| 摘要 |
PROBLEM TO BE SOLVED: To suppress the advancement of crevice corrosion that occurs to a fitting surface with a yoke 5 without adding new parts and causing size enlargement. SOLUTION: A metal film 7 is formed on the entire surface of the yoke 5. This metal film 7 has a characteristic that its corrosion potential is smaller than that of aluminum and larger than that of iron. As this metal film, a zinc film, for example, can be applied. According to this structure, the metal film 7 is formed on the surface of the yoke 5 on the fitting portion of the yoke 5 and an end frame 4 so that the iron, a material of the yoke 5, never directly contacts the aluminum, a material of the end frame 4. Furthermore, the corrosion potential of the metal film 7 is smaller than that of the aluminum and larger than that of the iron so that a potential difference of a local battery formed on the surface of the aluminum gets smaller. As a result, the advancement of the crevice corrosion can be suppressed that occurs to the fitting surface of the end frame 4. COPYRIGHT: (C)2006,JPO&NCIPI
|
