The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Zinc flame spray "gunning" for ship repair

Dear Sir, I'm most surprised that all over the net, there is a lot to find about zinc and anti-corrosion techniques, though there's nothing on a technique used in shipbuilding and ship repair: - blast cleaning (AlO2) a surface. - "gunning" with a zinc wire which is melted down and sprayed onto the surface thickness till 900 gr/m2. I'm looking for info about the technique and suppliers. Can someone help me ? regards,

Van de Walle Ghislain
- Belgium
1995

---

Hi, Gislain.

You might talk to Tafa Corp. [Concord, NH].

Although it's expensive, ASM International has a CD-ROM covering thermal spray technology. See www.asm-intl.org/mi.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1995

---

1995

Many thanks for the Tafa info. Considering buying the Tafa equipment we have talked with some major clients about the process. Most of them know the process of spraying zinc but don't see it as a replacement for hot dipping of zinc. Altogether one can say that the process over here is little known, and thus opinions are reserved about the quality. We should prefer such a process above hot dipping because we lose JIT delivery control and receive the materials often deformed.[Lorry- transport of about 70 km].

Does such a process withstand weather conditions like hot dipped zinc? Is there an adhesion problem? Can the layer thickness be controlled in an semi-automated process? Are we right to convince our costumers? Is there really a fe-contamination in hot dipping and how severe is the risk? Does sprayed zinc withstand better the outside air? Is the whole process of shot blasting and gunning zinc really less expensive?

Sorry for the amount of questions, but I'm a doubting soul whether we should go one way or another. Many thanks,

Van de Walle Ghislain
(returning) - Belgium

---

The only questions that I have any familiarity with are:

1). Iron contamination is not supposed to be a real problem in a well-operated hot dip line.
2). My understanding is that it doesn't matter a lot whether you apply the zinc by hot dipping, electroplating, mechanical plating, or whatever: "zinc is zinc" and the corrosion resistance and longevity are fairly much proportional to the thickness.

The companies in our directory listings may have some answers for your questions.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey