Famous in Star Trek IV The Voyage Home, it Al{2}O{3}, transparent aluminum is stronger than glass and the 3d hardest substance. This is what Munro reports as the windows of the Cybertruck. Bob Wilson
I see, but most of the applications they cite are for DOD where cost is less of an issue, and where armored windows might be a really good thing to have. IR properties in particular are going to be better with sapphire - for those applications that need it, but a consumer vehicle isn't one of them. And aren't these the windows where they threw the steel balls at them during the rollout - only to have the windows shatter?
That is what Sandy Munro reported. But I'll feel a lot better when he gets one to analyze. Bob Wilson
Unless someone has proof to show something else, I doubt if they are using anything other than glass laminates or special types poly carbonate. Again I am not a shatter expert, it looked liked regular glass for me The chart below shows the thickness and strength of the different glasses. Now why would most people need a glass that can resist 7.62 mm NATO 5 shots. The lower cost versions can resist at 9 mm 3 shots and I guess that should be sufficient for most ordinary mortals. Tesla is going to sell it at $39,000. He already has stainless steel 30x plates. Realistically, I do not think that he will spend or the car needs a Aluminum Oxynitirde window what has a higher density hence higher weight and also far higher cost. Is the objective to provide protection against odd shot or to foil full fledged attack. At this price point, I doubt if he going to for something very expensive. UL has different codes, I would surprised if Elon wants to UL 762 level 8 or 9, when UL 762 level 1 is better than current cars. Here is a pdf for the UL testing conditions https://web.archive.org/web/20110626221047/http://www.armorcore.com/docs/UL_752_Specification.pdf https://en.wikipedia.org/wiki/Bulletproof_glass Bulletproof glass (ballistic glass, transparent armor, and bullet-resistant glass) is a strong and optically transparent material that is particularly resistant to penetration by projectiles. Like any other material, it is not completely impenetrable. It is usually made from a combination of two or more types of glass, one hard and one soft[citation needed]. The softer layer makes the glass more elastic, so it can flex instead of shatter. The index of refraction for both of the glasses used in the bulletproof layers must be almost the same to keep the glass transparent and allow a clear, undistorted view through the glass. Bulletproof glass varies in thickness from 3⁄4 to 3 1⁄2 inches (19 to 89 mm).[1][2]
I suspect this glass came from their solar city development. They want a solar tile that is impervious to severe hail and this would be a good solution. Bob Wilson
In PV glasses you are trading off the following three technical factors: low reflection, high transmissivity, and high strength (and off course cost) You make the glass too thick, you lose transmisivity, which is the key to PV efficiency (how much sunlight hits the actual cell). High quality tempered glass (which can withstand hail on a car left outside in a hail storm (the body may sustain damage but not the windshield might) is usually used in solar panels. A good quality solar panel has a glass with thickness between 3-5 mm. Bullet proof glass gets into the 10-30 mm range. So I do not think they would use 10 mm thick glasses on a solar panel. So back to my original question on the design criteria: Is this to prevent a stray bullet or withstand a planned multi-round attack? This will decide glass quality, thickness and cost. Other than for top government officials, extremely rich businessman and possibly drug dealers and other criminals, do others need say UL 762 level 5 or higher protection. My guess is if they are using Aluminum Oxynitirde it probably came from their Space X development (as did the stainless steel). If they are using some sort of tempered laminates, it may have come from Solar City.
Texas Armoring Corporation (TAC), the largest manufacturer of armored vehicles for civilian use (https://www.texasarmoring.com/about/ ) uses polycarbonate and people pay a premium to buy those cars. Would Tesla really provide better features at a fraction of the cost. If the Cybertruck was that good, then Texas Armoring is out of business.
