Abstract: A green ceramic heater including a green heating resistor formed of an electrically conductive ceramic (e.g., silicide or carbide of a metal element such as W, Ta, or Nb) and an insulative ceramic (e.g., silicon nitride) and power supply leads (e.g., made of W), a first end of each power supply lead being connected to a corresponding end of the green heating resistor, the green heating resistor and the power supply leads buried in a green substrate formed of a material (e.g., silicon nitride) is fired, and subsequently, the resultant ceramic heater is heat-treated at 900 to 1,600° C., to thereby enhance flexural strength of the ceramic heater. The heat treatment is preferably carried out prior to forming a glass layer on an outer circumferential surface of the ceramic heater.

Abstract: A ceramic heater 2 is arranged in a metallic cylinder member 3 by forming a convergent taper portion 2t at the leading end 2a of the ceramic heater 2 and by positioning the leading end 3a of the metallic cylinder member 3 on the leading end side of a taper starting point P1 of the taper portion 2t. Solder is applied in the clearance between the inner circumference 3d of the metallic cylinder member 3 and the outer circumference 2b of the heater 2. An applied solder layer 10 is also formed on the leading end side of the taper starting point P1 of the taper portion 2t. The thick solder layer 10 present on the leading end side prevents a cut or broken off portion of the ceramic heater from separating or sliding out.

Abstract: A green ceramic heater including a green heating resistor formed of an electrically conductive ceramic (e.g., suicide or carbide of a metal element such as W, Ta, or Nb) and an insulative ceramic (e.g., silicon nitride) and power supply leads (e.g., made of W), a first end of each power supply lead being connected to a corresponding end of the green heating resistor, the green heating resistor and the power supply leads buried in a green substrate formed of a material (e.g., silicon nitride) is fired, and subsequently, the resultant ceramic heater is heat-treated at 900 to 1,600° C., to thereby enhance flexural strength of the ceramic heater. The heat treatment is preferably carried out prior to forming a glass layer on an outer circumferential surface of the ceramic heater.

Abstract: A gas sensor 1 includes an outer cylinder 18, a metallic shell 3, and a sensor element 2. The metallic shell 3 is disposed inside the outer cylinder 18. The sensor element 2 is disposed in a through-hole 30 formed in the metallic shell 3 and is adapted to detect a component of a gas to be measured. A sealing material layer 32 is mainly made of glass and is disposed between the inner surface of the metallic shell 3 and the outer surface of the sensor element 2. A cushion layer 34 formed of a porous inorganic substance is disposed in contact with the end of the sealing material layer 32 on the front-end side with respect to the axial direction of the sensor element 2. A cushion layer 33 formed of talc glass is disposed in contact with the end of the sealing material layer 32 on the rear-end side with respect to the axial direction of the sensor element 2.

Abstract: A ceramic heater 2 is arranged in a metallic cylinder member 3 by forming a convergent taper portion 2t at the leading end 2a of the ceramic heater 2 and by positioning the leading end 3a of the metallic cylinder member 3 on the leading end side of a taper starting point P1 of the taper portion 2t. Solder is applied in the clearance between the inner circumference 3d of the metallic cylinder member 3 and the outer circumference 2b of the heater 2. An applied solder layer 10 is also formed on the leading end side of the taper starting point P1 of the taper portion 2t. The thick solder layer 10 present on the leading end side prevents a cut or broken off portion of the ceramic heater from separating or sliding out.

Abstract: A gas sensor 1 includes an outer cylinder 18, a metallic shell 3, and a sensor element 2. The metallic shell 3 is disposed inside the outer cylinder 18. The sensor element 2 is disposed in a through-hole 30 formed in the metallic shell 3 and is adapted to detect a component of a gas to be measured. A sealing material layer 32 is mainly made of glass and is disposed between the outer surface of the sensor element 2 and the inner surface of the metallic shell 3 or between the outer surface of the sensor element 2 and the inner surface of an insulator 4 disposed between the metallic shell 3 and the sensor element 2. Cushion layer 33 and 34 are each made of a porous inorganic substance. At least either the cushion layer 33 or 34 is disposed so as to abut one end of the sealing material layer 32.

Abstract: A gas sensor has a structure in which an insulator is disposed inside a metallic shell, and a sensor element is disposed inside the insulator. A cavity is formed in the insulator to surround the sensor element. A sealing material mainly formed of glass is charged into the cavity in order to establish sealing between the inner surface of the insulator and the outer surface of the sensor element. The sensor element has a rectangular cross section, and the inner surface of the insulator defining the cavity has a sectional profile corresponding to the sectional profile of the sensor element.

