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Apparatus for Anodizing a Cylindrical Aluminum Coating On a Copper Piston

IP.com Disclosure Number: IPCOM000102286D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Singh, P: AUTHOR

Abstract

A thin aluminum coating is formed on a copper core, and the core is cut into short lengths to form components called pistons. The aluminum is anodized to give the piston a layer of electrical insulation. In the anodizing process, the pistons are placed in an electrolyte of dilute sulfuric acid and a current is passed through the pistons, and the ends must be masked during the anodizing process to maintain a suitable current density at the surface of the aluminum. An improved apparatus is provided for masking the pistons and making electrical contact to them.

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Apparatus for Anodizing a Cylindrical Aluminum Coating On a Copper Piston

       A thin aluminum coating is formed on a copper core, and
the core is cut into short lengths to form components called pistons.
The aluminum is anodized to give the piston a layer of electrical
insulation.  In the anodizing process, the pistons are placed in an
electrolyte of dilute sulfuric acid and a current is passed through
the pistons, and the ends must be masked during the anodizing process
to maintain a suitable current density at the surface of the
aluminum. An improved apparatus is provided for masking the pistons
and making electrical contact to them.

      Pistons are placed between two horizontal support plates that
have their inwardly facing surfaces covered with a layer of a
material such as rubber that is electrically insulating and is
compliant to seal the piston ends.  The electrolyte is maintained in
this region.  An electrical connection is made to each piston by
means of a spring- loaded contact needle that extends through a hole
in the upper support plate.

      One type of piston has a cup-like opening in one exposed copper
face, and a vent hole leads from this central opening to the outer
surface of the aluminum coating.  The apparatus is modified to
prevent the electrolyte from entering the vent hole.  The upper
support plate is constructed as part of an air chamber, and air flows
through the hole for the needle contact, into the opening in the
piston,...