WEBVTT

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[MUSIC PLAYING]

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The James Webb Space
Telescope will be launched

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into the extreme cold of space.

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To deal with these
harsh environments,

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engineers of the observatory use
special materials to build it.

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Well, one of the instruments
NIRSpec or Near Infrared

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Spectrograph used
silicon carbide.

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What exactly is silicon carbide?

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Well, we're here at Astrium
at Ottobrunn in Germany

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to find out.

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So Guenther, I guess
this is silicon carbide.

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What's so special about it?

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It's two times
stiff than steel--

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Wow, OK.

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--and five times
stiff than aluminum.

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Silicon carbide is
a ceramic material.

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And it offers
outstanding properties

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to fulfill the
mission of NIRSpec.

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So ceramic, like
porcelain or something?

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Yeah, in principle, yes.

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It's a lightweight
design, you see?

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The material offers
high stability.

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The optic stays aligned.

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So that is very important
for this mission.

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I can show you this
piece within NIRSpec

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when we are in the clean room.

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Mary, do you recognize
the piece of silicon

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carbide I have
shown you outside?

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Oh, yeah, it's that
part right there.

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It is part of an optical
element on NIRSpec.

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What parts are silicon carbide?

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Every gray colored
item you see here

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is made out of silicon carbide.

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It's representing 75% of
the structure you see.

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Do you guys actually
make silicon carbide?

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We don't manufacture it here.

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Boostec in France are
manufacturing these pieces

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out of silicon carbide.

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Hi, Michael.

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Hello, Mary.

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Gunther from Astrium
told us that you guys

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make the parts for NIRSpec
out of silicon carbide.

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What exactly is silicon carbide?

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Silicon carbide is
a synthetic material

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made of the chemical reaction at
high temperature of silica sand

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and carbon.

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Can I touch it?

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Yes

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It kind of looks
like a meteorite.

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Now, is this the stuff that
NIRSpec is made of, then?

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No, in fact, for
NIRSpec, we have

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to crush this into fine
powder, like this one.

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It's typically one
micron in in grams size.

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So is this the stuff, then,
that goes into making NIRSpec?

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Not yet, there is a
further step where we

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press this powder into blocks.

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We have just got the blank
for NIRSpec base baseplate.

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I will show it to you now.

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This material is
still very brittle.

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And it feels like
chalk or chocolate.

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It can be breaked
by hand, like that.

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It can be easily machined,
because the material is soft.

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Guenther told us that this
was going to be a ceramic.

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Is this a ceramic now?

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No, it's not yet a ceramic.

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It will become a ceramic
after being sintered.

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And sintering means what?

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Sintering involves a treatment
at high temperature, typically

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more than 2000 degrees Celsius.

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What is interesting
here is that you

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can see that it is
machined very quickly.

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This just gives them a
flat surface to work with?

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You have to get a flat surface
and also the good thickness.

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We have seen the press block.

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And afterwards, we
have to machine it.

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And for to machine it, it's
done with milling machines.

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And you're using these programs
to program the machine?

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Yes, here we are simulating
the program of the big base

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plate of NIRSpec.

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Once we put part in
the milling machine,

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we start green machining.

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It is here that
we shape the part.

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This will take
roughly two weeks.

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Where do we go after this?

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The part will be
sintered in order

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to transform the compact
of powder into the ceramic.

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What's he doing now?

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He's preparing the
measurement of this part

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with this coordinate
measuring machine.

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He will measure the
flatness of this area here.

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How precise do his
measurements have to be?

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Precise in the range
of a few micrometers.

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In 1 millimeter, you
have 1,000 micrometers.

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Here, it's non-destructive
inspection of the part.

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We first spray the
dye penetrant on.

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Then we rinse it off.

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Then we dry it.

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And we inspect it in the
dark room under UV light.

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And if we have
cracks in the part,

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we are able to see them
with this technique.

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For space application, we
do not tolerate any crack.

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If you have a small one, we
will remove it by grinding.

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We are able to do that.

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The UV allows us seeing the
cracks and the big holes.

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Here, we are looking
for very small holes.

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And this is on top of
that process we just

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saw with the UV light.

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What's he preparing to do now?

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This laser scanning
annal allows us

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to make 3D model very quickly
and to compare the real model

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with the theoretical one.

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We have here some
NIRSpec samples.

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And you have NIRSpec mirror,
flat mirror structure

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part of NIRSpec here,
which have been sintered.

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And now, you can touch it.

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The material is not brittle.

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While silicon carbide is used
to build space telescopes

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like Webb, its unique properties
are valuable for things

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right here on Earth, like
the water pump in your car.

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Thanks for joining us for this
edition of Behind the Web.

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[MUSIC PLAYING]

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