Fracture Behaviour of Zirconia-Reinforced Lithium Silicate Glass–Ceramic Composite

Fracture mechanisms in zirconia-reinforced lithium silicate glass–ceramic (ZLS) materials are important to evaluate its performances under load-bearing applications. However, due to its inherent brittleness nature, it is difficult to observe fracture behaviour. Hence, it is imperative to understand the fracture behaviour of the ZLS material. This study investigated the fracture behaviour of pre-crystallized ZLS glass–ceramic materials at nano-scale length using micropillar compression technique inside of scanning electron microscopy (SEM). Micropillar structures with dimension of 3 µm in diameter and 9 µm in length was fabricated using fibre ion beam milling inside SEM. Flat diamond puncher with 5 µm diameter was used to conduct the compression test. Compression properties (Young’s modulus, mechanical strengths (yield, fracture, compressive), ductility, resilience and toughness of the ZLS material were determined. The fractured micropillar of the pre-crystallized ZLS was observed during and after the compression using SEM. Pre-crystallized ZLS revealed micrropillar compression induced mushroom defect, micro cracking and delamination as its mode of fracture mechanisms. It had Young’s modulus of 62 ± 7 GPa, yield strength of 1850 ± 31 MPa, fracture strength of 1987 ± 25 MPa, ultimate compressive strength of 2010 ± 47 MPa, ductility of 4 ± 1%, resilience of 71 ± 4 J/m3 and toughness of 126 ± 9 J/m3. This study provided fundamental micro compression mechanisms associated to fracture behaviour of pre-crystallized ZLS for development of new microstructural design for these material for high quality dental restorations.