This Smartphone Case Is 3X Harder Than Steel

A new smartphone case is lightweight, thin, harder than steel, and as easy to shape as plastic. What’s the catch? You can’t purchase one—not yet, anyway.
This Smartphone Case Is 3X Harder Than Steel
What do you look for in a cell phone case? Hardness and weight. Courtesy of Yale University
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A new smartphone case is lightweight, thin, harder than steel, and as easy to shape as plastic. What’s the catch? You can’t purchase one—not yet, anyway.

Jan Schroers, who teaches mechanical engineering and materials science at Yale University, developed the technology for the cases in his lab and wants to bring the product into mass production.

“This material is 50 times harder than plastic, nearly 10 times harder than aluminum, and almost 3 times the hardness of steel,” Schroers said. “It’s awesome.”

For years, academic and commercial institutions have sought an effective technique for shaping these bulk metallic glasses (BMGs)—a new generation of strong-yet-pliable materials.

Electronics casings, in particular, have been identified as a desirable application. Yet past attempts at finding a shaping process were unsuccessful.

Supercooled Liquid

Schroers spent much of the past decade pursuing a fundamentally different approach to precisely shaping complex geometries. Instead of melting the BMG material and forcing it into a mold at high temperatures, he utilized a unique, supercooled liquid state for the material, in which the BMG softens sufficiently to allow for shaping.

With this technique, which Schroers calls thermoplastic forming, BMGs can be shaped like plastics. As a consequence, thermoplastic forming BMGs don’t require massive amounts of energy.

From there, Schroers focused on producing BMGs in sheets. That form, he reasoned, is the most conducive to practical, manufacturing applications.

This material is 50 times harder than plastic, nearly 10 times harder than aluminum, and almost 3 times the hardness of steel.
Jan Schroers, professor,, Yale University