Mechanisms of brittle-ductile transition and material removal in diamond cutting of silicon carbide

金刚石切削碳化硅脆塑转变及材料去除机制

基本信息

批准号：
392230176
负责人：
Professor Dr. Alexander Hartmaier
金额：
--
依托单位：
Abteilung Mikromechanische und makroskopische Modellierung
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/392230176?language=en
关键词：
Mechanisms brittle ductile transition material

项目摘要

Diamond cutting of hard and brittle ceramics offers several advantages over other machining methods, like for example grinding. However, it is also a is a technological challenge, because it requires a precise knowledge about the mechanisms of material removal to guarantee a stable process and a high-quality surface finish. While most ceramics behave in a completely brittle manner in macroscopic tests, micromechanical testing frequently reveals some ductility of the material. During diamond cutting such a brittle-ductile transition (BDT) can be observed, depending on the process parameters. It has been shown in the literature that operating the diamond cutting process in the ductile regime is of advantage, because it leads to an ultra-low surface roughness of the machined part. In the proposed research project, the diamond cutting process of silicon carbide (SiC) ceramics will be investigated on all relevant length scales with a combination of scalebridging material and process modeling and in-situ and ex-situ experiments. SiC is chosen as material because its applications in optical devices require an extremely high surface quality. Yet, the high hardness and brittleness of this ceramic poses enormous challenges to the process that can only be mastered if a fundamental insight into the mechanisms of material removal is gained. Consequently, the first objective of this research project is to study the mechanisms of the BDT in SiC under the conditions of diamond cutting. Furthermore, this project will result in a new understanding of the mechanisms of material removal during precision machining in both, the brittle and in the ductile regime, with an emphasis on the ductile material removal processes. As second objective of this project, the gained understanding and the developed scalebridging models will be applied to support process innovations to achieve a surface roughness of less than 10 nm during precision machining of SiC. Such a high machining precision can only be accomplished by a very detailed understanding of the underlying mechanisms and by using numerical models and key experiments to design the required tools. A key issue will be to control the precision machining process such that only ductile material removal takes place because this will produce better surface qualities. Hence, the fundamental part of the project is a necessary requirement to establish this kind of process innovation. While it is the nature of this project to describe rather material specific phenomena for the SiC system, it is expected that the achieved mechanistic understanding of the BDT and the material removal process can be transferred to precision machining of other ceramic systems, as well. Furthermore, we anticipate to gain some very fundamental insight into the physical phenomena that cause the partially high deformabilities and plastic flow behavior that are generic for many ceramics under conditions of nanoindentation and nanoscratching.

钻石切割硬易碎的陶瓷比其他加工方法具有多种优势，例如磨削。但是，这也是一种技术挑战，因为它需要有关材料去除机制的精确知识，以确保稳定的过程和高质量的表面饰面。虽然大多数陶瓷在宏观测试中以完全脆弱的方式行为，但微机械测试经常揭示材料的某些延展性。在钻石切割期间，可以根据过程参数观察到这种脆性的延性过渡（BDT）。在文献中已经显示，在延性状态下操作钻石切割过程是有优势的，因为它导致了加工部分的超低表面粗糙度。在拟议的研究项目中，将对所有相关长度尺度进行研究，结合缩放材料和过程建模以及原位和前静脉实验，对所有相关的长度尺度进行研究。选择SIC作为材料，因为其在光学设备中的应用需要极高的表面质量。然而，这种陶瓷的高硬度和脆弱性对这一过程构成了巨大的挑战，只有在获得对物料去除机制的基本见解时才能掌握。因此，该研究项目的第一个目标是研究钻石切割条件下BDT的机制。此外，该项目将对脆性，脆性和延性状态的精确加工过程中的材料去除机理有了新的了解，并重点介绍了延性材料去除过程。作为该项目的第二个目标，获得的理解和开发的规模模型将用于支持过程创新，以在SIC的精确加工过程中达到不到10 nm的表面粗糙度。这样的高加工精度只能通过对基本机制的非常详细的了解以及使用数值模型和关键实验来设计所需工具来实现。一个关键问题将是控制精确的加工过程，以便仅进行延性材料去除，因为这会产生更好的表面质量。因此，该项目的基本部分是建立这种过程创新的必要条件。尽管该项目的性质是描述SIC系统的相当特定的现象，但预计对BDT的机械理解和材料去除过程也可以将其传递到其他陶瓷系统的精确加工。此外，我们预计将对物理现象获得一些非常基本的见解，这些现象会导致在纳米识别和纳米捕捉条件下，对许多陶瓷的部分变形和塑性流动行为是通用的。