A New Frontier for Smart Phone Gorilla Glass: Alternative Strengthening Method for Increased Reliability and Efficiency
Chad Watson and Darryl Butt
More than 1 billion people utilize smartphones and touchscreens worldwide. The touchscreen glass, a key component of these devices, needs to be durable and scratch resistant to survive everyday use. The defining weakness of glass products is their poor ability to withstand tensile stresses. Sandia National Laboratories is exploring sodium-for-potassium ion exchange techniques, which induce surface compression to increase glass strength. Conventional ion exchange methods require lengthy processes (6-48 hours) for effective strengthening. An alternative strengthening method, field assisted ion exchange (FAIE), may reduce processing times (< 2 hours), while providing high surface and near-surface compressive stresses. Two apparatuses were designed for the investigation of FAIE-based glass strengthening. Both apparatuses are electrochemical cells bisected with square (30 x 30 x 2 mm) Corning 2317 alumino-silicate glass. An electric field is applied across the glass, which drives potassium ions from the molten potassium nitrate into the glass. Potassium ion exchange depth was determined using energy dispersive spectroscopy. The effect of applied electric field and time on the resulting exchange depth will be evaluated using a design of experiments approach. Determining the feasibility and strengthening effect of FAIE may lead to producing more efficient and reliable glass for industrial applications. Such glass could be used not only for smart phones, but also for strengthening architectural structures and transportation vehicles.
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