Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China; Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116024, China.
Ultrason Sonochem. 2018 Dec;49:233-240. doi: 10.1016/j.ultsonch.2018.08.012. Epub 2018 Aug 11.
In order to reduce the large residual stress in micro elelctroforming layer, megasonic assisted electroforming is proposed here. Micro electroforming experiments were performed with and without megasonic agitation, respectively. Four different megasonic power densities were applied to investigate the influence of megasonic agitation on reducing the residual stress. The residual stress was measured by X-ray diffraction (XRD) method. Experiment results show that the residual stresses fabricated with megasonic agitation are less than that fabricated without megasonic. When the megasonic power density is 2 W/cm, the residual stress can be the minimum value of -125.7 MPa, reduced by 60% in comparison with the value of -315.1 MPa electroformed without megasonic agitation. For exploring the mechanism of megasonic agitation on reducing the residual stress, the dislocation density and crystal orientation were calculated by the single-line Voigt profile analysis and Relative Texture Coefficient (RTC) method, respectively. The diameters and distributions of pits on the surface of electroforming layer were observed by the STM-6 tool microscope and counted by the Image-Pro Plus software. It reveals that one hand of the mechanism is the acoustic streaming produced by megasonic can strengthen the motion of dislocation in crystal lattice and makes the crystal lattices grow towards the equilibrium shape, which is benefit to crystallization with low residual stress. When the megasonic power density is 2 W/cm, the dislocation density increases to be the maximum value of 8.09 × 10 m and the difference between RTC and RTC decreases to be zero, which is consistent with the residual stress results. The other hand is that the stable cavitation produced by megasonic can provide residual stress release points during the electroforming process.
为了降低微电铸层中的残余应力，提出了兆声辅助电铸。分别进行了有和没有兆声搅拌的微电铸实验。施加了四种不同的兆声功率密度，以研究兆声搅拌对降低残余应力的影响。残余应力通过 X 射线衍射（XRD）方法测量。实验结果表明，有兆声搅拌的残余应力小于没有兆声搅拌的残余应力。当兆声功率密度为 2 W/cm 时，残余应力可以达到最小的-125.7 MPa，与没有兆声搅拌的-315.1 MPa 相比降低了 60%。为了探索兆声搅拌降低残余应力的机制，通过单线条 Voigt 轮廓分析和相对织构系数（RTC）方法分别计算了位错密度和晶体取向。通过 STM-6 工具显微镜观察电铸层表面的蚀坑直径和分布，并使用 Image-Pro Plus 软件进行计数。结果表明，一方面，兆声产生的空化流可以增强晶格中位错的运动，使晶格向平衡形状生长，这有利于残余应力较低的结晶。当兆声功率密度为 2 W/cm 时，位错密度增加到最大值 8.09×10 m，RTC 和 RTC 之间的差异减小到零，这与残余应力结果一致。另一方面，兆声产生的稳定空化在电铸过程中可以提供残余应力释放点。
