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Want a process for aluminum coating of steel

I'd like to apply a coating of aluminum to a steel substrate and then brush and anodize it. The coating is cosmetic at the request of a customer. While it needs to be resistant to atmospheric corrosion, it need not possess chemical resistance. Is aluminum coating of steel a long standing process in industry or is this a risky approach?

Michael E. Nelson
Product Development Engineer - North Berwick, Maine, USA
2004

Your idea looks good, smells good and feels good, but is not practical. There are three methods of coating steel with aluminum. 1, plating- has to be done in a closed tank, so is basically limited to small parts and application is not very thick. 2, vapor deposition- very thin. 3, Thermal spray- thick and fast, but rough and a degree of porosity. The thin coatings would be consumed in the anodizing process. The thick coating would not be very appealing without a lot of extra machine work and porosity might lead to rust. So, A more conventional finish would be more cost effective.

James Watts
- Navarre, Florida
2004

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James,

I'd respectfully disagree. The electroplating process works pretty well, (done by AlumiPlate) although it's rightfully more expensive than alternative methods of coating steel with aluminum. A few mils can be applied, and anodizing might only consume a portion of that. It's certainly worth a phone call.

Also, we have a number of parts IVD coated, and often apply a chromic anodize to them. I've not noticed any problems with the underlying steel rusting while sitting in our storage rooms before shipping.

Finally, there is also pack cementation and hot-dip methods of applying aluminum to steel substrates: I've no first hand experience with these, but my guess would be the surface would be rough- they would need the brush before anodize, likely not necessary with electroplate or IVD.

Lee Gearhart
metallurgist - E. Aurora, New York
2004