Mechanical Properties of Oxide Glasses at Constraint Gradients

约束梯度下氧化物玻璃的机械性能

• 批准号: 224699528
• 负责人: Professor Dr.-Ing. Joachim Deubener
• 金额: --
• 依托单位: Institut für Nichtmetallische Werkstoffe
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/224699528?language=en
• 关键词: Mechanical; Properties; Oxide; Glasses; Constraint

If any materials property had to be named the most relevant, the choice would probably fall to mechanical behavior. This holds especially for glasses, where practical (commonly available) and theoretical strength differs by one or more orders of magnitude and, hence, the potential for improvement appears most intriguing. Here, the bottleneck is the significant lack of fundamental understanding of the interplay between structural constitution and mechanical properties on the one side, and potential toughening strategies on the other side. Defects, primarily surface defects and their initiation are known as the primary reason for the large difference between theory and praxis. Today's empirical toughening procedures therefore focus on engineering specific surface architectures, mostly relying on the generation of residual compression. In the present project, both problems - the understanding of structure - property relations and quantitative, surface-targeting toughening strategies will be treated jointly. The proposed project will focus on extending and experimentally applying the theory of topological constraints to glass forming systems at compositional joints, where one or more structural parameters are known to change sharply. As technologically relevant model systems, mixed-network-former borosilicate, aluminosilicate and, optionally, titanate glasses have been chosen where boron and aluminum coordination, respectively, are known to sharply change in relatively narrow compositional regions. In addition to these two systems, tellurite glasses with a single network former (changing coordination as a function of network modifier content) and phosphate glasses (on the transition between covalent network and fully depolymerized, ionic state) will be considered. For each of those systems, the dependence of elastic properties, hardness, toughness, brittleness and - in cooperation with other participants of SPP 1594 - intrinsic strength will be assessed experimentally and related to relevant structural parameters on short and intermediate length scale. The focus on compositions at sharp structural gradients - "extreme compositions" - is motivated twofold: in such compositional areas, we expect the highest accuracy in identifying constitutive laws for the topological design of the mechanical properties of glasses. Secondly, the approach will enable further development of surface engineering tools (especially cation and anion exchange) where dedicated topological gradients can be generated at the surface, extending the classical view of chemical toughening. Primary objective of the first funding period is to perceive the dominant topological constraints with respect to the mechanical properties and to deduct temperature-dependent functions which will verify and extent the classical constraint theories. It is anticipated that in synergy with parallel activities of SPP 1594, these functions can be generalized to bridge the gap of knowledge between metallic and inorganic oxide systems. In preparation of the second funding period, engineering approaches to establish such topological gradients on glass surfaces and, hence, to create specific gradients of mechanical constraints will be considered.

如果必须将任何材料属性命名为最相关，那么选择可能会落在机械行为上。这尤其适用于玻璃杯，在该眼镜中，实际（通常可用）和理论强度的数量级有所不同，因此，改进的潜力似乎最吸引人。在这里，瓶颈是对一侧结构构成与机械性能之间相互作用的根本性缺乏根本性的理解，而另一侧的潜在韧性策略。缺陷，主要是表面缺陷及其起始被称为理论和实践之间较大差异的主要原因。因此，当今的经验加强程序集中于工程特定的表面体系结构，主要依赖于残留压缩的产生。在本项目中，将共同处理这两个问题 - 对结构的理解 - 财产关系和定量，表面定位的韧性策略。拟议的项目将着重于将拓扑约束的理论扩展到组成关节的玻璃形成系统，其中已知一个或多个结构参数会急剧改变。作为具有技术相关的模型系统，混合网络形成式硼硅酸盐，铝硅酸盐以及可选的钛糖玻璃是在相对狭窄的组成区域的急剧变化而急剧变化的。除了这两个系统外，将考虑具有单个网络的前透明玻璃（与网络修饰符含量的函数更改协调）和磷酸盐玻璃（关于共价网络和完全解放的离子状态之间的过渡）。对于每个系统，弹性性能，硬度，韧性，脆弱性以及与SPP 1594的其他参与者的依赖性 - 内在强度将进行实验评估，并与短和中间长度尺度上的相关结构参数有关。对尖锐结构梯度的组成的重点 - “极端组成”是有动机的：在这样的组成区域，我们期望识别镜头机械性能的拓扑设计的本构定律的准确性最高。其次，该方法将能够进一步开发地表工程工具（尤其是阳离子和阴离子交换），在该工具可以在表面上产生专用的拓扑梯度，从而扩展了化学韧性的经典视图。第一个融资期的主要目标是感知有关机械性能的主要拓扑约束，并扣除依赖温度的函数，以验证和规模经典约束理论。可以预料，在与SPP 1594的平行活动的协同作用中，可以推广这些功能以弥合金属和无机氧化物系统之间的知识差距。在准备第二个融资期间，将考虑在玻璃表面上建立此类拓扑梯度的工程方法，因此将考虑创建机械约束的特定梯度。