Spark plug electrode having iridium based sphere and method for manufacturing same
 A spark plug and method of making same, wherein the spark plug includes an iridium alloy tip portion which may take the form of a rivet or a sphere. The tip portion is coated with platinum, annealed and then resistance welded to a nickel-based electrode of the spark plug. The platinum coating helps to prevent cracks at the welding joint which might otherwise occur due to the differing coefficients of thermal expansion of the iridium-based alloy tip portion and the nickel-based alloy electrode. The iridium alloy tip portion is further not susceptible to attack by lead or combustive gases and therefore increases the life of the spark plug significantly. 
AlliedSignal Inc.
H H
H01T H01T
inventional inventional
Lee Randall Edgar Arnold Chin-Fong Richard Dale
Franz Leone Chang Taylor