Sciencemadness Discussion Board

Aluminum oxide (sapphire) glassware?

Fyndium - 15-10-2020 at 09:19

Phone screen protectors and other stuff is made from sapphire glass which seems to be superior in every aspect to normal glass from mechanic stress to thermal stress and conductivity. But how about it's chemical resistance? Could it be manufactured into useful shapes similar to other glassy substances?

unionised - 15-10-2020 at 09:25

The chemical resistance is also good.
But it can't be made into shapes the same way that glass can.
Glass softens gradually as it gets hotter; alumina melts quite sharply. You can't do "glassblowing" with it.

You can, in principle, cast it to shape but that's difficult.
And it's a long way from cheap.

Fyndium - 15-10-2020 at 09:32

That's why I wonder, if there were uses for any high end industry for sapphire glass equipment, would it be done? Is there any purpose at all which would not be fulfilled with boro or quartz?

Conceptually, melts of any degree can be rotomolded, although this is far from any complex shapes. The molds would need to be tantalum(coated), tungsten, graphite or something else.

Chemetix - 15-10-2020 at 15:42

If you really need a high temp clear glass then Aluminium Oxynitride would be the go. Fantastically expensive but with a melting point of 2150C compared to 1700C for quartz. It would be about as hi tech as you could go for a transparent glass/ceramic. Bulletproof and nearly indestructible. Alumina by comparison is brittle.

Fyndium - 16-10-2020 at 07:57

Oh well.. So why are there no ALON glassware yet? :D

njl - 16-10-2020 at 08:48

Quote: Originally posted by Fyndium  
Oh well.. So why are there no ALON glassware yet? :D


"Fantastically expensive" - Chemetix

Morgan - 16-10-2020 at 12:11

If I recall Al2O3 while capable of higher temperatures one should raise the heat at a slower rate than what fused quartz can withstand.

Fyndium - 16-10-2020 at 12:36

You can't deny it wouldn't be fancy to distill lead and other metals in flask.

zed - 17-10-2020 at 03:54

Hnuh? Aluminum Oxide glassware? Very hard. Very brittle. Look at an Old Saphire ring. Might be a lot of wear on the edges of the facets. In contrast some Quartz crystals are very tough. After a lifetime of wear, in a faceted ring, the stone may be immaculate.

If we needed white saphire glassware, we could craft it by the Verneuil Method, I suppose.
https://en.wikipedia.org/wiki/Verneuil_method

Alternately, I suppose an alteration of the Czochralski method might work. They used to craft laser rubies by utilizing that technique.
https://en.wikipedia.org/wiki/Czochralski_method

Hot, really really hot. Expensive

Ah, the Saphire Phone screens. Takes a big furnace.

Kind like baking a cake. https://www.businessinsider.com/how-sapphire-glass-screens-a...

The "cakes". 115 KG Saphire Boules. https://www.youtube.com/watch?list=RDCMUCO_vmeInQm5Z6dEZ6R5K...



[Edited on 17-10-2020 by zed]

wg48temp9 - 17-10-2020 at 04:37

Aluminium oxide is used as a ceramic in lots of things magnetrons (the pink purplish ceramic that does not contain Beryllium) high power vacuum valves, tig welding torch nozzles and high pressure sodium lamps to name just a few.

Like most ceramics its made by sintering so it will usually contain a sintering aid. So almost any shape could be made including the common shapes of laboratory glassware.

zed - 17-10-2020 at 10:06

Very clever these boys. When the guys came up with a use for large ultra-thin slices of Saphire, they found a way to make them.

Ah, if I just had one of those footstool sized boules, in a nice Padparadscha color, beautifully faceted... and I had a time machine. I would endeavor to be a benevolent Maharaja, and my Harem would love me.

Those Boules by the way, cost just plenty. Maybe not in tune with the price tag of, priceless. But still, plenty

Well the verdict is in. GT who's video we watched, screwed up.

They got in trouble with Apple. Many of the Boules they produced were defective. They could not be used to produce phone screens. I don't even know if the company still exists.

Though I'm sure if you called 'em, someone would be happy to take your money.

I wonder how much of their spiel was true?

They part about bombarding the crystal face with protons to displace thin sheets of crystal seemed kind if fantastic, but crystals do sometimes behave that way.

We peel off sheets of Mica. Diamonds cleave easily along certain lines. And Topazes sometimes delaminate when heated.

https://www.engadget.com/2019-05-06-apple-sapphire-glass-sup...


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Fyndium - 17-10-2020 at 10:40

200-500$/kg. So 500k$ for a ton of single crystal, I suppose?

Since it's mass produced, the price could be significantly lower because of the economies of scale effect.

Modern days it's pronounced anyways that whatever is mass produced, the price comes crashing down, compared to past ages when everything made were basically a prototype of it's own.

