Jet electrochemical machining of micro dimples with conductive mask
Jet electrochemical machining of micro dimples with conductive mask
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带导电掩模的微凹坑的喷射电化学加工
DOI：
10.1016/j.jmatprotec.2018.02.035
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发表时间：
2018-07-01
影响因子：
6.3
通讯作者：
Guo, Z. N.
中科院分区：
文献类型：
--
作者：
Chen, X. L.;Dong, B. Y.;Guo, Z. N.
微凹坑作为一种典型的表面织构，被广泛应用于许多领域，以提高材料的功能和性能。电化学加工是一种很有前途的微凹坑加工方法。但由于金属溶解的各向同性，电解加工中不可避免地会产生微凹坑的侧向根切，从而降低了加工局部化程度。提出了一种导电掩模喷射电解加工方法，以减少微坑的根切，提高加工局部化程度。该方法在加工过程中直接在工件上覆盖一层导电图形掩模代替绝缘图形掩模，通过降低微坑边缘的电场强度来减小微坑的根切。此外，采用金属喷嘴（内径2 mm）提供稳定的柱状射流，增强了掩模与工件的附着力，促进了加工区域电解液的更新，有利于形成深微坑。模拟结果表明，导电掩模可以有效地降低微坑边缘的电场强度，与绝缘掩模相比，轮廓的咬边现象明显减少。实验结果表明，采用导电掩模JEM时，当微坑深度增加到55 gm时，微坑的底切仅为9 gm，刻蚀因子（EF）达到6.11，是绝缘掩模的4倍。随着微坑深度从45 gm增加到85 gm，微坑的根切从7 sm增大到15 gm。材料沿深度方向的去除速度明显快于沿直径方向的去除速度，表现出较低的根切和较高的加工局部化程度。此外，与脉冲电流相比，直流电流更适合于在导电掩模JEM中形成深微坑。
Micro dimples as a typical surface texture has been used in many fields for enhancing the functionality and performance. Electrochemical machining (ECM) is a promising approach for generating micro dimple. However, due to the isotropy of metal dissolution, the lateral undercutting of micro dimple is inevitable in ECM, which reduces the machining localization. This paper proposed a method of conductive mask jet electrochemical machining to reduce the undercutting of micro dimple and improve the machining localization. In this method, a conductive patterned mask instead of insulated patterned mask was covered on the workpiece directly during machining, which could decrease the undercutting of micro dimple by reducing the electric field intensity at the edge of micro dimple. In addition, a metallic nozzle (inner diameter of 2 mm) was employed to provide a stable columnar jet flow for enhancing the attachment between the mask and workpiece as well as the renewal of electrolyte in machining area, which was useful for generating deep micro dimple. Simulated results showed that the conductive mask could reduce the electric field identity at the edge of micro dimple effectively, and the undercutting of the profile was evidently reduced compared to that generated with insulated mask. Experimental results indicated that with conductive mask JEM, the undercutting of micro dimple was just 9 gm when the depth increased to 55 gm, the etch factor (EF) reached to 6.11, and it was four times greater than that with insulated mask. With the depth increased from 45 gm to 85 gm, the undercutting of micro dimple enlarged from 7 sm to 15 gm. The material removal rate in depth was evidently faster than that in diameter, which showed a low undercutting and high machining localization. In addition, compared with pulse current, direct current was more appropriate for generating deep micro dimple in conductive mask JEM.