conductivity is imparted to the ceramic. Thus, electrifying of a bearing ball is prevented or effectively suppressed. This prevents the problem involved in production of balls of small diameter wherein such balls adhere to an apparatus (e.g., a container) during production thereof, thus hindering smooth progress of the production process. In addition, when ceramic balls are used in precision electronic equipment, such as a hard disk drive of a computer, which is operated at high rotational speed, adhesion of foreign substance due to electrification of the balls, and resultant generation of abnormal noise or vibration can be prevented or effectively suppressed.

Ceramic ball for bearing and ceramic ball bearing using the same

A conductive ceramic bearing ball made of composite ceramic and having a mixed microstructure of a silicon nitride phase and a titanium nitride phase. The content ratio of the silicon nitride phase to the titanium nitride phase is such that the conductive ceramic bearing ball has an average coefficient of linear expansion within a temperature range of 20&deg; C.-100&deg; C. of from 2&times;10 /K to 5&times;10 /K.

Conductive ceramic bearing ball, ball bearing, motor having bearing, hard disk drive, and polygon scanner

A sintered silicon nitride member formed predominantly of silicon nitride, wherein at least a surface of the sintered member has a lightness VS of 3.0 to 9.0 and/or a chroma CS of not greater than 3.0. The sintered member facilitates identification of defects such as pore and/or foreign matter of different color formed at the surface and is capable of enhancing inspection accuracy. Also disclosed is a sintered silicon nitride member in the form of a ceramic ball having such a lightness on its surface.

Sintered silicon nitride member and ceramic ball

A method of making spherical bodies from powder, which comprises (1) preparing an adjusted powder so as to have at least one powder characteristic selected from the group consisting of an average particle size, a powder particle size distribution and a BET specific surface area, (2) preparing nuclei having a particle size larger than that of the adjusted powder, (3) rotating the nuclei, and (4) adding the adjusted powder and a solvent to the rotating nuclei so that particles of the adjusted powder accumulate on the nuclei to form granular bodies. Also disclosed is a spherical body having a core or nucleus formed in the spherical body, an adjusted powder composition for forming a spherical body, and a method for manufacturing spherical sintered bodies of silicon nitride.

Method of manufacturing spherical bodies by rotation, spherical bodies made by the method and a powder composition for use in the method

A ceramic bearing ball capable of preventing irregular vibrations of, for example, a hard disk drive and having a high accuracy. The ceramic ball is characterized as having a sphericity of not more than 0.08 &mgr;m, a surface roughness of not more than 0.012 &mgr;m and a maximum surface pore size of 5 &mgr;m.

Ceramic bearing ball

A sintered alumina-based ceramic has a relative density of equal to or higher than 95%, an average grain size in a range of 10-25 .mu.m and a fracture toughness Kc equal to or lower than 3.0 MPam.sup.1/2 Furthermore. In a machinability evaluation test using a surface grinder, the ceramic exhibits equal to or less than 310 W of increase in the load on a motor rotating a grinding wheel of the surface grinder. The machinability evaluation test is performed under the following condition. (1) The dimension of a test piece of the sintered alumina-based ceramic is larger than 15 mm in width, larger than 30 mm in length and larger than 10 mm in height. (2) The test piece is fixed on a table of said surface grinder and ground by the grinding wheel along a direction of its length. (3) The grinding wheel has a dimension of 10 mm in width and 200 mm in outer diameter, and consists of synthetic (or artificial) diamond abrasive grains more than 80 wt % of which are in a grain size range of 74-88 .mu.m, and which are resin-bonded at 3.3 cts/cm.sup.3 of weight content per unit volume. (4) The circumferrential speed of said grinding wheel is 2400 m/min, the table traversing speed is 60 mm/min, and the infeed per traverse is 3 mm.

Sintered ceramic mainly composed of alumina and a sintered ceramic part

A porous ceramic material for a slidable member or unit such as a valve unit of a combination faucet. The porous ceramic material comprises a ceramic sintered body which is formed with pores dispersedly located therein. The pores are defined respectively by surface layers forming part of the ceramic sintered body. Each surface layer contains silicon in a content higher than that in other part of the ceramic sintered body. The porous ceramic material is prepared, for example, first by mixing ceramic powder and hollow particles each of which contains silicon so as to obtain a mixture; then by forming the mixture into a predetermined shape to obtain a formed body; and finally by sintering the formed body at a temperature higher than a melting point of each hollow particle to thus obtain the sintered body formed with pores and containing silicon.

Porous ceramic material and producing method of same, and valve unit

A porous ceramic material for a slidable member on unit such as a valve unit of a combination faucet. The porous ceramic material comprises a ceramic sintered body which is formed with pores dispersedly located therein. The pores are defined respectively by surface layers forming part of the ceramic sintered body. Each surface layer contains silicon in a content higher than that in other part of the ceramic sintered body. The porous ceramic material is prepared, for example, first by mixing ceramic powder and hollow particles each of which contains silicon so as to obtain a mixture; then by forming the mixture into a predetermined shape to obtain a formed body; and finally by sintering the formed body at a temperature higher than a melting point of each hollow particle to thus obtain the sintered body formed with pores and containing silicon.

Porous ceramic material

A bearing type wheel for a car which rollers through a car tunnel kiln, includes a plurality of rotating members such as rollers or balls interposed between respective inner rings and an outer ring. Each of the rotating members consists essentially of a sintered body of silicon nitride base (Si.sub.3 N.sub.4) ceramic.

Growing community of inventors

Ichinomiya, Japan

Tomonori Niwa