Kind: captions
Language: en
this is the first in a series of videos
about a chemical reaction discovered
over 125 years ago it releases a
tremendous amount of heat oh no the
GoPro liquefying metal it is so hot it
is not an explosive but it can cause
explosions oh that is crazy but the
reactants are so inert they can
withstand a blowtorch in definitely do
you think this whole thing's going to
blow up in my face in fact when
Hollywood directors wanted something
that looked like a nuclear bomb this is
the reaction they
chose but in its most common use one
basically unchanged in over a century it
has helped move billions of people all
over the
world in the late 1800s Carl and his
younger brother Hans goldshmid were
preparing to join the family business
there father owned a chemical factory
making dyes for Fabrics so they studied
chemistry under Robert bunson of Bunsen
burner
Fame after their father's early death
Carl took over management of the company
later joined by his younger
brother one of hans's first major
research a was to find a way to produce
pure Metals these were essential for
making dyes for everything from clothing
and tablecloths to wallpaper
at that time good dyes were hard to come
by most were faint and Faded further
after use some required the collection
of large quantities of exotic insects
these days we take color for
granted but in this drab world people
would pay handsomely for bright
colorfast
dyes one such Dy was Shield's green
which was chemically copper arsenite as
its name suggests it was toxic though
exactly how toxic is a matter of debate
still it became the dominant green dye
by the end of the 19th century because
its color was unbeatable the red color
of the British army officer's coats was
made from cotal a central American
insect mixed with tin the addition of
tin made the color darker and more
intense so the demand for Pure Metals
was
strong they had their experience in
purifying Metals by dissolving them in
Solutions or in acids and all kinds of
things the incoming cyanide solution
goes on dissolving the particles of gold
left in the sand after amalgamation and
liquefies it and then work with these
salts purify the Sals and then reduce
these Sals into their metal State and
every step that you would take would
then again cause problems right reducing
it in a furnace you have to deal with
all the exhaust and the contamination
through the car carbon and metals are
very difficult to separate from each
other they basically they form a mixed
Crystal right so they like an alloy
right they all become in a sense one
substance that has one melting point
which is why you have to kind of take
some steps to separate them so Hans came
up with a novel
idea he would react a metal oxide like
chromium oxide with aluminum metal and
his hope was that the oxygen would swap
Partners forming aluminum oxide and pure
chromium this type of reaction is now
known as an aluminothermic or thermite
reaction so I have come to visit
electrotherm in Germany a company that
is a direct descendant of gold schmits I
feel like they've set this up like a
tour of Willy Wonka's chocolate factory
but instead it's a thermite Factory here
we are going to try to replicate Han's
first successful reaction all
experiments in this video were performed
under the supervision of professionals
taking proper safety precautions
originally the first experiment was
using Chrome but we're using copper
which is comparable this is like 300 G
yeah 300 G of thermite pour it in all
right we pour it into The
Crucible and ignite all
right yeah that's it yeah a leave it
leave it leave
it
w that is like fireworks oh that's
impressive but you bet he was surprised
when he saw
[Laughter]
[Music]
that handful of aluminum
powder and then you get this as you can
see the reaction releases a lot lot of
energy the temperature of thermite
reactions typically exceeds 2000° C and
it can be as much as
2500 that's because aluminum forms very
strong bonds with oxygen when those
bonds form they release a lot of energy
way more than is required to break the
copper oxide bonds we started with this
energy melts all the products of the
reaction and makes them glowing
hot it is hard to express just how
bright they are it feels like staring at
the
sun if you see Clips in this video where
the highlights are Overexposed is
because it is so hard to judge how
bright the reaction will be and it's
almost always brighter than you
expect so that dropping down the bottom
there is that liquid copper that's
liquid copper and basically the solution
that was being created but if you get
this hot mixture of pure metal and
aluminum oxide how how do you separate
the two materials to isolate the pure
metal we're trying to set up an
experiment that no one has ever seen
