Experimental investigation of surfactant-mixed electrolyte into electrochemical discharge machining (ECDM) process
Experimental investigation of surfactant-mixed electrolyte into electrochemical discharge machining (ECDM) process
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DOI：
10.1016/j.jmatprotec.2017.07.017
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发表时间：
2017-12-01
影响因子：
6.3
通讯作者：
Hajian, Mansour
中科院分区：
文献类型：
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作者：
Sabahi, Nasim;Razfar, Mohammad Reza;Hajian, Mansour
利用电化学放电加工（ECDM），是通过同时施加化学和热现象在玻璃件上形成微通道的最合适的方法。几个参数影响微通道的质量。工具电极周围的气膜厚度是影响加工质量的重要参数之一，越薄的气膜厚度越有利于提高加工质量。本文通过对工具电极表面形成的单个气泡的理论分析，发现工具电极的润湿性和气泡与电解液之间的表面张力对气泡膜厚度有影响。在实验中，两种最广泛使用的表面活性剂，阴离子表面活性剂十二烷基硫酸钠（SDS）和阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）在不同的浓度，溶解在25重量%的KOH和NaOH碱性溶液中，以减少气膜厚度通过影响电解质的物理化学性质和电极的润湿性。实验结果表明，表面活性剂微通道的存在，具有较高的材料去除率（MRR），较低的过切和热影响区（HAZ）的形成。表面活性剂的存在降低了电解液的导热系数，提高了电解液的粘度，改善了微通道的表面质量。当电压为35 V，CTAB的质量分数为0.036%时，表面质量提高了73%，沟道边缘的硬度提高了144%。通道边缘硬度增加，表明热影响区减小。在不同浓度的表面活性剂中，临界胶束浓度（CMC）对切削性能的影响最大。由于阳离子表面活性剂CTAB具有较低的CMC，并且还通过在玻璃上呈现更多的OH自由基来增强化学蚀刻，因此与阴离子表面活性剂SDS相比，它对工艺输出的影响更大。
Using electrochemical discharge machining (ECDM), is the most appropriate method to create microchannels on glass pieces by applying chemical and thermal phenomena simultaneously. Several parameters affect the quality of microchannels. Thickness of gas film surrounded the tool-electrode is one of the most effective parameters, which thinner gas film would result in higher machining quality. In this study, according to the theoretical analysis of the single gas bubble formed at the tool electrode surface, it has been found that the wettability of tool electrode and surface tension between the bubble and electrolyte affect the gas film thickness. In the experiments, two most widely used surfactants which are anionic surfactant Sodium dodecyl sulfate (SDS) and cationic surfactant Cetyltrimethylammonium bromide (CTAB) in various concentrations, were dissolved in the 25 wt% KOH and NaOH alkaline solutions in order to reduce the gas film thickness by affecting the physicochemical properties of the electrolyte and the wettability of the electrode. The results obtained from the experiments indicated that in the presence of surfactant microchannels with higher material removal rate (MRR), lower overcut and heat affected zone (HAZ) were fabricated. Also, due to decrement of thermal conductivity and increment of viscosity of the electrolyte in the presence of surfactant, the surface quality of microchannels were improved. For example, at a voltage of 35 V and presence of 0.036 wt% CTAB in KOH, the surface quality improved 73% and the hardness of channel edge enhanced 144%. Increase in hardness of channel edge, indicates that the HAZ is reduced. Among different concentrations of surfactants, the critical micelle concentration (CMC) has the most influence on the machining performance. Since the cationic surfactant CTAB has lower CMC and also enhances the chemical etching by presenting more OH radicals on the glass, it has more influences on the process outputs compared to the anionic surfactant SDS.