ALU…
ZINC… stands for aluminium and zinc… fused in almost equal
proportions, as a coating for the steel sheet that is coated with a unique
silvery spangle composed of:
-
Aluminium
(55%),
-
Zinc
(43,4%) and
-
Silicon (1,6%)
The
result is: Steel's strength, Zinc's protection, and Aluminium's stability,
forming an extraordinary steel product from start to finish.
It
has excellent resistance to corrosion as a result of the two main
components of metallic coating: viz. aluminum on the surface of the
coating, which acts as a barrier to corrosive agents, and zinc to protect
the steel with an effect known as Sacrificial
Cathodic
Protection.
Sacrificial
cathodic protection occurs when a metal is coupled to a more reactive
(anodic) metal. This connection is referred to as a galvanic couple. In
order to effectively transfer corrosion from the metal structure, the
anode material must have a large enough natural voltage difference to
produce an electrical current flow. If
the zinc coating is scratched or otherwise locally damaged and steel is
exposed, the surrounding areas of zinc coating form a galvanic cell with
the exposed steel and protect it from corrosion. This is a form of
localized cathodic protection - the zinc acts as a sacrificial anode.
The
result of all of the above is that AZ185
Galvalume ® (with 25 micron coating on each side)
can offer
a 20-year plate guarantee
against
perforation due to corrosion.
Furthermore,
some outdoor exposure tests have shown that the sheet Aluzinc ® shows no
sign of rust after 30 years in most environments.
These
sheets also present a high resistance
to abrasion by its surface hardness and excellent reflective properties of
heat and light.
|
