Structural design of a scalable glass with high hardness and crack initiation resistance

The industry has always strived to design "hard" and "crack-resistant" glass. However, simultaneously realizing these properties in oxide glasses has been rare. Although Al2O3-rich hard and crack-resistant oxide glasses have been reported in the last decade, they exhibit two significant technological challenges that hinder their translation from laboratory to industry: (1) high processing temperatures (>2000 degrees C) and (2) small glass-forming regions (near eutectic). The present study reports the structural design of a hard and high modulus glass with high crack initiation resistance designed in the peraluminous region of rare-earth containing MgO-Al2O3-B2O3-SiO2 system. The glass can be processed at a temperature <= 1650 degrees C and exhibits Vickers hardness (H-v) of 7.84 GPa (at 1.96 N load) and indentation crack resistance (ICR) of 26.5 N. These H-v and ICR values are significantly higher than most commercial or non-commercial glasses (prior to thermal tempering, densification near T-g, or chemical strengthening). The glass has been scaled up to successfully produce slabs of dimensions 100 mm x 100 mm x 8 mm at laboratory scale with optical transmission of 90 +/- 2 %. The results presented here are scientifically intriguing and have considerable tangible implications, as they pave the path for the design and development of stronger glasses for functional applications.