Abstract: A circuit section of a NOx sensor has an output base including a pedestal portion which projects from a middle part of a support surface of a base portion. A circuit board on which a storage medium storing individual information of the NOx sensor is mounted is arranged on a mount surface of the pedestal portion. The circuit section has a seal portion which is arranged above the support surface of the base portion, and which covers the circuit board from upper and lateral sides, thereby watertightly sealing the circuit board. The seal portion has an enclose portion which, in a state where the enclose portion protrudes from a peripheral edge of the support surface to a second circumferential side surface of the base portion, encloses the base portion along the peripheral edge.

Abstract: A gas sensor having a sensor element including: a plate-shaped solid electrolyte body; and a pair of electrodes sandwiching the electrolyte body. The electrodes include a measurement electrode portion, and a standard electrode portion disposed in an inner portion of the sensor element. A lead portion, which extends along the surface of the solid electrolyte body, is connected to the standard electrode portion. The standard electrode portion is mainly formed with a precious metal and contains a ceramic. The lead portion is mainly formed of a precious metal and has a ceramic content smaller than the standard electrode portion. A porous portion, which extends to the inner portion of the sensor element along the surface of the solid electrolyte body, has a gas permeability higher than the lead portion, is mainly formed with a ceramic, and is connected to the standard electrode portion.

Abstract: The sintered ceramic body of this invention is a cylindrical insulator having a through hole used for spark plugs, which is characterized by comprising alumina as a main component and Sn component in an amount of 0.05-2 wt % as SnO and can be manufactured by a step of preparing a slurry by mixing a raw material powder comprising alumina as maakessmain component and Sn component in an amount of 0.05-2 wt % as SnO, water and a binder; a step of preparing a granulated powder from the slurry, a step of packing the granulated powder in a prescribed mold and pressing it to form a compact having the same shape as sintered ceramic body to be prepared and a step of sintering the compact.

Abstract: A sintered silicon nitride product comprises from 72 to 98% by weight of silicon nitride, from 1 to 8% by weight of vanadium pentoxide, and from 1 to 20% by weight of one or more oxides of rare earth elements. The vanadium pentoxide and the oxide of rare earth elements accelerate the densification of the sintered product, and provide high strength at high temperature as well as excellent oxidation resistance to the sintered product.

Abstract: A process for producing a multilayer circuit board composed of crystallized glass and copper-metallized circuit patterns, which comprises:(1) providing a green sheet of a crystallizable glass powder;(2) providing a copper paste comprising copper component (copper and/or copper oxide) and a glass powder in a proportion by weight of the copper component to the glass powder 95:5 to 75:25, copper oxide being calculated on copper;(3) printing a circuit pattern of the copper paste of step (2) on the green sheet of step (1);(4) coating on the green sheet of step (3) an insulating paste to form an insulating layer except for regions assigned for through holes;(5) printing on the insulating layer of step (4) a circuit pattern of the copper paste of step (2) and filling said holes with the copper paste make a conductive connection through said holes;(6) decomposing the binders by heating the product of step (5) under an oxidizing atmosphere at 400.degree.-850.degree. C.; and(7) heating the product of step (6) at 850.

Abstract: A dielectric ceramic composition, which has a high dielectric constant, low loss and stable temperature characteristics suited for the microwave frequency range, is obtained by the present invention. The dielectric ceramic composition according to the present invention is expressed as (Ba.sub.x Sr.sub.1-x)(Ni.sub.1/3 Nb.sub.2/3)O.sub.3 and with a mole fraction range of 0.ltoreq.x<1.

Abstract: An air/fuel ratio detector capable of producing an unambiguous output for both fuel-rich and fuel-lean regions. A solid-electrolyte oxygen-concentration-difference-actuated electrochemical cell sensor element is provided having a porous electrode formed on both sides of an oxygen-ion-conductive solid electrolyte. A solid-electrolyte oxygen pump element is also provided with a porous electrode formed on both sides of an oxygen-ion-conductive solid electrolyte. An oxygen reference element has a metal oxide semiconductor layer formed on one side of a substrate made of an air-impermeable member. The electrochemical cell sensor element and the pump element are disposed facing one another with a small gap therebetween. An air compartment open to the atmosphere is formed between that side of the pump element opposite the side facing the small gap and the side of the reference element opposite the side having the metal oxide semiconductor layer.

Abstract: A spark plug with a sphere-like center discharge electrode is obtained by pressing a sphere-like metal essentially consisting of noble metal Au, Ag and/or alloys thereof with Pd or the like set on a small end bore formed at a discharge end bottom of a ceramic insulator. Sealing of a sealing material and/or resistor material together with setting (sealing) of a terminal body may be done simultaneously with the pressing of the sphere-like metal on the small end bore by means of hot-pressing applied on the terminal rod head.