# Microwave Magnetron - Checking for Gold



## rusty

When messing with the magnetron I would like to remind those new to the forum to be cautious of the purple ceramic, it contains Beryllium oxide which is very toxic. You do not want to break the ceramic and if by accident do not breath the dust.

That said we'll get on with the project, earlier on I had asked if these brassy wire mesh things had any gold in them, someone said they had tested one and found it did contain gold, with nothing further said on the topic.

I have decided to run a test myself tomorrow and will post the results - here.

For the curious folks, I have dismantled the magnetron to show you what is inside. There are two very strong magnets, some aluminum fins for cooling and a large copper piece that I have scraped off exposing fresh copper.

Later I'll cut the ends off the copper chunk using the lathe, inside the copper it's hollow with some small rings silver soldered together, this makes using this copper for cementing silver an excellent candidate.

I do not have power to run the lathe so there will be no pictures showing the insides of the copper piece.

Some very old microwaves I had taken apart had the ends to the copper gold brazed, I do not find these often.

Regards
rusty


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## rusty

Digested the gold looking mesh, No GOLD.


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## macfixer01

I believe it's Beryllium (oxide) that some magnetrons contain, not Barium. Magnetron-based devices are used for performing vapor deposition of Barium and other metals onto external surfaces though, which may have caused some confusion.


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## rusty

Inside the magnetron you will not the segments are brazed into place, at first I thought silver but with the obvious signs of discoloration of the copper and bluing surely indicate plenty of heat is being generated at the magnetron. I now have second thoughts about silver being used in the brazing.

The brazing material used for the copper segments could be anything from a ruthenium palladium or gold alloy.

Center electrode is thoriated tungsten.

Photo credits for the inside view of the magnetron copper go to wikipedia.

One of my pictures shows the insides of the safety thermostat, the contacts look to be gold plated . You will find 2 or 3 of these inside each oven plus an assortment of other limit switches along with a couple of relays.

Each magnetron has two large round magnets.


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## stihl88

I found a small fine strand of Pt in one of the microwave components from a microwave i helped take apart with a friend on our lunch break.

Ive often wondered what the different colored copper is inside the magnetron around the brazed areas, i would have thought theres no reason to use gold.
The copper is super shiny also, could be that the copper has changed to "Super Copper" :mrgreen: 

Perhaps a nitric test is in order!


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## Ocean

stihl88 said:


> I found a small fine strand of Pt in one of the microwave components from a microwave i helped take apart with a friend on our lunch break.
> 
> Ive often wondered what the different colored copper is inside the magnetron around the brazed areas, i would have thought theres no reason to use gold.
> The copper is super shiny also, could be that the copper has changed to "Super Copper" :mrgreen:
> 
> Perhaps a nitric test is in order!



What is the market price for "Super Copper" these days? 8)


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## rusty

Gleaned from a Samsung Patent, the brazing material comprises used in the magnetron is about 70% to 74% silver by weight.

So it looks to be the best option to use the copper from the magnetron for cementing silver.

Microwave ovens produced 1980's and before are possible to have used precious metals alloyed into the brazing material.


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## rusty

Small target in the center of the copper has had some metal sputtered onto it, maybe turn out to be something precious.

The targets are non magnetic, they react very vigorously with nitric, acid solution turned brown, highly indicative of palladium.

Have you tested that with Stannous or DMG - Not yet.


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## qst42know

From your photo I can't detect any braze lines. Have they done away with a segmented assembly for a one piece extrusion? 

Looks a bit like wheel pasta. :lol:


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## rusty

qst42know said:


> From your photo I can't detect any braze lines. Have they done away with a segmented assembly for a one piece extrusion?
> 
> Looks a bit like wheel pasta. :lol:



Looking at the segments under 30x magnification, your right the copper is a one piece extrusion with the exception of the rings having been brazed on.

Thats a first for me, never even thought they could extrude copper.


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## qst42know

With the low cost of microwaves these days they have to shave every nickel out they can. What are they about $50 maybe less on sale?

They are doing some amazing things these days in metal forming. My brother works for a company that injection molds powder metal in a wax carrier. Once the wax is burned off and the part sintered they perform as well as machined from solid. Complex very accurate pieces can be produced requiring very little if any finishing.

http://www.netshapetech.com/


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## rusty

Eight coppers from microwave magnetron's weigh 1.35 lbs


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## rusty

rusty said:


> Small target in the center of the copper has had some metal sputtered onto it, maybe turn out to be something precious.
> 
> The targets are non magnetic, they react very vigorously with nitric, acid solution turned brown, highly indicative of palladium.
> 
> Have you tested that with Stannous or DMG - Not yet.



After digesting the targets in nitric acid I'm left with a brown precipitate, negative for palladium testing with DMG.

After stirring the precipitate settles out very quickly, now to figure out what the hell I got here in that test tube. 

The target is brittle and breaks easy, I do not think that is is tungsten as this metal reacts very slow to nitric acid but fairly quick in AR. So far I have only used nitirc acid and the metal dissolved fairly quick with out applied heat.


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## qst42know

From the first couple sentences of the abstract you may have some platinum group elements present or one of the simpler tungsten alloy versions.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6THY-3W0JVYW-4D&_user=10&_coverDate=02%2F03%2F1997&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1695371040&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=37de5232e485da27b1d3e744243bf738&searchtype=a

If you suspect rhenium you may want to ask Lou what safety precautions may be needed to work with it.


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## qst42know

Isn't tungsten soluble in hydrogen peroxide?


