Mechanical Characterization of ZrO₂ Rich Glass Ceramic

Abstract

Glass-Ceramics (GCs) find wide applications in electronic packaging, kitchenwares, optics, acoustic systems, aerospace industry, as armor materials, and as aesthetic material for dental restoration due to their simple processing, easy machinability, low porosity and high strength.. However, they are inevitably subjected to tensile load resulting in catastrophic failure due to their sometimes low fracture toughness and high brittleness. In this context, a zirconia containing lithium disilicate glass ceramic is developed and mechanically characterized. Its fracture toughness and hardness are measured using Chevron Notch Short Bar (CNSB) method and Vickers indent respectively.. Further, the material was subjected to single edge notched bar (SENB) loading in 3-point bend configuration. The non-linearity in the load-deflection curve suggested the presence of R-curve behavior which was subsequently measured. The results of this technique are compared with those of Corning Ultra Low Expansion (ULE) glass, which was used as a standard for the measurement. In the glass-ceramic material a rising R-curve, a desirable attribute as it suppresses subcritical crack growth, was evident. With higher fracture toughness, rising R-curve and improved brittleness index, this GC has advantaged mechanical attributes. Further, the fracture surface exhibited significant roughness as compared to ULE glass. With multiple potential factors contributing to the improved fracture toughness, each of their contributions is yet to be fully understood.