Spark plug with multi-layer firing tip

A spark plug comprising a center electrode assembly including a base electrode and a multi-layered firing tip including a weld end and a discharge end and wherein said base electrode includes nickel, said discharge end being formed of a first material that includes at least one element selected from the group consisting of iridium, platinum, palladium, rhodium, ruthenium, and rhenium and wherein said weld end is formed of a second material that includes a positive amount less than 45% by weight chromium and a positive amount less than approximately 2.0% by weight of any element selected from the group consisting of iron, platinum, iridium, ruthenium, rhenium, manganese, magnesium, aluminum, silicon, zirconium, tungsten, vanadium, osmium, copper, and gold, and a positive amount less than 2.7% by weight of rhodium, and a positive amount less than approximately 10% by weight cobalt.

A spark plug comprising:

• a center electrode assembly including a base electrode and a multi-layer firing tip including a weld end forming one layer and a discharge end forming another layer, said weld end being located between and in contact with said base electrode and said discharge end, said weld end being formed from a first material including nickel, chromium and wherein said weld end includes less than 3% of any element selected from the group consisting of ruthenium, rhenium, and rhodium and said discharge end is formed from a second material that is different in composition from that of said first material.

A spark plug having a center electrode assembly, said spark plug comprising:

• a multi-layer firing tip formed having a discharge portion secured to a weld portion, said weld portion being attached to the center electrode assembly and located between said discharge portion and the center electrode assembly, and wherein said discharge portion is formed from a material including at least one element selected from the group consisting of iridium, platinum, rhodium, ruthenium, rhenium, tungsten, and zirconium and wherein said weld portion is formed from a material different in composition from that of said discharge portion and including nickel and less than 10% of any element selected from the group consisting of iridium, platinum, rhodium, ruthenium, rhenium, tungsten, and zirconium.