Abstract: A silicon nitride-based sintered body containing silicon nitride-based grains, which are silicon nitride grains or sialon grains. In the silicon nitride-based sintered body, when the size of each silicon nitride-based grain is represented by its maximum grain size, the ratio of the number of silicon nitride-based grains having a maximum grain size of 1 ?m or less to the number of the entire silicon nitride-based grains is 70% or higher. Furthermore, in the distribution profile of no. % of silicon nitride-based grains with respect to maximum grain size, the maximum value of no. % (i.e., maximum no. %) of silicon nitride-based grains is 15 no. % or higher. Also disclosed is a cutting insert, which is formed of the silicon nitride-based sintered body.

Abstract: A method of manufacturing a circuit substrate includes the steps of preparing a conductor paste in which a powder of at least one of a metal boride and a metal silicide is added to a powder of silver (Ag), applying the conductor paste to a surface of a ceramic substrate which has been fired, applying a glass paste to the surface of the ceramic substrate after applying the conductor paste, firing the conductor paste applied to the surface so as to form a conductor trace, and firing the glass paste applied to the surface so as to form a coating layer.

Abstract: Spark plug has first and second electrodes. First electrode has tip principally made of noble metal and base material principally made of Ni. The tip is joined to the base material through fusion portion. Second electrode faces discharge surface of the tip. The fusion portion has overlap portion where first interface between the tip and the fusion portion and second interface between the base material and the fusion portion overlap in first direction perpendicular to the discharge surface. When viewing cross section which passes through a center of gravity of the overlap portion projected onto virtual surface parallel to the discharge surface and is perpendicular to the discharge surface, noble metal content is greater than 50 mass % at one end portion of the overlap portion in second direction extending along the discharge surface, and Ni content is greater than 50 mass % at the other end portion of the overlap portion.

Abstract: A gas sensor (100) extending in an axial direction AX including: a gas sensor element (120) which detects the concentration of a specific gas in a gas under measurement; a tubular metallic shell (110) having a polygonal tool engagement portion (110B) surrounding the gas sensor element (120); a tubular outer tube (103) which extends rearward from the metallic shell (110), surrounds the gas sensor element (120), and has an opening (103E) at a rear end thereof; a sealing member (191) which seals the opening (103E); and a tubular heat dissipating member (104) which surrounds the outer tube (103) and reduces the amount of heat transferred from the forward end side of the gas sensor (100) through the outer tube (103) to the sealing member (191). The maximum diameter D1 of the heat dissipating member (104) is equal to or less than the opposite side dimension D2 of the tool engagement portion (110B).

Abstract: A spark plug includes a plug cap having a plurality of through holes. In a cross section including an axial line, the plug cap includes an enlarging portion in a portion of a region between a first imaginary straight line and a second imaginary straight line, the first imaginary straight line extending through a front end of the end portion of a ground electrode and being perpendicular to the axial line, the second imaginary straight line extending through a back end of one of inner open ends of the through holes that is closest to a front end of the spark plug and being perpendicular to the axial line. The enlarging portion being a portion in which a minimum distance from an outer surface to an inner surface of the plug cap increases with increasing distance in a direction from back to front.

Abstract: In a circular cross section of a protector obtained by cutting the protector along a plane which is orthogonal to the axial direction and passes through gas introduction holes, one gas introduction hole and another gas introduction hole having an opening area different from that of the one gas introduction hole are arranged along an imaginary line passing through the center of the circular cross section such that the two gas introduction holes are located on opposite sides with respect to the center of the circular cross section.

Abstract: A spark plug wherein the occurrence of pre-ignition and misfires is suppressed. The spark plug includes a cover portion that covers a front end portion of a center electrode and a facing portion of a ground electrode from a front end side of the spark plug to form a pre-chamber space. The cover portion has injection holes that are through-holes. A total area A (mm2) of inner peripheral surfaces of the injection holes and a thermal conductivity B (W/mK) of a material of the cover portion satisfy a formula (1): 10<A×B<4000.

