Chinese stars

[Yus]

Two samples (stars) “Crackling Flower” and “Green Strobe” from the firewors cake “Time Show” GP512 were studied by XRD (X-ray phase analysis) and EMA (elemental microanalysis) on SEM (scanning electron microscope). The stars were cut into three parts, and the central part was further polished. Separately, the compositions of each layer were extracted and ground into powder. Analyzes were conducted without internal standards, therefore, the composition of the mixtures is approximate and needs to be adjusted.

 

Approximate composition of green strobe: Ba(NO3)2 - 70...75%, AlMg - 15...20%, organochlorine - 5...7%, Bi2O3 - no more than 3%, S - no more than 2%, binder - the rest. The color of star in the sky is dirty green, on the ground - acceptable.

 

The cracking flower star has three areas (layers) of different compositions. The first layer is the usual BP, the second layer is the common Chinese prime with the addition of perchlorate K and magnalium and titanium, the third layer is the core - copper oxide - bismuth oxide - magnalium system. Prime: KNO3 - 60...65%, KClO4 - 5...10%, S - 7...12%, C - 7...12%, AlMg - 10...15%, Ti - 3. ..5%. The titanium in the prime with size of 0.2 ... 0.5 mm. Approximate composition of the crackling core: CuO - 55...60%, AlMg - 35...40%, Bi2O3 - 5...10%. All formulations contain unidentified binder. The photo of the crackling star under the SEM is shown below.

 

[dagabu]

COOL!

[Sulphurstan]

Nice research Yus!

[Crazy Swede]

Very nice!

[Mixer]

Very interesting, but this binder is so elusive!

[kaotch]

Yus ,thanks very much for this info especially on the crackling flower ie the 2nd layer of prime. Did you get a measurement on the size of the AlMg ?

Regarding the binder did you try to dissolve the comp. in H2O and/or Alc or Acetone ? Those findings could give an indication as to what kind of binder was used.

[rsambo]

Yus, this is really great work and I've been playing with these for a bit now. I've found they strobe best using nitrocellulose as the binder. Phenolic resin rapidly kills the strobe. I managed to get the white version to work excellently but found only small additions of a chlorine donor destroyed the strobe but I hadn't added sulphur and that may be important? Thanks.

[Yus]

Thank you.

AlMg - 100 micron. Chlorine donor could be C6Cl6. But, yes more than 3% PVC destroy strobe effect. Binder can be SGRS. It forms very thin layer and it is difficult to analyse.

[kaotch]

@Yus. Thanks for your reply. What do you mean with C6CI6 ? I have looked it up but cannot get an answer. Sorry , but I don't have a chemical background.

[Arthur]

Hexachloro benzene. Lots of chlorine with little fuel value.

[kaotch]

Thanks Arthur.

Is there somebody ,in the EU , who could provide some ? Please PM.

[Arthur]

AFAIK it's banned in the EU.

 

added;

from wikipedia "Hexachlorobenzene was banned from use in the United States in 1966."

and " It has been banned globally under the Stockholm Convention on Persistent Organic Pollutants.^[1] "

So it shouldnt exist anywhere.

 

However one container of fireworks was reputedly sent straight to scrap when found to contain HCB and banned from sale. The Chinese will sell anything.

 

May possible be replaced by hexachloro Ethane.

Edited February 11, 2019 by Arthur

[rogeryermaw]

hexachloroethane sublimes at room temperature.

[Zmuro]

Great info. A very small amount of Bi2O3 is used and they still produce nice crackling effect. Has anyone tested this approximate formula?

[Mixer]

I think I would question that if it was strictly 140# Magnalium in the core (for the Crackling Flower).

Edited February 25, 2019 by Mixer