气膜孔三维扩散结构分块成形的电复合加工机理与工艺研究

气膜孔用以喷出冷却气流形成壁面气膜来隔热散热，保护航空发动机涡轮叶片在极端高温下工作。带有三维扩散结构的异形气膜孔可节省冷却气体用量且明显提高冷却效率，但其复杂结构成为先进气膜孔制造的关键难题之一。本项目提出采用棒状电极对三维扩散结构进行分块成形的电火花电解复合加工新工艺，并引入水基弱电解质混纳米粉工作液以改善工艺稳定性和表面质量。侧重研究复合能场作用下单晶高温合金材料去除机理和表面完整性调控机制，包括无损伤引导下的复合能场输出效应、气固液混合流场动态特性、电复合去除微观机理的基础问题。拟揭示出无重铸层表面成形规律和质变边界条件，进而拟解决电极伺服进给及端部形状保持方法、多参数在线调控能场技术等工艺问题，有望形成一套高效成形且无损伤的同步工艺。

Film cooling holes are used to spray cooling airflow for constructing the air wall film, which protects turbine blades of aeroengines to work at extreme high temperature. The film cooling holes with 3D diffusion structures significantly improve the cooing efficiency and save the cooling-gas amount. However, the complex diffusion structure is one of the key problems for machining the advanced film cooling holes. In this project, a novel block-divided electro discharge machining (EDM) and electrochemical machining (ECM) hybrid process is proposed for forming the 3D diffusion structure by use of a rod tool electrode. The process introduces the working fluid of nanopowders mixed water-based low-resistivity electrolyte to improve the processing stability and surface quality. This research would focus on the material removal mechanism and the regulatory mechanism of surface integrity of a single crystal high-temperature alloy during the machining process under the combined energy field, including the basic problems of the output effect of the combined energy with defect-free results, the dynamic characteristics of gas-solid-liquid combined flow field, and the micro-mechanism of electro combined removal effect. We plan to reveal the forming rule and the qualitative change boundary conditions driven by the surface performance without recasting layer. Furthermore, the key process problems would be solved such as the methods if tool electrode servo feeding and its end shape maintaining, the online control technology of multi-parameters for adjusting the combined energy field, etc. It is expected to achieve a set of efficient synchronized process for machining the defect-free 3D diffusion structures.