electrolysis between coated aluminium and SS screw

Question

electrolysis between coated aluminium and SS screw

dog241 (Aerospace)

(OP)

12 Jun 20 14:39

Hi,

I am not quite understanding about electrolysis.
I just would like to ask if coated aluminium parts are assembled with SS screw and they are used in marine application, would it be most likely to experience electrolysis, causing pitting corrosion and/or peeling off the coat on aluminium?

If so, what is the preventive measure? Would applying anti corrosion spray on SS screw or hole be helpful?

Please advise.

Regards,
MK

TugboatEng (Marine/Ocean) · Answer 1 · 2020-06-12 19:10:37

Yes, you're going to experience all of those problems. Silicone grease (Dow Corning 111) works well to prevent some corrosion. Low viscosity silicone sealants applied over the fasteners such as Dow Corning 734 also work well. Don't skip the chromate conversion coating. Use the correct marine grades of aluminum (copper free).

dogbural (Aerospace) · Answer 2 · 2020-06-15 01:37:03

Thanks Tugboat,

I will take a look at that.

Regards,
MK

TugboatEng (Marine/Ocean) · Answer 3 · 2020-06-15 07:06:05

I wish I knew what Furuno's process is for their radar units. They use aluminum housings with stainless fasteners and they hold up great for 20-30 years. The low viscosity silicone over fasteners recommendation is from their manual, the silicone grease is from personal experience. I have seen Furuno reference epoxy paint but theirs doesn't chalk from UV exposure like epoxy does.

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electrolysis between coated aluminium and SS screw