Electrochemical polishing of selective laser melted Inconel 718

Jain, Srishti; Corliss, Mike; Tai, Bruce L.; Hung, Wayne

doi:10.1016/j.promfg.2019.06.145

Cited by 42 publications

(12 citation statements)

References 24 publications

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“…This happens because there is partial melting of boundary particles and also an important thermal diffusion between solidified metal underneath and loose particles due to the big difference in temperature. [ 15 ] Strategies to remove powder particles attached to the surface include mechanical milling and/or polishing, [ 16 ] electrochemical polishing, [ 17 ] and a combination of abrasion and electrochemical polishing. [ 18 ] The roughness factor (ratio between real surface and completely flat one) decreases with surface area, starting at 6 and going to 3, with 4 being the average value for our 3D printed structures.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

Rocha

Delmelle

Georgiadis

et al. 2022

Advanced Energy Materials

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This promising method allows not only to decarbonize the current hydrogen production but to decarbonize other industries as well since the carbon-free electrolytic hydrogen (or derivatives) can replace fossil fuels in the transport and heating sectors as well. As a consequence, the International Energy Agency estimates a 140% growth in hydrogen demand by 2030, with water electrolysis being responsible for almost 40% of the total production. [1] There are three main water electrolysis technologies. The most mature one is alkaline water electrolysis (AWE), with a market share of ≈60%, followed by proton exchange membrane water electrolysis (≈30% market share), and solid oxide water electrolysis. [1,2] Besides being the most mature method, AWE also has the lowest capital cost (€/kW) at a given power input, [3] since it uses abundant and inexpensive materials. [4] The state-of-the-art AWE cell configuration is a zero-gap assembly. In this configuration, the electrodes, in general 2D electrodes such as perforated plates, expanded metals, or meshes, are pressed against a separator with a thickness on the order of hundreds of micrometers. [5] Recently, 3D electrode geometries such as foams and felts have been used with promising results, [6] especially when a forced electrolytic flow is imposed. [7] However, due to the stochastic nature of these geometries, gas removal may not be optimal. As an example, Kou et al. observed an enhancement in gas evacuation when replacing foams with periodic 3D structures. [8] An important method to build tailored 3D periodic metallic structures is additive manufacturing using laser beam melting (LBM), also known as selective laser melting (SLM). [9] In this process, a thin layer of powder is deposited over a substrate plate or on the previously deposited layer and a laser beam melts the powder particles selectively. To avoid oxygen contamination, the process is done in a closed chamber containing an inert gas. [10] With the almost unlimited possible geometries that it allows to fabricate, it is important to find generic guidelines as to what kind of structure presents the best electrolytic performance in view of enhanced gas removal.Recently, a study of membrane distillation for desalination has successfully shown that 3D printed spacers can enhance heat and mass transfer and reduce the formation of dead zones. [11] A zero-gap cell with porous electrodes is a promising configuration for alkaline water electrolysis. However, gas evacuation becomes a challenge in that case, as bubbles can get trapped within the electrode's 3D structure. This work considers a number of 3D printed electrode geometries with so-called triply periodic minimal surfaces (TPMS). The latter is a mathematically defined structure that repeats itself in three dimensions with zero mean curvature, and can therefore be expected to be particularly well-suited to enhance gas evacuation. Another advantage as compared to other state-of-the-art 3D electrodes like foams or felts lies in the fact that their porosity, which dete...

