GALVANIC’S FEATURES

The main property about galvanic treatments is the protection against atmospheric corrosion, originated from the electrochemical series of metals. The kind of corrosion that appears between the pairing faces of different metals when there is an electrolyte is known with the term “galvanic corrosion”. It usually affects the less noble metal because it is less electropositive. This hierarchy between different metals is determined by their electrochemical potential. They are classified from the least (less noble) electrodes to the more (more noble) electrodes in the following order:

Electrochemical series of metals

Element     E° (volt)
Mg°   -2,34
Al°     -1,67
Zn°    -0,76
Cr°    -0,71
Fe°    -0,44
Cd°    -0,40
Ni°    -0,23
Sn°    -0,14
Pb°    -0,13
Cu°    +0,35
Ag°    +0,80
Au°    +1,42

In the case of iron shielding, if you choose a noble coating, such as iron pond, the protection is solely due to the corrosion resistance of the coating barrier itself, which must be absolutely continuous and free from pores . When for any reason the coating is interrupted so that the underlying metal surface is discolored, at this point a local galvanic element that corrodes the iron more vigorously than without the coating will start acting.

If, on the other hand, the coating metal is less noble than the coated metal, like zinc on iron, it works in the same way until the coating remains continuous, thanks to the resistance against corroding agents. If a continuous solution, such as an engraving,is formed in the metal coating, the coating continues to exert its protective action by electrochemical effect because the galvanic element that has just formed being less noble, suffers corrosion while the underlying metal remains clogged and therefore protected.

Other technical aspects of galvanic coatings are related to abrasion resistance because, with a  special treatment such as nickel plating, a high surface hardness is conferred to the fabric.

Other features (mainly due to tin plating, silvering and gold plating) are the increased weldability and conductivity, wich is highly sought after in the electronics and electromechanical sectors, of the treated materials.

In recent years, the eco-friendly appearance of the coating has been very important, and it has been looking for deposits compatible  with the contact of food-borne substances (like pure pond). In addition, surface treatments are used to enhance the aesthetic appearance of artifacts in the decorative sector.