Sciencemadness Discussion Board

Binding Agent and Procedure for Electric Matches

malford - 26-6-2013 at 18:05

I am looking to produce an electric match for igniting a solid rocket motor. There are many posts and articles on the internet about doing this, but most involve nitrocellulose lacquer and black powder.

What are the other options for a binder?

Many solid rocket motor fuels use what I believe to be polyurethane which goes by the name of HTPB or R45 as the binder. I have never heard it mentioned, but it seems like this would be an option for electric match testing. Thoughts?

Also, I'd like to ask about something more novel: mixing PVC powder with the electric match composition, mixing with acetone to dissolve the PVC, applying to the electric match and drying. Any thoughts on this?

[Edited on 27-6-2013 by malford]

Fantasma4500 - 27-6-2013 at 14:32

i have a decently safe mix for ignition..
golden powder ignites very fast, but sadly burns with low temperature
rocket candy burns hot, but is not always very easy to get started just like that..

now if you powder both substances and mix 1:1 by volume you have something useful..

you can run a burnt copper wire (very very thin, from copper cables) through straw and fill it with your ignition mix of RC:GP 1:1

this will be a small tube you insert wherever you want to ignite stuff.. you could perhaps make several layers of this, so the ignition ignites and thereafter the other stuff goes off (slow flash?)

ive just thought about polystyrene in acetone, dont know if it would work tho, you could also use simple dextrine (heated corn starch, until it turns deeper yellow)

some might say that RC is very useless for pretty well anything, but i find it to have very high water tolerance, the GP however can break down over longer time into useless things, not sure how this really happens or what the products are but 1 month these could be stored for im sure

malford - 27-6-2013 at 19:51

For some reason, I did not think of that: using a case, like a small tube, instead of a binder to bind it to the heating element. I guess the reason I did not, is because it seems that leaving the powder loose would cause rapid deflagration or detonation, while we want a semi-rapid deflagration over 100-300 milliseconds. Any faster and we could risk destroying whatever it is that we want to ignite before it is ignited.

For an igniter, it seems a higher temperature would be better. Would a thermite composition work here? I have seen CuO/Al mixtures that burn very hot and quick. How about mixing magnesium powder with that and binding it to a piece of tungsten wire?

malford - 3-7-2013 at 11:46

I have prepared the following to test as a pyrotechnic initiator:

2.5 g nitrocellulose
3 oz acetone
5 g Mg
10 g Al
20 g KClO4

I am currently waiting to test some with fuse and electric matches. Theoretically, is this a sound composition?

hyfalcon - 3-7-2013 at 16:12

Antimony trisulfide and KClO3 makes a heat sensitive composition that you can mix and adhere to a Ni-chrome wire with your NC lacquer.

malford - 3-7-2013 at 16:24

Given that tungsten has a higher melting point, wouldn't that make a better choice for the wire? I have some 0.005" tungsten wire I intend to test.

hyfalcon - 4-7-2013 at 03:10

Any fine wire that will heat up with a minimum of applied voltage will work. Tungsten or Ni-chrome will work. Be cautious, if the wire if fine enough, even the low current of a continuity tester will ignite this composition. Battery button led continuity tester is about all you can safely use on this without them going off when you check them.

Edit-Can't spell.

[Edited on 4-7-2013 by hyfalcon]

Fantasma4500 - 4-7-2013 at 11:03

actually KMnO4 Mg works as a type of a star when you bind it
obviously very sensitive
but blackpowder should be more than enough
burns hot and ignites easily
perhaps add some aluminium for extra heat
no reason to make it more advanced at all.. were not doing advanced math here are we?

DubaiAmateurRocketry - 4-7-2013 at 11:10

Match powder works great for me.

I often melt down around 2000 match at once in boiling water, then when dry it in the sun for 2 days, i use it to ignite my rocket . I am guessing match powder burn at around 1700 degree celsius, with around 65% solid residue, and a fast burn rate.

The only reason i use match powder to ignite my rockets and not black powder or flash powder since BP burns at only around 1200 degree and flash powder is too fast. And match powder is just right.

hyfalcon - 5-7-2013 at 04:07

Well, I didn't tell everything. Hot ignitor prime makes up a layer under the NC lacquer. These things use miniscule amounts of chemicals. All they are supposed to do is get the train a movin' down the track.

malford - 6-7-2013 at 16:43

The composition I posted above works exceptionally well for this purpose. It burns at a moderate speed when bound with nitrocellulose and ignites easily. I also added some sulfur.

However, being stuck in my megalomaniacal ways, I now want to create the hottest composition possible. I am thinking of binding a manganese thermite. The incredibly hot Mn vapors would penetrate every space in a complex solid rocket motor core.

[Edited on 7-7-2013 by malford]

DubaiAmateurRocketry - 6-7-2013 at 22:27

Quote: Originally posted by malford  
The composition I posted above works exceptionally well for this purpose. It burns at a moderate speed when bound with nitrocellulose and ignites easily. I also added some sulfur.

However, being stuck in my megalomaniacal ways, I now want to create the hottest composition possible. I am thinking of binding a manganese thermite. The incredibly hot Mn vapors would penetrate every space in a complex solid rocket motor core.

[Edited on 7-7-2013 by malford]


If you are looking for high temperature.

use an oxidizer that decomposes exothermically, eg-- perchlorate.

use a hot burning metal like magnesium or aluminum that is very finely powdered. then add some other fuel like hexamine sugar so it burns slower and not explode like a flash powder, then u have a very good ignition fuel.

Dont add sulfur. sulfur burns pretty lower temperature.

malford - 7-7-2013 at 05:29

Dubai,

In the post to which I referred which you obviously did not see, I used the following composition:

2.5 g nitrocellulose
3 oz acetone
5 g Mg
5 g S
10 g Al
20 g KClO4

It burns hot enough to vaporize the mesh screen that the sample was burned on. The sulfur was to simply lower the ignition temperature. No hexamine was needed, the reaction does not explode when bound with NC.

[Edited on 7-7-2013 by malford]

Ral123 - 7-7-2013 at 06:15

How about small broken light bulb, soaked in NC/acetone. The wire will be fine with the mixture and the NC has low ignition temperature.

DubaiAmateurRocketry - 7-7-2013 at 06:20

Quote: Originally posted by malford  
Dubai,

In the post to which I referred which you obviously did not see, I used the following composition:

2.5 g nitrocellulose
3 oz acetone
5 g Mg
5 g S
10 g Al
20 g KClO4

It burns hot enough to vaporize the mesh screen that the sample was burned on. The sulfur was to simply lower the ignition temperature. No hexamine was needed, the reaction does not explode when bound with NC.

[Edited on 7-7-2013 by malford]


alright i was just giving an example of a need of moderating the burn rate

malford - 7-7-2013 at 09:15

Ral,

That is basically what I'm doing. I built an electric match with .005 tungsten which produces a lot of heat from only a 9v battery. Next I will use a large capacitor to disintegrate the wire.

For the NC bound composition that I tried, see above.

Next I will try MnO2 + Mg thermite and possibly Nd + I2O5 thermite, both bound with NC or HTPB. Thoughts?