Metal composite floats on water. Witches hope nobody notices.

[Kharakov]

http://www.iflscience.com/chemistry/new-metal-composite-so-light-it-floats

 

[skepticalbip]

Neat shit...

...........
The researchers, from the New York University Polytechnic School of Engineering and in collaboration with the U.S Army Research Laboratory, created the material by reinforcing a magnesium alloy with hollow silicon carbide particle spheres. Whilst giving the new material a lower density than water, it also meant that it was strong enough to withstand the stresses of it would face if used in seafaring ships.
...........

... but I would certainly have some questions before I set sail on a ship made from this stuff. The leading question being, does the alloying of this magnesium eliminate magnesium's flammable quality. Being in the middle of a magnesium fire doesn't seem to be something that would make for a pleasant sea voyage.

 

[bilby]

Neat shit...

...........
The researchers, from the New York University Polytechnic School of Engineering and in collaboration with the U.S Army Research Laboratory, created the material by reinforcing a magnesium alloy with hollow silicon carbide particle spheres. Whilst giving the new material a lower density than water, it also meant that it was strong enough to withstand the stresses of it would face if used in seafaring ships.
...........

... but I would certainly have some questions before I set sail on a ship made from this stuff. The leading question being, does the alloying of this magnesium eliminate magnesium's flammable quality. Being in the middle of a magnesium fire doesn't seem to be something that would make for a pleasant sea voyage.

View attachment 2986

A fire at sea is rarely a good thing; I don't know how easy this particular alloy is to ignite, but many alloys used in ship-building will burn spectacularly well once they do get started. The Royal Navy's Type 21 Frigates Ardent and Antelope were both bombed by the Argentines during the Falklands War, and sank after fires involving their aluminium superstructures proved impossible to extinguish.

That said, while magnesium does burn fiercely in air, it takes quite a lot of heat to get started - a carelessly discarded cigarette wouldn't be a risk.

A civilian vessel is even more unlikely than a warship to encounter a sufficiently fierce blaze to ignite a metal alloy structure - even if it was made from pure magnesium - and if it did, is likely to be doomed by such a severe fire regardless of its composition.

 

[skepticalbip]

A fire at sea is rarely a good thing; I don't know how easy this particular alloy is to ignite, but many alloys used in ship-building will burn spectacularly well once they do get started. The Royal Navy's Type 21 Frigates Ardent and Antelope were both bombed by the Argentines during the Falklands War, and sank after fires involving their aluminium superstructures proved impossible to extinguish.

That said, while magnesium does burn fiercely in air, it takes quite a lot of heat to get started - a carelessly discarded cigarette wouldn't be a risk.

A civilian vessel is even more unlikely than a warship to encounter a sufficiently fierce blaze to ignite a metal alloy structure - even if it was made from pure magnesium - and if it did, is likely to be doomed by such a severe fire regardless of its composition.

You are right but magnesium is much, much easier to ignite than aluminum. There is even a camping and/or survival fire starting tool being sold that is a block of magnesium with a flint rod and a steel striker. Shave some scrapings from the magnesium block and ignite them with a spark from the flint and there is the start for a camp fire.

Fire aboard a ship is a special concern of any seaman but they do happen. So having the ship made of fuel, that is all but impossible to extinguish, for any fire that does happen to occur doesn't sound like a great idea. However, I don't know how various alloys of magnesium would hold up in a fire.

ETA:
I thought I would check for the autoignition temperature of magnesium. It is 473 °C (883 °F), easily reached if there is a grease fire in the galley (or a fuel spill that catches fire) but, once burning, will reach temperatures in the thousands of degrees.

 

[Bomb#20]

You are right but magnesium is much, much easier to ignite than aluminum. There is even a camping and/or survival fire starting tool being sold that is a block of magnesium with a flint rod and a steel striker. Shave some scrapings from the magnesium block and ignite them with a spark from the flint and there is the start for a camp fire.

Fire aboard a ship is a special concern of any seaman but they do happen. So having the ship made of fuel, that is all but impossible to extinguish, for any fire that does happen to occur doesn't sound like a great idea. However, I don't know how various alloys of magnesium would hold up in a fire.

ETA:
I thought I would check for the autoignition temperature of magnesium. It is 473 °C (883 °F), easily reached if there is a grease fire in the galley (or a fuel spill that catches fire) but, once burning, will reach temperatures in the thousands of degrees.

From the article:

"The composite can be customized for density and other properties by adding more or fewer shells into the metal matrix to fit the requirements of the application. This concept can also be used with other magnesium alloys that are non-flammable."

Whether a magnesium alloy burns depends on what the other ingredients are. Adding a bit of calcium will do it.

 

[skepticalbip]

You are right but magnesium is much, much easier to ignite than aluminum. There is even a camping and/or survival fire starting tool being sold that is a block of magnesium with a flint rod and a steel striker. Shave some scrapings from the magnesium block and ignite them with a spark from the flint and there is the start for a camp fire.

Fire aboard a ship is a special concern of any seaman but they do happen. So having the ship made of fuel, that is all but impossible to extinguish, for any fire that does happen to occur doesn't sound like a great idea. However, I don't know how various alloys of magnesium would hold up in a fire.

ETA:
I thought I would check for the autoignition temperature of magnesium. It is 473 °C (883 °F), easily reached if there is a grease fire in the galley (or a fuel spill that catches fire) but, once burning, will reach temperatures in the thousands of degrees.

From the article:

"The composite can be customized for density and other properties by adding more or fewer shells into the metal matrix to fit the requirements of the application. This concept can also be used with other magnesium alloys that are non-flammable."

Whether a magnesium alloy burns depends on what the other ingredients are. Adding a bit of calcium will do it.

AHA,

I should have read more carefully. The answer to my initial question was in the article and I missed it.