
Scientists develop 'unbreakable' glass almost as tough as steel - Mz
http://ajw.asahi.com/article/sci_tech/technology/AJ201510290034
======
craigds
To nitpick, the article uses the words 'tough', 'hard' and 'rigid' to describe
this glass, though those all mean different things.

I'd suggest that _all_ glass is both hard and rigid, so presumably 'tough' is
what they're going for. If so, the glass should be able to withstand a large
tensile force without fracture or permanent deformation.

'unbreakable' is also a little disingenuous. Everything is breakable, given a
big enough hammer ;)

~~~
blt
Don't think it's nitpicking at all. I came away unsure whether the new
material is hard (scratch resistant) or tough (won't shatter when dropped). An
article about a new material that doesn't make the distinction fails
fundamentally.

~~~
vlehto
You might find it interesting that toughness and "won't shatter when dropped"
are different things.

Toughness(G) = slowly absorb energy without fracture.

Shattering is more dependable of:

Fracture toughness(Kc) = (E*G)^0,5

Where E = modulus. That explains why plastics with low E shatter easily while
being tough. Metals have additional hardening methods that allow them to go
beyond this rule.

PS. Your knowledge on the subject is already what I'd wish laymen had. So I
really don't mean any offense.

~~~
personjerry
To clarify, is fracture toughness the ability to withstand a sudden increase
in energy?

~~~
vlehto
Not really.. I had kind of error there. It's still often toughness when you
wish to study how material reacts to sudden increases in (kinetic)energy.

Fracture toughness describes relation between maximum tension and maximum
depth of pre-existing crack that still doesn't launch phenomena called "fast
fracture".

[https://en.wikipedia.org/wiki/Fast_fracture](https://en.wikipedia.org/wiki/Fast_fracture)

It's highly relevant in many cases, because most real world materials have
microscopic cracks. And because the load where fast fracture might happen is
often lot smaller than yield load.

Curiously Charpy impact test still indicates more toughness than fast
fracture. But it's never used to quantify toughness in real life.

[https://en.wikipedia.org/wiki/Charpy_impact_test](https://en.wikipedia.org/wiki/Charpy_impact_test)

Thanks for that comment. I need to clear this stuff bit more in my head.

------
Someone1234
This is cool regardless. But I am interested in cost and weight.

If it is too costly we might only see it used in niche applications (e.g.
aircraft windows?). But even then if it weighs more than regular glass it may
not even be utilised there.

I'd like to see it used on vehicle front windshields, cracks are a constant
pain in the butt, and they can leave the rear window and side windows as
regular glass for emergency escape (typically only the front one receives most
of the debris). But it really comes back to both weight and cost again.

~~~
gohrt
Your windshield is safety glass, so consideration must be given for the need
to dissipate energy when a human head collides with it.

[https://en.wikipedia.org/wiki/Windshield#Safety](https://en.wikipedia.org/wiki/Windshield#Safety)

Trivia: A famous lawsuit about the safety of windshield glass was the _Pane_
vs. Ford case in 1917

~~~
Johnny555
I don't think that safely fracturing when struck by a human is the safety
function referred to in the linked article - once a person hits the
windshield, the primary safety mechanisms (seatbelts, airbags, and structural
integrity of the car) have already failed, so whatever happens at the
windshield will make little difference.

What the article says is that the safety role of a windshield (besides not
breaking into dangerous shards of glass) is in being strong enough to maintain
the structural integrity of the passenger compartment:

 _Modern, glued-in windshields contribute to the vehicle 's rigidity, but the
main force for innovation has historically been the need to prevent injury
from sharp glass fragments. Almost all nations now require windshields to stay
in one piece even if broken, except if pierced by a strong force. Properly
installed automobile windshields are also essential to safety; along with the
roof of the car, they provide protection to the vehicle's occupants in the
case of a roll-over accident._