Abstract: A connection device for a ceramic gas sensor element includes a sensor assembly and a ring member. The sensor assembly has a ceramic element with a thickness t, an electrical connection portion formed on a side of the ceramic element, and at least one electrical lead in contact with the electrical connection portion, wherein the sensor assembly defines an outer dimension at a position corresponding to the electrical connection portion. The ring member is disposed around the sensor assembly to hold the at least one electrical lead in contact with the electrical connection portion such that the ring member has an inner dimension at a position corresponding to the connection portion that is smaller than the outer dimension of the sensor element. The ring member defines an axial length L that contacts the sensor assembly such that the thickness t and the axial length L satisfy the relation 0.23≦L/t≦13.

Abstract: A heat-resisting metal-sheathed cable for a sensor includes: an outer sheathing tube made of a heat-resisting metal; an inner sheathing tube made of a heat-resisting metal and disposed within the outer sheathing tube with a predetermined gap that includes an open ventilation passage between an inner circumferential surface of the outer sheathing tube and an outer circumferential surface of the inner sheathing tube; at least one conductor disposed within the inner sheathing tube; and a mass of insulating powder disposed within the inner sheathing tube and around the at least one conductor.

Abstract: This discloses an electronic component of a miniature size to be used as e.g. automobile engine peripheral components, such as an exhaust gas oxygen sensor, a heat sensor, and a heater. More specifically, the invention provides an electronic component integral with a heat resistant terminal that is pressure-fitting or shrink-fitted on a ceramic element of the electronic component. This electronic components shows great mechanical and electrical performance, withstanding the high temperature environment over 400 and up to 800.degree. C. to which the ceramic element of the component required expose.The terminal incorporated in this high temperature electronic component comprises a plurality of metal wire leads that electrically connect to a surface of a bar-like ceramic element, at least two ceramic insulators that surround the leads, and a thermal resistant metal ring that shrink-fits or pressure-fits around the ceramic insulators so that the metal leads press in a radial direction holding the element firmly.

Abstract: An oxygen sensor according to the present invention has battery element and a pump element in each of which porous electrodes are disposed on both faces of a solid electrolyte substrate. A minute current is supplied to the battery element after the start of energizing a heater and the activation of the sensor elements are judged on the basis of an interelectrode voltage generated at this energizing. A heater voltage is set to be 12V at the start of energizing. When the time period necessary for the interelectrode voltage to reach a predetermined voltage is short, the applied voltage is lowered to 11V. As a result, the time period necessary for judging the sensor elements to be activated can be made substantially constant irrespective of variations in sensor characteristics. After the activation judgment, the variation of the temperature of the sensor element is monitored on the basis of the interelectrode voltage.

Abstract: Silicon-nitride-based sintered body is produced by a primary sintering; applying a paste-like coating, in which a surface-homogenizing agent is at least one kind of inorganic constituents selected from the group consisting of C, Bn, AlN and Si.sub.3 N.sub.4 provided that C is present at least 5% by weight of the inorganic constituents, on a primary sintered body; and subsequently performing a secondary sintering under a pressure higher than that at the primary sintering.

Abstract: A sintered body of silicon nitride with high density, strength, toughness, and hardness, which can be used for a structural part of an engine, etc. The sintered body of the invention includes 80 to 94 wt % Si.sub.3 N.sub.4, 2 to 10 wt % Mg compound calculated in MgO equivlent, and 2 to 10 wt % Y compound calculated in Y.sub.2 O.sub.3 equivalent. The Si.sub.3 N.sub.4 contains 5 to 40% .alpha.-phase. The sintered body is manufactured in the following steps: (a) mixing powdery Si.sub.3 N.sub.4 with a Mg compound and a Y compound in the above proportions, and then molding the mixture in which the Si.sub.3 N.sub.4 powder contains 80% or more .alpha.-phase and its grains are 1 .mu.m or less in diameter on average; (b) performing primary sintering at 1,600.degree. C. or less in an atmospher of nitrogen or of an inert gas at 20 atm or less; and (c) performing secondary sintering at 1,400.degree. to 1,600.degree. C. in an atmosphere of nitrogen or of an inert gas at 300 atm or more.

Abstract: A turbine rotor having a ceramic turbine wheel having an improved resistance to cracking and breaking. The turbine wheel is made of a ceramic material having pores formed therein with a maximum diameter of 20 .mu.m distributed in the blade portion of the wheel at a porosity of 2 to 10 vol. %. Preferably, the volume porosity of the pores is gradually decreased from the blade surface to the interior of the blade portions.