Fracture Toughness and Hardness of Transparent MgO–Al2O3–SiO2 Glass-Ceramics

Hard and strong transparent glass-ceramics (TGCs) can be used as cooktop plates, telescope mirrors, armor materials, and screens for smartphones and tablets. In this work, transparent glass-ceramics from the MgO-Al2O3-SiO2 (MAS) system were obtained after a refined heat-treatment protocol. The evolution in fracture toughness, KIC (Single Edge Precracked Beam), and Vickers hardness (H-V) were characterized as a function of the crystallization progress. The K-IC of the parent glass was 0.6 MPa m(1/2), whereas the TGC samples present values around 1.1 MPa m(1/2). The average glass hardness was 8.5 & PLUSMN; 0.8 GPa for loads of 0.6-5 N, whereas the H-V of the TGC samples varied from 9 to 10 GPa, for indentation loads ranging from 4.9 to 9.8 N. These results are discussed in light of our previous findings on the evolution of elastic modulus in the same glass-ceramics.