Difficulty igniting Fe2O3/Al thermite mixture
Kiwihvguy, Tue Dec 01 2015, 02:54AMI'm having trouble igniting a mixture of thermite using magnesium ribbon. I made sure the iron oxide mixture was dry and had very little water content by heat drying it, and my aluminium powder is reasonably fine. It was ground with a coffee/seed grinder and the result was a mixture of very fine dust but the majority of the powder particles are about 0.5mm in size.
I understand the surface area of the aluminium powder has to be very high, so perhaps my powder needs to be even finer?
Re: Difficulty igniting Fe2O3/Al thermite mixture
Hon1nbo, Sat Dec 05 2015, 05:08AM
You may try shaving some magnesium into a powder and have it at the base of the ribbon entry.
I personally stopped using magnesium years ago due to reliability and safety concerns. I currently use an ignition mixture from United Nuclear for lighting my thermite. I dip electronic rocket ignitors from Aerotech in it. (I use Aerotech since you can get insulated leads easily, and thermite is conductive).
Cheers,
-Jim
Hon1nbo, Sat Dec 05 2015, 05:08AM
You may try shaving some magnesium into a powder and have it at the base of the ribbon entry.
I personally stopped using magnesium years ago due to reliability and safety concerns. I currently use an ignition mixture from United Nuclear for lighting my thermite. I dip electronic rocket ignitors from Aerotech in it. (I use Aerotech since you can get insulated leads easily, and thermite is conductive).
Cheers,
-Jim
Re: Difficulty igniting Fe2O3/Al thermite mixture
Down with Umbrella, Wed Dec 30 2015, 02:29AM
Try using a simple sparkler. Recently I was experimenting with this and I thought my ratios were off but the problem ended up being my ignition source was just too low. 99cent sparklers make great fuses.
Down with Umbrella, Wed Dec 30 2015, 02:29AM
Try using a simple sparkler. Recently I was experimenting with this and I thought my ratios were off but the problem ended up being my ignition source was just too low. 99cent sparklers make great fuses.
Re: Difficulty igniting Fe2O3/Al thermite mixture
johnf, Wed Dec 30 2015, 03:46AM
The sparkler idea is good one
your problem is that the aluminium is not fine enough
you need explosive grade Al powder ie sub micron particle size then even a match will ignite it.
johnf, Wed Dec 30 2015, 03:46AM
The sparkler idea is good one
your problem is that the aluminium is not fine enough
you need explosive grade Al powder ie sub micron particle size then even a match will ignite it.
Re: Difficulty igniting Fe2O3/Al thermite mixture
Hon1nbo, Wed Jan 27 2016, 12:45AM
Sparklers have safety issues as well. They are chaotic, and throw too many metal flakes before the flame reaches the base of the sparkler.
If you have made the Al that fine and it is actually explosive, then regulation issues come into play in most jurisdictions as well.
-Jim
Hon1nbo, Wed Jan 27 2016, 12:45AM
johnf wrote ...
The sparkler idea is good one
your problem is that the aluminium is not fine enough
you need explosive grade Al powder ie sub micron particle size then even a match will ignite it.
The sparkler idea is good one
your problem is that the aluminium is not fine enough
you need explosive grade Al powder ie sub micron particle size then even a match will ignite it.
Sparklers have safety issues as well. They are chaotic, and throw too many metal flakes before the flame reaches the base of the sparkler.
If you have made the Al that fine and it is actually explosive, then regulation issues come into play in most jurisdictions as well.
-Jim
Re: Difficulty igniting Fe2O3/Al thermite mixture
Enceladus, Thu Feb 09 2017, 04:59AM
Exactly right. The simplest method I have seen for getting from what you have to "fine enough" is with a ball mill. Either the drum tumbler type or the type where a turnstyle-like rotor pushes 4 large steel balls around a circular race filled with the powder. (I don't know the specific name of the second type.)
It probably wouldn't hurt to mill your oxide too.
FYI, Copper thermite is even more energetic than iron.
Enceladus, Thu Feb 09 2017, 04:59AM
johnf wrote ...
your problem is that the aluminium is not fine enough
your problem is that the aluminium is not fine enough
Exactly right. The simplest method I have seen for getting from what you have to "fine enough" is with a ball mill. Either the drum tumbler type or the type where a turnstyle-like rotor pushes 4 large steel balls around a circular race filled with the powder. (I don't know the specific name of the second type.)
It probably wouldn't hurt to mill your oxide too.
FYI, Copper thermite is even more energetic than iron.
Re: Difficulty igniting Fe2O3/Al thermite mixture
Hazmatt_(The Underdog), Fri Feb 10 2017, 03:43AM
I think you guys are overlooking the obvious here.
When you have Al powder that is not pure Al, like 6061 its hard to burn because of the alloying metals, so you make it burn easy!
You make up your thermite with an excess of iron oxide, then mix in the magnesium powder. The Magnesium consumes some of the iron oxide, but it gets it going, enough so that you can use a butane torch to light it. Just make sure you get the hell away fast.
Hazmatt_(The Underdog), Fri Feb 10 2017, 03:43AM
I think you guys are overlooking the obvious here.
When you have Al powder that is not pure Al, like 6061 its hard to burn because of the alloying metals, so you make it burn easy!
You make up your thermite with an excess of iron oxide, then mix in the magnesium powder. The Magnesium consumes some of the iron oxide, but it gets it going, enough so that you can use a butane torch to light it. Just make sure you get the hell away fast.
Re: Difficulty igniting Fe2O3/Al thermite mixture
futurist, Mon Feb 13 2017, 10:35PM
Thermite reaction starts when some of the aluminium melts. Sparklers are fine because sparks don't have enough heating
capability to do that. I've found that the most convenient method to start common thermite is potassium permanganate
with a bit of glycerol. That is if you don't have some commercial ignition mixture. If half a teaspoon of permanganate
fails to start a thermite there is something badly wrong with the mixture.
futurist, Mon Feb 13 2017, 10:35PM
Thermite reaction starts when some of the aluminium melts. Sparklers are fine because sparks don't have enough heating
capability to do that. I've found that the most convenient method to start common thermite is potassium permanganate
with a bit of glycerol. That is if you don't have some commercial ignition mixture. If half a teaspoon of permanganate
fails to start a thermite there is something badly wrong with the mixture.
Re: Difficulty igniting Fe2O3/Al thermite mixture
IamSmooth, Fri Mar 03 2017, 08:27PM
I remember setting off thermite in high school. I wound up putting a crater in my street road. It melted through everything. Anyway, the aluminum and rust were as fine a baby powder. I set it off with a magnesium ribbon without a problem. Once it starts you can not stop it until the fuel runs out.
IamSmooth, Fri Mar 03 2017, 08:27PM
I remember setting off thermite in high school. I wound up putting a crater in my street road. It melted through everything. Anyway, the aluminum and rust were as fine a baby powder. I set it off with a magnesium ribbon without a problem. Once it starts you can not stop it until the fuel runs out.
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