Development of SiO2 - Li2O - ZrO2 dental glass-ceramic systems with extended lifetimes: crystallization mechanisms and resistance to subcritical crack growth

开发具有延长使用寿命的 SiO2 - Li2O - ZrO2 牙科玻璃陶瓷系统：结晶机制和抗亚临界裂纹扩展

• 批准号: 459555007
• 负责人: Professorin Dr. Friedlinde Götz-Neunhoeffer
• 金额: --
• 依托单位: Zahnklinik 1 - Zahnerhaltung und Parodontologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/459555007?language=en
• 关键词: Development; SiO2; Li2O; ZrO2; dental

Glass-ceramics based on Lithium silicates today constitute the most commercially successful restorative material for dental applications. Compared to typical feldspar-based dental ceramics, lithium disilicate (Li2Si2O5) crystals benefit from a preferred crystal growth along the crystallographic c-axis. Elongated crystal phases enable the tailoring of anisotropic microstructural architectures in congruence with those employed by natural design, such as in dental enamel. The deliberate orientation of microstructural features appears to be a cornerstone in biology´s strategy to achieve optimal mechanical performance, an approach applicable to inorganic materials as well. Unfortunately, the currently existent lithium disilicate systems are particularly susceptible to stress-assisted subcritical crack growth in the glass phase. This phenomenon is accelerated by the development of thermal residual stresses between the glass and crystal phases. Especially affected are glass-ceramics in the system SiO2 – Li2O – ZrO2. The incremental addition of ZrO2 to the base glass alters the typical nucleation and crystallization kinetics known for lithium disilicates, involving the heterogeneous nucleation of Li2SiO3 and the later transformation to Li2Si2O5 at higher temperatures. This results in a residual glass phase enriched with ZrO2. The underlying mechanisms involved in this process, the relationship to the SiO2/Li2O ratio, and their ultimate imbrications in shaping the glass network structure, are still poorly understood. As part of an interdisciplinary project, the effects of compositional variations in the SiO2 – Li2O – ZrO2 glass system will be thoroughly investigated. The kinetics of nucleation and crystallization constitute the central focus of our interest, including a detailed characterization of the glass network structure and properties of the residual glass with respect to slow crack growth resistance and influence of thermal residual stresses. The implications on the local and global mechanical behavior will be probed systematically with focus on the optimization of microstructural design and phase compatibility, aiming on the development of dental ZrO2-containing lithium disilicates for extended clinical lifetimes.

以硅酸锂为基础的微晶玻璃是目前最成功的牙科修复材料。与典型的长石基牙科陶瓷相比，二硅酸锂(Li2Si2O5)晶体具有沿晶体c轴择优生长的优势。细长的晶体相使各向异性微结构结构的剪裁与自然设计所采用的结构一致，例如在牙釉质中。微结构特征的刻意取向似乎是生物S策略的基石，以实现最佳的机械性能，这一方法也适用于无机材料。不幸的是，目前存在的二硅酸锂系统特别容易在玻璃相中发生应力辅助亚临界裂纹扩展。玻璃和晶相之间的热残余应力的发展加速了这一现象。受影响最大的是SiO_2-Li_2O-ZrO_2系微晶玻璃。在基础玻璃中逐渐添加ZrO2改变了已知的二硅酸锂的典型成核和晶化动力学，包括Li2SiO3的异相成核和随后在较高温度下转变为Li2Si2O5。这导致了富含氧化锆的残余玻璃相。这一过程中涉及的潜在机制，与SiO_2/Li2O比率的关系，以及它们在塑造玻璃网络结构中的最终叠加，仍然知之甚少。作为一个跨学科项目的一部分，将彻底调查SiO_2-Li_2O-ZrO_2玻璃系统中成分变化的影响。形核和析晶动力学是我们感兴趣的中心焦点，包括关于慢裂纹扩展阻力和热残余应力的影响的玻璃网络结构和残余玻璃的性能的详细表征。将系统地探讨其对局部和整体力学行为的影响，重点是微结构设计和相兼容性的优化，旨在开发用于延长临床使用寿命的牙科含ZrO2二硅酸锂。