 _Today’s windshields are a safety device just like seat belts and airbags.
The installation of the auto glass is done with an automotive grade urethane
designed specifically for automobiles. The adhesive creates a molecular bond
between the glass and the vehicle. If the adhesive bond fails at any point on
the glass it can reduce the effectiveness of the air bag and substantially
compromise the structural integrity of the roof._

~~~
Natsu
Windshields are laminated safety glass, which it sounds like you might be
confusing with tempered safety glass. There's a huge difference in how those
break.

Laminated glass remains in one solid mass held together by the plastic sheet
in the middle, while tempered glass explodes into tiny pieces that are sharp
but not overly harmful. Ordinary annealed glass breaks into long, dagger-like
pieces that are dangerously sharp, which is why it's tempered or laminated
into safety glass.

So the windshield is meant not to break apart, because it's laminated rather
than tempered. The polymer lining between the lites of glass prevents it from
scattering and causes it to be quite impact resistant. [1] Conversely, you'd
really hate to have tempered glass as your windshield, if it broke the entire
thing would just pop into tiny pieces that would get into your eyes. If a rock
hit hard enough to break a hypothetical tempered windshield, the parts that
didn't pop would be filled with cracks and impossible to see through due to
being white from being filled with tiny cracks, though you could just bat them
out of the way as any parts were partially intact would simply crumble when
moved.

The side windows are tempered, incidentally. If you've ever broken a side
window, you know what I mean about the whole thing just exploding. [2] If you
manage to pop it, the entire window will just fall apart easily, which might
be good if you had to leave from the window of a car. It can cause small cuts
and scratches and such, but it's not terribly dangerous unless it gets in your
eyes, even if, say, a sheet of 3mm, 33 1/4 x 73 1/4 inch glass breaks while
you're holding it. [3] It's no fun, but when you compare it to the fact that
annealed glass accidents have been fatal, it's not so bad. [4] Yes, I used to
work for a glass factory, so when I say that I've seen hundreds of tons of
broken glass, the word 'tons' should be understood in the literal, 2,000 lbs
sense of the word.

[1] Source: Determined empirically by beating on damaged pieces of it with a
shovel, when said pieces wouldn't fit into the dumpster. Or you can read this,
whatever: [http://sem-proceedings.com/10f/sem.org-IMPLAST-2010-SEM-
Fall...](http://sem-proceedings.com/10f/sem.org-IMPLAST-2010-SEM-
Fall-s004p01-Blast-Impact-Resistance-Laminated-Glass-Structures.pdf)

[2] See also:
[https://www.youtube.com/watch?v=xPwaq_6aXbo](https://www.youtube.com/watch?v=xPwaq_6aXbo)
This normally happens only if hit from the corner or an edge, but it can
happen just randomly. We usually saw this in winter, but only a few times a
year, meaning there was at most about a 1 in 10,000 chance of spontaneous
breakage in my experience and probably significantly less based on the average
daily volume numbers I remember. When there's something containing the edge of
tempered, it sometimes just takes on a white, broken look due to all the
cracks, but crumbles to the touch. It tends to just disintegrate like in the
video most of the time, though.

[3] Source: Direct, personal experience on multiple occasions for that very
size and many others. This is an every-day kind of thing and causes no injury
to someone with proper safety gear.

[4] Source: I'm directly aware of at least one such accident where someone was
found dead after having their neck cut when attempting to dispose of a cracked
sheet. I also provided first aid to someone who could've lost a hand to
injury.

~~~
vlehto
I thought windshields are tempered _and_ laminated. Not that it significantly
changes what you said. Just explains why occasional shards flying away from
windshields are not that sharp.

~~~
Natsu
I have never heard of a glass that's tempered & laminated. I'm not sure you
could temper a glass flat enough to laminate it, either--it moves on rollers
during the entire tempering process to keep it (mostly) flat, but it's nowhere
near as flat as it is coming from the float plant and distortion is measured
as part of the QC process.

You also can't temper any laminate that I know of--the liner would simply melt
and cause a mess in the furnace. Our tempering furnace operated in the
700-800F range.

They might seam the edges of the laminate, though, like you do with annealed
glass before tempering. I didn't work with windshields, only window glass,
including some 6mm clear tempered that went to Google.