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Section: Resultsmentioning

confidence: 99%

Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

Rocha

Delmelle

Georgiadis

et al. 2022

Advanced Energy Materials

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show abstract

“…Buffing, grinding, lapping, abrasive flow polishing, plasma electrolytic polishing, magnetic abrasive polishing, laser polishing, and electrochemical polishing can be used to achieve sub-micron surface finish (Figure 25a and 25b). Under optimal conditions (Figure 25c), surface finish has been improved from 17 µm to 0.25 µm of as-printed IN718 [62], but the presence of micropores and detrimental phases in microstructure prevented further polishing. The combination of conductive matrix of IN718 and the presence of non-conductive phases such as pores, inclusions, precipitations and slag prevent uniform surface finish by electrochemical polishing (Figures 25b and 25c).…”

Section: Inconel 718mentioning

confidence: 99%

“…The as-built SLM IN718 components have rough surface roughness due to the layer-by-layer manufacturing of the components which causes the 'stair case' effect. In addition, the balling effects from partially melted powder on the side walls lead to extremely poor surface finish in the order of 17-20µm Sa area surface finish [62]. The surface roughness is dependent on the AM techniques and the print parameters used to fabricate the component.…”

Section: Factors Influencing Fatigue Of Slm In718mentioning

confidence: 99%

Testing Techniques and Fatigue of Additively Manufactured Inconel 718 – A Review

Balasubramanian

Philpott²,

Hyder³

et al. 2020

IJEMM

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Additive Manufacturing (AM) of metallic components shows unfavorable properties in their as-built state; surface roughness, anisotropy, residual stresses, and internal /surface defects are common issues that affect dynamic properties of AM metals. This paper reviews traditional fatigue testing techniques, summarizes published fatigue data for wrought and additively manufactured metals with focus on Inconel 718. Surface and volume defects of AM metals were presented and how post processing techniques could improve fatigue performance were shown. Different methods for normalizing fatigue data were explored due to varying results of different fatigue testing techniques.

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“…Furthermore, the applicability to limited materials, risk of toxicity and selective phase dissolution also raises concern regarding chemical polishing. 17,18 To overcome the problems associated with existing postprocessing methods, researchers started exploring the potential of electrical discharge machining (EDM) technology in post-processing metal AM components. Most of the metal AM alloys used in industries are of difficult-to-cut in nature due to high hardness.…”

Section: Introductionmentioning

confidence: 99%

Finishing the surface micro-layer of additively manufactured TiAl alloy using electro-thermal discharge assisted post-processing

Boban

Ahmed

2023

Journal of Micromanufacturing

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Selective laser melting (SLM) of titanium–aluminium (TiAl) alloy components has gained significant attention in the modern industrial world. The flexibility of the SLM process in producing complex shapes with minimum utilization of material and energy makes it dominant over other manufacturing techniques. As aerospace and biomedical industries demand complex-shaped TiAl alloy components, part fabrication using SLM becomes the ultimate solution. However, the unacceptable level of surface integrity and anisotropic behavior of SLM components demand post processing operations such as laser polishing, chemical polishing, and conventional polishing methods. In this study, a recently developed polishing method called wire electrical discharge polishing (WEDP) is performed on TiAl alloys for obtaining a smooth and defect-free surface. This study aims to investigate the micro-layer modification occurring to the WEDP-processed surface in detail. The experimental results establish the effectiveness of WEDP method in terms of improved surface integrity. The surface finish (Sa) got enhanced by ~88% after WEDP processing. In addition, the thickness of recast layer formed by WEDP was found to be minimum. Moreover, post-processing of TiAl alloy resulted in better surface morphology specifically at lower settings of peak current. It is noteworthy that the migration of wire material was minimum with zinc-coated brass electrode compared to the normal brass electrode. Hence, coated wire electrodes are recommended for WEDP process. In short, an excellent surface integrity can be achieved using WEDP process through favorable surface modification aided by lower peak current and coated wire electrodes. Furthermore, less electrode wear observed in WEDP process enables the deployment of lower feed rates leading to minimal electrode consumption.

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Electrochemical polishing of selective laser melted Inconel 718

Cited by 42 publications

References 24 publications

Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

Testing Techniques and Fatigue of Additively Manufactured Inconel 718 – A Review

Finishing the surface micro-layer of additively manufactured TiAl alloy using electro-thermal discharge assisted post-processing

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