Spark plug

Patent metadata

Field	Value
Publication number	US-9627857-B2
Application number	US-201515118954-A
Country	US
Kind code	B2
Filing date	Jan 13, 2015
Priority date	Feb 24, 2014
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

An object of the present invention is to provide a spark plug which includes, at at least one of a center electrode and a ground electrode, a tip having excellent spark wear resistance in a high temperature environment, thereby having excellent durability. A spark plug includes a center electrode and a ground electrode disposed with a gap provided between the center electrode and the ground electrode. At least one of the center electrode and the ground electrode includes a tip which defines the gap. The tip includes a metal base material containing Ir as a main component, and oxide particles containing at least one of oxides having a perovskite structure represented by general formula ABO 3 (A is at least one element selected from elements in group 2 in a periodic table, and B is at least one element selected from metal elements). When a cross section of the tip is observed, an area proportion of the oxide particles is not lower than 1% and not higher than 13%.

First claim

What is claimed is:

1. A spark plug comprising a center electrode and a ground electrode disposed with a gap provided between the center electrode and the ground electrode,
wherein at least one of the center electrode and the ground electrode includes a tip which defines the gap,
the tip includes a metal base material containing Ir as a main component, and oxide particles containing at least one of oxides having a perovskite structure represented by general formula ABO3, where A is at least one element selected from elements in group 2 in a periodic table, and B is at least one element selected from metal elements, and
when a cross section of the tip is observed, an area proportion of the oxide particles is not lower than 1% and not higher than 13%.

2. A spark plug according to claim 1 , wherein
the metal base material contains Rh, and
a ratio (M/N) of a number M of the oxide particles present on a crystal grain boundary of the metal base material relative to a total number N of the oxide particles contained in the tip is equal to or lower than 0.85.

3. A spark plug according to claim 1 , wherein crystal grains of the metal base material have an average grain size of 3 to 150 μm.

4. A spark plug according to claim 1 , wherein the oxide particles have an average particle size of 0.05 to 30 μm.

5. A spark plug according to claim 1 , wherein the metal base material contains not less than 1 mass % and not greater than 35 mass % of Rh.

6. A spark plug according to claim 5 , wherein the metal base material contains not less than 5 mass % and not greater than 20 mass % of Ru.

7. A spark plug according to claim 1 , wherein the metal base material contains not less than 0.4 mass % and not greater than 3 mass % of Ni.

8. A spark plug according to claim 1 , wherein the oxide is at least one of SrZrO3, SrHfO3, BaZrO3, and BaHfO3.

9. A spark plug according to claim 1 , wherein the tip has a cylindrical shape and has a diameter R of at most 1 mm.

10. A spark plug according to claim 1 , wherein in a cut surface of the tip that has been cut along a plane passing through an axis of the tip, a ratio (F/L) between a length F, of a fusion portion formed by fusion of the tip and the center electrode and/or the ground electrode, on a straight line indicating a joint surface between the tip and the center electrode and/or the ground electrode in a range from one side surface of the tip to another side surface of the tip and a length L of the tip in a direction perpendicular to the axis is equal to or higher than 0.6.

Assignees

• Ngk Spark Plug Co

Inventors

• Sumoyama Daisuke
• Kanemaru Tomonori

Classifications

• C22C30/00

  Alloys containing less than 50% by weight of each constituent · CPC title

• H01T13/32

  characterised by features of the earthed electrode · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• C22C5/04

  Alloys based on a platinum group metal · CPC title

• H01T13/39 Primary

  Selection of materials for electrodes · CPC title