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Chemistry / Re: What is the correct recipe for flash powder?
« on: 11/08/2013 08:13:33 »
As for any reaction, just write down the reaction equation, then multiply the proportions by the atomic/molecular weights of the reagents. That will give you the theoretical optimum chemical ratio. Now consider what losses may occur as the reaction proceeds in a particular physical structure - you will probably decide to add a bit more oxidant to ensure complete combustion of the metal, but to make a persistent visible flame (the point of flash powder rather than an explosive) you might use less oxidant and rely on a third element (like suphur) burning in air to maintain the aluminium or magnesium flame as the charge disperses.
However the rate of any solid reaction depends on the surface/volume ratio of the constituents, and serious technological cunning is required. To get a good flash, you need to mill the components together without heating them, and possibly to coat the metal particles with your slow-burn (sulphur) component. That is the trade secret you should learn on your pyrotechnics course - patience will be rewarded!
However the rate of any solid reaction depends on the surface/volume ratio of the constituents, and serious technological cunning is required. To get a good flash, you need to mill the components together without heating them, and possibly to coat the metal particles with your slow-burn (sulphur) component. That is the trade secret you should learn on your pyrotechnics course - patience will be rewarded!