before and it's actually going to allow
us to see inside The Crucible we cut The
Crucible in half and we're attaching two
pieces of thermally resistant glass each
4 mm thick as a window into the reaction
people said this would be impossible
that you wouldn't be able to see
anything or that the glass would just
break we've never done this on camera
and and really seeing it this way and
this clearly and I think it's going to
be fascinating to then start to analyze
and make sense of this now this glass
has been specially treated so it
shouldn't shatter immediately when it
comes into contact with molten metal
that is hot that is really hot but the
melting temperature of silica is around
1700°
C which is definitely lower than the
temperature of the reaction so the glass
certainly will melt the hope is it melts
slowly enough to contain the reaction
the glass will melt and at the end we
have just a very thin layer of the glass
at the
end so you were ignited it's up to you
to place the IGN I think I think someone
else should ignite it I think someone
else should ignite it why because I
don't trust myself we saw how incapable
I was of of of igniting yesterday that's
it leave it leave it leave it for this
reaction we'll be using iron thermite so
a combination of iron oxide and aluminum
metal okay it's good let's do
[Music]
this
holy oh no the GoPro
[Music]
oh
boy oh no oh
[Music]
no that's the end of the
GoPro the reaction starts at the igniter
and expands outwards in all
directions to me it almost looks like
ants or mold or something it looks
organic in how it sort of
spreading you you see a pulse yeah boom
boom boom it's living yeah that's what
it looks
like why is there pulsing I don't know
okay we try to
understand we never knew that it did
that we do this for 100 years and and
suddenly you find out you know every
portion that gets ignited does
[Music]
that do you think that's gas escaping up
and that's almost what causes the
pulsing like some some gas heats up and
then it it shoots up and then it makes
space for the next one that's what you
seem to see over here
yeah wow that is hot that is really hot
I wanted to get a closer look so I asked
them to put some thermite on top of
glass and then I would shoot from below
using this prob blend I'm ready okay
we're
rolling it's rolling it's rolling it's
rolling it's rolling it's rolling there
it goes there it goes there it goes
there it goes there it goes there it
goes yeah the exposure is pretty good oh
my goodness
incredible this is the closest I think
anyone's ever filmed a thermite
[Music]
reaction you can see that the reaction
proceeds in bursts it reacts fast but
then pauses for a moment before
advancing
[Music]
again take it uh uh sure yeah take it
take it take it take it take it take it
oh boy I have two ideas about why this
might be first thermite is a mixture of
grains big particles of aluminum and
iron oxide and they need to be present
in the right ratio to react efficiently
maybe a little pocket reacts out to
where the ratio is slightly less ideal
until the heat builds up enough to
trigger the reaction in the next pocket
my second idea is that in between the
grains there is air the reaction heats
the air which expands increasing the
pressure between the grains and possibly
pushing some of the unreacted material
away from the reaction front so once
that air escapes the next patch can
ignite once all the thermite has reacted
things get really
violent molten metal is ejected out of
the top of the Cru
and inside the liquid is sloshing
around this could be due to some of the
materials boiling actually turning from
liquid into a gas now I know it sounds
wild to think about Metals boiling but
the boiling point of aluminum is around
2500 C iron boils above 2,800 C and
there are other elements in the mixture
like manganese that boil at just 2,000 C
now once that boiling stops the that
liquid settles down and now comes the
key to making pure
metal the density of liquid iron is more
than twice that of liquid aluminum oxide
so iron settles to the bottom as
aluminum oxide floats to the
top now when the metal melts through the
bottom of The Crucible the first liquid
to pour out is
iron only after it has drained does the
aluminum oxide or slag follow you can
actually see the change from Iron to
aluminum oxide liquid iron has a
viscosity like water so you can see it
coming out there and splashing and then
the slag starts right
there yeah it comes out smooth really
cool wo and this is more like warm honey
yeah you can totally see it
[Applause]
[Music]
[Applause]
[Music]
wow it definitely gives you a sense of
being right there and you can see the
Flames coming off the front and it still
records look at the bubbles on the
glass you see those
bubbles and the Beautiful shot of the
iron pouring out oh no oh no I mean this
