- Corrosion
Resistance - The AlumiPlate aluminum
coating provides excellent corrosion protection particularly in salt
and/or typical industrial acidic environments. Three mechanisms
are at work in this protection. First, the AlumiPlate layer is
pore free and provides a physical barrier. Second, pure (99.9+%) aluminum
forms a thin, tenacious, non-degenerating oxide almost immediately upon
contact with air. And third, the pure aluminum layer acts as a sacrificial
anode to nearly any metal that it is plated onto so that even if there
are minor abrasions or scratches in the AlumiPlate layer and areas of
the basis metal are exposed, the aluminum surrounding the pores will
oxidize more readily, being less noble than, say, steel for example, and
in this way sacrifices itself providing protection of the basis metal.
Typically a 0.5 mil AlumiPlate aluminum coating (as plated , no
chromate conversion) will provide over 1,200 hours of ASTM B117 salt
spray resistance (no red rust). Chromated AlumiPlate aluminum
provides an outstanding 6,000+ hrs of protection in ASTM B117 testing
with no red rust! Resistance to some acidic environments is
also very high. Kesternich testing (DIN 50018) determines a
coating's resistance to SO 2 environments (typical acid rain
constituent) and AlumiPlate aluminum survives an outstanding 20 cycles
of the 2.0 g/l concentration and 40 cycles of the 0.2 g/l concentration
testing. Aluminum plating is an attractive alternative to
cadmium for corrosion protection applications. This makes the
coating especially attractive for Marine, Off-Shore, Chemical
Processing, Aerospace, Automotive and many other applications.
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information on Corrosion Resistance
- Galvanic
Corrosion Protection - The ability of
the AlumiPlate aluminum coating to protect from galvanic corrosion in
steel-to-aluminum (or various other dissimilar metals-to-aluminum)
applications is one of the unique properties that an aluminum coating
offers. For example, in applications where steel fasteners must be
used in conjunction with aluminum structures, the use of AlumiPlate
aluminum-plated fasteners protects those aluminum structures from
galvanic corrosion better than any other plated surface.
- High
Temperature (1000º F / 550º C) Applicability - Unlike many conventional plating systems which
are destroyed or lost at higher temperatures, AlumiPlate aluminum offers
good protection for base metals in high temperature applications.
The melting point of aluminum is 1,220ºF (660º C).
AlumiPlate aluminum will protect surfaces from corrosion at
significantly higher temperatures than virtually any other conventional
plated metals except for nickel.
- High
Purity Aluminum (99.9+%) - The fact
that AlumiPlate aluminum is high purity aluminum will tell many
engineers and coating specialists just about all they need to know about
the surface properties of the AlumiPlate coating. There are many
applications for which the surface properties of ultra-pure aluminum make
it the best solution to the problems or challenges that customers are
experiencing but it cannot be used because the physical strength of the
pure aluminum is insufficient for use as a component material. The
use of high purity aluminum plating combined with the physical
properties of other materials such as steel, copper or even aluminum
alloys allows some customers to pursue applications that they currently
cannot with conventional plating systems. Also there are some
applications for which there is a need for ultra-pure aluminum as a
component material.
- Non-Aqueous
Process - The actual aluminum plating
step in the process is done in a patented, aprotic (proton-free) ,
non-aqueous electrolyte which does not evolve hydrogen or expose parts
to free hydrogen during plating. While several techniques exist
for the non-aqueous surface preparation of metals prior to plating,
aqueous pretreatment is currently used prior to plating most metals.
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Hydrogen Embrittlement
- Non-Porous
- This unique property of an
amorphous, pore-free coating structure is one of several differences
between the electrodeposited AlumiPlate layer and vapor-deposited
aluminum. A 0.3 mil (8µm) layer ensures a pore-free aluminum
coating. This property helps provide the outstanding corrosion
resistance of AlumiPlate aluminum, and combined with the ability to
plate the aluminum to varying thicknesses, allows the AlumiPlate layer
to be bight-dipped and/or anodized (clear, colored or hard-coated) and
eliminates the need for shot-peening densification after plating.
- Ductile/Formable
Post-Plating - Aluminum is a soft and
ductile metal. Elongation of over 50% without fracture has been
measured. Depending on the basis metal and the intermediate
layers, if any, the AlumiPlate layer can be bent, flexed, stretched,
rolled or drawn without cracking or peeling.
- Good
Throwing Power - Because the
AlumiPlate process is a true electrodeposition process done in a liquid
bath, parts with complex geometries and even some with inside diameters
can be plated with an even layer of aluminum. The throwing power
of AlumiPlate aluminum is similar to that of electrolytic cadmium.
