A spark plug having a center electrode and a ground electrode wherein the spark portion of at least one of the center electrode and ground electrode includes a base material and a protective material that substantially prevents corrosion of the base material....http://www.google.fr/patents/US7569979?utm_source=gb-gplus-shareBrevet US7569979 - Spark plug having spark portion provided with a base material and a protective material
Spark plug having spark portion provided with a base material and a ...
