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| Reel-to-reel
electrolytic deposits on aluminium and its alloys |
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Introduction
PEM
process called "by direct electrolytic bronzing"
Application
for reel-to-reel treatment |
|
 Introduction
:
The application of a metal deposit on aluminium-based materials
caters to technical requirements, notably:
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 improvement
of the quality of electrical contacts, |
| endowing
surfaces with an aptitude for wetting by soft brazes (brazing
aptitude) |
| protect
the substrate against corrosion and, in particular, the effects
of galvanic couples caused by contact between copper and silver. |
Tin, nickel,
copper and silver are the main deposits that, when these materials
are coated with them, make it possible to use the correct electrical
conduction and heat properties of these materials under the severest
conditions of use. It remains that these deposits are applied by
electrolytic means in practically all cases, and they must be strongly
bound to the base in order to withstand the strong mechanical and
above all thermal stresses inherent in this type of use. |
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PEM
process called "by direct electrolytic bronzing":
The quality of the base metal/deposit junction (or adhesion) depends
mainly in the case of aluminium and its alloys on the execution
of the stages that lead to the final deposit:
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the
technique of preparation of the base surface that governs
the "mechanical strength" of the deposit |
| the
placement of metallic sub-layers inserted between the "preparation"
and the final deposit, which governs its "thermal resistance"
and corrosion resistance. |
The PEM preparation
technique called "direct bronzing", which consists in depositing
a Cu-Sn alloy directly on the strongly-"activated" substrate caters
best to the first requirement.
Proper management of the choice of the sub-layers (nature and thickness)
answers the second requirement just as effectively.
This process, which has demonstrated its reliability for more than
35 years has been approved by many manufacturers and authorities,
such as the EDF [French public power company] (EDF standard HN 20.5.61).
It caters to the most demanding needs, such as:
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bending
of tin-plated and nickel-plated flat bars to right angle;
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| cutting
and crimping of nickel-plated strips; |
| brazing
of tin-plated or nickel-plated items with soft solder; |
| no
deterioration in these junctions over time up to 150°C (no
separation after 100 hours at 200°C; one after a 250°C thermal
shock). |
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Application
for reel-to-reel treatment
The process initially developed for static bath treatment has been
carried over, with the same advantages, to reel-to-reel treatment.
There are a number of industrial applications for this, such as:
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dull
and bright tin-plating or bright reflowed tin-plating, or
also nickel-plating of flat bars, rigid sections and tubes
3 to 8 metres long intended for the production of electrical
engineering items such as busbars, cable grips, diode radiators,
etc; |
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tin-plating
or nickel-plating of thick strips of aluminium intended for
manufacturing involving cutting and crimping |
Note that these
2 coatings have excellent brazing aptitude, even after machining. |
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SOFIPEM,
Siaugues St Romain 43300 SIAUGUES STE MARIE - FRANCE
Tel: +33 (0)4.71.74.21.09 - Fax: +33 (0)4.71.74.26.57
- Email : contact@sofipem.com
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