Three
anodize coatings for use in a wide
range of functional and decorative
applications
Type I (Chromic) Anodize
Chromic anodize is the thinnest
anodic film and is used primarily
in military and aerospace
applications that require strong
corrosion resistance and adhesive
bondability.
Because it is typically just
0.0001 in. thick chromic anodize
is more functional than
decorative. It is seldom
dyed, except on precision optical
housings and lens retainers, which
usually call for black dye
following anodize.
Most chromic anodized parts are
subsequently painted or primed for
later bonding and must
consequently be wrapped and
handled with special care.
Type II (Sulfuric) Anodize
Sulfuric anodize is the standard,
most widely known film. The
coating can range from twice as
thick to eight times as thick as
Type I (chromic) anodize.
This added thickness allows
sulfuric anodize coatings to
accept dyes readily, allowing them
to offer both decorative and
highly functional properties at
the same time.
Dyed coatings tend to be 0.0006 to
0.0008 in. thick while the
thickness of clear or undyed films
typically run 0.0002 to 0.0004 in.
Sulfuric anodize - used in
applications as diverse as
architecture, aerospace,
manufacturing, automotive, and
computers - has been one of
Anoplate's featured finishes since
the company's founding in 1960.
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| This optical component for the medical industry is hard-anodized outside for durablity, and Type II black-anodized inside to minimize reflection. |
Type III (Hardcoat) Anodize
Hardcoat anodize - or hard anodize
- produces a tough outer skin on
aluminum surfaces that need extra
abrasion resistance, corrosion
resistance, or dielectric
strength.
Up to several mils thick, hardcoat
anodize offers surface hardness
greater than that of hard chrome (HRC
> 70) combined with the light
weight of aluminum. It is
specified in a broad array of
applications, including those
diverse as food packing equipment,
textile feeding devices,
photographic film-tracking
components, and paper rolls in
photocopiers.
The finish requires close
coordination of current density,
bath temperature, and additive
chemistry. Close control
over current ramping during the
coating's initial formation is especially
important to prevent burning of
the processed parts.
Hardcoat is rarely dyed except for
identification purposes or for
blackening to produce optical
non-reflectivity. As such,
hardcoat is seldom used in
decorative applications and is a
truly functional finish that is
often enhanced by sealing with a
flouropolymer as PTFE.
Other Anodizing Available
from Anoplate
- Titanium
anodize (AMS 2488, Type 2)
- Galvanic
anodize for magnesium (Dow 9)
applications)
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