Copper liner

[xoo1246]

I'm working on a SC that uses a thin copper liner. I will be propelling the the liner by some ANNM(the highest Vod I can accomplish this far).
The AN has been dried, still I'm a bit worried about Cu(NO3)2 forming when the liner is in contact with the AN. I filled the container once to get an aproximate number on how many grams it could hold, emptied it and left it, some AN was left and after a a day blue dots were visible. The copper cone had been cleaned and thus there wasn't much oxide on the surface. I have cleaned it again with iron wool to remove the marks. Now I have to assemble it again.

The question is, can the problem be solved by heating the liner under a flame for a while to create a protective coating of copper oxide? I don't want to coat it with glue and I don't want my device to auto-ignite. (EDIT: I will try it overnight on a piece of copper plate, but I want to have your opinion on the mather too)

While I'm at it, what kind of stand-off is acceptable when it comes to an inperfect cone such as this one(certainly not 6xd), and should the the cone sides be overlapped?

Here are pictures of the device for anyone interested:

<a href="http://w1.478.telia.com/~u47802930/SCPrototype01.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype01.jpg</a>
<a href="http://w1.478.telia.com/~u47802930/SCPrototype02.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype02.jpg</a>
<a href="http://w1.478.telia.com/~u47802930/SCPrototype03.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype03.jpg</a> (won't use legs)
<a href="http://w1.478.telia.com/~u47802930/SCPrototype04.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype04.jpg</a>
<a href="http://w1.478.telia.com/~u47802930/SCPrototype05.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype05.jpg</a>
<a href="http://w1.478.telia.com/~u47802930/SCPrototype06.jpg" target="_blank">http://w1.478.telia.com/~u47802930/SCPrototype06.jpg</a> (taken minutes ago, it looks uggly now due to all the rough handeling)

<small>[ August 05, 2002, 05:18 PM: Message edited by: xoo1246 ]</small>

[kingspaz]

its not copper nitrate you should be worried about but tetramine copper nitrate (TACN).
<a href="http://www.roguesci.org/ubb/ultimatebb.php?ubb=get_topic;f=1;t=000417" target="_blank">http://www.roguesci.org/ubb/ultimatebb.php?ubb=get_topic;f=1;t=000417</a>
it should only form the hydrated form when the AN is in place because of residual moisture inside the AN. but i wouldn't bet on it! you could coat the inside of the cone with solder. solder is composed of lead and tin which don't form complexes. making the copper oxide coating will increase the reaction as it is the oxide layer that reacts with the AN. nomatter how well you polish the cone it will ALLWAYS have an oxide layer because its allways in contact with oxygen in the air.

edit: my point with the hydrated form was that its insensitive as a primary as i've tested it for possibilities and it couldn't be detonated. with a cap it would probably be detonable though.
but don't rely on the hydrated TACN forming. all you need is a pocket of dryness and you'll have dehydrated TACN which is (i guess) about as sensitive as TACC which is a primary explosive.

<small>[ August 05, 2002, 05:31 PM: Message edited by: kingspaz ]</small>

[Polverone]

What about heating the liner and coating it with wax? That should protect the metal from any interaction with the NH4NO3. You can also find spray-on plastic coatings in craft stores that would probably do the same job.

[xoo1246]

Thanks, everyday you learn something new. I had though about coating it with wax/spray plastic/glue, but I wanted to know if CuO was ok first. Once again, thanks.

<small>[ August 05, 2002, 07:18 PM: Message edited by: xoo1246 ]</small>

[Anthony]

I think a standoff of 2x cone height is said to work for improvised stuff.

What's the angle of your liner by the way?

I wouldn't overlap the edges of the cone as the variance in liner thickness would probably give a non-uniform jet.

[xoo1246]

I have fixed it now, used the edge of a plastic bag resistant to NM that fit very good(heated it in some water for an even better fit). The angle is around 60 degrees. (diameter 4.6 cm, height 4 cm). The plastic spray I had at home didn't work, neither did a glue said to be resistant to RC fuel(obviously they didn't think about NM in fuels). Didn't try vax, since I have an ok solution now. I will try 2xd as stand-off.

Edit: I did overlap around 1mm, will see how it works, probably tomorrow.

<small>[ August 06, 2002, 01:35 PM: Message edited by: xoo1246 ]</small>

[bonnsgeo]

hem ..xoo .. i know its not the topic but i sent u an email about blu tac ...could u read it ? :rolleyes:
thx
bye

[Yi]

Looks nice :) Whats the thickness of the copper and how much ANNM are you using? I might repeat your test with Picric acid if i manage to get enough.

For anyone planning on wax coating copper liners, once the wax is on there it will come of very easily <img border="0" title="" alt="[Frown]" src="frown.gif" />