A magical corrosion proof, marine growth proof, strong metal. What was it?

Discussion in 'Materials' started by Matthew777, May 16, 2020.

  1. Matthew777
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    Matthew777 New Member

    Many years ago I taught science on the island of Guam. In the harbor you could dive to a Japanese dive bomber at a depth of about 30 feet. After 40 years of sitting upside down on the bottom of the sea the entire plane was a piece of junk. Marine growth covered it and profound corrosion had taken root. Except one surface, the hydraulic landing struts. Those two hydraulic rams were shiny as new with zero marine growth on them. No rusting, pitting, or discoloration of any kind were evident on those shafts. What magical formula was in that stainless steel? Did they use some toxic metal that industry can no longer use? I have always wondered about this, I see stainless rust all the time but those struts still perplex me after 30 years. Vibranium?
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Was it chromed ? Not that I'm aware if Chromium resists growth.
     
  3. kapnD
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    kapnD Senior Member

    It’s possible that the surface is too smooth for the marine growth to adhere to.
     
  4. Tiny Turnip
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    Tiny Turnip Senior Member

    Hydraulic components are commonly chrome plated. It is very hard and wear resistant, very corrosion resistant, provides a smooth surface to seal against, highly toxic and very expensive.
     
  5. trip the light fandango
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    trip the light fandango Senior Member

    Most likely a high titanium content in the surface treatment of the shaft isn't it?
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Titanium is anti-biotic ? I know silver certainly is, I've seen silver coins dug up that have been buried a century, and shiny like new.
     
  7. Tiny Turnip
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    Tiny Turnip Senior Member

    I'd put my money on chrome on the basis of its toxicity - I don't think titanium is particularly poisonous, and - I'm no historian, (or metallurgist, mind) but assuming this is a WW2 wreck, the vintage - didn't think titanium came in until a bit later?
     
  8. trip the light fandango
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    trip the light fandango Senior Member

    Electroplating was a much higher standard around that vintage, I would guess that titanium would be laid at a particular temperature , like in a bearing case, I don't know which it is though.
     
  9. Eric ruttan
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    Eric ruttan Junior Member

    Probably chrome, coated in hydraulic oil. I guess thats toxic enough to do the job.
    There is no way it's titanium.
    It was probably pitted and rotted, but in the sun, with all the rotted plane around it, it looked good and reflected well, but, if removed and brought up, would be found to have no intregity.
     
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  10. Barry
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    Barry Senior Member

    If the exterior of the rod is chrome plated, the substrate would have had to have had an electroless nickel plating process first. Chrome is subject to micro cracking ie porous. Being in a salt water environment the salt would have penetrated the
    chrome and attached the base metal causing corrosion underneath it.
     
    Last edited: May 17, 2020
  11. trip the light fandango
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    trip the light fandango Senior Member

    Copper nickel, "elements of boat building" Dave Gerr, at the end he talks about its longevity and that there is no need to anti foul, thanks Oldmulti for the download. It could be that the shafts were electroplated with more copper and nickel than in usual chrome plating.. Titanium was first used commercially by Du Pont in 1948. First military use was by Russia in 1960s, gee that interweb is handy.
     
    Last edited: May 17, 2020
  12. trip the light fandango
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    trip the light fandango Senior Member

    this is incorrect..wrong..
     
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  13. Barry
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    Barry Senior Member

    Electroless Nickel
    While most metal plating involves applying a direct electrical current to the object, in electroless nickel (EN) plating, the object reacts to the plating bath chemistry, creating a uniform and smooth, layer with very little surface porosity. The even deposition makes it an ideal choice for complex, non-line of sight, geometries and often eliminates grinding after plating. EN is applied to improve the corrosion and wear resistance of an object. Electroless nickel metal is a softer metal than chrome and can range from 40 to 60 HRC depending on the phosphorous content. Many times, a layer of hard chrome is applied over the nickel layer maximizing the objects ability to resist corrosion and wear.
    re US Chrome
     
  14. gonzo
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    gonzo Senior Member

    Monel or other CuproNickel alloy.
     

  15. Will Gilmore
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    Will Gilmore Junior Member

    If the hydraulic piston casing remains intact, bio matter replacing gaskets and seals, that would help to electrically isolate the pistons from being part of a galvanic cell. The coating of hydraulic oil and the chrome casing help protect it.

    I don't know about it's resistance to marine growth, but that sounds reasonable.

    -Will (Dragonfly)
     
    Last edited: May 20, 2020 at 8:50 PM
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