ELECTRODE FOR AN IGNITION DEVICE

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An electrode for an ignition device is made from a Ni-based nickel-chromium-iron alloy which has improved resistance to high temperature oxidation, sulfldation, corrosive wear, deformation and fracture includes, by weight of the alloy : 14.5-25%% chromium; 7-22%% iron; 0.2-0.5%% manganese; 0.2-0.5%% silicon; 0.1-2.5%% aluminum; 0.05-0.15%% titanium; 0.01-0.1%% total of calcium and magnesium; 0.005-0.5%% zirconium; 0.001-0.01%% boron, and the balance substantially Ni. It may also include at least one rare earth element selected from the group consisting of : yttrium, hafnium, lanthanum, cerium and neodymium in amounts ranging from 0.01-0.15%% by weight, and incidental impurities, including cobalt, niobium, molybdenum, copper, carbon, lead, phosphorus or sulfur. These total of these impurities will typically be controlled to limits of 0.1%% cobalt, 0.05%% niobium, 0.05%% molybdenum, 0.01%% copper, 0.01%% carbon. 0.005%% lead, 0.005%% phosphorus and 0.005%% sulfur. The ignition device may be a spark plug which includes a ceramic insulator, a conductive shell, a center electrode disposed in the ceramic insulator having a terminal end and a sparking end with a center electrode sparking surface, and a ground electrode operatively attached to said shell having a ground electrode sparking surface, the center electrode sparking surface and the ground electrode sparking surface defining a spark gap therebetween. At least one of the center electrode or the ground electrode includes the solution-strengthened Ni-based nickel-chromium-iron alloy. The Ni-based nickel-chromium-iron alloy electrodes of the invention may also include a core with thermal conductivity greater than that of the Ni-based nickel-chromium-iron alloy, such as copper or silver or their alloys.© KIPO & WIPO 2009