Through the use of special supplemental anode racking, the AlumiPlate
process can plate into some holes where the depth exceeds two
diameters.
- Unrestricted Range of Thicknesses - The AlumiPlate SM process can be
used to plate parts with aluminum thicknesses from 0.0001 inches to
0.015 inches (0.1 mils - 15 mils) (2 µm - 400 µm).
- Uniform Thickness - The AlumiPlate process is a galvanic process
and therefore follows the physical rules of any galvanic process such as
electrolytic cadmium or zinc plating. There is no pronounced
"dogboning" and, with the exception of the inside of internal
geometries, the aluminum layer is functionally of uniform thickness.
- Non-Leveling
- The AlumiPlate aluminum coating
functionally conforms to the surface of the part being plated.
- Electrically
Conductive - The electrical
conductivity of AlumiPlate aluminum is approximately 62% that of copper
and is one of the best conductors of all of the non-precious
metals. Aluminum also can offer better materials compatibility
than expensive gold and silver coatings for some applications.
- Thermally
Conductive - Aluminum has three times
the thermal conductivity of steel and can be used as a thermally
conductive, corrosion resistant coating which can offer excellent
matching of thermal expansion coefficients and materials compatibility.
High-purity AlumiPlate aluminum has near superconductivity at
temperatures approaching Absolute Zero.
- Reflectivity
- Electroplated aluminum has very
good specular reflectivity in the visible region (~88% @ 750µm to ~92% @
400µm) when plated and single point diamond machined. Reflectivity
can be as high as 86% (@ 0.8µm) to 98% (@ 3.0µm).
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information on Diamond Turnability
- Scratch Resistant/Self-Healing - While high purity AlumiPlate™ aluminum
is a soft metal coating (similar to cadmium plating), it is also
wear-resistant in that scratches or impingements "heal"
quickly (i.e., the impingement tends to "smear" or burnish the
aluminum rather than to chip, crack or fracture it and even if the
AlumiPlate layer is scratched through to the basis metal, the
surrounding aluminum acts a a sacrificial anode to prevent oxidation
corrosion of the basis metal). Also, the oxide layer formed by
anodization of the high purity AlumiPlate aluminum surface can be very
hard and wear-resistant.
- Excellent Surface Appearance - Aluminum offers a clean, white metal,
aesthetically attractive matte surface whether as-plated or
anodized. Depending on the geometry of the parts, the surface can
be precision machined, polished, bright-dipped and/or anodized, and once
anodized, colored to further enhance surface appearance and/or
function.
- Chemically Polishable - Aluminum can be electroplated onto a smooth
surface and it can be chemically polished ("bight-dipped") for
applications requiring a shiny surface appearance or reflectivity.
- Anodizable
on Non-Aluminum Substrates - The
pore-free coating allows AlumiPlate plated parts to be clear or
hard-coat anodized. AlumiPlate aluminum can be plated onto and
anodized on nearly any conductive substrate including but not limited to
steels, copper, aluminum alloys, stainless alloys, beryllium and metal
matrix composite materials and other various alloys. Part
geometries such as blind holes and/or intricate interior surfaces can
pose challenges for anodizability applications and, because Plating With
Aluminum is a rack plating process, rack marks (or contact points) must
be masked during anodizing.
- Electrically Non-Conductive When Anodized - The aluminum oxide layer formed by anodizing
is non-conductive and can be a good electrical insulator, especially in
high temperature applications. The ability to change an
electroplated surface from electrically conductive to non-conductive is
unique to AlumiPlate aluminum.
- Colorable
During or After Anodizing - The
ability to permanently color the surface of anodized aluminum makes the
AlumiPlate layer an attractive choice for a wide variety of appearance
or performance reasons. The coloring could be used to color-code
different types of components. Applications abound where
aesthetics play an important role such as in the Marine, Recreation,
Automotive, Decorative, Sporting Goods, Die Casting, Jewelry and many
other industries.
- Wide
Variety of Post-Treatments Available -
Post-treatments applicable to the aluminum plated surface include
chromate conversion coatings, clear or hard anodization, Dow conversion
coatings, stripping, electroforming, electro-chemical polishing
("bright dipping"), and others.
- No
Heavy Metal in the Aluminization Process - While the typical current practice is to apply an intermediate
strike layer of 2-5µm of nickel prior to the aluminum layer for some
metals, the aluminum itself is
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