As a predominantly lithium-metasilicate-containing glass-ceramic, Obsidian® (Glidewell Laboratories, USA) has a peculiar composition and microstructure among other dental lithium silicates, warranting an evaluation of the crystallization process to establish relationships between microstructural evolution and mechanical properties. Blocks of the pre-crystallized material were processed into slices measuring 12 × 12 × 1.5 mm³ and subjected to the mandatory crystallization firing by interruption the heating ramp at temperatures between 700 °C and 820 °C (dwell time between 0 min and 10 min). The crystallization peaks of the base and the pre-crystallized glass were obtained by differential scanning calorimetry (DSC). The coefficient of thermal expansion and the glass transition temperature were derived from differential thermal analysis (DTA). X-ray diffraction (XRD) was performed to quantify and characterize the crystal phase fraction, whose microstructural changes were visualised using FE-SEM. The ball-on-three-balls surface crack in flexure method was used to track the evolution of fracture toughness. The microstructural evolution during crystallization firing was characterized by two regimes of growth: (i) the progressive revitrification (dissolution) of the 5 μm-sized Li₂SiO₃ polycrystals manifested at the boundaries of nanometric single coherent scattering domains (CSDs); (ii) the non-isothermal period is marked by an Ostwald ripening process characterized by the growth of the single crystalline structures into 0.5 μm polycrystals. The decrease in the crystal fraction of Li₂SiO₃ crystals from 41 vol.% to 37 vol.% is accompanied by the formation of a small amount of Li₃PO₄ (6 vol.%), maintaining the total crystal phase fraction mostly constant. The K_Ic accompanied the reverse trend of crystallinity, departing from 1.63 ± 0.02 MPa√m at the pre-crystallized stage to 1.84 ± 0.06 MPa√m after 10 min at 820 °C in a linear trend. Toughening appeared counter-intuitive in view of the decreasing crystal fraction and size, to rather relate to the relaxation of the residual stresses in the interstitial glass due to the spheroidization of the initially anisotropic, elongated Li₂SiO₃ crystals into round, nearly equiaxed particles, as let suggest from the disappearance of the extensive microcracking.

作为一种主要含有偏硅酸锂的玻璃陶瓷，Obsidian®（美国格莱德韦尔实验室）在其他牙科硅酸锂中具有独特的成分和微观结构，需要对结晶过程进行评估，以建立微观结构演变和机械性能之间的关系。将预结晶材料块加工成尺寸为 12 × 12 × 1.5 mm ^{3 的}切片并通过在 700 °C 和 820 °C 之间的温度（0 分钟和 10 分钟之间的停留时间）中断加热斜坡来进行强制结晶烧制。通过差示扫描量热法（DSC）获得基体和预结晶玻璃的结晶峰。热膨胀系数和玻璃化转变温度来自差热分析 (DTA)。进行 X 射线衍射 (XRD) 以量化和表征晶相分数，其微观结构变化使用 FE-SEM 进行可视化。弯曲方法中的球对三球表面裂纹用于跟踪断裂韧性的演变。结晶烧制过程中的微观结构演变以两种生长方式为特征：₂ SiO ₃多晶出现在纳米单相干散射域 (CSD) 的边界处；(ii) 非等温期的特点是奥斯特瓦尔德熟化过程，其特征是单晶结构生长成 0.5 μm 多晶。Li ₂ SiO ₃晶体的晶体分数从 41 vol.% 减少到 37 vol.% 伴随着少量 Li ₃ PO ₄ (6 vol.%) 的形成，保持了大部分的总晶相分数持续的。该ķ _Ic的伴随结晶度的反向趋势，从预结晶阶段的 1.63 ± 0.02 MPa√m 到 820 °C 10 分钟后的 1.84 ± 0.06 MPa√m 呈线性趋势。考虑到晶体分数和尺寸的减小，增韧似乎与直觉相反，这与由于初始各向异性、拉长的 Li ₂ SiO ₃晶体球化成几乎等轴的圆形颗粒而导致的间隙玻璃中残余应力的松弛有关，正如从广泛微裂纹的消失所暗示的那样。