In a series of dynamic impact tests performed by Intertek, the MetaShieldGLASS coating increased the sharp impact break resistance of untempered aluminosilicate by 100 percent, and chemically tempered aluminosilicate by 150 percent. The latter is the most commonly used glass in smartphones and tablets worldwide. MetaShield studies determined MetaShieldGLASS is also effective in increasing the break resistance of widely used soda lime glass thicker than 3mm.
The MetaShieldGLASS coating is being sold to and applied by contract and OEMs; it is not currently designed as a consumer product.
The lab test results have implications for several industries. Aluminosilicate glass is used in automobile windows, mobile devices, with home goods, in windows, within medical equipment, glass containers, skylights, augmented reality and ordinary eye glasses, and even on space shuttles.
“That such a thin coating can have such a dramatic effect really speaks to the miraculous promise of advanced materials,” MetaShield CEO Martin Ben-Dayan said. “In some cases, MetaShield’s technology can also improve sustainability by allowing for glass options that can be thinner and lighter without sacrificing break-strength quality.”
Intertek, a multinational, London-based independent third-party testing company, conducted a series of dynamic impact drop-ball tests in their Kentwood, Mich. Facility –following standards and methods developed by researchers at Asahi Glass Co in Japan – comparing uncoated glass samples against glass samples that were coated with the transparent MetaShieldGLASS formula.
In a series of “drop-ball” tests, MetaShieldGLASS improved break resistance 83 percent in blunt impacts and 100 percent in sharp impacts on 0.55mm untempered glass coated with MetaShieldGLASS. The same tests on 0.55mm Gorilla Glass 3 (chemically tempered aluminosilicate) samples improved break resistance by 222 percent during blunt impact and 150 percent in sharp impact testing. Thirty samples of 0.55mm glass were used for each format and glass type for a total test size of 240 samples.
“By combining enhanced properties, simple application, and a form factor that is near invisible, MetaShieldGLASS provides a fantastic and potentially transformative cost/benefit to glass industry stakeholders,” Ben-Dayan said.
“Our unique coating, the result of several years of development using the combined work of theoretical physicists, chemists and engineers, adds only a negligible size and weight,” said Jacob Schliesser, PhD, materials chemist at MetaShield. “Because it is transparent, thin, and simple to apply, MetaShieldGLASS can be easily integrated into existing manufacturing processes.”
While many advanced thin films are difficult and expensive to apply, the MetaShieldGLASS formula is applied using conventional spray, dip or flood coating along with a rapid UV cure. The process time is less than five minutes for complete end-to-end application. MetaShieldGLASS is designed and tested for application using commercially available systems and there is no specialized or custom equipment required.
MetaShieldGLASS, when applied onto glass, currently achieves an average hardness of 550 MPa in nano-indentation testing (ISO 14577-1), and 5H in pencil hardness (JIS K5600-5-4), which is significantly better than common plastics.
Testing for MetaShieldGLASS also demonstrated the overall robustness of the formula. Thermal cycling (ASTM D6944-15), UV extended exposure (ASTM G155), and humidity extended exposure (ASTM D224-15) resulted in no obvious changes to the coating.
Abrasion testing on coated glass samples, using a Linear Taber Abraser with a total weight of 500 grams and 1000 cycles of 0000 steel wool, resulted in a low ΔHaze of ~0.35 percent. ΔHaze is defined as the difference between the haze of the coating before and after abrasion testing.