Rust.
How the hell do you burn something that is already oxidized?
Meet Chlorine Trifluoride: The Chemical That Sets Fire to Asbestos on Contact
From Gizmodo, July 2015:
First discovered back in the 1930s, chlorine trifluoride is a rather curious chemical that easily reacts, sometimes explosively, with just about every known substance on Earth.
Just to get the ball rolling, here’s a few of the more unusual things chlorine trifluoride is known to set fire to on contact: glass, sand, asbestos, rust, concrete, people, pyrex, cloth, and the dreams of children…
Obviously the first question to answer here is how chlorine trifluoride is somehow able to cause asbestos, a substance that is known for being almost completely fire retardant, to catch on fire. Well, that’s because chlorine trifluoride is a more powerful oxidizing agent by mass than oxygen itself. Meaning it’s capable of rapidly oxidizing things that would normally be considered practically “impossible” to set aflame, like asbestos. Chlorine trifluoride is such an effective oxidizer that it can even potentially set fire to things that have seemingly already been burned up, like ash or spent charcoal.
The substance is so highly reactive that famously unreactive elements like platinum, osmium and iridium will begin to corrode when they come into contact with it. Notably tough elements like titanium and tungsten are also regarded as being wholly unsuitable to storing the chemical because they set on fire as soon as they come into contact with it.
The only known way to store chlorine trifluoride “safely”, which we use in the loosest possible sense, is to put it inside of a sealed containers made of steel, iron, nickel or copper which are able to contain the chemical safely if they’re first treated with flourine gas. This is because doing so will coat the metal in a thin fluoride layer, with which the chemical won’t react. However, if this layer is compromised in anyway, or the metal isn’t completely dry, chlorine trifluoride will begin to react violently and cause the vessel to explode.
A few of the other things known to not react with chlorine trifluoride include nitrogen, the inert gases and polychlorotrifluoroethylene. Rather fortunately, chlorine trifluoride doesn’t react with air unless it happens to contain a larger than average amount of water vapor.
Speaking of which, when chlorine trifluoride comes into contact with water, it will react explosively with it and as a fun byproduct creates large amounts of dangerous gasses such as hydrofluoric acid and hydrochloric acid. Hydrofluric acid in particular is incredibly dangerous and along with being able to melt things like glass and concrete, can permanently damage your lungs and eyes. As if that wasn’t worrying enough, if you’re ever unlucky enough to get hydrofluric acid on your skin, it doesn’t actually hurt until a few hours later. After it has absorbed a bit, it starts destroying your nerves and bones and can ultimately cause cardiac arrest when it gets into your blood stream. In fact, in 1994 a lab technician in Australia accidentally spilled hydrofluric acid on his lap and despite immediately executing safety procedures including hosing off, immersing himself in a swimming pool, and later extensive medical care (including needing to have one of his legs amputated), within two weeks of the accident, he was dead.
Unsurprisingly, the Nazis were really interested in the military applications of chlorine trifluoride. After all, it’s a substance that reacts explosively with water (humans are largely bags of water), and for those that don’t come in contact with it directly, there’s the byproduct of the deadly gasses. Further, there is really little one can do to put out the fires it causes directly other than to let them burn off. If you throw water on the source of the problem, it will get worse. The reaction here also doesn’t require atmospheric oxygen to burn, so trying to use that method of fire suppression won’t work either....MORE
