Anodizing of Aluminum: The Duralectra Process
Anodizing
of aluminum is an electrochemical process that thickens and
toughens the naturally occurring protective oxide. The electrical
charge and mild acid “oxidize” the surface of the aluminum,
forming microscopic crystals of aluminum oxide. This oxide
surface is very hard, much harder than the base material,
but very thin, often only a thousandth of an inch. The
resulting finish, depending on the process, is the second
hardest substance known to man, second only to the diamond.
The anodic coating is part of the metal, but has a porous
structure, which allows secondary infusions, (i.e. organic and
inorganic coloring, lubricity aids, etc.). The anodizing
prevents further oxidation, so the piece will not “rust” or
corrode any further, and also makes the surface much more wear
and scratch resistant.
Most anodized products have an extremely long life span and
offer significant economic advantages through maintenance and
operating savings. Anodizing is a reacted finish that is
integrated with the underlying aluminum for total bonding and
unmatched adhesion.
A lower initial finishing cost combines with lower
maintenance costs for greater long-term value.
Since the anodizing process is a reinforcement of a naturally
occurring oxide process, it is non-hazardous and produces no
harmful or dangerous by-products.
DURALECTRA
uses two types of
anodizing processes, sulfuric anodize and
Sanford Process Hardcoat®
anodizing.
Sulfuric anodize, commonly referred to as Type II anodizing,
is formed by using an electrolytic solution of sulfuric acid at
room temperature. This will produce a generally clear coating.
1/3 of the coating thickness will build up per surface and 2/3
will be penetration.
Type II sulfuric anodizing provides for several desirable
qualities such as:
- Corrosion
Resistance
- Durability
- Electrical
Insulation
- Can be dyed various colors
Sulfuric anodize coatings are often sealed to enhance
corrosion resistance, lock in dyes, or both.
Hardcoat anodize, commonly referred to as Type III anodizing,
is formed by using an electrolytic solution of sulfuric acid.
This will produce a generally gray coating .001” to .002” thick
with 50% buildup and 50% penetration.
Hardcoat anodizing provides for several desirable qualities
such as:
- Corrosion Resistance
- Very High Durability
- Electrical Insulation
DURALECTRA’S use of the
Sanford Process® for hard
coat anodize has the additional advantages over traditional hard
coat anodize
- Dying with bright colors (when the
Sanford Quantum Process®
is used)
- Allows hard coating of all aluminum
alloys including 2000 series and all cast alloys
- Higher abrasion resistance
- Uniformity of coating
MIL Standards
for Hard Coat Anodizing
Hard
Coating Standards
MIL-A-8625
Aluminum Anodizing:
Processing Standards
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