离子推力器溅射沉积物防剥离放电室的设计及激光选区熔化增材制造研究

Design of sputtered deposits flake suppression discharge chamber for ion thruster and research on laser-selective melting additive manufacturing

关键词:  离子推力器  放电室  溅射沉积物  选区激光熔化  抑制

Key words:  Ion thrusters  Discharge chambers  Sputtered deposits  Selected area laser melting  Suppression

摘要:

为了抑制离子推力器寿命末期由溅射沉积导致的放电室膜层剥落物脱落，首先采用理论研究和试验的方法开展了剥落物抑制放电室的设计，基于零件结构和增材制造特点开展了零件工艺性分析并提出解决方案，实现了放电室增材制造，开展了离子推力器放电室溅射物防脱落性能测试。结果表明：放电室内表面设计纹理化结构排布形式为正六边形，凸起部分外接圆直径0.5 mm，间距0.25 mm，高度0.5 mm时可降低溅射沉积物脱落概率及碎屑尺寸，通过分层旋转扫描，选择激光功率425 W，扫描速度1 200 mm/s工艺参数可实现大尺寸薄壁、具有复杂微小特征钛合金回转体制造，通过结构拓扑，镂空点阵结构、工艺参数和空间摆放位置优化，成型零件壁厚一致性偏差小于0.10 mm。放电室优化前后推力器性能稳定，各工作点关键参数相对误差小于4%。本文的研究为离子推力器放电室溅射沉积物脱落抑制方法和复杂结构的激光选区熔化增材制造成型提供了工程应用方案。

Abstract:

In order to suppress the flake of the discharge chamber caused by sputtered deposits at the end of the life of the ion thruster， firstly， the design of a flake suppression discharge chamber was carried out using theoretical research and experimental methods， processability analysis of mechanical parts was carried out and solutions were proposed based on the structure of the discharge chamber and the characteristics of additive manufacturing. Additive manufacturing of the discharge chamber was realized， and the suppression effect of flake in the discharge chamber for ion thruster was carried out. The results show that the design of the textured structure on the surface of the discharge chamber in the form of a square hexagon with a raised outer circle diameter of 0.5 mm， a pitch of 0.25 mm and a height of 0.15 mm can reduce the probability of sputtered deposits falling off and the size of flakes. The process parameters of laser power 425 W and scanning speed 1 200 mm/s can be used to manufacture large， thin-walled titanium alloy rotating bodies with complex micro features by layered rotary scanning. By optimizing the structural topology， the hollowed-out 3D lattice structures， the process parameters and the spatial placement， the deviation in wall thickness consistency of the formed discharge chamber is less than 0.10 mm. The thruster performance is stable before and after the optimization of the discharge chamber， and the relative error of key parameters at each operating point is less than 4%. The research in this paper provides engineering applications for sputtered deposit shedding suppression methods in ion thrusters discharge chambers and laser-selective melting additive manufacturing forming of complex structures.