Electroplating of aluminum
A light metal with a wide range of applications
History and word origin
Aluminum is the most common metal in the earth's crust and the third most common element after oxygen and silicon. Although very ignoble, it is protected by a natural passivation. Thus, it does not react with air or water at room temperature.
Compared to other metals, aluminum has not been known for long. Humphry Davy described it in 1808, but it was not until 1825 that Christian Orsted succeeded in making it. In the early years, it was more expensive than gold.
Its name derives from the Latin word alumen for alum.
Characteristics
Aluminum is a relatively soft and tough metal, the properties of which can be extensively changed by alloying. As a wrought alloy, it can be easily forged, pressed or formed at low temperatures. Many parts are manufactured using the aluminum die-casting process, which can also be easily machined. Due to its low mass, aluminum is "the" metal for lightweight construction.
Electroplating and NICAL®-process
By anodizing "anodizing" aluminum, the naturally existing oxidation layer is artificially strengthened. In many cases, however, this very frequently used surface coating does not meet the desired requirements for the workpieces or products. Electroplating aluminum with other metals significantly expands the range of applications for this light metal. In order to apply metals such as chrome, nickel, copper or tin, special processes are required to deal with the "natural" oxide layer.
With the NICAL®-process, Rieger Metallveredlung has developed a pre-treatment process for aluminum and its alloys. For years, this process has been used for a subsequent further galvanic coating. Bright nickel / bright chrome, tin, hard chrome or gold and silver, for example, can be applied as a further galvanic layer.
NICAL® coatings are characterized by their good adhesion to a wide range of aluminum alloys.
The susceptibility to corrosion of galvanized aluminum could be reduced by eliminating the need for sub-copper plating.