~~~
vlehto
Tempered laminated exists. But I can't find anything about it being used in
car windshields. My bad, sorry.

The way I would do it would be chemical tempering before laminating. Then you
probably have lot less warping.

~~~
Natsu
Yes, the break pattern of a windshield is consistent with annealed glass. If
it were tempered, the entire window could become an opaque white whenever it
was damaged by a rock and that just wouldn't be safe. Not that the 'spiderweb'
pattern is easy to see through, but it's better than being fully opaque.

I'm not familiar with any tempered laminates as we never made such, but a
chemical process sounds more reasonable than trying to get laminated glass
through a tempering furnace or laminate two tempered lites.

------
mvgoogler
Am I being overly cynical when I interpret: “We will establish a way to mass-
produce the new material shortly ... We are looking to commercialize the
technique within five years.” as "We have no clue how to mass-produce this but
hope we can figure it out in five years if someone gives us money"?

It's hard to imagine how a gas-based "containerless processing system" will
lend itself to producing the thin, uniform sheets of glass for windows or
complex shapes like tableware.

It's a cool prototype, but figuring out how to produce at scale is often the
hard part.

~~~
wycx
Indeed. A method of making glass via a containerless processing system that I
am aware of, is aerodynamic levitation, wherein a ball of starting material is
suspended in a stream of gas, such as Ar, and heated by lasers. This method is
used in systems that tend to crystallise rapidly rather than quench to a nice
glass, since the thermal mass of the sample is very small and you can take all
the heat away instantly by tunring off the laser. Samples prepared by such a
method are typically 100s to 1000s of microns in diameter. I would be very
interested to hear how they would scale this method to industrial production,
if aerodynamic levitation is how they made their glass.

------
astrodust
Sounds like a hybrid between glass and "transparent aluminium".

~~~
justinsaccount
So... Gorilla glass?

edit: yeah...

From:
[https://en.wikipedia.org/wiki/Gorilla_Glass](https://en.wikipedia.org/wiki/Gorilla_Glass)

Gorilla Glass is a brand of specialized toughened glass developed and
manufactured by Corning, now in its fourth generation,[1] designed to be thin,
light and damage-resistant. This type of glass is not unique to Corning;
similar glasses include Asahi Glass Co. Dragontrail and Schott AG
Xensation.[2][3]

The alkali-aluminosilicate sheet glass [snip]

(The link is to asahi.com)

~~~
logfromblammo
Gorilla glass uses a post-solidification hardening step.

The glass described in the article uses a higher aluminum content than any
other mass-produced glass, to the point where any contact with a solid surface
would produce alumina crystals rather than incorporate the aluminum into the
glass structure.

So they levitated a glass bead with a continuous stream of air until it
solidified. The bead is very strong, but they have no idea how to work the
resulting glass into fibers or sheets.

------
seesomesense
Sorry, But That New Glass From Japanese Researchers Isn't Unbreakable

[http://www.forbes.com/sites/carmendrahl/2015/11/03/sorry-
but...](http://www.forbes.com/sites/carmendrahl/2015/11/03/sorry-but-that-new-
glass-from-japanese-researchers-isnt-unbreakable/)

------
cordite
A few questions on applicability

1\. Would this be good for a car? Is having a mostly unbreakable windshield a
good thing?

2\. How would it handle for cookware? Will it last even if an ignorant person
left it in the oven for hours on end?

3\. What about uses on phones? Can I have both a scratch resistant touch
screen that also doesn't fracture if I drop it 3ft onto asphalt?

4\. What does it do in reaction to sunlight? How insulative is it if used in
buildings and homes?

