Minority Predoctoral Fellowship Program

描述（由申请人提供）：分层结构解决了在不同表面上具有不同要求的系统的竞争需求。在全陶瓷牙冠中，外观必须美观，内部必须坚固，两者的结合必须抗疲劳。目前的结构是通过创建一个坚固的核心，然后通过一系列劳动密集型的步骤，将瓷单板分层到核心上。如果芯材和单板都可以使用现代成型技术（计算机辅助设计和制造或固体自由曲面制造）独立制造，然后连接，则芯材和单板的性能都可以优化，不可避免的成型损伤可以最小化，劳动强度的步骤可以大大减少。单独制造的层可以使用玻璃连接融合，创建一个连接层，将核心保持在单板上。在连接过程中，原子或离子在层之间的界面上混合（相互扩散）。相互扩散的程度影响复合层体系的力学性能。虽然该技术已应用于其他领域，包括玻璃到金属密封、燃料电池和密封电子封装，但据我们所知，玻璃连接件的性能尚未被系统地评估，用于承受疲劳载荷的层。本研究的总体目标是研究玻璃连接对层状陶瓷系统性能和寿命的影响。演示模型将是用于牙冠的层状陶瓷，对玻璃连接对性能和寿命影响的基本理解与层状陶瓷系统的多种其他应用相关，并可以为创建抗损伤成分分级系统提供见解。

DESCRIPTION (provided by applicant): Layered structures address the competing needs of systems with dissimilar requirements on different surfaces. In all- ceramic dental crowns, the exterior must be aesthetic and the interior must be strong and the combination must be fatigue resistant. Current structures are prepared by creating a strong core and then, through a series of labor-intensive steps, layering the porcelain veneer onto the core. If the core and veneer could both be independently fabricated using modern shaping technologies (computer aided design and manufacturing or solid freeform fabrication) and then joined, both core and veneer could be optimized for performance, inevitable shaping damage could be minimized, and the labor intense steps dramatically decreased. The individually fabricated layers could be fused using a glassy join, creating a join layer holding the core to the veneer. During the joining process, atomic mixing of atoms or ions across the interface between the layers (interdiffusion) occurs. The degree of interdiffusion influences the mechanical properties of the combined layer system. While this technology has been applied in other fields, including glass to metal seals, fuel cells, and hermetic electronic packaging, but, to our knowledge, performance of glass joins has not been systematically evaluated for applications where the layers are subjected to fatigue loading. The overall objective of this research is to investigate the effects of glass joins on performance and lifetime of layered ceramics systems. The demonstration model will be layered ceramics used in dental crowns and the fundamental understanding of the effects of glass joins on performance and lifetime has relevance to multiple other applications of layered ceramic systems and could provide insight into creation of damage-resistant compositionally graded systems.