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One of the rarest but still most famous mineral on Earth's surface is gold. It has been used for luxury--Tut's funeral mask and the crown of Montezuma come into mind--and currency for thousands of years.

But there is one feature about gold that intrigues me greatly--it is near-immune to corrosion.

So with that feature in mind, can gold be used for more than just vanity or wealth? For example, if I melt a certain amount of gold to make up 1-5% of the steel alloy for construction of large buildings, would this be practical?

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    $\begingroup$ Just look inside your PC or handy, and you may notice that gold is used for electronic parts: thanks to its tendency to not corrode in any way it makes up great long time useful contacts. You may even find it at your iPhones battery contacts. But for construction? Even that suit from Ironman (the Movie) is said to contain gold, which I think is humbug. But just wait for the guys with expertise from that area... $\endgroup$ – Confused Merlin Jan 19 '16 at 6:50
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    $\begingroup$ Gold is highly conductive of both heat and electricity and therefore useful in a variety of engineering disciplines, highly reflective and therefore useful as a sun shade, highly malleable and therefore useful as a foil to wrap your sandwiches in (though it's a bit pricey for that)... Honestly, it's a very useful metal. It's rubbish for most structural purposes, though, since it's so soft. $\endgroup$ – user867 Jan 19 '16 at 6:52
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    $\begingroup$ If we could just stop people thinking it's valuable because it's shiny we could do so much more with it. $\endgroup$ – Separatrix Jan 19 '16 at 12:21
  • $\begingroup$ Lucky for us that Gold has some other properties beside being shiny. Why would alchemists want to create some Gold from Lead ? $\endgroup$ – Kii Jan 19 '16 at 12:36
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    $\begingroup$ I don't think anything quite screams "Im a overly wealthy dissociated from reality asshat" quite like eating a precious metal that has neither flavor nor nutritional value... $\endgroup$ – James Jan 19 '16 at 15:08
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I'll suggest you have a look at Gold - Modern Applications on Wiki.

It covers a very wide area of uses, like

  • Electronics connectors
  • Non-electronic industry
  • Commercial chemistry
  • Medicine
  • Food and drink

Just some common examples: The connectors of your expensive head phones or smart phone charger. As a reflective layer in high end CDs, heat shielding in high end machines.

Your idea of using gold in a steel alloy isn't feasible though. Quite apart from the question whether such an alloy is actually possible to make (I have no idea), it would be very expensive, as you'd quickly need tons and tons of gold for the steel of even a single sky scraper. Honestly, there is not even enough gold in the world that we know of.

Apart from this we already know of very proven corrosion resistant steel alloys that will suit most needs people have.

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    $\begingroup$ Note that, additionally to what you mention, the density of gold (increasing weight) and its "softness" make it less useful for construction. $\endgroup$ – clem steredenn Jan 19 '16 at 7:28
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    $\begingroup$ Gold leaf (very thin gold foil) has been used for centuries, and a very thin layer of gold "could" be used to protect against corrosion, but the expense would outweigh the benefits. $\endgroup$ – Thucydides Jan 19 '16 at 10:52
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    $\begingroup$ @Thucydides: You are wrong there. The reason why electronic contacts are gold plated is exactly to protect from corrosion (and thus provide good electrical connection with the least amount of noise). Look at any medium or high-grade sound equipment (cables, speakers, head phones, ...) and you'll see that the contacts are gilded. $\endgroup$ – fgysin reinstate Monica Jan 19 '16 at 12:04
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    $\begingroup$ The question asked if gold could be used to stop corrosion in structural elements, and the answer is yes, but the expense isn't worth it (especially since you can get the same effects more cheaply using various alloys or simply painting over the structure rather than coating it in gold. $\endgroup$ – Thucydides Jan 19 '16 at 15:24
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Alloying iron with gold is probably not the best way to get a nice stainless steel. In fact there are ways to make inox steel (inoxydable) without gold right available. In this case the steel is alloyed with chromium, Vanadium, Molybdenum (among others).

To use the nice property of gold to be immune to corrosion you might not want to alloy it but to thinly coat the things to be protected, e.g. in electronics manufacturing Electroless nickel immersion gold (ENIG) is used as surface plating for printed circuit boards to protect copper and nickel traces on the board from oxidation.

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  • $\begingroup$ Although some applications require both oxidation and reduction resistance. Something like gold might suit better for such environments. $\endgroup$ – Jim2B Jan 20 '16 at 16:20
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Gold is used in building Surface Plasmon Resonance microscopes, one important application of which is label free immuno-assays (i.e. measuring very small levels of proteins in biological samples).

https://en.wikipedia.org/wiki/Surface_plasmon_resonance

I imagine there are lots and lots of scientific applications that use gold for various reasons.

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  • $\begingroup$ Gold as conductive coating is used in electron microscopy as well. $\endgroup$ – Trang Oul Jan 20 '16 at 9:20
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In addition to previous answers, it's also commonly used in dental fillings.

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Given that gold is a heavy soft metal, I would imagine it could be used as a substitute for lead in such applications a fishing weights, bullet slugs and roof flashing. It would have the benefit of being less polluting too.

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  • $\begingroup$ Though it would be ridiculously pricey... $\endgroup$ – fgysin reinstate Monica Jan 20 '16 at 9:37
  • $\begingroup$ My grandfather investigated the replacement of lead shot with other metals. We eventually figured that Niobium would be a very good substitute too, except for the cost. We eventually settled for copper. $\endgroup$ – Jim2B Jan 20 '16 at 16:19
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Along with all of the great answers above, as a space-faring fan I like the deal with blocking sunny radiation: http://www.geek.com/science/geek-answers-why-does-nasa-use-so-much-gold-foil-1568610/

I can't easily find the relevant ancient-alien-theory articles, nor do I take them all too seriously, but they show some nifty illustrations of how spacecrafts can benefit from being completely covered in gold. According to some theories the aliens only came to Earth for gold, and its worth was just that - coat-o'-gold for yee ol' spaceship.

Gonna paint my waggon, gonna paint it good...

And while you're off travelling the galaxy in your "check out my golden ship", don't forget to bring along some golden snacks: http://www.odditycentral.com/news/golden-kaiser-schnitzel-comes-with-real-gold.html

As for gold in a steel alloy, you're in for a disappointment. Modern steel doesn't corrode so quickly that it'll benefit much from a 1-5% gold infusion, and at the 5% mark I think you'll start seeing some softening of the alloy (which can be bad in big buildings, but some smaller ones might benefit from this.. it really depends on what you're building). Anywho, it'll be prohibitively expensive.

Besides, you won't have enough gold on earth to build much. You might consider using a pyramid to create extras: http://www.abovetopsecret.com/forum/thread1022234/pg1

Or just the neighbourhood nuclear reactor/accelerator: https://en.wikipedia.org/wiki/Synthesis_of_precious_metals#Gold_synthesis_in_an_accelerator

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  • $\begingroup$ For uses requiring high conductivity or high reflectivity the other gold family metals (silver and copper) are usually better or close enough that there's no reason to not use the cheaper metal - unless corrosion resistance is essential. $\endgroup$ – Jim2B Jan 20 '16 at 16:18

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