Shaft Coating in Marine Enviroment (inside&out)
Shaft Coating in Marine Enviroment (inside&out)
(OP)
We are trying to select a coating system for marine shafting. The shaft material is 4340 carbon steel. Both the interior and exterior must be coated. The shafts vary in dia. from 6" to 14" and lenght 5' to 14'.





RE: Shaft Coating in Marine Enviroment (inside&out)
Take a look at electroslag surfacing. It's expensive, but works quite well.
Andy
RE: Shaft Coating in Marine Enviroment (inside&out)
Is 4340 absolutely necessary... VS, say a high-grade marine environment qualified SSTL?
Is the shaft exposed-to, or worse, submerged in sea-water or bilge-water?
Caution: shafts with coatings of any substantial thickness, [especially applied to interior surfaces], MAY be a nightmare to balance.
Regards, Wil Taylor
RE: Shaft Coating in Marine Enviroment (inside&out)
The coating systems we are considering are :
1. Nylon 11 powder coating
2. Inorganic zinc rich coatings prime coating for interior, poly system exterior
3. Amine 2500
4. High Solids
RE: Shaft Coating in Marine Enviroment (inside&out)
On the metal side, why not consider electroless Ni - many plating companies have baths that can accommodate the sizes you list, the coating is uniform thickness and hydrogen cracking should not be a problem if the plater is advised of the material; or thermal spray coating - D-gun or HVOF coating of 316SS will be very durable. Other metals including bronzes and copper-nickel alloys are also available as T/S coatings. This can be done in a shop or in the field, although special tools are needed to T/S coat in side small bores.
Happy hovering!
RE: Shaft Coating in Marine Enviroment (inside&out)
RE: Shaft Coating in Marine Enviroment (inside&out)
RE: Shaft Coating in Marine Enviroment (inside&out)
For external application, you could consider laser cladding.
Materials including stainless steels (316)and nickel alloys (alloy 625) can be metallurgically bonded to alloy steels including 4340 with minimal dilution (1% to 3%), very small heat affected zone and virtually no distortion. The coating is fully dense and will pass Aust. Std. pressure vessel weld bend codes, so adhesion is not a problem. Coatings can be strategically placed and deposition thickness can be varied to suit your application, starting from 0.25mm or thicker. Shafts up to 10 tonne weight and 7 metres long have been clad using lasers in Australia.