Dacromet coating questions

A. Hi Bhushan. There are so many different exposure situations that I don't think any such number is valid. Rather, the thickness to be specified is according to how severe the environment is. For example, for zinc electroplating, 5 microns is considered appropriate for mild conditions, 8 microns for moderate, 12/13 for severe service per ASTM B633. So I'd say 15 microns of Dacromet is appropriate for "severe" exposure, but I would not try to express it in any specific number of years.

Luck & Regards,

A. Dacromet is a trademark of Metal Coatings International, and it describes a zinc-rich dip-spin coating. It is a way of applying a sacrificial coating of zinc. My understanding is that it offers greater corrosion resistance than zinc electroplating (probably because it's thicker).

Salt spray testing is not a meaningful way to predict the life of zinc-based coatings though. The protection they afford in the real world comes from the formation of stable and insoluble zinc carbonate corrosion products that develop over time with exposure to the carbon dioxide in the open air.

A. Dacromet coatings (include Geomet coatings) is known by many professional people in China. Also it will develop rapidly in the field of metal anti-corrosion.

Hi, Bryan. Probably. Dacromet is one brand name of what people might call "zinc flake coating". But please remember that you must never specify a coating that loosely nor quote to do a coating that is so loosely defined. A colloquialism like this might be used in a technical article, in context, where the meaning will not be misconstrued, but specifications must be carefully detailed. Good luck.

Regards,

A. Hi, Ani.

Dacromet is a proprietary product containing zinc flakes, aluminum powder, metal oxides, and binders. Metal Coating International will tell you that much, and maybe a little more of what you want to know, but not everything about it, because it will be trade secret. Good luck.

Regards,

A. Hi Betsy. I think you need to contact NOF Metal Coatings (formerly Metal Coatings International) for the straight scoop rather than relying on rumor, but my guess is that perhaps they have decided to move exclusively to their Geomet line which is, per my understanding, very similar but chromium-free.

There are several other suppliers of zinc-rich dip-spin coatings, including The Magni Group, Doerken, Sermagard, and Zintek -- but whether they are an "acceptable replacement" will depend on what the spec says. Good luck.

Regards,

A. Hi Mack. There are a lot of things that could have gone wrong, from operational errors to unreasonable expectations. As a starting point can you please quantify what you mean by "got trouble with surface adhesion" and what the base metal was?

If you phone a doctor and tell her you have a fever, it might mean infection, but that single symptom doesn't say enough; similarly, although poor adhesion often means insufficient cleaning, that's not always the case. Good luck.

Regards,