is impressive work for a camera camera
that's on fire we're going to put a
cobblestone normal street paver inside
here it's made of limestone We'll pour
the thermite on top and then ignite it
yes and then we'll see that the
Cobblestone is less dense than that
solution it's going to come up to the
surface
yes whoa
okay it looks like it's taking into
pieces that's a good bit of
lava did you see it oh yes ordinary
rocks like cobblestones rise to the
surface just like the slag as the denser
metal drops to the bottom and this is
key to producing High Purity metal in
The
Crucible so Hans goldmit had developed a
process to make pure metals like
chromium copper and iron this could be
great for chemistry and making dyes but
Hans suspected it could have even
broader applications he patented the
process in 1895 and wrote it up for
publication he wrote the procedure that
I have here is in its principle so
extraordinarily simple that I could
hardly have undertaken the time to
present if not for its surprising and
extraordinary effects thermite was a
solution looking for
problems one of the first applications
of thermite was to weld metal Parts in
remote locations wherever you need a
very very strong very reliable weld in
kind of a remote area where you don't
have the luxury of bringing you know
tons of equipment and tons of welding
gear that is useful for
thermite you know some of the first
customers were in fact shipping
companies when some shaft would break in
the middle of the ocean at the time you
would be lost and now having like
thermite to be able to at least fix that
in some way that would get you home was
actually very useful it was being able
to fix something or to fix cracks in
engine blocks and to be super mobile
with
it because you know like we say it takes
two guys in the
bucket of course in this case the iron
thermite would actually not produce pure
iron but rather steel this was done by
including carbon and other alloying
elements in the thermite powder nobody
needs pure iron pure iron is actually
useless it's very soft it corrodes
immediately even in dry air and nobody
will want that right you need iron with
some carbon in it exactly right you need
iron with some carbon that makes it a
steel so the majority of thermite
produced today is steel thermite you
have this steel mill that you can you
know move wherever you want it to
have after the the end of the Cold War
we would use thermite basically to
destroy say gun barrels from
tanks basically you have a portion of
thermite that you basically stick into
the gun barrel and then you would ignite
it and then it will basically weld the
gun barrel and destroy it and it will be
completely useless afterwards those are
all kinds of weapons or stuff that were
not useful anymore that we use thermite
to destroy because it's very quick and
it's very safe and it's very final and
it's very final once you've put that in
there is absolutely no way of making use
of that weapon again
modern application of thermite is to use
the heat generated to destroy
information past a certain temperature
the curee temperature magnets lose their
magnetism so information stored on
magnetic hard drives at high enough
temperatures becomes
unrecoverable this looks like a very
different form of thermite I'm used to
seeing it as a powder before it was also
powder and we dry it can I pick it up or
yes it's not I mean that just it it's
like a normal piece of tile yeah lay it
down that's
amazing that is
cool so if we want to make sure no one
can read the information on this hard
drive I could put this on top yeah there
you
go when we ignite the The Crucible we
have this high temperature for for a
short
moment and here we have it for 10
minutes so everything is destroyed so
you're controlling the energy release to
make it slower here yes the temperature
is not so high and reaction is slower I
am going to light this thermite tile in
all four corners and it's going to
generate heat for about 10 minutes and
we'll see what it does to this laptop
all right let's light
it
ooh I like this
see how it's
oozing
whoa It's a totally different
effect
whoa yeah that's getting
hot it's getting to the laptop now this
is really cool like you got to see the
molten goo coming out from underneath
that laptop that is
wild a
after seeing so much thermite this is a
totally different version of it look at
the puddle of metal
[Music]
there yeah nobody's getting any data off
that
laptop that is
awesome I did not expect to see the logo
in therm right can I lift it of
[Laughter]
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of the video and now back to
thermite now you might think given the
amount of energy given off that thermite
could be used as an
explosive but it's actually not well
