The three metal wires used for metalizing structural steel are zinc, aluminum, and the 85% zinc / 15% aluminum alloy. Coatings of these metals protect steel in three ways.
The three metals used to protect steel in atmospheric or immersion service are 99.99% zinc, aluminum in the range of 99.0-99.5%, and the zinc aluminum alloy composed of 85% zinc and 15% aluminum. The following is general information on each of these sprayed-metal coatings.
Metalized zinc coatings are used in rural, industrial, and marine environments. The three mechanisms of protection described above are most pronounced with zinc, and it is by these three mechanisms, barrier, galvanic action, and corrosion product development that zinc and zinc alloy coatings protect steel.
Zinc is the most active of the three coating metals and provides a high degree of cathodic protection to the underlying steel. Zinc’s corrosion resistance is unique; it has a high corrosion rate, which is offset by the formation of the aforementioned corrosion products on the metal coating’s surface.