Ngk Spark Plug Company, Limited

Hiroaki Nasu

Wataru Matsutani

Kazuhiro Kodama

Chiaki Kumada

Katsunari Ninomiya

Makoto Sugimoto

Makoto Sugita

Akito Sato

Yoshito Uemura

Toru Nakamura

Hirohito Ito

Kenji Moritani

Shingo Kuwahara

Mitsuru Yoshida

To provide a technology of improving the corrosion resistance of a spark plug. A spark plug having a metal shell on the outer surface of which a nickel plated layer is formed as a protective surface film. The nickel plated layer is such that when the atomic concentrations of constituent elements are measured in a depth direction by an X-ray photoelectron spectroscopy (XPS), the concentration of carbon atoms is 1.0% to 10.0% at a depth at which the atomic concentration of Ni elements is 80%.

Spark plug

A spark plug includes a metal shell, a ground electrode joined to a front end portion of the metal shell and a nickel layer formed on the ground electrode, wherein the ground electrode has a base material exposed region in which a base material of the ground electrode is exposed; and wherein the nickel layer includes an outer-lateral-side nickel layer located on an outer lateral surface of the ground electrode at a position adjacent to the base material exposed region and satisfies a condition of LA&#x2267;25 &#x3bc;m, where LA is a length from a first part of the outer-lateral-side nickel layer having a thickness equal to 80% of a maximum thickness of the outer-lateral-side nickel layer to a second part of the outer-lateral-side nickel layer having a thickness equal to 20% of the maximum thickness of the outer-lateral-side nickel layer in a longitudinal direction of the ground electrode.

A spark plug superior in salt corrosion resistance and stress corrosion cracking resistance is provided. The spark plug includes a metallic shell coated with a composite layer which includes a nickel plating layer and a chromate layer formed on the nickel plating layer. The spark plug is characterized in that the nickel plating layer has a thickness A which satisfies a relational expression 3 &#x3bc;m&#x2266;A&#x2266;15 &#x3bc;m and that the chromate layer has a thickness B which satisfies a relational expression 2 nm&#x2266;B&#x2266;45 nm.

Spark plug, and main metal fitting for spark plug

An adhesion of a nickel plating layer to a metal shell is improved, and an effect of improving a corrosion resistance by providing the nickel plating layer is sufficiently exerted. A spark plugincludes a cylindrical metal shellthat extends in an axial CLdirection, and a nickel plating layerthat is made of metal containing nickel as a main component and covers an outer surface of the metal shell. In a monochrome image of 256 gradations where black is 0 and white is 255, which is obtained by observing a cross-section perpendicular to an outer surface of the nickel plating layer by a transmission electron microscope with an acceleration voltage of 200 kV, an average value in 256 gradations of the monochrome image is 170 or larger and 230 or smaller.

Spark plug and metal shell for spark plug

A spark plug having a metallic shell covered with a nickel plating layer and having a groove portion formed between a tool engagement portion and a gas seal portion and having an orthogonal-to-axis sectional area of 36 mmor less.

Spark plug having stress corrosion cracking resistance

A spark plug includes an insulator extending along an axis and a metal shell provided on the outer periphery of the insulator. The metal shell includes a thread portion for threadedly engaging with a mounting hole of an internal combustion engine and a seat portion having a tapered surface whose outer diameter decreases gradually toward a leading end side. The tapered surface contacts with a bearing surface of the internal combustion engine when the thread portion is engaged with the mounting hole. Annular protruding portions or a helical protruding portion are formed within a range on the tapered surface from an outermost peripheral portion to a part forming an outer diameter occupying 95% of the diameter of the outermost peripheral portion. The arithmetic mean roughness of a surface of the tapered surface within the range is set to 1-5 &#x3bc;m on a section including the axis.

Spark plug and method of manufacturing the same

A spark plug comprising: a center electrode extending along an axis; an insulator provided about the outer peripheral surface of the center electrode; a metal shell provided about the outer peripheral surface of the insulator; a noble metal tip provided at the leading end portion of the center electrode; one end of the ground electrode fixed at the leading end of the metal shell, and the other end of the ground electrode forming a gap with the leading end of the noble metal tip; a stopper preventing the noble metal tip from moving relative to the central electrode; a molten portion formed by irradiating laser or electron beam; and a closed space formed between the basal portion of the noble metal tip and the center electrode. The molten portion welds the center electrode and a part of the basal portion of the noble metal tip.

Spark plug for internal combustion engine and manufacturing method thereof

A spark plug includes a tubular metal shell extending in an axial direction, wherein the metal shell includes: an externally threaded portion formed on a tip end side of an outer periphery of the metal shell; a seat portion formed on a rear end side of the externally threaded portion in the axial direction and protruding radially outward; and a nickel layer provided on an outer surface of the metal shell, wherein the nickel layer contains phosphorus, and a phosphorus concentration in a portion in which a nickel concentration is 50 at % in a thickness direction of the nickel layer itself is 6 at % or more and 20 at % or less.

Spark plug having a novel nickel coating for the metal shell

Provided is a spark plug that is excellent not only in salt resistance but also in stress corrosion cracking resistance. The spark plug includes a metal shell covered by a composite layer including a nickel plating layer and a chromate layer formed on the nickel plating layer. The chromate layer has a film thickness of 2 to 45 nm and Cr element concentration of not more than 60 at % and contains Ni in addition to Cr.

Spark plug, metal shell for spark plug, and method of manufacturing spark plug

In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 &#x3bc;m to 0.5 &#x3bc;m.

Glow plug and spark plug, and manufacturing method therefor

The invention relates to a process for treating a chromate waste liquid containing an organic acid component. This process includes (a) adding a chromium precipitation accelerating agent containing at least one of a calcium component and a magnesium component, to the chromate waste liquid; and (b) adjusting the chromate waste liquid to having a first pH of 9 or higher, thereby precipitating a chromium component from the chromate waste liquid and thereby reducing a concentration of a dissolved chromium component of the chromate waste liquid.

Process for treating chromate waste liquid

A chromate film-containing plug metal component which is a metal component for a spark plug or a glow plug, wherein: the metal component has a surface, at least part of the surface being coated with a chromate film comprising at least 95% by weight of trivalent chrome based on 100% by weight of a total chrome content in the chromate film; and the chromate film comprises dye particles.

Chromate film-containing plug metal component and method for producing the same

In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 &mgr;m to 0.5 &mgr;m.

In a spark plug, a complex chromate coat that contains a chromium component and a phosphorus component as cationic components, at least 90 wt % of the chromium component being trivalent chromium and the phosphorus component being present in an amount of 1 to 15 wt % as calculated for PO , is formed on the surface of the galvanized main metal shell of a spark plug. If a silicon component is substituted for the phosphorus component, it may be present in an amount of 5 to 75 wt % as calculated for SiO .

Spark plug and producing method therefor

A method for manufacturing a spark plug, the spark plug includes: a cylindrical metal shell having a portion to be caulked and a tool-engaging portion that is to be attached on an engine; an insulator that is inserted into the metal shell and extends axially; and a caulking metallic mold, the method including caulking the portion to be caulked to be fixed to an outer circumferential face of the insulator with the caulking metallic mold, where in the caulking metallic mold includes a face, the face including a hard carbon film that includes an amorphous carbon phase, and the face is contact with or sliding to the portion to be caulked.

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Aichi, Japan

Hiroaki Nasu