suited for that purpose what makes
thermite so interesting and so important
is that you can control it so well if
you have an explosion you can kind of
calculate the energy really well and say
it's you know x amount of megga that you
get out but it's really hard to say over
what time maybe one of the reasons why
this is not explosive it's because when
you have explosive reactions typically
your
reactants are solid and the products are
gases which obviously expand a lot and
create a lot of pressure but in this
case both the reactants and products are
solids or solids and liquids right you
have so much control over what's going
on W I feel like I got a sunburn from
that this property makes it possible to
take down structures where explosives
would cause too much
damage in 1933 4 weeks after Adolf
Hitler became the chancellor of Germany
the Reich stag building in Berlin was
set on fire and it would only be fully
repaired 24 years later but the burnt
out steel Dome had lost its structural
integrity and needed to be removed now
conventional explosives would have
caused irreparable damage to the rest of
the old building so on November 22nd
1957 thermite charges were strapped to
the Dome and when ignited they melted
through the steel which fell neatly into
the for former Pliny Hall below allowing
the repairs to be completed applications
like this are possible because the
thermite reaction can be carefully
controlled they have the ingredients so
dialed in that you can actually ignite
thermite indoors without fear of molten
metal flying all over the
place this mixture includes some pieces
of pure steel they don't participate in
the reaction but they do absorb heat as
they melt so they help control the rate
of reaction and the temperature
reached there you go all
right that's it that's it I don't think
it was in oh
boy
waa wow it's interesting like looking at
it through dark glasses it looks like
like a cornbread muffin or
something one of the really important
parameters to control is how long after
the reaction starts does the metal start
flowing out the bottom of The
Crucible this is known as the tap time
it's critical because if the tap time is
too short the metal inside doesn't fully
separate from the slag but if the tap
time is too long then the metal
dissolves more silica from the walls of
The Crucible and it also comes out
colder than it could have been so the
chemistry of the steel actually changes
over the the longer it stays in there
the longer it stays in there and this is
why it's very important for us to be
able to control control how long it
actually stays there you want the tap
time to be somewhere in the middle just
right we've set up this experiment here
to test can we control the time when the
steel comes out so the idea is it should
come out of this one first then this one
then that one we're going to ignite all
three simultaneously and see what
happens you good three two
one yes
they all ignited at almost exactly the
same
time but the top time of the first
Crucible we got one was by far the
shortest
two it' be amazing if this one one stops
and the third one
goes like that would be very very
impressive come on third one
wow W that's great that's
fantastic another attribute that can be
controlled is the temperature of the
metal here we have two different
versions so we have a version with 12%
damping and here we have with 25
sometimes you want the metal to come out
a little hotter or a little colder there
we go
nicely controlled
ignition well that one goes a lot more
whoa you can see the 12% one went
first
whoa you can see that you know this one
starts first so you can get a bit of a
sense but I feel like both of them reach
2,000 I don't know is the one on the
right side is one of the less dampen
portions and the other one is one of the
more dampened ones we could dramatically
change the temperatures in both
directions a little bit higher and
significantly
lower all of this control is achieved by
carefully adjusting the thermite mixture
this is the starting point of the making
of thermit about once or twice a day a
truck comes and drops in this this is
MIL scale so this is basically a mixture
of different ion oxides when you hot
roll steel the the surface of the steel
is very reactive because it's so hot and
there is so much water involved to cool
the the rollers so that the surface
actually oxidizes very quickly and
creates this Mill scale and then they
use like water jets to blow it off the
steel surface and for the Rolling Mill
this is just a waste product
right waa there you go that is cool
the mil SC from outside comes in here
and then gets dried because thermit and
water they're not exactly friend and you
want the mill scale to be as dry as
possible and then stay dry so this is
how we dry
it the iron oxide is shaken up the
