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Dangle89
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Sweet  I have 85% H3PO4 here already
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Tdep
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Quote: Originally posted by Dangle89  | What are some OTC glass etching solutions?
I'm fairly sure all HF (even those low concentration rust removers) products have been banned in AUS. Either for health reasons or because they
figured someone was gonna buy cheap $5 rust remover, then spend a bazillion dollars on an UF6 enrichment plant for their back yard  |
While not cheap, Mitre 10 does stock solutions of ammonium bifluoride as a tile enchant. Sort of expensive but just an acidification from OTC HF. Not
that i'd recommend it, how they can sell a product with only a tiny 'poison' sign on it surprises me.
Oh and more Aussies! We really are making a surge here, before long we'll have our own subforum!
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j_sum1
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Hey! I'm not an aussie. I just live here!
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Dangle89
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| Quote: Originally posted by Tdep |
While not cheap, Mitre 10 does stock solutions of ammonium bifluoride as a tile enchant. Sort of expensive but just an acidification from OTC HF. Not
that i'd recommend it, how they can sell a product with only a tiny 'poison' sign on it surprises me.
Oh and more Aussies! We really are making a surge here, before long we'll have our own subforum! |
Wow! That is good to know  Maybe one day if I feel like having a high chance of
dieing I might buy some to try and make some F compounds
I cant believe you can buy such a dangerous chemical at a hardware store, no questions asked! From what I was reading on DFAT it looked like you might
have people with guns smashing through the skylights just for looking at it! Was on the same list as Pu and U compounds!
Yeah I have been very surprised at the amount of aussies that have reached out to me since joining
Thanks for the warm welcome everyone
Dangle
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Dangle89
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Actually, on thing that have a chance of killing you I was chatting to a mate
about an easy way to make very small amounts of fairly pure HI.
He suggested possibly Hydrazine (N2H4)(aq) + I2(s) = HI(aq) + N2(g) - Not balanced.
I know there are other posts on making HI but figured I would quickly chuck this in here (happy to move it if it becomes a massive discussion)
Just looking for a Yes / No answer.
Looking at making kinda 5-10ml of HI at a time and If I bought 500ml It would probably degrade to I2 and water long before I could use it all! And
really couldn't be assed to set up a distillation setup for 10ml!
Again happy to move this somewhere if that would be more appropriate!
Oh, also Al powder is on its way so NaxWO3 will be attempted soon!
Dangle
[Edited on 2-8-2015 by Dangle89]
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deltaH
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Well let's hope with a properly tweaked thermite, you can get the 'bronze' to melt, then there will be no need for HF compounds.
I said earlier that you could probably fuse your tungstic acid and sodium tungstate simultaneously to make a polytungstate soda 'glass', but it
occurred to me that your crude tungstic acid probably has a variable amount of water.
It would probably be best to fuse them separately to first prepare anhydrous WO3 and Na2WO4 each, probably easier then to weigh an accurate ratio so
as to hit a 'x' = 0.9 for sodium in the final stoichiometry and maximise the gold colour.
Please take lots of photos, we love photos 
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Dangle89
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Should be all good
Good ol wiki says H2WO4 decomposes at 100C so will chuck a few grams on the hotplate at 140-160C before I start
Will do with the photos!
So far, different methods to try are:
1. Heat WO3 with Na2WO4 in a crucible with a MAP gas torch while carbon electrodes sit in the mix attached to a 12V battery.
2. After more research, maybe ignite a mixture of WO3 and Na metal. If something seems to work here I will also use a chunk of Li metal And if I feel REALLY keen maybe with K metal...  Probably not gonna do the K though!
3. A thermite mixture of Al, WO3 and Na2WO4.
If method 1 doesn't work can use the "glass" for method 3
Have I missed anything or any other ideas?
Also will start off (after very very small milligram tests to make sure It won't blow half of Canberra up!) with total mixtures of a MAX of 1g (WO3 +
Na metal will be less!) but do you reckon I should use a piece of Mg ribbon to get it going? I will probably be able to answer my own question after
the micro tests but just worried about contaminating the product more  Any other
Ideas for starting a thermite reaction "safely" without adding any foreign matter to the mix?
Cant wait!!!
Dangle
[Edited on 2-8-2015 by Dangle89]
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Dangle89
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Was thinking... If I put a small prill of I2 on some Al powder and dropped a drop of water on it to start a small AlI3 reaction would that have enough
heat to start the other main reaction?
It does not look like a WIx compound exists. NaI is easily water soluble as is AlI3 so if the reaction has enough energy to start the thermite one we
might have a winner!
