Laser Assisted Machining of Ceramic Parts with Complex Features

本项目旨在为各种结构陶瓷材料的激光辅助加工(LAM)提供理论和实验上的科学依据，从而显著降低陶瓷零件的制造成本和改善其端态性能。LAM过程的理论处理将被用来确定陶瓷在LAM过程中的热机械行为，通过建立热模型、材料的温度相关特性、本构模型和过程模拟模型。将进行支持性实验，以表征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等方面的加工性能。氮化硅零件的可行性研究证明了LAM的能力，它实现了长达约40分钟的刀具寿命，表面光洁度与磨削相当，亚表面损伤裂纹和热影响区很少，并且在标称加工条件下显著高于磨削。在这项成功的可行性研究的基础上，激光辅助车削技术将扩展到各种重要的结构陶瓷材料的加工，如碳化硅(SiC)、氧化铝(Al_2O_3)、莫来石、氧化锆(ZrO_2)和氮化硅(Si3N_4)。特别是，拟议的研究旨在通过开发必要的在线监测和控制技术来发展制造复杂几何形状零件的能力。这将导致，连同发展的建模能力，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.