Sciencemadness Discussion Board

aluminium powder Eckart 5413H and 5481H

woelen - 3-2-2016 at 04:57

I am experimenting with thermites and oxide mixes recently and for this purpose I purchased some Eckart aluminium powder. The seller where I could purchase aluminium has two kinds of aluminium powder, the one denoted as Eckart 5413 Super H and the other as Eckart 5481 Super H. I purchased the latter, because it was somewhat cheaper. It is a dark grey powder, nearly black.

The material which I have works fairly well with oxides (I tried with Bi2O3 and with CuO). With the Bi2O3 it burns like a sparkler, with CuO it does not work safely, the reaction is WAY too violent, actually it explodes :o and gives a brown cloud of smoke.

What is the difference between these two kinds of aluminium powders? If I do a google search I find no info, only links to sellers of the stuff (mostly eBay sellers). If I understand correctly, the Eckart powders are intended to be used as pigments. I use it for chemistry experiments.

Why don't they simply specify the properties of the Al-powder? Or are 5413H and 5481H well-known codes (which I am unaware of) which tell something about the properties of the material? They certainly do not seem standardized codes in the world of chemistry.

NedsHead - 3-2-2016 at 05:37

Interesting, I searched and as far as I can tell 5481 and 5413 are Eckart codes for for particle size, 5481 being 5000 mesh and possibly no longer in production, no idea what the "super H" denotes.

I found a listing on Ebay advertising "Military Grade Eckart 5413H Aluminum Powder German Blackhead Dark 5413 Indian" if that wording at all helps.

while searching I discovered that stearin is milled with Aluminium to make German dark Aluminium powder, I thought that was a useful little discovery
https://en.wikipedia.org/wiki/Stearin

[Edited on 3-2-2016 by NedsHead]

Praxichys - 3-2-2016 at 05:52

According to various sources, 5481H is no longer produced. This is confirmed by the Eckart website.

Technical data for the 5413 can be found here:
http://www.eckart.net/uploads/tx_driveeckartproducts/EE-0475...

And I think an equivalent to the 5481 might be this:
http://www.eckart.net/uploads/tx_driveeckartproducts/EE-0471...

Unofficially, a search of various forums and stores reveals the following properties:

Active metal Content:
5481 = 92%
5413 = 80%
PYRO UZ = >91%
Average Particle size:
5481 = 2-3 micron (4000-5000 mesh)
5413 = 15 micron (listed as 325 mesh)
PYRO UZ = 95% passes 45 micron (~325 mesh)

Unfortunately there is a lot of 'salesmanship' tainting the credibility of data gleaned from online shops. I'm curious myself, but this is all I could find in a cursory search.

Do you have a microscope? Perhaps examining a sample of each will shed some light on this.

careysub - 3-2-2016 at 08:46

A description (with a microphotograph apparently) of Eckart #5413-H Super is found here on the Skylighter site.

Skylighter is a long-established, very well known pyro dealer whose descriptions are reliable I think. Eckart #5413-H is described as a 3 micron stearin coated powder.

http://www.skylighter.com/german-dark-aluminum-powder.htm

I have Indian blackhead aluminum from Skylighter which is an 8 micron coated powder for doing thermite reactions. I thought 3 micron was too fine (8 micron might be also). Haven't used it yet though.

woelen - 3-2-2016 at 10:11

I do not have a microscope, but the powder which I have must be very fine. It has a dark gray silk-like look and its density is low. An amount of 200 grams fills up a decent glass jar of 400 ml or so. The powder is free flowing, it can be poured easily from a spoon. Everything which comes in contact with the powder becomes covered with a grey layer. Even rubbing with a piece of tissue paper does not completely remove the grey stain, which makes working with the powder quite annoying. I expect that to be caused by the extremely small particle size.

I only have the 5481H powder, I cannot speak about 5413H.

[Edited on 3-2-16 by woelen]

Detonationology - 3-2-2016 at 10:26

I was under the impression that just about all copper based thermites were susceptible to exploding. I've never made it myself, but I have seen many videos of this occurrence.

https://www.youtube.com/watch?v=QRqFRCTnYNY

https://www.youtube.com/watch?v=CrG1n7Av_z8

https://www.youtube.com/watch?v=eCeqcrJTfjs

phlogiston - 3-2-2016 at 11:12

The numerical codes do specify some information about the alloy. The system is described in an ANSI standard, (but the ISO and CEN standards conform to the same number system)

In the 5xxx series of alloys, magnesium is the main alloying element
The other digits specify modifications of the original alloy composition or specify the purity of the aluminium.

The H indicates the temper (H=strain hardened).

