Microstructural evolution and physical behavior of a XXXX disilicate glass-ceramic.

@entity11898 @entity3358 @entity174 @entity6637 @entity1091
BACKGROUND: Elucidating the microstructural responses of the @entity1091 disilicate system like the popular IPS e.max   CAD ( @entity6637 ), made specifically for computer-aided design and computer-aided manufacturing (CAD-CAM), as a temperature-dependent system unravels new ways to enhance material properties and performance. OBJECTIVE: To study the effect of various thermal processing on the crystallization kinetics, crystallite microstructure, and strength of @entity6637 . METHODS: The control group of the @entity6637 samples was heated using the standard manufacturer heating-schedule. Two experimental groups were tested: (1) an extended temperature range (750-840  C vs. 820-840  C) at the segment of 30  C/min heating rate, and (2) a protracted holding time (14min vs. 7min) at the isothermal temperature of 840  C. Five other groups of different heating schedules with lower-targeted temperatures were evaluated to investigate the microstructural changes. For each group, the crystalline phases and morphologies were measured by @entity11898 ( @entity11898 ) and scanning electron microscope (SEM), respectively. Differential scanning calorimeter (DSC) was used to determine the activation energy of @entity6637 under non-isothermal conditions. A universal testing machine was used to measure 3-point flexural strength and @entity174 toughness, and elastic modulus and @entity3358 were measured by a nanoindenter. A one-way ANOVA/Tukey was performed per property (alpha=0.05). RESULTS: DSC, @entity11898 , and SEM revealed three distinct microstructures during @entity6637 crystallization. Significant differences were found between the control group, the two aforementioned experimental groups, and the five lower-targeted-temperature groups per property (p<0.05). The activation energy for @entity1091 disilicate growth was 667 (  29.0)kJ/mol. CONCLUSIONS: Groups with the extended temperature range (750-840  C) and protracted holding time (820-840  C H14) produced significantly higher elastic-modulus and @entity3358 properties than the control group but showed similar flexural-strength and @entity174 -toughness properties with the control group. In general, rapid growth of @entity1091 disilicates occurred only when maximum formation of @entity1091 metasilicates had ended.
