17-10-2006, 11:01:07
Otra actualización:
No encuentro el uso del ácido bórico más que en pirotecnia, y de todas formas no se considera 100% efectivo:
A dust mask should be worn when working with aluminum powder. Mixtures containing nitrates and aluminum powder are prone to heating up spontaneously and may ignite, especially when wet. This is caused by the reduction of the nitrate by aluminum, forming amides. These very basic compounds react further with aluminum powder in a very exothermic reaction that can cause spontaneous ignition. An ammonia smell is often produced in this reaction. Adding 1 to 2% boric acid to compositions containing nitrates and aluminum is common practice and will often prevent spontaneous ignition, although this should never be relied upon. It is advisable to avoid using water to bind such compositions. Red gum or shellac with alcohol or nitrocellulose lacquer are preffered binder and solvents.
....
Large masses of ammonium nitrate have been known to explode on some occasions although it is very unsensitive. Smaller quantities are less likely to detonate. The risk of detonation increases when ammonium nitrate is molten or mixed with fuels such as metal powders or organic substances. Ammonium nitrate should never be mixed with chlorates as this may result in ammonium chlorate formation, possibly leading to spontaneous ignition. Mixtures of metal powders and ammonium nitrate are likely to heat up spontaneously and may ignite, especially when moist. This can sometimes be prevented by the addition of small amounts of boric acid (1 to 2%), but in general it is better to avoid these mixtures at all. The hygroscopic nature of ammonium nitrates makes this problem worse (also see aluminum).
http://www.wfvisser.dds.nl/EN/cheminfo_EN.html
No encuentro el uso del ácido bórico más que en pirotecnia, y de todas formas no se considera 100% efectivo:
A dust mask should be worn when working with aluminum powder. Mixtures containing nitrates and aluminum powder are prone to heating up spontaneously and may ignite, especially when wet. This is caused by the reduction of the nitrate by aluminum, forming amides. These very basic compounds react further with aluminum powder in a very exothermic reaction that can cause spontaneous ignition. An ammonia smell is often produced in this reaction. Adding 1 to 2% boric acid to compositions containing nitrates and aluminum is common practice and will often prevent spontaneous ignition, although this should never be relied upon. It is advisable to avoid using water to bind such compositions. Red gum or shellac with alcohol or nitrocellulose lacquer are preffered binder and solvents.
....
Large masses of ammonium nitrate have been known to explode on some occasions although it is very unsensitive. Smaller quantities are less likely to detonate. The risk of detonation increases when ammonium nitrate is molten or mixed with fuels such as metal powders or organic substances. Ammonium nitrate should never be mixed with chlorates as this may result in ammonium chlorate formation, possibly leading to spontaneous ignition. Mixtures of metal powders and ammonium nitrate are likely to heat up spontaneously and may ignite, especially when moist. This can sometimes be prevented by the addition of small amounts of boric acid (1 to 2%), but in general it is better to avoid these mixtures at all. The hygroscopic nature of ammonium nitrates makes this problem worse (also see aluminum).
http://www.wfvisser.dds.nl/EN/cheminfo_EN.html
[A los creyentes] les competerá difundir lo que otros han acuñado; ya que ningún hombre suelta y expande la mentira con tanta gracia como el que se la cree.