Non-chromic acid chemical conversion coating

Non-chromic acid chemical conversion coating

What is non-chromium chemical conversion coating?

It is a corrosion-resistant film intended to provide rust prevention on aluminum materials, which contains no hexavalent chromium, a substance which became regulated under RoHS directive in Europe and so forth as an environmentally hazardous substance.



A corrosion-resistant film which contains zirconium instead of chromium.


The film is colorless and transparent. However, the base material becomes slightly whitened by activation (etching) which is the preprocessing and thus the finished appearance becomes slightly whiter.

Corrosion resistance

It is equivalent to the colorless hexavalent chromium chemical conversion coating (Alodine, etc.).
The coating on aluminum casting and die cast products will be inferior to the coating on aluminum alloys in corrosion resistance as the film is affected greatly by the base material.

塩水噴霧試験 Alloys Castings
A5052 AC4C ADC12
24 hours ~ ×
72 hours ~ ×

○・・・No corrosion  ×・・・Corrosion observed


  • There is little dimensional change with the film thickness being 1μm or smaller. However, there may be dimensional decrease by about 1μm by the preprocessing etching.
  • The treated products conduct electricity (surface insulation resistance value 0.7Ω・cm3).

Cautionary notes, etc.

Surface irregularity may occur if the material is being re-treated after peeling.

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