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## qst42know

This may help.

http://books.google.com/books?id=foLRISkt9gcC&pg=PA54&lpg=PA54&dq=tungsten+soluble+in+hydrogen+peroxide&source=bl&ots=-ssFAaoXCY&sig=xE2nZJLCxu2WTJvI066OnX07lkM&hl=en&ei=FKyPTZPpHaSN0QH9tdisCw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCsQ6AEwAg#v=onepage&q=tungsten%20soluble%20in%20hydrogen%20peroxide&f=false


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## rusty

I'll be the first to admit that I do not have any clue to what I' doing, and that this post maybe the last one for this experiment.

The metal being digested is the target from the center of the microwave magnetron. Non magnetic, very brittle, attacked by dilute cold nitric.

The target first test tube subjected to dilute nitric acid turned the solution green with a salmon pink precipitate

Sample from first test tube after heating turned the solution yellowish with salmon pink precipitate. .

Small sample, not incinerated which left some nitric residue, with the addition of hydrochloric acid turned the solution a reddish color with no precipitate left behind.

Last test tube, precipitate in Ar, solution is burgundy red, some precipitate left but the AR is working vigorously on it.

With out a clue as to what I should be testing for, the best idea I'm able to come up with is to filter the AR then see if anything will cement down with copper scraps. But this will not tell me what I have, only that it is something below copper in the electromotive series. Which would indicate precious metals.


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## qst42know

Anything cement on copper from the AR solution?


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## rusty

qst42know said:


> Anything cement on copper from the AR solution?



You posted same time I was editing my post, that is exactly what the plan is. Cement with copper.

Perhaps one of our valued chemists could comment on the color of the AR

Regards
rusty


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## stihl88

I didn't think Tungsten could be attacked with Nitric?


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## rusty

As I write this the metals in my AR solution are being precipitated, an interesting observation.

When I remove the copper wire there is enough solution on it to react, the reaction I'm going to gamble on is photosensitive and not a reaction to air.

The wire comes out bright and shiny then gradually an inky blue film forms that gradually turns darker. If you have the patience to watch the short youtube video you will see the change taking place.

[youtube]http://www.youtube.com/watch?v=4Vbuvxh-49Q[/youtube]

This picture shows just how dark the inky blue film becomes after exposure.


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## qst42know

So do you figure there is enough to go after or just enough to satisfy your curiosity?


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## rusty

qst42know said:


> So do you figure there is enough to go after or just enough to satisfy your curiosity?



Enough of what.

How do I place value on an unknown substance.

The pictures below are the precipitate from the AR.


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## rusty

From the remaining solution, I diluted a bit in a test tube with water then added 8 drops of DMG - no visible reaction. 

Next I poured some of the reaming solution onto a filter paper then added stannous, instantly turned green. Same results using a Q-Tip.

Here is a short youtube of the reaction. No gold in microwave just some palladium to the sputtering target from inside the copper vacuum tube. I have not conducted any tests to see if there is anything beyond silver in the contact. The weather is warming up, no more time to play the summers are too short to waste.

I've enjoyed doing these little experiments.

[youtube]http://www.youtube.com/watch?v=OlaxJ8gx-z0[/youtube]


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## Barren Realms 007

You might want to go bck nd try the test again, I don't think you used enough test solution and it might need a couple more drops to get a better test result. Uh I do. :mrgreen:


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## rusty

Barren Realms 007 said:


> You might want to go bck nd try the test again, I don't think you used enough test solution and it might need a couple more drops to get a better test result. Uh I do. :mrgreen:



Yea I thought I was short on using the DMG myself and added about 12 drops to be sure, anyhow I went outside a moment ago to check on the test tube and here is what I found.

The DMG has reacted with something in the solution turning it inky blue. Does anyone here have an idea what would react with DMG to give this color.


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## patnor1011

DMG was dissolved in isoprophyl alcohol. Maybe alcohol reacted with something in there?


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## Harold_V

rusty said:


> The DMG has reacted with something in the solution turning it inky blue. Does anyone here have an idea what would react with DMG to give this color.


I routinely got an inky blue reaction when washing cemented silver that came from tungsten bearing contacts. I'd wash with HCl, which instantly developed the color. I have no clue if or why DMG is responsible for the color you see.

I almost never tested in volume. There's nothing you can determine in a test tube that can't be determined by a single drop in a spot plate cavity. 

Harold


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## lazersteve

There are lots of metals that will make blue solutions.

Yours looks dark blue to me, I'd guess it may be cobalt, no guarantees though.

Steve


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## NoIdea

Evening All – I know this an old post, but it sort of ended….

Have you tried the borax bead test, Cobalt is the only metal I can find that gives a blue positive for the hot and cold test.

Deano


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## copycat

This is not brass, too shinny. I compared some PCI gold fingers to them. Match exact in color.


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## Auggie

There are minute amounts of silver (in the keypad mylar) and sometimes gold (in the PCBs as copycat points out) in microwave ovens, but for the most part they are copper (transformer, and you will find the magnetotron has a nice slug of copper in it if you cut one open) and steel mines. I'm surprised rusty was able to find palladium in the magnetotron, but I would gather it's not enough to even lick off.

The old microwave ovens sometimes have large gold-laden mylars, and the really old ones sometimes even have phenolic PCBs with gold plating for where the keypad buttons are pushed.


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## jimdoc

Auggie said:


> you will find the magnetotron has a nice slug of copper in it if you cut one open)
> 
> Watch for beryllium in the magnetron, you don't want to cut into anything with the hazards of beryllium dust. It wouldn't be worth it for precious metals let alone copper.
> 
> Jim


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