Crystallization behaviour and hardness of glass ceramics rich in nanocrystals of ZrO2

This research is mainly directed toward the development of hardness of glass ceramic by adding different amounts of ZrO2 to the glass and by applying different heat-treatments. Differential thermal analysis (DTA), X-ray diffraction (XRD) and Scanning electron microscope (SEM) were used to study the crystallization behaviour of the glass samples. The only observed crystalline phases were tetragonal and monoclinic zirconia. Hardness was found to increase by increasing time and temperature of heat-treatment due to the formation of monoclinic phase as a result of the martensitic reaction. This transformation opposes crack opening. © 2008 Elsevier Ltd and Techna Group S.r.l.