Non-corroding non-tarnishing inexpensive lustrous yellow metal gold alternative alloys?

[anon359]

First allow me to say that I'm not a metallurgist and know next to nothing about it, and that's why I've come here.

I'm looking for a non-corroding non-tarnishing inexpensive lustrous yellow metal alloy that could act as a cheap gold alternative, largely for decorative purposes.

The lionshare of its application will be decorative much like you'd see somewhere like Buckingham palace. Here's a virtual tour showing you what I'm talking about:

http://www.royal.gov.uk/virtualtours/BuckinghamPalaceVirtualTour/grand_staircase.HTML

The next most prominent use will be furniture and then finally a few pieces of jewelry. They don't necessarily all need to be the same alloy, but most aside from the jewelry will be for indoor appplication. Much of it will likely need to be resistant to chlorine as there will be a pool nearby which I understand would destroy electroplating. There aren't really any plating methods that I've heard of personally that could even really take the kind of punishment furniture or a staircase would need to take without scratching or worse and revealing the metal underneath, which is why I'm asking about alloys.

Generally, I think polished brass seems like a good choice except for the fact that it both tarnishes and corrodes. I don't know if there's something it could be alloyed with to prevent that while retaining a similar appearance, or another alloy entirely, but that's why I'm here. Polished brass also looks nice since it has a bit of a more saturated color. The idea color would be something like so:

(most notably the center)

In all honesty, it doesn't even necessarily even need to be a metal. It could be some kind of synthetic material as long as the conditions are met.

Any ideas?

 

[btrueblood]

Manganese bronze and silicon bronze have much better corrosion resistance (tarnish more slowly) than brass. The former is used for the U.S. Sacajawea dollar coin, and both alloys see use for such things as ship's propellors.

 

[EdStainless]

There is a ton of reference work on this, after all people have been trying to mimic gold for centuries.
There are some yellow Cu based alloys that have very good corrosion resistance.
There are also some very gold coating applied by CVD of PVD that are very hard, durable, and corrosion resistant. These can be applied over common materials.
Keep trying different key words in google, there is a lot out there.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[btrueblood]

Forgot about titanium nitride (TiN) coatings, good call Ed.

 

[anon359]

Thanks guys. Very useful info.

 

[TVP]

Copper alloys are available in a number of colors including gold. The latest Euro coins feature Nordic Gold, a copper alloy, specifically developed for that purpose. Use the following links for more information:

A Guide to Working With Copper and Copper Alloys

http://www.copper.org/publications/pub_list/pdf/a1360.pdf

Nordic Gold alloy used for Euro coinage (CuAl5Zn5Sn1)

http://www.kme.com/assets/uploads/files/datasheet/ri/mds_mz31_cual5zn5sn1_english.pdf

http://www.predecimal.com/euroarticle.htm

http://www.ecb.europa.eu/euro/coins/common/html/index.en.html

 

[Ceramicguy]

For a ceramic option, consider Kyocera's sintered titanium nitride. It is produced in their Vancouver Washington plant.

Bruce

http://accuratus.com

 

[ornerynorsk]

Brass and other metals are commonly lacquered to retain the shine.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[anon359]

How would manganese bronze do in jewelry?

 

[btrueblood]

Well, given that it's used in coinage, it would probably do ok -- i.e. be nontoxic with the right chemistry (no lead or arsenic, etc.). Past that, what do you want the alloy to do as jewelry?

 

[anon359]

The same thing as you would want from any gold or silver jewelry I suppose. You wouldn't want it to leave a green mark on your skin, you wouldn't want it to rust or tarnish, and you'd want it to retain its luster without needing all that much maintenance. I suppose you'd also want it to be durable enough to not get damaged from everyday use.

 

[RedVette]

anon359,

If you're looking for something having the qualities you're looking for in addition to durability, aluminum bronze is probably the best bet for you at the current time. I've also been searching for a cheaper, more durable substitute for gold, and copper alloys was the only thing of any promise. So I decided to experiment with C954 aluminum bronze:

It has a lovely golden color with a very slight reddish tinge. However, it will tarnish over frequent exposure to skin contact due to the reaction from the chemicals in the oils and sweat, so it may not be the best choice for jewelry items in constant skin contact. Nonetheless, the tarnish is marginal compared to traditional bronze and easily polished. Just gotta put up with the vinegar-like smell from the chemical reaction between the sweat and copper oxide. But if left alone as under display conditions, it'll last for years!

The bronze alloy with the best overall combination for a cheap gold substitute is gonna have to be an alloy with a copper percentage somewhere between that of common brass and aluminum bronze. On the one hand, you go too low in the copper content and the color will lean more towards green, and on the other, if you go too high, it'll be too red and tarnish darker. The ancients also sought the same thing, as exemplified by the high value of Corinthian Bronze, which was used to construct the Jerusalem temple gates and documented to "resist tarnishing." The technique behind this ancient alloy is lost to history, but it occurred to me that a possible solution to this quest is a copper alloy containing substantial levels of chromium. The chrome oxide should do for the bronze what it does for iron in stainless steels, effectively yielding a stainless bronze. But I don't know why there isn't such an alloy. Perhaps the chemistry prevents a proper alloying of the elements...

 

[anon359]

Don't metallurgists do that sort of thing? Perhaps someone here should try it. From a quick google search it looks like Copper Alloy No. C18200 Chromium Copper does exist.

 

[btrueblood]

All copper alloys will tarnish over time. I don't think maganese, silicon, or aluminum bronzes will give you a green finger after wearing it for a day, but after several months, all bets are off. If you want a noble (non-tarnishing) metal, use gold, platinum, rhodium, silver, etc. There's a reason for their use as jewelry.

 

[anon359]

They also happen to be obscenely expensive which is the reason one looks for alternatives. Clearly if money weren't an issue it'd be a no-brainer.

 

[btrueblood]

Then look at stainless steel with a TiN coating, as suggested back at post #3.

 

[EdStainless]

And if we are talking about skin contact remember, no Ni allowed.
Which is a shame because NAB looks more like gold and it is much more corrosion resistant.
For middle aged men in the US it isn't an issue, but among younger women in the US and EU the sensitivity to Ni is very high.
Over 35% will develop a reaction on contact to a Ni bearing alloy. Everything from SS to Ni plating.
They wore too much cheap Ni plated jewelry as children.

Use a martensitic SS (410) and TiN coat it. It will look great and be very durable.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[mrfailure]

What about aluminum anodized to a gold color?

 

[anon359]

How do you guys feel about ZrN(C) where the amount of carbon is used to adjust the color over TiN? I really can't help but feel like any kind of PVD or thin coating is just going to wear off under years of heavy use. I think some kind of alloy would be much better. I imagine it'd probably be easier to work with too since you wouldn't need to send it off somewhere to have the PVD done then risk damaging it later. Also, if using the PVD method what would be the preferred metal base? Titanium? Stainless steel? Tungsten Carbide?

 

[EdStainless]

It depends (I just love saying that) on the service.
You need a substrate that is corrosion resistant in the environment, and strong enough to not deform. A ferritic or martensitic stainless should work very well for this.
If you are talking about push plates on doors or things that just get touched then coatings on a hard stainless substrate should be very durable. Most of these coatings are hard, so they are wear resistant.
In places where there may be abrasive wear like stairs it gets more difficult.
One approach would be to use an alloy, but maybe not solid. An overlay of an expensive (and maybe not very strong) material over a stronger and less expensive substrate would work. In this case though instead of the coating being thin it would be much thicker.


= = = = = = = = = = = = = = = = = = = =
Plymouth Tube