> On Sep 9, 2016, at 1:23 PM, Doug Ingraham <d...@dustyoldcomputers.com> wrote: > > On Fri, Sep 9, 2016 at 12:39 PM, Peter Cetinski <p...@pski.net> wrote: > >> >>> On Sep 9, 2016, at 10:55 AM, Doug Ingraham <d...@dustyoldcomputers.com> >> wrote: >>> >>> Transparent aluminum exists. It is called sapphire. Sapphire is the >>> crystalline form of aluminum oxide. If you recall, Apple was thinking of >>> using it for the touch screen face of the iphone. >>> >> >> Ah yes, but can you make in sheets 60 feet by 10 feet by 1 inch thick and >> withstand the pressure of 18,000 cu ft of water? :) > > > The answer is probably yes, but not for anything like a reasonable amount > of money or in a reasonable amount of time. It would probably take a > couple of years to grow a crystal that size. There was a company making > the ovens used to make billets of sapphire about 18 inches in diameter and > a foot tall from which they would cut out the pieces they would need with > presumably a diamond saw. These billets would take something like a month > to grow so you would need a lot of them to make your screens in the multi > million quantities. And these billets had imperfections you had to work > around. In 1986 it would probably have taken Mr Scotts technical know how. > > Actually it actually *does* exist and is reasonable to manufacture. Here’s the article: http://www.nrl.navy.mil/media/news-releases/2015/transparent-armor-from-nrl-spinel-could-also-ruggedize-your-smart-phone
It’s basically a sintered process where the ceramic is formed (this particular one is called spinel) and the process is to put the powder in a press, raise the temperature and evacuate the air. The result is a clear crystal that has better properties than glass. The size of the piece is only limited by the size of the press. TTFN - Guy
