Ultrastrong Translucent Glass Ceramic with Nanocrystalline, Biomimetic Structure

Transparent/translucent glass ceramics (GCs) have broad applications in biomedicine, armor, energy, and constructions. However, GCs with improved optical properties typically suffer from impaired mechanical properties, compared to traditional sintered full-ceramics. We present a method of obtaining high-strength, translucent GCs by preparing ZrO2–SiO2 nanocrystalline glass ceramics (NCGCs) with a microstructure of monocrystalline ZrO2 nanoparticles (NPs), embedded in an amorphous SiO2 matrix. The ZrO2–SiO2 NCGC with a composition of 65%ZrO/35%SiO2 (molar ratio, 65Zr) achieved an average flexural strength of 1 GPa. This is one of the highest flexural strength values ever reported for GCs. ZrO2 NPs bond strongly with SiO2 matrix due to the formation of a thin (2–3 nm) amorphous Zr/Si interfacial layer between the ZrO2 NPs and SiO2 matrix. The diffusion of Si atoms into the ZrO2 NPs forms a ZrOSi superlattice. Electron tomography results show that some of the ZrO2 NPs are connected in one direction, forming in situ ZrO2 nanofibers (with length of ∼500 nm), and that the ZrO2 nanofibers are stacked in an ordered way in all three dimensions. The nanoarchitecture of the ZrO2 nanofibers mimics the architecture of mineralized collagen fibril in cortical bone. Strong interface bonding enables efficient load transfer from the SiO2 matrix to the 3D nanoarchitecture built by ZrO2 nanofibers and NPs, and the 3D nanoarchitecture carries the majority of the external load. These two factors synergistically contribute to the high strength of the 65Zr NCGC. This study deepens our fundamental understanding of the microstructure-mechanical strength relationship, which could guide the design and manufacture of other high-strength, translucent GCs.透明/半透明玻璃陶瓷（glass ceramics, GCs）在生物医学、装甲、能源与建筑领域拥有广阔应用前景。然而，与传统烧结全陶瓷相比，光学性能提升的玻璃陶瓷往往会伴随力学性能的劣化。我们开发了一种制备高强度半透明玻璃陶瓷的方法：通过构建以非晶态SiO₂为基体、内嵌单晶ZrO₂纳米颗粒（nanoparticles, NPs）的微观结构，制备得到ZrO₂–SiO₂基纳米晶玻璃陶瓷（nanocrystalline glass ceramics, NCGCs）。当组分为65%ZrO₂/35%SiO₂（摩尔比，下称65Zr试样）时，该ZrO₂–SiO₂ NCGCs的平均抗弯强度可达1 GPa，为目前已报道的玻璃陶瓷最高抗弯强度值之一。由于在ZrO₂ NPs与SiO₂基体之间形成了厚度为2~3 nm的非晶态Zr/Si界面层，ZrO₂ NPs与SiO₂基体之间实现了强结合；同时，Si原子扩散进入ZrO₂ NPs后形成了Zr—O—Si超晶格结构。电子断层扫描结果显示，部分ZrO₂ NPs沿单一方向相互连接，形成长度约500 nm的原位ZrO₂纳米纤维；该类ZrO₂纳米纤维在三维空间内呈有序堆叠排布。这种ZrO₂纳米纤维构成的纳米结构，与皮质骨内矿化胶原纤维的微观架构具有相似性。强界面结合实现了载荷从SiO₂基体向由ZrO₂纳米纤维与NPs构建的三维纳米结构的高效传递，而该三维纳米结构承担了绝大多数外加载荷。上述两大因素协同作用，共同赋予65Zr NCGCs优异的高强度性能。本研究深化了对微观结构与力学强度之间构效关系的基础认知，可为其他高强度半透明玻璃陶瓷的设计与制备提供指导。