Nickel Corrosion

While nickel makes up 0.007 per cent of the earth's crust and is today one of our most useful metals, it was virtually unknown until the 1600s and was not isolated as an element until 1751. Early chemists called it Kupfer-Nickel (kupfer for copper), because nickel was originally found in association with copper ores, and nickel, after the German "Old Nick" or Satan, because it was initially so difficult to extract from those ores. Nickel is malleable, resists corrosion, and maintains its mechanical and physical characteristics under extreme temperatures. Once it was isolated and these valuable properties were recognized, nickel assumed a growing role in commerce and industry. By the early 1800s, nickel was being used to make a nickel-copper-zinc alloy, which could be silver plated. The technique of nickel plating was developed in about 1870. Moreover, the first pure nickel coin was struck in 1881. Each of these uses continues today.

Nickel is electrodeposited (plated) for many reasons. First and foremost nickel provides a decorative appearance because of its ability to cover imperfections in the base metal (leveling). This deposit can be made brilliant and when covered by a thin layer of decorative chrome will maintain its brilliance even under severe conditions. When nickel is applied in "duplex" form, excellent corrosion protection can also be achieved. This requires plating two different kinds of nickel (semi-bright and bright nickel). Nickel deposits also offer more wearability than softer metals such as copper or zinc and thus can be used when wear resistance is needed. Because nickel is magnetic, nickel can sometimes be plated where the ability to be magnetized is needed. Finally, nickel can be made to plate with little or no stress and is therefore used for electroforming or for aerospace applications where stress needs to be held to a minimum. In many applications, many of these requirements are required simultaneously so nickel is often not plated for just one reason.

To find much more on nickel based alloys consult the plentiful Nickel Development Institute site.