Then I could easily set up a water drip system that gives me time to run to a safe distance
Edit - Just found WI4 exists but don't think it is easy to make. couldnt find any info on synthesis.
Thoughts anyone?
[Edited on 2-8-2015 by Dangle89]
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deltaH
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This thermite should start easily IMHO because the oxidant is a low melting glass. I'd use a magnesium ribbon if you have it. The contamination should
be minimal and besides, that will simply form MgO, really pretty much similar to Al forming Al2O3.
I would start with option 3 and use the others as fall-back options, it's so much simpler than 1 and 2... no need to make your life that difficult!
*******************
You can try your hand on some simple jewellery castings, e.g. pendants, if you can get it to melt. I wonder what the density of tungsten bronze is?
Probably less than WO3, i.e. ~7g/cm3.
[Edited on 2-8-2015 by deltaH]
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Dangle89
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Ok sounds good
Was just worried that there would be a higher affinity to form MgWO4 rather than NaxWO3.
MgWO4 is a type of Wolframite.
http://arxiv.org/ftp/arxiv/papers/1107/1107.0160.pdf
Did some more research and MgWO4 has pale blue luminescence so if I end up with something that is a golden colour with a almost Osmium like blue tinge
in the sun I reckon that would look even more amazing!
https://en.wikipedia.org/wiki/Phosphor
Don't know much about luminescence but it says MgWO4's wavelength is 473 nm, which is in the visible light range, so would it look light blue in
sunlight?
Might have too make some MgWO4 as a side project now too
Wow when I started this I thought W compounds were boring! How wrong I was
Yup have gold and sliver smithing equipment here so if looks as amazing as I am hoping will definitely be wearing the product around
[Edited on 2-8-2015 by Dangle89]
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deltaH
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Indeed, but let's get the thermite to work first. It's easy to forget, with a name like "tungsten bronze" that these things are in fact mineral
materials. Getting them to melt and more specifically, survive intact, is probably not going to be easy.
The product is going to be polycrystalline, so there could well be issues with it being too brittle. There's also strain and rates of cooling that
could affect things, so it might just blow up in complexity, excuse the pun.
While I'd love to be wrong, my gut feeling says this will make tiny grains of the stuff, similar to making a silicon thermite? Those grains may be
well mixed with Al2O3 which will complicate matters... but time will tell.
Might just end up with a tungsten glitter powder when all is said and done
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Oscilllator
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| Quote: Originally posted by battoussai114 | | Jokes aside, I think phosphoric acid also attacks Aluminum Oxide and it should be available OTC, not sure how it would react with the tungsten
bronze... |
I have bought 30% phosphoric acid OTC as a rust remover in Australia, however it turned out to be in the form of a horrible milky emulsion. I didn't
really try to separate it, but one possible way would be neutralise the acid with your cheapest base then crystallise out the sodium phosphate.
Re-acidification should yet you the acid back along with some salt contamination.
You could of course try and extract the milky stuff with a solvent, but I really don't think that will work.
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deltaH
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Do we really know that phosphoric acid can dissolve calcined aluminium oxide for sure? The latter is tough as nails i.t.o it's chemical
inertness (high T increases crystallinity at the expense of reactivity). Does anyway have a reference for this? To be honest, I'm very sceptical about
this...
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battoussai114
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| Quote: Originally posted by deltaH | | Do we really know that phosphoric acid can dissolve calcined aluminium oxide for sure? The latter is tough as nails i.t.o it's chemical
inertness (high T increases crystallinity at the expense of reactivity). Does anyway have a reference for this? To be honest, I'm very sceptical about
this... |
Dunno about calcined alumina, but:
http://jes.ecsdl.org/content/143/2/619.abstract
http://www.phosphatesfacts.org/pdfs/PhosphatesMetalFinishing...
http://www.google.com/patents/US5389194
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deltaH
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Thanks battoussai114, as I understand it, these are polishing techniques for very thin layers of aluminium oxide.
Aluminium phosphate is insoluble, so I doubt very much that phosphoric acid can be used to dissolve bulk alumina.
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battoussai114
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| Quote: Originally posted by deltaH | Thanks battoussai114, as I understand it, these are polishing techniques for very thin layers of aluminium oxide.
Aluminium phosphate is insoluble, so I doubt very much that phosphoric acid can be used to dissolve bulk alumina.
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Sorry, my bad! forgot about how phosphates tend to not be soluble and just expected that longer etching times would lead to further dissolving of the
oxide layer, or the alumina in the case of the bronze experiment.
