Ngk Insulators, Inc.

Nagoya University

The Kansai Electric Power Co., Inc.

Yoshihiko Ishida

Makoto Tani

Isao Oda

Nobuo Tsuno

Shoji Seike

Yuji Asai

Toshihiko Nakagawa

Sekio Uemura

Mikindo Saiga

Naoyuki Kanetake

Hiroshi Kimoto

Makoto Kobashi

A PTC thermistor device has a PTC thermistor member and electrodes. The electrodes, are formed on respective surfaces of the PTC thermistor member. The PTC thermistor member contains a matrix phase, and conductive particles dispersed throughout the matrix phase. The matrix phase contains an electrically insulating first inorganic material and an electrically insulating second inorganic material. The first inorganic material undergoes phase transition in terms of crystal structure type and change in volume, at the phase transition temperature thereof. The second inorganic material is fibrous.

PTC thermistor member

An inorganic-metal composite body exhibiting PTC behavior at a trip point temperature ranging from 40&deg; C.-300&deg; C., including an electrically insulating inorganic matrix having a room temperature resistivity of at least 1&times;10 &OHgr;&middot;cm, and electrically conductive particles uniformly dispersed in the matrix and forming a three-dimensional conductive network extending from a first surface of said body to an opposed second surface thereof, wherein the composite body has a room temperature resistivity of no more than 10 &OHgr;&middot;cm and a high temperature resistivity of at least 100 &OHgr;&middot;cm. Preferably, the electrically conductive particles are made of a Bi-based alloy containing at least 50 wt % Bi, and have an average diameter, &phgr; , of 5-50 &mgr;m and a 3&sgr; particle size distribution of 0.5 &phgr; -2.0 &phgr; . Also disclosed is an inorganic PTC device including an intermediate electrode layer to insure adhesion of outer termination electrodes to the PTC composite body, and a method of forming the composite body, which method effectively deals with the volatility of the electrically conductive particles.

Inorganic-metal composite body exhibiting reliable PTC behavior

A PTC composite material including a matrix of ceramic material having one of a cristobalite crystal structure and a tridymite crystal structure, each doped with an oxide of at least one of Be, B, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge and W, and a conductive phase dispersed throughout the matrix. The conductive phase includes at least one of a metal, silicide, nitride, carbide and boride.

PTC composite material

An inorganic-metal composite body exhibiting PTC behavior at a trip point temperature ranging from 40&deg; C.-300&deg; C., including an electrically insulating inorganic matrix having a room temperature resistivity of at least 1&times;10 &OHgr;&middot;cm, and electrically conductive particles uniformly dispersed in the matrix and forming a three-dimensional conductive network extending from a first surface of said body to an opposed second surface thereof, wherein the composite body has a room temperature resistivity of no more than 10 &OHgr;&middot;cm and a high temperature resistivity of at least 100 &OHgr;&middot;cm. Preferably, the electrically conductive particles are made of a Bi-based alloy containing at least 50 wt % Bi, and have an average diameter, &phgr; , of 5-50 &mgr;m and a 3&sgr; particle size distribution of 0.5 &phgr; &minus;2.0 &phgr; . Also disclosed is an inorganic PTC device including an intermediate electrode layer to insure adhesion of outer termination electrodes to the PTC composite body, and a method of forming the composite body, which method effectively deals with the volatility of the electrically conductive particles.

A PTC composite material including a matrix of ceramic material having one of a cristobalite crystal structure and a tridymite crystal structure, each doped with an oxide of at least one of Be, B, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, and Ge, and a conductive phase dispersed throughout the matrix. The conductive phase includes at least one of a metal, silicide, nitride, carbide and boride.

A conductive composite sintered body exhibiting PTC behavior, including a high electrical resistance matrix and 20 vol %-40 vol % electrically conductive particles dispersed in the matrix to form an electrically conducting three-dimensional network therethrough. The electrically conductive particles are selected from bismuth, gallium, or alloys thereof, and an average distance between the particles, when viewed in an arbitrary cross-section through the sintered body, is no more than 8 times the average particle diameter of the particles. The resistivity of the sintered body is low at temperatures below the melting point of the electrically conductive material and increases substantially at or above the melting point.

Conductive ceramic-metal composite body exhibiting positive temperature coefficient behavior

An apparatus for transmitting and receiving ultrasonic waves has a transmitter for sending a pair of ultrasonic waves to a sample. The pair of ultrasonic waves have substantially symmetric waveforms with respect to zero sound pressure. One of the ultrasonic wave is separated from the other ultrasonic wave. An acoustoelectric, ultrasonic transducer receives the pair of ultrasonic waves affected by the sample. The acoustoelectric, ultrasonic transducer converts the pair of ultrasonic waves into a pair of electric signals accompanied by phonon-charge carrier interaction. Each of the electric signals includes an acoustoelectric signal insensitive to phase and a piezoelectric signal sensitive to phase. A processing device processes the pair of electric signals so as to remove the piezoelectric signal and obtain the acoustoelectric signal. The initial ultrasonic waves have opposite phase so that superimposition of the pair of electric signals by the processing device offsets the piezoelectric signals, thereby obtaining the acoustoelectric signals.

Apparatus and method for transmitting and receiving ultrasonic waves

An ultrasonic transducer unit for use in pulse-echo ultrasonic investigation has a plurality of components including a piezoelectric ultrasonic wave transmitting element, an acoustoelectric ultrasonic wave receiving element and electrodes therefor. To provide a compact and efficient transducer, these components are bonded together in an integrated multilayer structure in which the transmitting element and receiving element are superimposed in the direction of propagation of transmitted and received ultrasonic waves. The receiving element may be a ZnO single crystal. An insulating layer isolates two components from each other.