Abstract: Disclosed is a spark plug including: an insulator having an axial through hole formed with a first hole region and a second hole region larger in inner diameter than the first hole region; a center electrode having a collar portion disposed in the second hole region; a resistor disposed in the second hole region, with a front end of the resistor being located apart from a rear end of the center electrode; and a conductive seal material arranged at least between the center electrode and the resistor within the second hole region, wherein the center electrode has a recess recessed from the rear end thereof toward the front, wherein the recess is provided at least at a location of a maximum outer diameter section of the collar portion, and wherein the conductive seal material is filled into the recess from the rear end of the center electrode.

Abstract: A spark plug includes: a central electrode extending from a front end side to a rear end side along an axis; an insulator including a front end section formed to be a bottomed tube surrounding a tip of the central electrode; a metal shell shaped to be tubular and structured to support the insulator such that the front end section of the insulator projects to the front end side from a front end section of the metal shell; and a plurality of ground electrodes each of which includes a first end forming a discharge gap with the front end section of the insulator and includes a second end connected to the front end section of the metal shell. The plurality of ground electrodes include a pair of ground electrodes different from each other in size of their discharge gaps.

Abstract: A spark plug that can suppress pre-ignition of a combustible air-fuel mixture that has flowed into the sub-chamber. The spark plug includes a ground electrode that joins to a metal shell and forms a spark gap; and a cap member that covers a center electrode and the ground electrode and forms a sub-chamber. A first fused portion that joins the metal shell and the cap member is located on the front-end side relative to the spark gap. At least a part of a first facing portion at which the metal shell and the cap member face each other is located on the sub-chamber side relative to the first fused portion. The first fused portion is not formed in an inner peripheral surface of the metal shell and an inner peripheral surface of the cap member.

Abstract: A substrate holding device includes a base body that has a flat plate-like shape and in which gas holes that open in an upper surface of the base body are formed, and a plurality of protrusions that protrude upward from the upper surface of the base body. A groove that opens in a lower surface of the base body and that is connected to the gas holes is formed in the base body, and a plurality of protrusions that protrude downward are formed in the groove.

Abstract: A particulate sensor (1) having a sensor-side positioning portion (11k) for determining the circumferential position of a sensor main body (5) with respect to a sensor attachment portion (120) when the particulate sensor (1) is attached to the sensor attachment portion (120). The sensor attachment portion (120) has a pipe-side positioning portion (121) which conforms to the sensor-side positioning portion (11k) and is configured such that, when the particulate sensor (1) is attached to the sensor attachment portion (120), the circumferential position of the sensor main body (5) with respect to the sensor attachment portion (120) is always set to a fixed circumferential position.

Abstract: The durability of a ceramic sintered body is improved, and a reduction in its light emission intensity and the occurrence of a chromaticity variation are suppressed. The ceramic sintered body contains alumina and a compound represented by M13-XM2XM35O12. The volume percent of the compound in the ceramic sintered body is from 3% to 70% inclusive. The ratio of the intensity of XRD from a complex oxide of aluminum and M2 to the intensity of XRD from the compound in the ceramic sintered body is less than 0.05. The average grain diameter of the alumina contained in the ceramic sintered body is from 0.30 (?m) to 3.00 (?m) inclusive. M1 is at least one selected from Sc, Y, and lanthanoid elements, and M2 is at least one selected from lanthanoid elements except any lanthanoid element selected for M1. M3 is at least one of Al and Ga, and X is from 0.003 to 0.500 inclusive.

Abstract: A spark plug wherein both pre-ignition and misfires are suppressed. The spark plug includes a center electrode; a ground electrode; a cylindrical insulator; a metal shell that accommodates the insulator therein; and a cover portion that covers a front end portion of the center electrode and a facing portion of the ground electrode to form a pre-chamber. The insulator includes an outer peripheral surface exposed to the pre-chamber, the cover portion includes a portion exposed to the pre-chamber, and the metal shell includes a portion exposed to the pre-chamber. When a surface area of the outer peripheral surface is a first surface area A (mm2), and a total surface area of the portion of the cover portion and the portion of the metal shell is a second surface area B (mm2), the spark plug satisfies a relational expression 1:0.10<A/B<0.70.