This document explains it in some detail: http://www.european-aluminium.eu/wp-content/uploads/2012/01/...

It is my experience too that CuO/Al explodes. I was planning to try compressing it to form pellets to see if it would slow the reaction down, but never found the time.

IrC - 3-2-2016 at 11:54

Quote: Originally posted by phlogiston  
It is my experience too that CuO/Al explodes. I was planning to try compressing it to form pellets to see if it would slow the reaction down, but never found the time.


Wouldn't the simpler approach be going up in size of the particles. Has anyone experimented with using Al milled to be no smaller than say 25 microns? Or doing a series of experiments stepping the size up to where the reaction behaves more like a thermite with reaction rates too slow to explode?

MrHomeScientist - 3-2-2016 at 13:58

The one time I attempted the CuO thermite it reacted very quickly and sputtered a lot, but wasn't particularly violent. Skip to 2:50 in my thermite compilation video.

My hypothesis is that since the CuO was home made, it may have been full of reaction-slowing impurities.

Don't worry, I knew of it's reputation and ran far away after I started the ignition countdown (adding glycerin to the KMnO<sub>4</sub>;).


Also I have some experience with particle size. For the longest time I could not get a chromium(III) oxide thermite to work, but switching to a finer aluminum powder did the trick. I think my original Al was 80 mesh, and I now use 400.

[Edited on 2-3-2016 by MrHomeScientist]

Herr Haber - 3-2-2016 at 16:08

Quote: Originally posted by careysub  


I have Indian blackhead aluminum from Skylighter which is an 8 micron coated powder for doing thermite reactions. I thought 3 micron was too fine (8 micron might be also). Haven't used it yet though.


I have ignited 63 microns atomized (spherical) mixed with Iron Oxyde from the pigments store with simple visco fuse.
So yeah, I'd say yours is too fine for that. Keep if for things that you want to go boom ;)
On the other hand, the finer the particles, the lesser the density so maybe coarser aluminium with coarser Fe Oxyde will get you better results at what you are trying to burn through (I use old frying pans!). I'm pretty sure that in this case the source of ignition should also be a lot hotter (Mg ribbon?)

Herr Haber - 3-2-2016 at 16:19

Quote: Originally posted by IrC  
Quote: Originally posted by phlogiston  
It is my experience too that CuO/Al explodes. I was planning to try compressing it to form pellets to see if it would slow the reaction down, but never found the time.


Wouldn't the simpler approach be going up in size of the particles. Has anyone experimented with using Al milled to be no smaller than say 25 microns? Or doing a series of experiments stepping the size up to where the reaction behaves more like a thermite with reaction rates too slow to explode?


Yes yes yes! Totally agree! Besides from Copper Oxyde, Mn Oxyde is even more explosive so there's nothing to recover usually.

So for me, the idea is to recover "some" of the pure element for my collection and the simple pleasure of saying "I did it".

I have some ultra fine and pure SiO2 collected from a quarry nearby my home. Suffice to say that during WW2 it was considered of sufficient strategic importance to be sent by U-boat to Japan for the manufacture of optical instruments.
There are 5 quarries with sand of that quality on the planet I've been told. Sure, since WW2 more processes were developpend to have "pure" SiO2 but I dont think I have to explain to my fellow mad scientistist why I want to extract Silicium from this sand !

careysub - 3-2-2016 at 16:46

Quote: Originally posted by Herr Haber  


Yes yes yes! Totally agree! Besides from Copper Oxyde, Mn Oxyde is even more explosive so there's nothing to recover usually.


For a less violent reaction go with a manganese in a lower oxidation state than manganese dioxide (MnO2, Mn(IV) oxide).

Choices are Mn2O3 (Mn(III) oxide) or Mn3O4 (Mn(II,III) oxide) or MnO (Mn(II) oxide). MnO2 can be reduced to these lower states.

Lead dioxide thermite also produces an explosive reaction, and um, lots and lots and lots of lead vapor. Don't try this near any inhabited area.

MrHomeScientist - 4-2-2016 at 06:03

Quote: Originally posted by Herr Haber  
Yes yes yes! Totally agree! Besides from Copper Oxyde, Mn Oxyde is even more explosive so there's nothing to recover usually.

Again, that hasn't been my experience. Manganese dioxide thermites are slightly more energetic than iron oxide, but are nowhere near explosive. I've done many of them. See 1:22 in my video linked above. The problem recovering metal from manganese thermites is not that they are 'explosive', but that the boiling point of manganese is very close to the temperature the thermite runs at. Thus most of the manganese boils off during the reaction, greatly reducing yield. That said, I've been able to recover nice Mn nodules from MnO<sub>2</sub> thermites.
A different oxidation state of Mn would be interesting to try sometime. You'd still run into the boiling point problem, though.

