Sciencemadness Discussion Board

Catalysts for NaNO3 black powder?

OneEyedPyro - 7-1-2024 at 03:17

I've recently made some NaNO3 black powder but it's difficult to ignite and burns way slower than with KNO3 (unconfined at least). I've tried several different ratios and so far the best was 70:15:15 but it's dirty, hit or miss to ignite in a flintlock and barely if any more powerful than with KNO3.

Getting to the point. I was wondering if there are any catalysts or reactive fuels that might bump up the sensitivity and burn rate, any ideas?

Rainwater - 7-1-2024 at 03:32

Sodium nitrate is deliquescent. Thats the main reason it is not used for this. Your powder is likly wet

[Edited on 7-1-2024 by Rainwater]

OneEyedPyro - 7-1-2024 at 04:10

Quote: Originally posted by Rainwater  
Sodium nitrate is deliquescent. Thats the main reason it is not used for this. Your powder is likly wet

[Edited on 7-1-2024 by Rainwater]


It was recrystallized, dried at 110C for an hour and immediately placed in mason jars. The humidity is very low here inside during winter and it had a very short time exposed to air during processing. I don't think its hygroscopicity is the issue but maybe.

Rainwater - 7-1-2024 at 06:57

I don't think that's hot enough to drive off water. NaNO3doesn'tt melt until about 300c. By increasing the heat while monitoring the weight, you should reach a point where the weight no longer changes. Then you can be sure its dry

Tsjerk - 7-1-2024 at 10:38

Put it in a vacuum desiccator over something more hygroscopic than NaNO3, and over a lot more than the NaNO3 you have in your mixture.

Laboratory of Liptakov - 7-1-2024 at 11:37

Problem is not in huminidity, but in low reactivity NaNO3. You can try add 10% ascorbic acid. Or instead sulphur use 15% acorbic acid. Also you can try add Fe2O3 3% into your done BP. Sodium BP has limited range of use. Generally...:cool:
If you rich, you can add nitrocellulose 7% under acetone / porridge and create new grains. It decrease hygroscopicity and increase senzibility on any flame.

OneEyedPyro - 7-1-2024 at 16:42

Quote: Originally posted by Laboratory of Liptakov  
Problem is not in huminidity, but in low reactivity NaNO3. You can try add 10% ascorbic acid. Or instead sulphur use 15% acorbic acid. Also you can try add Fe2O3 3% into your done BP. Sodium BP has limited range of use. Generally...:cool:
If you rich, you can add nitrocellulose 7% under acetone / porridge and create new grains. It decrease hygroscopicity and increase senzibility on any flame.


It's free flowing with no clumps even after sitting for a week or so, it certainly seems dry. NaNO3 just appears less willing to give up its oxygen than KNO3, though I was under the impression that the sodium salt had a lower decomposition temperature.

Never thought of vitamin C as a sensitizer or reactive fuel but it's worth a try I suppose.
I had considered NC to coat the granules but I'm a bit nervous about pressure levels in black powder firearms. I think I'll load up some modern smokeless powder cartridges and see how that goes first if I do use NC.

Thanks LL!

DennyDevHE77 - 8-1-2024 at 00:19

Quote: Originally posted by Laboratory of Liptakov  
Problem is not in huminidity, but in low reactivity NaNO3.


It's true, I've had flame retardant tubes burn 4 times longer (and less consistently) on sodium nitrate than on potassium nitrate. Moreover, even 20% of sodium nitrate greatly reduced the burning rate of ordinary black powder
Quote: Originally posted by Laboratory of Liptakov  
Also you can try add Fe2O3 3%


Would iron oxide work without organics? I thought it was added to fiber-based substances, like sorbitol, sucrose, etc.


[Edited on 8-1-2024 by DennyDevHE77]

Laboratory of Liptakov - 8-1-2024 at 01:04

DennyDevHE77.....Yes, the Fe2O3 increase burn effect sugars very effective. But since we are dealing with chemical experiments of all kinds, it is possible to try Fe2O3 in BP as well. Even if the effect was zero. Simply, try it. Nothing dangerous.....:cool:

Rainwater - 8-1-2024 at 18:43

reference

$$4KNO_3 + 7C + S \rightarrow 3CO_2 + 3CO +2N_2 + K_2CO_3 + K_2S$$
Code:
T = 273.15 Kelvin ΔH -1072.1897 kJ/mol ΔS 1274.7753 J mol/K ΔG -1420.3945 kJ/mol


$$4NaNO_3 + 7C + S \rightarrow 3CO_2 + 3CO +2N_2 + Na_2CO_3 + Na_2S$$
Code:
T = 273.15 Kelvin ΔH -1149.5540 kJ/mol ΔS 1314.5835 J mol/K ΔG -1508.6325 kJ/mol




My experience with these types of reactions is limited to 2 days a year, so go with what the good dr says. thermodynamics suggest the sodium variation would release more energy per mole of product. This seams counterintuitive to me, that your experiment had a different result.