spiral ramp to the top floor there the
particles are separated into different
sizes and compositions before being
mixed with alum umum powder this also
has to be very dry I imagine it's not as
much a problem here because the way that
it's being manufactured it doesn't
contain any water with the ion oxide
it's getting blown off with the water
jets we have to control all the elements
the reactive Elements which is the ion
oxide and the aluminum to make sure that
every portion has their very defined
reactivity and then we get the reaction
that we want and also the chemical
qualities and the steel that we want
you guys use this word portion portion
yeah that's the way that we use the a
portion is basically one bag of
thermite No cameras always breaking the
rules this guy so the portions are
bagged up individually and stored in the
warehouse this is our warehouse but this
is only one of them and this is not even
the
biggest can I ask you one question
here okay yesterday we saw there's a
tremendous amount of energy in
thermite and in this Warehouse there's a
tremendous amount of thermite so the
question for you is is this in any way
dangerous that's a it's a fair question
there's no there's it's it's a fair
question they set up this demonstration
for me to see how safe thermite is to
handle they want me to try to ignite
this full Crucible of thermite with
increasing sized ignition sources
but I wasn't entirely confident this was
a good idea maybe you can help me ignite
it where's Kristof have you tried this
by the way
no well then under these circumstances I
would get you some safety gear I'm to
95% sure that he cannot ignite it 95
there you go that's sa in 20 is that is
that how we're doing it
this is a fireproof
suit at least they will be footage how
it
[Laughter]
happened so first here's a little
lighter all right let's give it a shot
see if I can get this to ignite three 2
one uh I'm making some of the thermite
particles here quite hot so that they
are actually glowing Orange
oh oh oh it's getting quite bright are
you getting worried watching that no
we're not getting wor I heard you make a
noise and I was like no he's getting
worried I shouldn't I shouldn't keep it
on the same spot do you think this whole
thing's going to blow up in my face no I
hope not so you can see like even
getting it glowing hot glowing hot it
still won't
ignite all right let's let's pull out a
bigger
torch I'm going to try with this one got
a nice big blue flame there
I feel like this is not as hot as the
other lighter so I'm getting a little
bit of orange
there but just
barely we're going to have to bring out
the big
guns all right let's torch it in three
two
[Music]
one do you think we can build up enough
heat how hot
500 is he saying 500 yeah I can see a
lot of thermite glowing orange there's
some pieces coming
out a nice and glowing 700
700° but it I think this is an excellent
demonstration that thermite is not going
to ignite under normal conditions
wow there you go it's still glowing did
it melt yeah that can happen it can melt
and not uh not ignite not ignite what
the that is absolutely
nuts obviously there is a lot of
potential energy here but getting that
energy is really really difficult so if
if it would catch a fire and you know
whatever the the wooden pallets will
burn that would not you would not be
able to ignite the would not even no it
would just sit there and it would just
ignore
you the key to this lack of reactivity
is the aluminum
powder the aluminum is quite stable
because it's covered in aluminum oxide
and only if it gets so violently heated
that that layer breaks down in a large
number of particles then the reaction
can start so the aluminum oxide is like
the secret stopper of thermit exactly
the seal
this reaction has a very high activation
energy so it can't be started by a
lighter or a propane
torch okay this is why we've been using
barium hydroxide igniters basically the
same stuff that's in sparklers happy New
Year it gets hot enough to break through
the aluminum oxide layer and start the
reaction we want to make sure that the
ignition temperature is so so high that
you can only light it
deliberately cuz once it's
going I'm going to push the button in 3
two there is no way of stopping
[Music]
it that is
crazy I was filming in Germany for a
full 5 days so this is just a taste of
what's to come we'll find out how
thermite reacts with its environment and
we'll have a dedicated video on the most
common application of
thermite welding railroad tracks
together they probably will be millions
of people watching this video most of
them have probably ridden on a train
what is the likelihood that they have
ridden over one of your thermite
welds they will 100% 100%
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