[Edited on 2-4-2016 by MrHomeScientist]

blogfast25 - 4-2-2016 at 06:37

Quote: Originally posted by MrHomeScientist  
The problem recovering metal from manganese thermites is not that they are 'explosive', but that the boiling point of manganese is very close to the temperature the thermite runs at. Thus most of the manganese boils off during the reaction, greatly reducing yield. That said, I've been able to recover nice Mn nodules from MnO<sub>2</sub> thermites.
A different oxidation state of Mn would be interesting to try sometime. You'd still run into the boiling point problem, though.



The idea that lower Mn oxides can solve the problem of low yield is lalgely a myth. I tested that with homemade MnO (from pyrolysis of MnCO3 under CO2 blanket) and noted no improvement at all.

That's because the problem is Mn's 'low' BP of 2061 C, so close to the MP of alumina, as now has been pointed out ad nauseam. To get metal/slag separation you have to exceed the MP of alumina, so by definition the vapour pressure of the Mn will always be close to 1 atm.

30 % yield is about the most you can hope for with a well-designed MnOx thermite.

Herr Haber - 4-2-2016 at 15:43

Quote: Originally posted by MrHomeScientist  
Again, that hasn't been my experience. Manganese dioxide thermites are slightly more energetic than iron oxide, but are nowhere near explosive. I've done many of them. See 1:22 in my video linked above. The problem recovering metal from manganese thermites is not that they are 'explosive', but that the boiling point of manganese is very close to the temperature the thermite runs at. Thus most of the manganese boils off during the reaction, greatly reducing yield. That said, I've been able to recover nice Mn nodules from MnO<sub>2</sub> thermites.
A different oxidation state of Mn would be interesting to try sometime. You'd still run into the boiling point problem, though.

[Edited on 2-4-2016 by MrHomeScientist]


Ok, understood. So what to the naked eye looks like a more explosive reaction than Fe or even Cu thermites is just Mn boiling and vaporizing. I sure wasnt comparing to an EM explosion but now I understand better what I saw. This would also confirm why the Cu thermites "appear" more explosive and less Cu is recovered because of it's boiling point right?
The only time I did a whole flower pot Cu thermite there wasnt much left in the flower pot (which cracked...), but I do remember there were a lot of shiny copper balls all around the test site (a limestone quarry this time, it was easy to spot on the white floor). I remember I was glad I ran further for this test than for the Iron thermite ;)

Well, I'll stick to the SiO2 test I had in mind then ! The trouble with the formulations seen here and there seem that I'll have a lot of impurities (some use sulfur as a tinder). But then, I have a whole quarry at my disposal to make all the tests I want.
Sorry for wandering off topic and thanks again all of you for your input.

[Edited on 4-2-2016 by Herr Haber]

Bert - 4-2-2016 at 21:46

I would suggest a coarser grade of atomized Aluminum if you want to have the reaction products more localized after a Goldschmidt reaction. Surface area of the reactants is closely correlated to reaction rates, if you want something less spectacular and are not constrained by ease of initiating the reactions, use the coarse stuff.

A great deal of hands on experience in reaction rates versus particle size and shape informs those of us who design and compound pyrotechnic mixtures.

One of your Al flake powders was primarily marketed for pyrotechnic use in flash powders. The other was aimed more at the pigments and coatings sector, but saw use in pyrotechnics as well. Neither would be my choice if KABOOM! was not intended.

The CuO/Al mixture with very fine flake Al powders has been used in aerial salutes and movie SFX explosion simulations, it is a bit "frisky" for making and retaining a nice button of reduced metal.

chipwit - 9-8-2016 at 14:03

Cu2O/Al is used to weld copper conductors to the rails on railroads. While working for the railroad, I did a little conductor welding and the mixture also had some metallic copper in it. The components were also pretty coarse, about sand sized.

careysub - 9-8-2016 at 15:17

Quote: Originally posted by blogfast25  


The idea that lower Mn oxides can solve the problem of low yield is lalgely a myth. I tested that with homemade MnO (from pyrolysis of MnCO3 under CO2 blanket) and noted no improvement at all.

That's because the problem is Mn's 'low' BP of 2061 C, so close to the MP of alumina, as now has been pointed out ad nauseam. To get metal/slag separation you have to exceed the MP of alumina, so by definition the vapour pressure of the Mn will always be close to 1 atm.

30 % yield is about the most you can hope for with a well-designed MnOx thermite.


Unless someone designed a manganese collection retort and ran it under a CO2 atmosphere.

Would not the vaporizing manganese reoxidize in air and add to the apparent energy of the reaction?