In this case I agree that the acid wouldn't dissolve alumina... back to HF I guess. =/
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deltaH
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No worries. Aluminium chloride, on the other hand, is very soluble and according to Wikipedia:
| Quote: | | Hydrated aluminium trichloride is prepared by dissolving aluminium oxides in hydrochloric acid. |
However, no reference is provided 
It would be nice to have looked up the details on that, e.g. temperature and time in acid, nature of the alumina, etc.
Perhaps one needs hot acid and a long time. Again, effects on the bronze unknown.
In some respect, tungsten bronze can be viewed as a kind of sub oxide of tungsten, so if it were to react with HCl hypothetically, it would form
sodium chloride, water and tungsten chlorides. The latter hydrolyzes rapidly to the oxide, so I am guessing this dissolution in HCl in unlikely since
the reverse reaction is so favoured?
[Edited on 5-8-2015 by deltaH]
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Mesa
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@OP: Out of interest, how long did it take after dissolving the tungsten in H2O2(to make H2WO4) til WO3 began to precipitate out?
I've only made a soluble tungstic acid from HCl and a tungstate, I am wondering if there is a significant difference in decomposition rates.
[Edited on 5-8-2015 by Mesa]
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battoussai114
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Roughly 4 days to partially dissolve 0.5g tungsten sample took from a welding rod (pure tungsten rod, not those with additives) in a big excess of
peroxide. There was still a thin shell of tungsten left last time I checked and there was some bubbles coming off it, I'll check back tomorrow to see
how is it doing.
The Peroxide was 36% when I originally bought it, but I'm pretty sure it's way weaker now as It's been sitting in the lab for quite some time.
If anyone is interested I'm attaching a old publication on dissolution of tungsten in H2O2.
Attachment: ac60176a021.pdf (281kB)
This file has been downloaded 500 times
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blogfast25
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| Quote: Originally posted by deltaH | No worries. Aluminium chloride, on the other hand, is very soluble and according to Wikipedia:
| Quote: | | Hydrated aluminium trichloride is prepared by dissolving aluminium oxides in hydrochloric acid. |
However, no reference is provided
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Whether or not an aluminium oxide dissolves in acid depends on several factors.
Here's an Al2O3 for you:
https://en.wikipedia.org/wiki/Ruby
You think it dissolves in HCl/H2SO4? 
How about this one?
https://en.wikipedia.org/wiki/Bauxite
(A: NO!)
Freshly precipitated Al(OH)3, carefully dried will dissolve easily in dilute mineral acids but anything that has a bit of 'thermal history' is a real
question mark. That is true of many metal oxides, BTW.
[Edited on 5-8-2015 by blogfast25]
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deltaH
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Yeah, it's the usual story, which is why it would have been nice to see a reference on that wiki article. Like I said way back up in the thread,
calcined Al2O3 is tough as nails, I was exactly thinking of ruby
I don't see anything but fluorides having a chance to be honest and I think that is now consensus! Problem, is that fluorides may well dissolve the
tungsten bronze as well
Maybe we're lucky and the temperature get hot enough to melt/fuse the tungsten bronze, then simple physical methods of removing the Al2O3 would
suffice
[Edited on 5-8-2015 by deltaH]
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Dangle89
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Hello All
One of my girlfriends family members lost her unborn baby the other day so haven't had much of a chance to give the NaxWO3 any thought
Back on it now though!
Saw this video the other day:
https://www.youtube.com/watch?v=73YmP_JSrlU
Was wondering, if this fella managed to dissolve the left over Al2O3 from his thermite reaction, the Al2O3 from the WO3 / Al reaction should be able
to be dissolved too yeah?
Not sure if the NaxWO3 will dissolve / convert to different compounds but just wanted to check if, from the video above, people think that the "waste"
from this reaction would be the same or if we are back to using HF
Will be trying the NaxWO3 very soon and will post lots of pics on the thread soon :-) Keep an eye out and hopefully we might have something resembling
NaxWO3 soon!
Thanks everyone!
Dan
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j_sum1
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If that is MrHomeScientist's video, it works well. I have followed his method exactly and intend to do it again.
The thing about Si is that (a) it forms decent sized lumps in the thermite reaction and (b) it is completely impervious to attack by HCl. I wouldn't
guess the same from tungsten sodium alloy.
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deltaH
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'Sodium-tungsten bronze' is a very misleading name, it is NOT an alloy of tungsten and sodium.
It belongs to the group of materials known as perovskites AFAIK, just like some superconductors.
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j_sum1
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@deltaH.
Point conceded. (Actually I thought it was an intermetalic.) However, I still would not make assumptions about what acids it may or not be resistant
to -- not without some research.
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