Alocrom is actually trade
name for the process of chemically coating aluminium
alloys with a view reducing corrosion, increasing
their electrical conductivity, and helping to
provide good adhesion with a paint or powder coating.
Alocroming / alodining is therefore essentially
a 'chromate conversion coating i.e. a layer of
chromate salt is formed on the surface of the
aluminium alloy by applying acidified chromate
to it. This process is carried out on aluminium
alloy components and parts as a preparation before
any powder coating or painting. It can also used
on its own as external coating e.g. on panels
and fascias of various kinds. Alocrom also has
the advantage of working well when applied to
alloys which have high amounts of silicon, which
would on ordinarily make anodising difficult.
Names and Types
There are different names and brands to describe
what is essentially the same process and preparation
-Alocrom or Alodine, and there are other related
treatments for aluminium e.g. the use of Deoxidine
to prepare the surface of the aluminium before
the Alocrom itself is applied.
In original ICI types of Alocrom have different
numbers for use in different situations. For example
Alocrom 1000 doesn't really change the appearance
of the surface it's applied to and produces a
low electrical resistance. Alocrom 1200 however
has a golden appearance, is good for all types
of aluminium alloys. It prevents corrosion but
has more of an effect on the electrical resistance
i.e. it gives electrical conductivity. |
