The Register’s Tim Worstall reports that man-made sapphire could replace Gorilla Glass as the material of choice for scratch-and-crack-resistant mobile phone screens in the near future, according to a recent speculative piece from MIT Technology Review which notes that:
“Manufactured sapphire – a material that’s used as transparent armor on military vehicles – could become cheap enough to replace the glass display covers on mobile phones. That could mean smartphone screens that dont crack when you drop them and cant be scratched with keys, or even by a concrete sidewalk.
Worstall notes that glass is made with many different compositions: standard plain glass is silica (silicon dioxide); glass for cathode ray tube screens is usually 25 per cent lead oxide to stop the radiation frying your brain; camera lenses are 25 per cent or so lanthanum oxide; face masks for deep sea divers are heavily doped with thallium oxide to correct for problems created by the weird refractive index at great depths, and Corning’s Gorilla Glass is silica glass with extra potassium ions added. Sapphire is an aluminium oxide, and while it’s not quite and wholly true to say that it’s just aluminum glass, that’s a useful way of thinking about it.
Silica is basically beach sand, priced at perhaps $20 or $30 a tonne, while Alumina might be $300 a tonne at present, so current price differences for screens are roughly $3 for Gorilla Glass, and $30 or more for sapphire, but as sapphire production is refined and volume increases the price will come down to perhaos $10 or less for a smartphone screen, which most industry insiders queried by Worstall on the topic think would be competitive with Gorilla Glass at its $3 since the sapphire is some three times stronger, three times less likely to crack if dropped, and three times harder to scratch.
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