| 摘要 |
A metal pipeline for use in an automobile having a protective coating layer comprising a metal tube, a zinc-nickel alloy plating layer formed on the outer circumferential surface of the metal tube, a chromate layer formed on the zinc-nickel alloy plating layer and an extrusion molded thermoplastic resin coating layer formed on the chromate layer. A nickel plating layer is formed under the zinc-nickel alloy plating layer. The metal pipeline having the protective coating layer has excellent durability under severe corrosive circumstances including external mechanical forces and also has excellent heat resistance, corrosion resistance and impact shock resistance.
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