Spark plug

Patent metadata

Field	Value
Publication number	US-2016294164-A1
Application number	US-201415036572-A
Country	US
Kind code	A1
Filing date	Sep 10, 2014
Priority date	Nov 20, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A spark plug that includes a center electrode and a ground electrode. The center electrode is disposed providing a gap with the center electrode. At least one of the center electrode and the ground electrode includes a tip forming the gap. The tip includes a main body portion and a front surface layer. A composition of the main body portion is Pt as a main constituent and Rh of 5 mass % or more and Ni of 0 mass % or more to less than 8 mass %. The front surface layer is disposed at least at a surface radially outside of an axial line extending in a direction from a center of the main body portion to the gap. The front surface layer contains Ni of 8 mass % or more and has a thickness of 2 μm or more.

First claim

1 . A spark plug comprising:
a center electrode; and a ground electrode disposed providing a gap with the center electrode, wherein at least one of the center electrode and the ground electrode includes a tip forming the gap, and the tip includes a main body portion and a front surface layer, a composition of the main body portion being Pt as a main constituent and Rh of 5 mass % or more and Ni of 0 mass % or more to less than 8 mass %, the front surface layer being disposed at least at a surface radially outside of an axial line extending in a direction from a center of the main body portion to the gap, the front surface layer containing Ni of 8 mass % or more and having a thickness of 2 μm or more.

2 . The spark plug according to claim 1 , wherein
a composition of the main body portion is Ni of 0 mass % or more to 1 mass % or less.

3 . The spark plug according to claim 1 or 2 , wherein
the front surface layer contains Ni of 40 mass % or more and has a thickness of 2 μm or more.

4 . The spark plug according to claim 1 , wherein
for a region having a thickness of 0.2 mm from a surface of the tip forming the gap to an opposite side from a side that the gap is positioned, a total content proportion of Ni and an element having lower melting point than Ni to a total mass of the region is 7 mass % or less.

5 . The spark plug according to claim 1 , wherein
the center electrode including the tip or the ground electrode including the tip is formed by bonding a surface where the main body portion is exposed at the tip to the center electrode or the ground electrode.

6 . The spark plug according to claim 1 , wherein
when the tip projects from the ground electrode by 0.15 mm or more and a cross section in a radial direction of an axial line direction extending in a direction from a center of the main body portion to the gap at any given position of the tip projecting by 0.15 mm or more is observed, at an outer peripheral surface in contact with an atmosphere, a part of a curvature radius R of 0.33 mm or more is present.

Assignees

• Ngk Spark Plug Co

Inventors

• Sumoyama Daisuke
• Shibata Tsutomu

Classifications

• H01T13/39 Primary

  Selection of materials for electrodes · CPC title

• B32B15/018

  one layer being formed of a noble metal or a noble metal alloy · CPC title

• C22C19/03

  based on nickel · CPC title

• B32B15/01

  all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)} · CPC title

• C22C19/05

  with chromium · CPC title