# Aluminum and "Gold"



## GoldRob (Jan 19, 2022)

I came across so military grade scrap so time ago and this was a part of it. It is aluminum and a gold like coating. I dropped a small sample in some muratic and the reaction was instantly for aluminum, but it did not dissolve the gold "plating". I don't believe it is gold. Because why gold plate a cover. Should I take to the scrap yard for aluminum or possible soak in saltwater for some time
E.


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## Martijn (Jan 19, 2022)

Scrape off a piece of the plating and test with a drop nitric if it dissolves.
If it doesn't, add a drop of HCL and test with stannous.


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## justinhcase (Jan 19, 2022)

Martijn said:


> Scrape off a piece of the plating and test with a drop nitric if it dissolves.
> If it doesn't, add a drop of HCL and test with stannous.


Yes, anything you can do to separate the metals manually will save you effort later.
Some would try and dissolve the main body of alloys, effective but completely uneconomical.


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## Quiklearner (Jan 19, 2022)

Being a military application, it is possible that the aluminum has been electro-chemically treated (anodized) for corrosion resistance giving it that golden appearance. Be careful that it isn't beryllium.


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## snoman701 (Jan 19, 2022)

Your lighting is rough, so I can't tell, but gold plated aluminum is a thing. There is a nickel plate put on the aluminum, then gold is plated over top. Sometimes it can be quite valuable, sometimes not.


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## GoldRob (Jan 20, 2022)

Thanks everyone for the replies and advice. This is all the Nitric that I have. I will take better pictures. The fist one was with flash and with out. I have an Idea. Going to test it with this.


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## GoldRob (Jan 20, 2022)

10k, 14K, 18K, and 22K. I don't know what this proves. I could be some sort of paint. This is the very first time using this test kit. Any help in determing these results would be much appreciated. I started on the left with 10k, than to the right to 22k. I left it like that for about 5 minutes. Which is the last photo.


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## GoldRob (Jan 20, 2022)

I was trying to get a close up of the scratch area. Underneath of the "gold" area looks like copper. I know that one I am pretty sure was aluminum, when using muratic on a small piece related, but when the reaction was over. The gold pice was still in tact.


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## Martijn (Jan 20, 2022)

Gold dissolves in Aqua Regia and can be tested with stannous to see if that what dissolved is actually gold. 

Those testing solutions are to compare the reaction to a known carat sample. To be used to determine the minimal gold content of items that are made of carat gold. 
Really, it could be anything until you test it.


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## GoldRob (Jan 20, 2022)

I could flat rate this piece to anyone who could test it. I am on Oahu and dealing with acid over here is like dealing with radioactive waste. If any on Oahu has the means please let me know. If anyone from the states could test I could work out some kind of arrangement.


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## JohnH2300 (Jan 20, 2022)

Quiklearner said:


> Being a military application, it is possible that the aluminum has been electro-chemically treated (anodized) for corrosion resistance giving it that golden appearance. Be careful that it isn't beryllium.


I worked in the corrosion shop my last year in the Navy, the color is pretty close if anodized but I never anodized anything with that kind of pattern.


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## JohnH2300 (Jan 20, 2022)

GoldRob said:


> I came across so military grade scrap so time ago and this was a part of it. It is aluminum and a gold like coating. I dropped a small sample in some muratic and the reaction was instantly for aluminum, but it did not dissolve the gold "plating". I don't believe it is gold. Because why gold plate a cover. Should I take to the scrap yard for aluminum or possible soak in saltwater for some time
> E.


Would you happen to know what that plate came from? I worked corrosion shop as well as avionics years ago.


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## GoldRob (Jan 20, 2022)

John I believe this was a board called Eclipse. I think they are now BAE.


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## Lino1406 (Jan 21, 2022)

That can be some nitride


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## Lou (Jan 21, 2022)

Looks like gold plated RF equipment to me. Happens all the time.


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## nickvc (Jan 21, 2022)

Remember aluminum will also dissolve in lye and other strong bases which is why trying to cyanide strip it will not work so to recover the gold you will have to dissolve it completely or maybe try reverse AR where you cover the material in nitric which passivities the aluminum and add very small increments of HCl to just dissolve the gold, not tried that method on aluminum so start with a small experiment to see whether it works .


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