基于阴极复合运动的游离微珠摩擦辅助电铸机理研究

Electroforming is an important precision machining method for modern manufacturing industry. The property of deposited layer on electroforming product with complicated profiles varies from part to part because of pins and nodules on the surface in traditional electroforming process. For complex thin-wall part, a free-beads-polishing-assisted electroforming manufacture technology with compound cathode movement is proposed. Nonconductive free beads can polish the growing deposited layer slightly, perturb the ionic discharge and crystallization process. Therefore, the nodules, pits and porosity are eliminated, the grains are refined. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits, which will improve the properties and deposition rate of deposits effectively. The proposed research focuses on the research of new phenomena and mechanisms of deposited layer in electroforming process under the slightly polishing and perturbation of free beads with compound cathode movement, as well as the properties. Intensive study will be conducted include the mechanism of free beads’ diffuse action, the simulation and modeling of electric and flow field in electroforming. A free-beads-polishing-assisted electroforming technology system is also constructed to provide new technological means for electroforming metal products, especially with complex shapes.

电铸是现代制造业重要的一种精密加工方法。传统电铸工艺中，阴极沉积层表面由于针孔、结瘤等缺陷，导致局部材料性能差异较大而使零件失效。本项目针对轮廓线复杂的回转体薄壁件，提出阴极复合运动游离微珠摩擦辅助电铸技术，利用不导电耐磨游离微珠对正在生长的沉积层进行微量磨削，并扰动电沉积的离子放电和结晶过程，彻底消除电铸层的结瘤、凹坑和孔隙等缺陷，细化晶粒。阴极一边在水平面内平动，一边绕自身轴旋转，通过两种运动的复合来增强微珠在溶液中的游离弥散效果，提高微珠对阴极表面摩擦的均匀性，消除缺陷，提高铸层材料性能和电铸速度。本项目将重点研究复合运动的阴极在游离微珠均匀磨削和扰动条件下，金属电沉积出现的新现象和新理论以及电铸材料的新特性，深入研究微珠的均匀弥散化作用机理，电铸电场和流场的仿真与建模等关键技术，建立弥散态微珠辅助磨电铸制造技术体系。为复杂型面回转体薄壁金属件的快速一次性电铸成形提供新途径。

电铸是基于电沉积原理的高精度形性一体化整体制造技术，在航天、航空、兵器、模具等领域有着重要应用。传统电铸工艺中，阴极沉积层表面由于针孔、结瘤等缺陷，导致局部材料性能差异较大而使零件失效。本项目针对轮廓线复杂的回转体薄壁件，提出阴极复合运动游离微珠摩擦辅助电铸技术，利用不导电、耐磨游离微珠对正在生长的沉积层进行微量磨削，并扰动电沉积的离子放电和结晶过程，彻底消除电铸层的结瘤、凹坑、孔隙等缺陷，细化晶粒。阴极一边在水平面内平动，一边绕自身轴旋转，通过两种运动的复合来增强微珠在溶液中的游离弥散效果，提高微珠对阴极表面摩擦的均匀性，消除缺陷，提高电铸层材料性能和电铸速度。针对推力室外壁等复杂曲面形状零件，采用阴极平动及转动的复合运动结合摩擦辅助电铸技术的方式进行电铸镍并优化工艺参数的试验研究。论电流密度、平动速度和自转速度等工艺参数对电铸层组织结构和机械性能的影响，并进行优化。采用正交试验法，通过多种测试方法对不同工艺参数下的电铸镍试验所制备得镍电铸层的表面形貌、显微硬度和抗拉强度进行测试和分析。试验结果表明，各工艺参数对镍电铸层抗拉强度影响最显著的是电流密度；平动速度和电流密度在对镍电铸层延伸率影响的显著性上相当；对镍电铸层显微硬度影响最显著的是平动速度，电流密度的影响次之。试验通过各因素对各指标影响的综合平衡分析，得到了使电铸层具有较高综合性能的最优工艺参数组合。在平阴极动速度为20mm/s，自转速度为1r/min，电流密度为6A/dm²条件下，得到了抗拉强度为581MPa，延伸率为17%，显微硬度为248HV的综合性能最优化镍电铸层。为液体火箭发动机推力室外壁等复杂型面回转体薄壁金属件的快速一次性电铸成形提供新途径。