Ignition Device Electrode Composition

Abstract

An ignition device includes a ground electrode, center electrode, or both composed of a cobalt-based alloy including: Ni in an amount between about 20 and 24% by weight; Cr in an amount between about 20 and 24% by weight; W in an amount between about 10 and 16% by weight; and Co in an amount between about 32 and 47% by weight or alternately an iron-based alloy comprising: Cr in an amount between about 18 and 24% by weight; Al in an amount between about 4 and 7% by weight; and Fe in an amount between about 67 and 78% by weight. It is believed that the electrode alloys may also include Zr and B in an amount, by weight, of 0.005-0.5% Zr and 0.001-0.10% B. Center or ground electrodes of the invention may also include firing tips attached at a sparking end thereof. The firing tips may be formed of at least one of gold, a gold alloy, a platinum group metal or a tungsten alloy.

Description

RELATED APPLICATIONS[0001]This patent application claims priority to U.S. Provisional Patent Application Ser. No. 60 / 823,672, filed Aug. 28, 2006 which is hereby incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]This invention generally relates to ignition devices such as spark plugs for internal combustion engines or igniters in gas turbines and jet engines. More specifically, this invention relates such ignition devices having iron or cobalt based electrodes.RELATED ART[0003]Electrodes having noble metal firing tips are widely used in ignition devices. Platinum and iridium based alloys are the materials of choice for such firing tips, while a nickel-based alloy is usually the preferred material for the electrode bodies to which these tips are attached.[0004]Ideal characteristics for the electrode body material are high temperature corrosion resistance, good high temperature mechanical strength, good heat transfer capability, cold formability, low raw mat...

AI Technical Summary

Benefits of technology

[0006]This invention provides alloy compositions for alternative electrode materials that exhibit superior performance characteristics for use as the body material for spark plug center and ground electrodes. In particular, these alloys provide superior performance at a lower cost as a potential replacement for nickel-based alloys as the body electrode material for spark plug designs, particularly those which incorporate firing tips of noble or other high temperature materials for the sparking surface.

Problems solved by technology

For example, this combination is not optimal for weldability of the tips to the electrodes, formability of the electrodes, and resistance of the electrode material joints to high temperature oxidation.

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