Absorptivity measurements during laser powder bed fusion of pure copper with a 1 kW cw green laser

Nordet, G.; Gorny, Cyril; Mayi, Yaasin; Daligault, Julien; Dal, Morgan; A., Effernelli,; Blanchet, Etienne; Coste, Frédéric; Peyre, Patrice

doi:10.1016/j.optlastec.2021.107612

Cited by 17 publications

(5 citation statements)

References 27 publications

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“…The former is more relevant to the research community because it only requires one laser source. We note that this scenario might change depending on the material because the penetration depth can also be affected by the absorptivity of the material. − In other words, apart from the laser power, the absorptivity of the material will also affect the access to the bulk of the material. − Nevertheless, this method of attenuating the laser power and source to decouple the surface and bulk can be used to investigate the surface and bulk chemistries of MXenes and related materials.…”

Section: Resultsmentioning

confidence: 99%

Decoupling the Surface and Bulk Reactivities of MXenes and Catalytic Activity Tuning through Surface Chemistry Modification

Yoo

Djire

2023

ACS Catal.

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MXenes, a family of two-dimensional (2D) materials based on transition metal carbides and nitrides, show great promise as electrocatalysts for electrochemical reactions but suffer from a lack of fundamental understanding of their electrocatalytic mechanisms. Decoupling the surface and bulk reactivities are key to understanding the electrocatalytic mechanisms of these emerging nanomaterials. Herein, we use Raman spectroscopy to decouple the surface and bulk reactivities of the Ti 2 NT x MXene. By attenuating the Raman intensity, we were able to control the penetration depth of the incident light. We show that with 5−10% laser power, we can restrict the access to the surface of the Ti 2 NT x MXene, which shows predominantly the oxide phase from the passivation layer. With 50−100% laser power, we can penetrate the bulk of the MXene material, as evidenced by the Ti−N bond network characteristics. By using this approach, we can study and understand the surface reactivity of MXenes, which has not been understood. To expand these findings to electrochemical reactions, we have analyzed the surface reactivities of the pristine and NaOH treated Ti 2 NT x MXenes using Raman spectroscopy and hydrogen evolution reaction (HER). The surface chemistry of the NaOH treated Ti 2 NT x MXene was different from that of the pristine ones and showed predominantly −OH termination groups and no −F. This resulted in an excellent HER activity of ∼100 mV overpotential at 10 mA cm −2 and an impressive Tafel slope of 98 mV dec −1 . These results are comparable to those for the benchmark Pt/C in the alkaline electrolyte. To summarize, we propose an approach for decoupling the surface and bulk reactivities of MXenes and a simple method to tune their HER activity to match those for noble metals. This approach can be applied to other materials and systems to accelerate the discovery of electrocatalysts and electrode materials.

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Section: Resultsmentioning

confidence: 99%

Decoupling the Surface and Bulk Reactivities of MXenes and Catalytic Activity Tuning through Surface Chemistry Modification

Yoo

Djire

2023

ACS Catal.

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“…With rise of the surface temperature of the melted zone, the absorption coefficients increase, and with the development of the keyhole, further increase is promoted by the phenomenon of multiple reflections. The model of multiple reflections inside the black body developed by Gouffé [31] can be applied to the description of the evolution of absorption coefficient inside the cylindrical keyhole in function of its aspect ratio defined as x = H KH /2R l [32]:…”

Section: The Discussion On the Factors Controlling The Keyhole Develo...mentioning

confidence: 99%

In-situ study of keyhole behavior during a laser pulse applied to the dissimilar metal joint

Tomashchuk

Duband

Jouvard

2023

Metall. Res. Technol.

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In the present study, the method of frontal observation of the keyhole through the fused quartz window is applied to the dissimilar combinations between stainless steel 316L and different metals chosen to illustrate four typical cases of mismatch in physical properties: a much lower vaporization temperature (316L/magnesium alloy AZ31), a much higher vaporization temperature (316L/pure niobium), a more reflective and conductive metal (316L/aluminum alloy A5754) and an extremely reflective metal (316L/pure copper). A standalone Yb:YAG laser pulse was applied to the dissimilar couple/quartz and metal/quartz joints. Each of these cases was studied using image treatment of the obtained high-speed videos and post-mortem observation of the interaction zone. Basing on the analysis of the physical properties of the metals and their interdependencies, the first criterion of keyhole development in the dissimilar joint is proposed. It is concluded that in case of Yb:YAG laser welding of stainless steel with metals having thermal conductivity ≤200 W · m−1 · K−1, the keyhole development is dominant in the metal having lower vaporization temperature, while for the 316L combinations with the metals having thermal conductivity >200 W · m−1 · K−1, the keyhole development remains dominant on the 316L side, but its progression is slowed down by the neighboring metal.

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“…Recently, continuous short-wavelength lasers of 515 nm (green) and 450 nm (blue) have begun to emerge for use in L-PBF systems, due to the aforementioned higher energy pure copper absorptivity of these wavelengths. Contrary to NIR lasers, the current optical hardware capabilities of these short-wavelength lasers appear to have a minimum beam spot size of 200 µm [109][110][111][112][113][114], which results in an illuminated area that is up to six times as large as that of a typical 80 µm beam spot size for NIR lasers. In fact, even for the same beam spot size and laser process parameters over a range of different scan speeds, Hori et al [110] observed that the copper meltpool bead size for a blue laser was consistently two to four times larger than that of a NIR laser (see Figure 20).…”

Section: Thin-wall Structuresmentioning

confidence: 99%

Recent Advances in the 3D Printing of Pure Copper Functional Structures for Thermal Management Devices

Choong,

Krishnan,

Gupta

2023

Technologies

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Thermal management devices such as heat exchangers and heat pipes are integral to safe and efficient performance in multiple engineering applications, including lithium-ion batteries, electric vehicles, electronics, and renewable energy. However, the functional designs of these devices have until now been created around conventional manufacturing constraints, and thermal performance has plateaued as a result. While 3D printing offers the design freedom to address these limitations, there has been a notable lack in high thermal conductivity materials beyond aluminium alloys. Recently, the 3D printing of pure copper to sufficiently high densities has finally taken off, due to the emergence of commercial-grade printers which are now equipped with 1 kW high-power lasers or short-wavelength lasers. Although the capabilities of these new systems appear ideal for processing pure copper as a bulk material, the performance of advanced thermal management devices are strongly dependent on topology-optimised filigree structures, which can require a very different processing window. Hence, this article presents a broad overview of the state-of-the-art in various additive manufacturing technologies used to fabricate pure copper functional filigree geometries comprising thin walls, lattice structures, and porous foams, and identifies opportunities for future developments in the 3D printing of pure copper for advanced thermal management devices.

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Absorptivity measurements during laser powder bed fusion of pure copper with a 1 kW cw green laser

Cited by 17 publications

References 27 publications

Decoupling the Surface and Bulk Reactivities of MXenes and Catalytic Activity Tuning through Surface Chemistry Modification

Decoupling the Surface and Bulk Reactivities of MXenes and Catalytic Activity Tuning through Surface Chemistry Modification

In-situ study of keyhole behavior during a laser pulse applied to the dissimilar metal joint

Recent Advances in the 3D Printing of Pure Copper Functional Structures for Thermal Management Devices

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