Letter 24066

Importance of nickel acetate [Washington] 

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I am not well versed in the anodization process (beyond the basics). I am laser marking (CO2 laser, 10.6um) a blue anodixed aluminum part and having some difficulties. Typically, the CO2 laser will remove the pigment/die from the anodized layer and show through the bare aluminum, creating a very sharp contrast without removing the anodization. This new blue part is not acting this way. My customer says that it is standard type II sulfuric acid with a nickel acetate coating. I think the problem is the nickel coating. The 10.6um wavelength is usually pretty well reflected by nickel. My question is - is the nickel acetate coating required? what does it do? is it used on standard low-grade aluminum anodization of other colors? From my reading, it appears that it is primarily a seal for "blue" dye. Does it perform some other useful function?

Iyvind Hansen
- Mukilteo, Washington, USA

Nickel Acetate Seal inhances the corrosion protection of all Type II anodizing, dyed and/or clear

If you do not have a particular cruel corrosion environment then you may request you anodizing sealed in 210 F DeI or distrilled water.

"Sealing" is merely hydrating the Aluminum Oxide Molecule which is very small, into a Hydrated Aluominum Oxide Molecule which is larger and hence plugs the tiny hollow columns in the coating.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

The Laser engraving does work well on the Anodize, the problem is very much the nickel. Metals for what ever reason require a frequency of 1064 nano's to exite the metal to vaporize it for the engraving.

We utilized a 50 watt CO2 laser and it worked great for many things. We ran into problems when we tried Polished metals. We also learned that pulsing frequency matters also.

Epilog laser was VERY helpful in our quest for information.
anyways....... maybe this will help in a selection of lasers for future reference.

The Power is not always the important thing in laser engraving. Matching the frequency of the beam to the
application at times is the MOST important thing.

At 1064 nano's frequency 20 watts can be PLENTY to engrave
metals................

re-statement............. I re-read the post and realized you are using 10.6. Can you change the pulse frequency of the beam? We varied the pulse frequency and found a frequency that worked for our application. I will have to try the Nickel sealer to learn more about this situation.

winks.........

Densell Peters Jr.
- Marina Del Rey calif... USA

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