Control of Fracture Damage in Precision Machining of Ceramics

该项目将研究先进陶瓷材料的无损伤超精密加工工艺。目标是提高对纳米级陶瓷磨削过程中材料去除过程的理解，并最终能够控制过程中磨削损伤的产生。研究计划包括将韧性磨削模型扩展到增韧陶瓷，并确定这些材料所需的磨削加工参数。通过控制表面增韧，在陶瓷表面引入工程化学力学效应，进一步改进磨削工艺。本研究的目标是开发一种实时声发射反馈系统来测量和控制磨削过程中的损伤。通过初步研究，确定了声发射对材料去除过程的敏感性。了解这种敏感性的基础及其与地下裂缝生成的关系，将指导有效控制策略的制定。预计这项研究的直接结果是：(1)由首席研究员开发的延性磨削模型将扩展到包括坚韧的先进陶瓷材料；(2)将研究陶瓷加工中的化学机械效应对改变陶瓷表面特性的潜在影响，从而提高候选陶瓷材料的可加工性；(3)对裂缝产生的声发射信号进行分析，对这些弹性波及其与磨削引起的地下损伤的关系进行基础研究。

The project will study damage-free ultraprecision machining processes on advanced ceramic materials. The goal is to generate an improved understanding of the material-removal processes that occur in nanometer-scale grinding of ceramics, and ultimately to be able to control grinding damage generation in-process. The research plan includes extending the ductile-regime grinding model to include toughened ceramics, and defining grinding machining parameters required for these materials. Further modification of the grinding process by the introduction of engineered chemomechanical effects on the ceramic surface will be developed, through controlled surface toughening. A goal of this research is to develop a real-time acoustic emissions feedback system to measure and control grinding damage in-process. Through preliminary research, the sensitivity of acoustic emissions to material removal processes has been established. Understanding the basis of that sensitivity and its relationship to subsurface fracture generation will guide development of an effective control strategy. It is expected that as a direct result of this research: (1) models for ductile-regime grinding, developed by the principal investigator, will be extended to include tough, advanced ceramic materials; (2) chemomechanical effects in machining of ceramics will be studied with regard to their potential for altering the surface properties of ceramics, thereby enhancing the machinability of candidate ceramic materials; and (3) fracture-generated acoustic emissions signals will be analyzed in a basic study of the these elastic waves and their relationship to grinding-induced subsurface damage.