I wouldn't be surprised at all that within this century we would be using graphene and diamonds for electric conductors, possibly even in a superconductive state. The time when diamonds will be sold by the kilo, the size of mandarins. Oh, well, why not just make then as large like silicon boules?

zed - 17-10-2020 at 11:11

OK. Sapphire screens may not happen for a while. They haven't figured it out yet. Now, you can buy big ass sapphires, and make them into screens, but how scratch and fracture proof they will be, remains to be seen. And, they will be expensive.

https://www.theverge.com/circuitbreaker/2017/5/4/15544426/ht...

Lets look at Aluminum Oxynitride!

Well, either Aluminum Oxynitride or Spinel might be good
prospects. Either has a Mohs hardness of approximately 8.

The important thing being a hardness higher than Silica. Our planet's most common abrasive. Moh's scale 7

So, maybe Spinel is doable. I have a link, but it ain't great.

The Navy has been attempting to develop it for Armor and Bullet proof glass, but they aren't talking about it very much, right now. So, it is possible, they lost interest. Or, they now have the attitude that it is "none of your damned business!".
Which would mean that it is too good to share.

https://www.dailymail.co.uk/sciencetech/article-3062461/Your...

More on Spinel.

https://www.nextbigfuture.com/2014/05/nanostructured-ceramic...

This is not new. Plastics may be reluctant to shatter, but they are easy to scratch. https://www.upi.com/Science_News/2019/04/01/No-more-broken-p...


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Dr.Bob - 17-10-2020 at 16:27

When the Czochralski method was mentioned above I did not regognize it, but now I remember seeing 5" diameter crystals of silicon that were made at IBM NY back in the 1980's (they were going up to 12" ones in Vermont). That was back when mainframes used lots of huge chips.

That was an amazing sight to see a single crystal of silcon the size of a log of firewood. I still have some slices of silicon that were used to test quipment. We cleaned them by washing them in tantalum racks with boiling hot sulfuric acid. now that was some harsh stuff, everything on the wafer was oxidized, fingerprints, oil, dirt, fingers, etc.

I have always wanted a pair of glasses made of aluminia that would be super thin and scratch resistant. maybe the AlON would be better, but plastic does not survive me well, even polycarbonate. Diamond or Silicon Carbide would also work, but haven't found them yet at my optician.

[Edited on 18-10-2020 by Dr.Bob]

Fyndium - 18-10-2020 at 00:59

The Czo process is probably the most developed special single crystal manufacturing line so far.

But wasn't the aluminum oxide at 9 Mohs?

metalresearcher - 18-10-2020 at 03:02

Quote: Originally posted by unionised  
The chemical resistance is also good.
But it can't be made into shapes the same way that glass can.
Glass softens gradually as it gets hotter; alumina melts quite sharply. You can't do "glassblowing" with it.

You can, in principle, cast it to shape but that's difficult.
And it's a long way from cheap.



Then Quartz glassware won't be possible as well as Quartz also has a sharp melting point. But it is possible to make glassware from such substances.

Morgan - 18-10-2020 at 09:19

Fun facts/tidbits

Why/why not sapphire
https://rayotek.com/tech-specs/material-comparisons.htm#q1

https://www.makeitfrom.com/compare/Fused-Silica-Fused-Quartz...

https://www.researchgate.net/figure/Principle-of-sapphire-cr...



[Edited on 18-10-2020 by Morgan]

Fyndium - 18-10-2020 at 10:27

Sapphire is a sort of superglass by those properties. It lacks some thermal stress for quartz, but as ordinary glass can shatter for fun, borosilicate handles about 160C, quartz can be quenched glowing hot to water, if what someone said is true.

zed - 19-10-2020 at 06:02

Glasses Dr. Bob? I would consider Sapphire like glass. Too brittle.

Plastics? Yes they scratch, but I have discovered a partial solution.

I was able to rehabilitate a pair of plastic lens, by "rubbing" them out, with a product called scratch-out.

Yup! It is a very fine abrasive designed for polishing CDs and DVDs. Kinda watery, comes in a tube. Use a finger tip, then perhaps a soft cloth, to polish the lenses.

This however, I no longer need to do. I bought multiple pairs of glasses, very inexpensively.

I had a current prescription, and I figured I'd like to have back-up glasses, on account of it being the end of the world as we know it, and everything.

I took a chance, and I ordered glasses online.

Zenni glasses. I ordered 7 pairs. All, different styles. Came to about a hundred bucks...total.

They arrived in a few weeks. The prescription? It was filled perfectly! The frames themselves, varied in overall quality, but for the price....They were Great.

No special coatings or tints, I just bought basic glasses. I'm good to go. The world can go to hell in a hand basket, and I might not be able to stop it. But, I will be able to SEE it.

Seriously. Some of the glasses I purchased were only about $12. Dollars a pair! Frames and Lenses. And, they were nice.

I was very pleased.

https://www.zennioptical.com

Oh, yeah. And that other thing.

https://www.youtube.com/watch?v=Z0GFRcFm-aY

[Edited on 19-10-2020 by zed]