But also having made my own BP before, the milling/mixing procedure proved to be the most important step. Its effects dominated other variables such as the carbon source.

Assuming the OP's mixture is dry, and milled to perfection.
The melting point and decomposition temperature of the sodium salt is lower than that of the potassium one. But the sodium sulfide byproduct, has a higher melting point higher than K2S. Meaning that everything points to the Na-BP should outperform the K-BP

How could this difference between the reactions be explained on paper?



[Edited on 9-1-2024 by Rainwater]

Laboratory of Liptakov - 9-1-2024 at 02:14

A simple method for measuring the quality of ground BP:
Rub the dust between your fingers. No grain should be felt. The sensation must be the same as when you rub talcum powder between your fingers. Whatever the calculation is on paper, sodium BP is always slower than potassium BP under the same conditions. And by approximately 30%. Another significant variable value is the charcoal source. One of the highest burning rates is provided by the dry distillation of Frangula Alnus wood.
https://en.wikipedia.org/wiki/Frangula_alnus
:cool:

DennyDevHE77 - 9-1-2024 at 04:40

I believe finely pelletized black powder on sodium nitrate exploded from a detonator primer may show good results.

OneEyedPyro - 9-1-2024 at 05:17

Quote: Originally posted by Rainwater  

How could this difference between the reactions be explained on paper? [Edited on 9-1-2024 by Rainwater]


The sodium salt has a lower melting point, boiling point, decomposition point and more oxygen content by mass or volume. I guess sometimes reality doesn't match up with what you'd expect from a glance at the chemistry.
The answer can only lie in the combustion byproducts of NaNO3 BP having different physical properties, perhaps creating an insulating effect or something similar which slows the transfer of heat through the powder.

When fired in a muzzleloader using 209 primers it worked fine and gave slightly higher peak velocities to the same volume of standard FFF BP but resulted in a nearly identical average velocity due to a wider standard deviation. In a flintlock it was all over the place velocity wise.

NaNO3 flash powders can undergo DDT at milligram quantities if milled close to sub micron particle size. I've not found this to be true with KNO3. I'm guessing the sulfur byproducts are the culprit, I'll try ascorbic acid in its place as LL suggested when I get around to it.

Rainwater - 9-1-2024 at 08:57

I think at the temperature and pressures involved, the formation of carbonate salts would be unlikely. Many times i've smelled NOx after a day of shooting. Even my cleaning oil advertises it neturals acids to protect the rifling. I think the referenced chemical equations are too inaccurate for a thermodynamics comparison.

OneEyedPyro - 9-1-2024 at 09:51

Quote: Originally posted by Rainwater  
I think at the temperature and pressures involved, the formation of carbonate salts would be unlikely. Many times i've smelled NOx after a day of shooting. Even my cleaning oil advertises it neturals acids to protect the rifling. I think the referenced chemical equations are too inaccurate for a thermodynamics comparison.
As far as I know, carbonate is a considerable byproduct of BP combustion.

The sodium and more importantly its respective byproducts are the only outliers compared to regular BP.
I'm not implying a chemically impeding effect but rather a physically impeding effect of those byproducts by slowing the thermal transfer rate.
Na and K are similar but different and their respective sulfates, sulfides plus whatever other sulfur related compounds formed in the chaos may have considerably different physical properties.

I haven't really thought about it until recently and thus haven't really researched enough to say that with any certainty, just a hunch.

Laboratory of Liptakov - 9-1-2024 at 09:58

Quote:

NaNO3 flash powders can undergo DDT at milligram quantities if milled close to sub micron particle size. I've not found this to be true with KNO3. I'm guessing the sulfur byproducts are the culprit, I'll try ascorbic acid in its place as LL suggested when I get around to it.


Sulphur has OB - 100. Vitamine C - 90.9. Thus replacement can be without counting OB. BP can be SN 70 C 15 AA 15 (mixture with OB - 20.7 on CO2)....:cool:

Rainwater - 9-1-2024 at 13:15

Quote: Originally posted by OneEyedPyro  
As far as I know, carbonate is a considerable byproduct of BP combustion.


Sorry, i see how I worded that wrong. What i ment to suggest is that the initial conditions likly would not favor carbonate formation. During the combustion phase of the reaction, temperatures can exceed the decomposition temperature of the carbonates producing oxides instead, at least momentarily. Once the reaction is out of the barrel, pressures and tempatures alot less, the fine dispersion of oxides will quickly react with the CO2 and form carbonates.