Material Removal Processes in Fine-grained Ceramic Materialsat Low Contact Loads

电话：+86-9800920 微晶陶瓷广泛应用于电子和光学领域。 这些应用的性质要求表面非常光滑，没有变形损坏。 对于光滑表面的生成，通过塑性微切削工艺进行材料去除是必不可少的。 硬质、刚性压头和陶瓷表面之间的接触为研究与各种加工过程相关的材料响应和材料去除机制提供了良好的模型系统。 在本项目中，将开发一种专门适用于分析与材料去除过程相关的陶瓷微塑性的技术，用于从低载荷压痕试验中估计陶瓷的屈服强度和弹塑性、应力-应变行为。 它将涉及测量压痕下的塑性开始，力-穿透曲线的确定，以及压痕过程的有限元建模。 材料去除的机制将研究使用低负荷，划痕实验与光学透明陶瓷。 这种配置提供了一种独特的设置，用于直接观察接触区中发生的变形和断裂现象。 切削力，变形力学，韧性切屑形成的阈值负荷将在这些实验中进行分析，连同参数的影响，如压头形状和划痕速度。 将开发一个有限元模型的塑性切削过程中，导致连续的芯片形成陶瓷利用机械加工和非对称，楔形压痕的固体压头之间的类比。 这项研究有望对陶瓷加工中的表面生成以及电子和光学超光滑表面的可控生成有一个基本的了解。

DMI-9800920 Yang Micro-crystalline ceramics are widely used in electronics and optics. The nature of these applications requires that the surfaces be very smooth and free of deformation damage. For the generation of smooth surfaces it is essential that material removal occur by a plastic microcutting process. The contact between a hard, rigid indenter and a ceramic surface provides a good model system for studying material response and material removal mechanisms of relevance to various machining processes. In this project, a technique uniquely suited for analyzing microplasticity in ceramics of relevance to material removal processes will be developed for estimating the yield strength and elastic-plastic, stress-strain behavior of ceramics from low-load indentation tests. It will involve measurement of the onset of plasticity underneath an indentation, determination of the force-penetration curve, and finite element modeling of the indentation process. The mechanism of material removal will be studied using low-load, scratch experiments with optically transparent ceramics. This configuration provides a unique setting for directly observing the deformation and fracture phenomena occurring in the contact zone. Cutting forces, deformation mechanics, and the threshold load for ductile chip formation will be analyzed in these experiments, together with the effect of parameters such as indenter shape and scratch velocity. A finite element model of the plastic cutting process leading to continuous chip formation in ceramics will be developed by exploiting the analogy between machining and asymmetric, wedge indentation of a solid indenter. The study is expected to lead to a fundamental understanding of surface generation in machining of ceramics and the controlled generation of ultra-smooth surfaces for electronics and optics.