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Author: Subject: Electroless plating Re on Mg
FragranceLover89
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[*] posted on 29-10-2020 at 16:05
Electroless plating Re on Mg


I attempted electroless deposition of Re on Mg to make a corrosion resistant Mg ring. I bought a sintered Re metal cylinder on ebay (XRD showed it matched Re) and put it in an ammonia/H2O2 solution to produce perrhenic acid. A gold colored iridescent film formed on the Mg after contact with the solution, which may have been a layer of Re. The ring later (4 months) oxidized in air and became rough. Adding vitamin c to the plating solution seemed to make an Re complex (red/orange color), however this did not effect plating on Mg. Mg and Re have similar crystal structures (hcp) and lattice constants. I don't know how safe Re is. Apparently tungsten and tungsten carbide are carcinogenic but Re seems more like manganese chemically so it might be safer?

I got the chance to melt some of the Re powder in a vacuum arc furnace and made a cool pellet (photo below).

* I just remembered I was inspired to do this after depositing a black (CuS) layer on Mg with copper/ammonia with some sulfide(?) while I was trying to de-tarnish silver. It was a really cool looking texture and surprisingly durable. If I remember correctly that solution was kind of a witches brew. It had borax, copper, gallium (very small amount), ammonia, magnesium, aluminum, and tarnished silver. The coating was really slick like boron but probably not boron. IDK.

IMG_0660.JPG - 1.5MB IMG_0661.JPG - 1.5MB

[Edited on 30-10-2020 by FragranceLover89]

[Edited on 30-10-2020 by FragranceLover89]

[Edited on 30-10-2020 by FragranceLover89]

[Edited on 30-10-2020 by FragranceLover89]

[Edited on 30-10-2020 by FragranceLover89]
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FragranceLover89
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[*] posted on 1-11-2020 at 19:57


Here is the rhenium coating ~1 year later. Note the golden yellow color.

IMG_0743.JPG - 458kBIMG_0744.JPG - 1.5MB
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[*] posted on 1-11-2020 at 23:56


I had a similar experience with zinc metal, added to an acidic solution of ammonium perrhenate. I added granules of very pure zinc to such a solution, hoping to get a nicely colored lower oxidation state compound in solution, but instead, the zinc became covered by a gold-colored (albeit much lighter than real gold) layer and the reaction quickly came to a standstill.

Rhenium metal does not have such a gold color. I have sintered rhenium pellets, 0.75 grams each, and these are grey. I also have a few square cm of rhenium foil. This has a silvery color. Maybe the mix of rhenium and the base metal on which the rhenium is plated has a more yellowish color?




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chornedsnorkack
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[*] posted on 2-11-2020 at 06:53


Rhenium trioxide is also described as a red solid with a metallic lustre resembling copper, insoluble in water and dilute acids and bases.
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[*] posted on 2-11-2020 at 18:42


I forgot to mention that this metal cylinder was originally clean white Mg. The dark spots also contain Rhenium. To get a lower oxidation state I would try adding vitamin C to perrhenates. I definitely saw a red/orange colored solution.

[Edited on 3-11-2020 by FragranceLover89]
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[*] posted on 2-11-2020 at 21:52


Quote: Originally posted by FragranceLover89  
I forgot to mention that this metal cylinder was originally clean white Mg. The dark spots also contain Rhenium.


Rhenium dioxide is described as gray to black.
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[*] posted on 3-11-2020 at 18:36


I am guessing you are right. It is likely a mixture of ReO2 and ReO3 in a super thin layer. It is iridescent so the gold color is likely due to thin film interference.
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