What commonly available alloy has the best corrorsion resistance properties?

What commonly available alloy has the best corrorsion resistance properties?
I am building a chamber that needs to last 500 years. It will be
indoors, but I need it to resist the effects of time and the elements. I added commonly because I cannot afford some rare exotic metal.
Also, can anyone recommend a good metal rod, tube manufacter that supplys their wares in metric sizes? (US based)
Thanks.
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The 300 series stainless alloys would work fine, 316L is likely the best amongst them. It's readily available at a reasonable price, and easily fabricated.
Harold
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How does Aluminium stand up against stainless steel? Also would it help protect the metal if I coated it with gold?
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I'd be inclined to think aluminum would tend to reduce to the ore from which it came, assuming it got exposed to moisture. If not, it would likely stand up to time just fine. It forms a skin of aluminum oxide almost instantly when exposed to atmosphere, which protects it from further corrosion.
A surface finish of gold would certainly make it more resistant to corrosion, but you may not have the means to apply the gold. It's not as easy as you might imagine, due to the aluminum reducing the gold from solution, or the gold migrating into the aluminum after it has been applied, assuming you were successful in getting it that far. A protective barrier of nickel would probably have to be applied, then gold. It would likely be cheaper in the long run to use stainless, which would be resistant to corrosion from all atmospheric conditions, and would stand up better to fire----although unless it was well insulated, the contents of the chamber would be destroyed by heat. Aluminum, by contrast, would melt. In either case, you're not going to be protected against excessive heat, so you'll have to research proper insulation if that's a concern.
Harold
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Purple plague, anyone? Aluminum and gold do strange things indeed.

Does he have to be heat resistant?
The other issue is for a chamber of that size, he could just as well use pure gold as the material as the cost would be inconsequential.
Oh wait, I meant to say, for a chamber of that size, his best bet would be concrete, as the cost for any metal would be prohibitive.
Hmm. Where in the center does the truth sit? It would be easier if he said he was making a box to put his DNA in, or if were buildign a bomb shelter to house his entire extended family. <g>
Honestly concrete's not a bad choice. How about granite, seriously?
Fireproof, create a cavity inside a block, with a tight fitting lid and possibly some sort of gasket, put the lid on and there you are.
Worked for the pharos, eh? (though not with granite)
Jim
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In 500 years it is unlikely to still be indoors. Bronze ship nails have survived 2000 years of salt water immersion so that is a good start.
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James wrote:

Concrete.
It worked well for the Romans.
Cheers Trevor Jones
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My first choice would be a 70/30 copper nickel alloy.
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Glenn Ashmore

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The cheapest hot-rolled crap you can find in a scrap yard, w/ about 5 coats of rustoleum+epoxy paint. Also, wall thickness will be directly proportional to longevity. 16 ga? 1/8? 1/4?? Could also go w/ plastic on a metal frame. 500 years, eh? Man, you must be takin one helluva vitamin.... -- Mr. P.V.'d formerly Droll Troll

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If it will be indoors, what kind of "elements" do you expect to have to resist? Does it need to be fireproof? Earthquake resistant? How structurally sound does it have to be? How big?
If it's going to be inside, it sounds like aluminum would work fine. The cap of the Washington Monument seems to do ok, and it's exposed.
James wrote:

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I would suggest going to a archaeological museum and looking at artifacts. Items made of copper seem to perform relatively well even after being buried. Stainless steel has not been around for long, but seems to be a [relatively] inexpensive, very slowly corroding material.
i

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Monel is one of the best in the marine industry. It's very nobel.

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Yes, it is, and also VERY expensive. Stainless is a bargain by comparison.
Harold
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I agree that stainless is a bargain in the short term. If you figure cost in relation to time monel is cheap compared to stainless. I've seen 80 year old monel deck hardware (chocks and cleats) look and act like it had been installed last week and I've seen 5 year old stainless deck hardware (chocks and cleats) look like it had been installed last week, but act like it was made of peanut brittle.
Eide

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in
deck
but
Excuse me if this is repitition (I haven't read this thread), but stainless is vulnerable to stress-corrosion cracking, especially in a marine environment. If it's under constant load and it's exposed to salt water, or even to salt air, it's likely to fail sooner or later.
OTOH, I have monel trolling lines that are now 50 years old and they don't break. That isn't constant load, of course, but it's remarkable nonetheless.
-- Ed Huntress
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Monel is good stuff, I've been using a 55 gal monel strainer for a burn barrel for 30 years and it was old when I inherited it.
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in
deck
but
That shouldn't be an issue in the circumstances described. Salt water is tough on stainless because of chlorine. There should be none of that present as the device was described. For that reason, the expenditure for monel is likely a waste. Remember, the original post said: "I cannot afford some rare exotic metal." My one inquiry on monel a few years back disclosed a price of something like $15/lb. Could be it's more now, what with copper prices having gone through the ceiling.
Monel would raise the cost of materials in excess of 400% as opposed to stainless, and would likely serve no better. Were it used on a boat that saw a sea environment, I'd agree with you.
Harold
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    This sounds like a "time capsule". A quick web search found this page, which offers some suggestions -- including about things which you may not have considered:
    http://www.si.edu/scmre/takingcare/timecaps.htm
    Good Luck,         DoN.
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The chamber is going to be around 6" in diameter and 12" in length, wall thickness is going to be 5mm. Its purpose is to hold data disks for long term storage. The chambers are going to be placed into fire safes and the safes will be placed into underground bunkers.
Would plating the Stainless with gold help prevent corrosion?
The chambers will be filled with nitrogen gas to help preserve the disks. What would you recommend for a seal? It cannot be any substance such as rubber due to outgassing. I need something that makes a good seal and does not deteroriate rapidly. The chambers will be opened periodically, around every 50 years to refresh the disk media.
Can you also recommend a good machine shop in the Phoenix, AZ area? I need a place that can weld all the pieces together.
Thank you for your help.
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The problem with long term media storage is not deterioration but lack of playback hardware. I have lots of media from a mere 25 years ago that cannot be read, not because of deterioration but because no hardware is available. Try to find a punch card reader, a paper tape reader, a Sony PortaPak reel-to-reel video player, a Beta video player, a video disk player, a Polaroid film projector, an 8-track tape player, an 8 inch drive, a single-sided 5 1/4" Apple II drive, a CP/M single density Osborne drive, any number of tape drives, and so on.
Unless you are packing the hardware away with the media, deterioration is not going to be your problem...
Is this an art project? Or does someone actually expect to retrieve this data?

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