Laser Assisted Machining of Ceramic Parts with Complex Features

本项目旨在从理论上和实验上为各种结构陶瓷材料的激光辅助加工（LAM）建立科学基础，从而显著降低陶瓷零件的制造成本和提高其最终状态性能。LAM过程的理论处理将用于确定陶瓷在LAM过程中的热力学行为，通过开发热模型，材料的温度依赖特性，本构模型和过程模拟模型。将进行配套实验，以表征加工性能，包括加工样品的亚表面损伤和表面光洁度、刀具磨损和最大材料去除率。氮化硅零件的可行性研究表明，LAM的刀具寿命约为40分钟，表面光洁度与磨削相当，几乎没有亚表面损伤裂纹和热影响区，在标准加工条件下，材料去除率明显高于磨削。基于这一成功的可行性研究，激光辅助车削工艺将扩展到加工各种重要的结构陶瓷材料，如碳化硅（SiC）、氧化铝（Al2O3）、莫来石、氧化锆（ZrO2）和氮化硅（Si3N4）。特别是，拟议的研究旨在通过开发必要的过程监测和控制技术来发展制造复杂几何形状零件的能力。这将与已开发的建模功能一起，促进LAM在工业中的实施。

This project seeks to theoretically and experimentally establish a scientific basis for laser assisted machining (LAM) of various structural ceramic materials, which can significantly reduce the fabrication costs and improve end-state properties for ceramic parts. Theoretical treatments of LAM processes will be used to determine the thermo-mechanical behavior of ceramics during LAM, by developing thermal models, temperature dependent properties of the materials, constitutive models and process simulation models. Supporting experiments will be performed to characterize machining performance in terms of sub-surfacedamage and surface finish of machined specimens, tool wear and maximum material removal rate. The feasibility study with silicon nitride parts demonstrated the capabilities of LAM by achieving long tool life of approximately 40 minutes, surface finish commensurate with those of grinding and little sub-surface damage cracks and heat affected zone as well as significantly higher material removal rates than grinding under nominal machining conditions. Based on this successful feasibility study, laser assisted turning processes will be expanded to machining of various important structural ceramic materials such as siliconcarbide (SiC), alumina (Al2O3), mullite, zirconia (ZrO2) and silicon nitride (Si3N4).In particular, the proposed research seeks to develop the capability to fabricate parts with complex geometry by developing requisite in-process monitoring and control techniques. This will lead, along with the developedmodeling capabilities, to facilitating the implementation of LAM in industry.