Precipitation and surface adsorption of metal complexes during electropolishing. Theory and characterization with X-ray nanotomography and surface tension isotherms

Nave, Maryana I.; Chen-Wiegart, Yu Chen Karen; Wang, Jun; Kornev, Konstantin G.

doi:10.1039/c5cp03431k

Cited by 4 publications

(3 citation statements)

References 61 publications

(91 reference statements)

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“…The same happens in the case of silver electropolishing in a cyanide solution where no oxide layer is formed [ 129 ]. The electropolishing of tungsten in an aqueous solution of potassium hydroxide leads to the formation of a gel-like structure around the anode, based on the concept of ionic adsorption [ 130 ], which can be seen in Figure 14 .…”

Section: Theories Of Electropolishingmentioning

confidence: 99%

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Electropolishing and Shaping of Micro-Scale Metallic Features

2022

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Electropolishing (EP) is most widely used as a metal finishing process. It is a non-contact electrochemical process that can clean, passivate, deburr, brighten, and improve the biocompatibility of surfaces. However, there is clear potential for it to be used to shape and form the topology of micro-scale surface features, such as those found on the micro-applications of additively manufactured (AM) parts, transmission electron microscopy (TEM) samples, micro-electromechanical systems (MEMs), biomedical stents, and artificial implants. This review focuses on the fundamental principles of electrochemical polishing, the associated process parameters (voltage, current density, electrolytes, electrode gap, and time), and the increasing demand for using environmentally sustainable electrolytes and micro-scale applications. A summary of other micro-fabrication processes, including micro-milling, micro-electric discharge machining (EDM), laser polishing/ablation, lithography (LIGA), electrochemical etching (MacEtch), and reactive ion etching (RIE), are discussed and compared with EP. However, those processes have tool size, stress, wear, and structural integrity limitations for micro-structures. Hence, electropolishing offers two-fold benefits of material removal from the metal, resulting in a smooth and bright surface, along with the ability to shape/form micro-scale features, which makes the process particularly attractive for precision engineering applications.zx3

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Section: Theories Of Electropolishingmentioning

confidence: 99%

“… Examination of electropolished tungsten in KOH solution where wire is surrounded by gel-like structure [ 130 ]; copyright granted by author (Konstantin, 2015 [ 130 ]). …”

Section: Figurementioning

confidence: 99%

Electropolishing and Shaping of Micro-Scale Metallic Features

2022

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“…The phenomenon of electropolishing has been explained through several other theories that describe concepts such as acceptor ions [ 28 ], passivation (strongly passivating metals) [ 29 ], and adsorption (noble/precious metals) [ 30 ] for certain metals. Additionally, there are various waveforms used in electropolishing, including direct current (DC) [ 31 ], forward pulse current (PC) [ 31 ], and pulse/pulse reverse current (PPR) [ 32 ].…”

Section: Introductionmentioning

confidence: 99%

Optimization of forward pulsed currents for combining the precision shaping and polishing of nickel micro mould tools to reduce demoulding defects

Zaki,

Zhang,

Gilchrist

2024

Int J Adv Manuf Technol

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Precise tooling is vital for defect-free production of micro injection moulded (μ-IM) or hot-embossed products. The demoulding stage of such moulding and forming processes poses a serious challenge to the integrity of thin miniature features because of friction, adhesion, and thermal stresses. Typically, micro moulds involve geometrically textured patterns or features such as linear ridges, pillars, channels, and holes, the characteristic dimensions of which range from 10 to 300 μm. Realistically complex mould designs, containing precision micro features (enhanced fillet radius and positive draft angle) and high surface quality, are presented in this work. Electropolishing based on forward pulse currents (PC) has been used to shape and polish Ni micro moulds that contain sets of micron-scaled linear ridges and star patterns in order to ease the separation of moulded polymeric parts from the metallic mould during ejection and demoulding. The use of forward pulsed currents improved the mould design by increasing the fillet radii and draft angle while keeping the surface roughness low and maintaining a good surface shine. An optimization study of forward PC using a green solution of nickel sulfamate varied EP times (0–70 min) and duty cycles (40, 50, 60, and 70%) at a process conditions of 2.8 V, 50 °C, and 250 rpm. The best topographical and morphological changes were observed for a typical microfluidic channel (w × h, 100 × 110 μm) with an EP time of 70 min and 50% duty cycle: fillet radius increased by 3.8 μm, draft angle by 3.3°, and the channel width reduced by 11.4% while surface roughness changed by 8.6% and surface shine improved by 48.9%. Experimental validation was performed using hot embossing wherein the electropolished Ni mould replicated the micro channels and star patterns in PMMA chips with notably fewer burrs, material pile up, and no feature distortion. Moreover, there was a reduction in the side wall roughness of micro channels in PDMS casting with electropolished Ni mould by 16%. Hence, this work presents a significant scientific contribution to improving the efficiency of micro mould tools and reduces the defects caused by friction and adhesion in replicated polymeric parts.

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Complexity of Products of Tungsten Corrosion: Comparison of the 3D Pourbaix Diagrams with the Experimental Data

Nave

Kornev

2016

Metall Mater Trans A

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Precipitation and surface adsorption of metal complexes during electropolishing. Theory and characterization with X-ray nanotomography and surface tension isotherms

Cited by 4 publications

References 61 publications

Electropolishing and Shaping of Micro-Scale Metallic Features

Electropolishing and Shaping of Micro-Scale Metallic Features

Optimization of forward pulsed currents for combining the precision shaping and polishing of nickel micro mould tools to reduce demoulding defects

Complexity of Products of Tungsten Corrosion: Comparison of the 3D Pourbaix Diagrams with the Experimental Data

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