Denso Corporation

Kabushiki Kaisha Toyota Chuo Kenkyusho

Takahiko Homma

Kazumasa Takatori

Toshiatsu Nagaya

Hisaaki Takao

Tatsuhiko Nonoyama

Yasuyoshi Saito

Masaya Nakamura

Mitsuru Asai

Shigetaka Wada

Hiroaki Makino

Jun Sugiyama

To provide a production method of a polycrystalline ceramic body with excellent density, a preparation step, a mixing step, a forming step and a heat-treating step are performed. In the preparation step, a coarse particle ceramic powder, and a fine particle powder having an average particle diameter of &#x2153; or less of the average particle diameter of the coarse particle ceramic powder are prepared. In the mixing step, the coarse particle ceramic powder and the fine particle powder are mixed to produce a raw material mixture. In the forming step, the raw material mixture is formed to a shaped body. In the heat-treating step, the shaped body is heated and thereby sintered to produce a polycrystalline ceramic body. In the heat-treating step, a temperature elevating process and a first holding process are performed and at the same time, a second holding process and/or a cooling process are performed. In the temperature elevating process, heating is started to elevate the temperature and in the first holding process, the shaped body is held at a temperature T&#xb0; C. In the second holding process, the shaped body is held at a temperature T&#xb0; C. lower than the temperature T&#xb0; C. In the cooling process, the shaped body is cooled at a temperature dropping rate of 60&#xb0; C./h or less from the temperature T&#xb0; C.

Production method of polycrystalline ceramic body

A piezoelectric actuatorincludes a piezoelectric element, which has a pair of electrodes formed on the surface of a piezoelectric ceramic member, as a drive source. The piezoelectric actuatorsatisfies at least one of the following requirements (a) to (c):

Piezoelectric actuator

The piezoelectric actuator includes a piezoelectric element () including a sheet of piezoelectric ceramic and electrodes formed at least part of the surface of the sheet of piezoelectric ceramic, and a holding member () holding the piezoelectric element ();

This invention provides a piezoelectric ceramic composition that does not contain lead, can be sintered at a normal pressure and is excellent in at least one of a piezoelectric constant, an electro-mechanical coupling coefficient, a dielectric loss, a relative dielectric constant and a Curie point, its production method, and a piezoelectric device and a dielectric device each utilizing the piezoelectric ceramic composition. The invention relates to a piezoelectric composition expressed by the general formula {Li(KNa)}(NbSb)O, each of x, y and z respectively falling within composition ranges of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0 and 0&#x2266;z&#x2266;0.2 (with the exception of x=z=0), and its production method. The invention further relates to a piezoelectric device having a piezoelectric body formed of the piezoelectric ceramic composition described above and a dielectric device having a dielectric body formed of the piezoelectric ceramic composition described above.

Piezoelectric ceramic composition, its production method, and piezoelectric device and dielectric device

This invention provides a piezoelectric ceramic composition that does not contain lead, can be sintered at a normal pressure and has a high electro-mechanical coupling coefficient and a small dielectric loss, its production method, and a piezoelectric device utilizing the piezoelectric ceramic composition. The invention relates to a piezoelectric composition containing a compound expressed by the general formula {Li(KNa)}(NbTa)O, each of x, y and z respectively falling within composition range of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0 and 0&#x2266;z&#x2266;0.4, as its main component, and further containing nickel or a nickel-containing compound. To provide a piezoelectric device that does not contain lead, can be sintered at a normal pressure and has a high electro-mechanical coupling coefficient Kp and a small dielectric loss, the piezoelectric ceramic composition of the invention is expressed by the general formula {Li(KNa)}(NbTa(MnW)O, each of x, y, z and n respectively falling within a composition range of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0, 0&#x2266;z&#x2266;0.4 and 0&#x3c;n&#x2266;0.1.

Piezoelectric ceramic composition, its production method and piezoelectric device

A piezoelectric ceramic composition not containing lead, able to be sintered at ordinary pressure, and superior to the past in at least one of the properties unique to piezoelectric ceramic compositions such as the piezoelectric dconstant, that is, a piezoelectric ceramic composition having a compound of a general formula {Li(KNa)}(NbTaSb)Owhere x, y, z, and w are in the ranges of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1, 0&#x3c;z&#x2266;0.4, and 0&#x3c;w&#x2266;0.2 as a main ingredient, where the piezoelectric ceramic composition contains at least one metal element selected from (1) palladium, silver, gold, ruthenium, rhodium, rhenium, osmium, iridium, and platinum, (2) nickel, iron, manganese, copper, and zinc, or (3) magnesium, calcium, strontium, and barium as an added element, and a method of production of the same and a piezoelectric element and dielectric element utilizing that piezoelectric ceramic composition.

Piezoelectric ceramic composition and method of production of same, piezoelectric element, and dielectric element

A physical sensor having a pressure sensing layer having such property that electrical resistance is changed by application of a stress, and electrical insulating layers which are integrally formed on opposite two surfaces of the pressure sensing layer, respectively, wherein the pressure sensing layer has a matrix comprising glass, and an electrically conductive particle having electrical conductivity and dispersed in the matrix and preferably, the electrically conductive particle includes RuO, and a thickness of the pressure sensing layer is 1 &#x3bc;m to 200 &#x3bc;m, and it is preferable that one pair of electrodes are disposed on the pressure sensing layer.

Physical sensor

A rotary component of a rotary device for heat engines, such as a turbine wheel of a gas turbine or a turbocharger, formed in an integral ceramic-fiber-reinforced sintered ceramic structure. The reinforcing ceramic fibers in the edges of the vanes of the rotary component are oriented radially to prevent the chipping of the edges of the vanes liable to occur in a direction perpendicular to the direction of thickness of the vanes. The rotary component is formed by molding a mixture of a ceramic powder, ceramic fibers and organic additive or additives in a mold having a cavity having the same shape as that of the rotary component except that the depth of sections of the cavity corresponding to the vanes is greater than the height of the vanes to be formed, sintering the molding, and cutting the vanes of the molding in a predetermined height.

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Owariasahi, Japan

Takahiko Homma