Abstract: A metal terminal includes a front-side terminal member and a rear-side terminal member. The front-side terminal member includes a female connection portion, and the rear-side terminal member includes a male connection portion. The female connection portion has an insertion port in which the male connection portion is inserted. The insertion port is formed in a shape that prevents the insertion port and the male connection portion from coming into contact with each other when the male connection portion is inserted therein. The female connection portion includes a terminal contact portion which brings the male connection portion and the female connection portion into contact with each other by pressing the male connection portion toward the female connection portion inside the female connection portion.

Abstract: A spark plug having a metal shell and an insulator, wherein a stepped portion that includes a rear-end-side facing surface that retains an insulator either directly or via another member is provided at an inner periphery of a metal shell. The stepped portion includes a first convex portion that includes the rear-end-side facing surface, a second convex portion that is disposed on a front end side of the first convex portion and that is adjacent to the first convex portion, and a connection portion that connects the first convex portion and the second convex portion to each other.

Abstract: A method of manufacturing a spark plug (1) including a disposing step, a contacting step, and a deforming step. In the disposing step, a mounting screw portion (30) is inserted into a gasket (50) and the gasket (50) is disposed between the mounting screw portion (30) and a seat portion (32). In the contacting step, from a front end side, a jig (60) is brought into contact with the gasket (50) disposed by the disposing step, and the jig (60) is moved toward the rear end side until a load applied to the jig (60) from the gasket (50) reaches a predetermined set load. In the deforming step, after the contacting step, the jig (60) is further moved toward the rear end side by a predetermined set distance XS. Consequently, the gasket (50) is pressed by the jig (60) and an inner edge portion (55) of the gasket (50) is deformed inward in a radial direction of the gasket (50).

Abstract: A sensor including a sensor element, a metallic shell, a terminal fitting, a cylindrical case, lead wires, a connector portion, and a cylindrical heat shield tube. The heat shield tube includes a first tube and a second tube. The second tube is disposed on a distal end side of the first tube and covers an outer surface of the rear end side of the case, while providing an overlapping portion that overlaps the first tube. A rear end side of the first tube is adjacent to the connector portion. A total length T of the heat shield tube and a length S of the overlapping portion satisfy T/10?S ?T/5. Further, a length L1 of the first tube and a length L2 of the second tube satisfy T/2?L2<L1.

Abstract: An employed rear mold is comprised of a plurality of mold pieces. The plurality of mold pieces include a first mold piece which forms a first partial internal surface of the internal surface of the rear mold along the entire circumference of the internal surface, and a second mold piece which is located axially forward of the first mold piece and forms a second partial internal surface of the internal surface of the rear mold along the entire circumference of the internal surface. Releasing the molded body includes starting to move the first mold piece rearward in relation to a rear molded portion, and, subsequently to starting to move the first mold piece, starting to move the second mold piece rearward in relation to the rear molded portion, thereby disassembling the rear mold into the plurality of mold pieces.

Abstract: A spark plug that provides an increase in the combustion speed of an engine. The spark plug includes a center electrode, a ground electrode, an insulator, and a cover portion. In a cross-sectional area of a region surrounded by an inner wall surface of the cover portion in a cross section taken along a plane perpendicular to an axial line CX of the spark plug, the cover portion includes: a narrow portion positioned on the front end side with respect to the ground electrode in the direction of the axial line CX and narrowed such that the cross-sectional area is smallest; and a cover front portion positioned on the front end side of the narrow portion and having the cross-sectional area that is larger than the cross-sectional area of the narrow portion and that is largest at the front end of the cover front portion.