4 ms·

Magnesium parts are already in widespread use. The covers you see on the sides of motorcycle engines/transmissions are often magnesium. In solid form the risk

by 83 4y ago

Magnesium parts are already in widespread use. The covers you see on the sides of motorcycle engines/transmissions are often magnesium. In solid form the risk is mitigated because there isn't enough surface area for the reaction with oxygen, it's the powder/shavings that are a concern. You can actually weld magnesium parts without it igniting. Reading up on it a little more - it seems with enough heat solid magnesium can start a self-sustaining burn without oxygen. I wish I could find a laymans explanation of the difference between oxygen fueled magnesium powder fire and self sustaining. Must take an awful lot of heat if a welding arc isn't hot enough to cause this. Edit: Also think of steel wool and how well it burns, but a block of steel not so much.

forgotusername6 4y ago
I used to have a flowerpot furnace and cast small objects. I once stumbled upon a car that had been burnt out. The engine block had dripped down the road and I was able to collect some of the melted pieces. It would pop and spit when poked once cast, very different to the aluminium I often used, and I wondered at the time whether it was the magnesium in the block that was doing it.
BurningFrog 4y ago
If the magnesium is not reacting with oxygen, it must react with something else to produce more heat than is put in. I discount the possibility of nuclear reactions :)
lazide 4y ago
Welding arcs definitely can cause magnesium fires. Generally the shielding gas used to protect from oxidation prevents it, but it's easy to screw up. It's a tricky metal to weld because of it. Generally you also need to preheat it so you don't get cracking, which makes it even more of an issue. There is a passivated oxide layer that forms (similar to aluminum) which generally reduces the risk, but if it's compromised (like from cleaning the weld area)....
GravitasFailure 4y ago
Magnesium can't burn without oxygen, but it will happily rip the oxygen out of water and sand, making it exceptionally annoying to put out.
elihu 4y ago
Magnesium isn't entirely without risk. Here's some firefighters spraying water on a Jeep Liberty (see 1:11): https://www.youtube.com/watch?v=KY9ri-UOoLo https://www.youtube.com/watch?v=KY9ri-UOoLo

by 83 4y ago

forgotusername6 4y ago

I used to have a flowerpot furnace and cast small objects. I once stumbled upon a car that had been burnt out. The engine block had dripped down the road and I was able to collect some of the melted pieces. It would pop and spit when poked once cast, very different to the aluminium I often used, and I wondered at the time whether it was the magnesium in the block that was doing it.

BurningFrog 4y ago

If the magnesium is not reacting with oxygen, it must react with something else to produce more heat than is put in. I discount the possibility of nuclear reactions :)

lazide 4y ago

Welding arcs definitely can cause magnesium fires. Generally the shielding gas used to protect from oxidation prevents it, but it's easy to screw up. It's a tricky metal to weld because of it. Generally you also need to preheat it so you don't get cracking, which makes it even more of an issue. There is a passivated oxide layer that forms (similar to aluminum) which generally reduces the risk, but if it's compromised (like from cleaning the weld area)....

GravitasFailure 4y ago

Magnesium can't burn without oxygen, but it will happily rip the oxygen out of water and sand, making it exceptionally annoying to put out.

elihu 4y ago

Magnesium isn't entirely without risk. Here's some firefighters spraying water on a Jeep Liberty (see 1:11): https://www.youtube.com/watch?v=KY9ri-UOoLo https://www.youtube.com/watch?v=KY9ri-UOoLo