Ultrasonic transducers

A phase-insensitive ultrasonic transducer has a zinc oxide single crystal as a piezoelectric semiconducting acoustoelectric element, providing high sensitivity and operable over a range of wavelengths of the ultrasonic waves. The electrical conductivity of said zinc oxide single crystal may be selected in the range 10.sup.-8 to 10.sup.-2 .OMEGA..sup.-1.cm.sup.-1. The single crystal can have an attenuation rate for ultrasonic waves of 10 MHz of at least 0.8 cm.sup.-1.

Ultrasonic transducer

A solid oxide fuel cell is disclosed, which includes flat plate-shaped solid oxide fuel cell elements. The solid oxide fuel cell element includes an ion-conductive ceramic plate, and an air electrode and a fuel electrode formed on opposite surfaces of the ion-conductive ceramic plate, respectively, wherein conductive strips which have less resistance than the electrode are continuously formed on a surface of at least one of the air electrode and the fuel electrode. A solid oxide fuel cell is also disclosed, which includes a separator plate made of a material having oxidation resistance, reduction resistance and electron conductivity, an air electrode spacer made of a material having oxidation resistance and electron conductivity, the above flat plate-shaped solid oxide fuel cell element, and a fuel electrode spacer made of a material having reduction resistance and electron conductivity, wherein the separator plate, the air electrode spacer, the flat plate-shaped solid oxide fuel cell element and the fuel electrode spacer are successively laminated in this order. An oxidizing gas chamber is defined by the separator plate, the air electrode spacer and the element, and a fuel gas chamber is defined by the separator plate, the fuel electrode spacer and the element. A process is also disclosed for producing such a solid oxide fuel cell element.

Solid oxide fuel electrodes and process for producing

A solid oxide fuel cell including a flat plate-shaped solid oxide fuel cell element. The cell element is composed of an ion-conductive ceramic plate formed with ribs connected with each other in a plane, an air electrode formed on one main surface of the ion-conductive ceramic plate, and a fuel electrode formed on the other main surface of the ion-conductive ceramic plate. In producing the fuel cell, a flat plate-shaped green sheet made of an ion-conductive ceramic molding material is press contacted with a rib-forming green sheet made of a material of the same kind and having a unitary shape formed by connecting elongated portions to each other. The contacted green sheets are sintered together to form an ion-conductive ceramic plate. In an alternative, a flat plate-shaped green sheet and a rib-forming green sheet may be separately sintered and then bonded with each other to form an ion-conductive ceramic plate. The ion-conductive ceramic plate is formed with an air electrode surface and a fuel electrode on opposite main surfaces, respectively.

Solid oxide fuel cell and method for producing the same

A solid oxide fuel cell comprising a separator plate made of a material having stability against oxidation and reduction and electronic conductivity, an air electrode spacer made of a material having oxidation resistance and electronic conductivity, a flat plate-shaped solid oxide fuel cell element, a fuel electrode spacer, and another separator plate made of a material having oxidation resistance, reduction resistance and electronic conductivity, and another separator plate. The separator plate, the air electrode spacer, the solid oxide fuel cell element, the fuel electrode spacer and another separator plate are successively laminated in this order. The solid oxide fuel cell element including an ion-conductive ceramic plate, and an air electrode and a fuel electrode formed on opposite surfaces of said ceramic plate, respectively. An oxidizing gas chamber is defined by the separator plate, the air electrode spacer and the element, and a fuel gas chamber is defined by the element, the fuel electrode spacer, and another separator plate. A process for producing such a solid oxide fuel cell comprises the steps of forming the ion-conductive ceramic plate by sintering, forming the air electrode and a fuel electrode on opposite surfaces of the ceramic plate, respectively, and successively laminating the separator plate, the air electrode spacer, the solid oxide fuel cell element, the fuel electrode spacer and another separator plate in this order.

Solid oxide fuel electrodes and process for producing the same

A method for continuous thermogravimetric analysis of coal, or other materials rich in carbon, for volatile matter and ash content, including the steps of exposing a coal sample to an atmosphere consisting essentially of about 1 to 5% by volume of oxygen and the remainder being nitrogen and inevitable impurities at a first specified temperature for a first given time, weighing the coal sample to determine a first weight loss during the first given time, the first weight loss corresponding to the amount of volatile matter in the coal sample, burning the coal sample under an oxygen atmosphere having a higher than normal oxygen concentration for a second given time at a temperature sufficient to burn carbon containing materials in the coal sample, and weighing the coal sample to determine a second weight loss during the first given time and the second given time, the second weight loss corresponding to the amount of volatile matter and the amount of ash content in the coal sample.

Method for continuous thermogravimetric analysis of coal

In a metal-ceramic combination wherein a monobloc ceramic member comprising a base, a protrusion integrally formed on the base and an easement portion on and around the root of the protrusion, is combined with a metallic member, an improved combination having an excellent strength in total is obtained by fitting the protrusion tightly into a recession or conduit of the metallic member, leaving clearance of 0.5 mm or more between the easement portion and a defined edge of joint interface of the said two members. The combination of the invention is particularly useful for engine parts to be subjected to high temperatures and repeated stresses such as a turbocharger rotor, piston, tappet, rocker arm, exhaust valve, cam and the like.

Metal-ceramic combination

A ceramic valve seat is disclosed herein. A face portion of the valve seat at which the valve seat is to contact with a valve is made of a ceramic material. At least edge portions of the valve-contacting face portion of the valve seat are rounded. By so constructing, impact force due to contact between the valve and the valve seat and stress concentration can be mitigated.

Growing community of inventors

Nagoya, Japan

Yoshihiko Ishida