| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrode tip for a spark plug which is suppressed in high temperature volatilization wear than an inclination functional material layer formed by a thermal diffusion method, improved in durability with respect to spark wear by improving high temperature strength of the electrode tip, and realizes low cost, by suppressing the amount of precious metal used by further realizing thin diameter. SOLUTION: As for the electrode tip for spark plug, when a protective film, consisting of an alloy having iridium and rhodium as the main components, is coated on a surface of a core material made of iridium or an iridium alloy, the protective film is formed by a gas-phase method, and the composition of the protective film is made to be iridium only or mainly iridium on the surface of the core material, and along the film growth direction, rhodium content is made to increase continuously and/or in stepwise manner, and iridium content is made to decrease continuously and/or in stepwise manner, and on the outermost surface, rhodium is made to be contained by 75-100 wt%. COPYRIGHT: (C)2006,JPO&NCIPI
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