5\. Is it non reactive for biomedical uses? Does it deteriorate over time? How
stable is it?

~~~
govspy
>2\. How would it handle for cookware? Will it last even if an ignorant person
left it in the oven for hours on end?

Pyrex has been around since the 1910s and doing this just fine ever since.

~~~
nly
Pyrex _will_ shatter if you take it out of a blistering hot oven and pour cold
water on it (e.g. to let stuck on food soak).

~~~
yyyyyak
Yah...I just learned this the hard way. I took it out of the oven and put in
on the cold granite countertop.

------
tb303
Finally, we can keep humpback whales in our starships!

~~~
joehenriod
Serious question, couldn't they have just used steel walls and grabbed the
whales no problem?

I see no reason that they needed to be able to see through the walls and look
at the Wales inside.

------
venomsnake
This could revolutionize knife making. A steel knife is always like a saw on
micro level. A glass (like obsidian) could get properly sharp. A glass with
the properties of steel is a dream come true.

------
marcosdumay
Wait. A big elasticity coefficient is not the same as 'unbreakable'.

Being a mixture of silicates and alumina, I'll be very surprised if this is
not fragile. There's nothing about it on the article.

~~~
personjerry
Glass itself isn't always "fragile"
[https://en.wikipedia.org/wiki/Prince_Rupert%27s_Drop](https://en.wikipedia.org/wiki/Prince_Rupert%27s_Drop)
so perhaps we'll be pleasantly surprised

~~~
eric_the_read
Oh man, I love Prince Rupert's Drop. As usual, Smarter Every Day has a great
video on them:
[https://www.youtube.com/watch?v=xe-f4gokRBs](https://www.youtube.com/watch?v=xe-f4gokRBs)

------
Johnny555
But is it as scratch resistant as hardened glass? Having glass that doesn't
fracture when dropped is nice, but not if it means it gets scratched up from
the keys in my pocket.

------
SixSigma
I think the "containerless processing technique" is an acoustic levitator. My
friend was on the team building one for a Japanese investor who wanted to make
a wine glass that didn't break when you knocked it over on your fancy granite
worktop.

See one working [https://youtu.be/0K8zs-KSitc](https://youtu.be/0K8zs-KSitc)

------
hoodoof
Make bottles out of this, sell them, return a deposit to get them back. Wash
them. Reuse.

------
tcpekin
Here's a link to the paper itself if you have access:
[http://www.nature.com/articles/srep15233](http://www.nature.com/articles/srep15233)

------
fixxer
Please start with the iphone. Damn thing shatters if I look at it funny.

~~~
testrecord
Man, I've never had a problem with a broken iPhone screen. I worked for months
on a pretty large construction site breaking up concrete while dropping my
phone fairly regularly and it's still aces.

Obviously a stronger screen would be great, but a case does wonders if you
want a functioning phone for now.

~~~
fixxer
yup, hindsight...

I never had a problem with a phone screen breaking until the 6 plus. My
OnePlus is bulletproof.

------
infinity0
I bet the British government will try to ban this too.

------
Overtonwindow
Put it on an iPhone and it will shatter. Guaranteed.

------
ashmud
Is this anything like aerogel?

~~~
Sephr
Aerogels aren't known for their structural strength or elasticity, but for
their extreme insulative properties.

------
such_a_casual
I wonder if it's safe to smoke out of.

~~~
qnaal
aluminum is a known neurotoxin

~~~
daughart
Only at very high concentrations: Adverse neurological effects have been
observed in rats and mice at doses of 100–200 mg Al/kg/day, while the USDA
limit is 0.10–0.12 mg Al/kg/day for adult (25–30- and 70+-year-old) males and
females. Aluminum is the 3rd most common element in the Earth's crust and
humans have evolved given a certain level of environmental exposure.
([http://www.atsdr.cdc.gov/toxprofiles/tp22-c2.pdf](http://www.atsdr.cdc.gov/toxprofiles/tp22-c2.pdf))

