Surface Energy and Wetting in Island Films

Дукаров, С.В.; Kryshal, A.P.; Sukhov, V. N.

doi:10.5772/60900

Cited by 10 publications

(5 citation statements)

References 52 publications

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“…Assuming that there is a negligible change in the true contact area between the neighboring powder particles after application of the tin coating, the surface energy of the material that is present at the outer surface of the powder particles should play a crucial role in determining the powder flowability. Accordingly, the improvement in the powder flowability after applying the tin coating could be attributed to two factors: Firstly, to the low surface energy of tin (574 mJ/m 2 [44]) compared to the high surface energy of copper (1650 mJ/m 2 [45]). Secondly, to the tin coating layer exhibiting a thickness of several nanometers, which eliminated the prior high-energy copper-copper cohesive forces that used to exist between the neighboring copper powder particles before application of the tin coating.…”

Section: Property Cusn03 (R2-lpbf)mentioning

confidence: 99%

Highly conductive and strong CuSn0.3 alloy processed via laser powder bed fusion starting from a tin-coated copper powder

Jadhav

Deprez

et al. 2020

Additive Manufacturing

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Despite the high demand, the successful fabrication of fully dense, highly conductive, and strong copper components via laser powder bed fusion (LPBF) is not readily evident. This is mainly due to the low optical absorption of copper, which inhibits the complete melting of copper powders when using commercially available fiber-laser-based LPBF machines. Accordingly, this article proposes a novel approach of using optically absorptive metal-coated copper powders for the fabrication of fully dense, highly conductive, and strong copper components via LPBF. To validate this approach, the surface of the copper powder is modified by applying a very thin (62 ± 14 nm) layer of metallic tin via an immersion plating technique. The application of only a 0.28 wt% of metallic tin coating significantly improved the room temperature powder optical absorption by ~170% at the fiber laser wavelength. Consequently, crack-free and fully dense copper parts combining high thermal conductivity of 334 ± 4 W/(m•K) and electrical conductivity of 80 ± 1% international annealed copper standard (%IACS) with a good tensile strength of 256 ± 14 MPa, yield strength of 203 ± 4 MPa, and ductility of 21 ± 2 % have been fabricated using a fiber laser with an output laser power of 500 W.Furthermore, the article also describes the negative influence of the presence of a high amount of (0.091 wt%) sulfur, which originates from the organic additives during sub-optimal coating conditions, on the LPBF processing behavior of CuSn alloys. As such, high sulfur-containing tin-coated copper powders do not allow the fabrication of fully dense parts due to the occurrence of solidification cracks and the formation of pores. Subsequently, the optimum tin coating methodology, which limits the amount of sulfur below 0.0025 wt%, is described. The use of sulfur-free powder is recommended for the successful LPBF processing of fully dense parts made of copper and copper alloys.

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Section: Property Cusn03 (R2-lpbf)mentioning

confidence: 99%

Highly conductive and strong CuSn0.3 alloy processed via laser powder bed fusion starting from a tin-coated copper powder

Jadhav

Deprez

et al. 2020

Additive Manufacturing

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“…The cracks may form in part as a result of the lack of wettability of the oil solution on the substrate, although we could not confirm this hypothesis with contact angle measurements because of the rapidity at which the emulsion particles spread. However, it has been observed previously that compositions that produce uniform crack-free films are those that best wet the substrate, and increased interfacial tension between the solution and the substrate can produce cracked films. , To make membranes for water filtration testing, we used emulsions with an oil composition of 1:4 o-DCB:DMF. For the casting method, the solvent evaporation rate is 0.5 mL/h at 21 °C in a well-ventilated area.…”

Section: Results and Discussionmentioning

confidence: 99%

“…However, it has been observed previously that compositions that produce uniform crack-free films are those that best wet the substrate, and increased interfacial tension between the solution and the substrate can produce cracked films. 28,29 To make membranes for water filtration testing, we used emulsions with an oil composition of 1:4 o-DCB:DMF. For the casting method, the solvent evaporation rate is 0.5 mL/h at 21 °C in a wellventilated area.…”

Section: Pickering Emulsion Formationmentioning

confidence: 99%

Emulsion Assembly of Graphene Oxide/Polymer Composite Membranes

Ngo

Yuan

et al. 2023

ACS Appl. Mater. Interfaces

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Graphene oxide/polymer composite water filtration membranes were developed via coalescence of graphene oxide (GO) stabilized Pickering emulsions around a porosity-generating polymer. Triptycene poly(ether ether sulfone)-CH 2 NH 2 :HCl polymer interacts with the GO at the water−oil interface, resulting in stable Pickering emulsions. When they are deposited and dried on polytetrafluoroethylene substrate, the emulsions fuse to form a continuous GO/ polymer composite membrane. X-ray diffraction and scanning electron microscopy demonstrate that the intersheet spacing and thickness of the membranes increased with increasing polymer concentration, confirming the polymer as the spacer between the GO sheets. The water filtration capability of the composite membranes was tested by removing Rose Bengal from water, mimicking separations of weak black liquor waste. The composite membrane achieved 65% rejection and 2500 g m −2 h −1 bar −1 . With high polymer and GO loading, composite membranes give superior rejection and permeance performance when compared with a GO membrane. This methodology for fabrication membranes via GO/polymer Pickering emulsions produces membranes with a homogeneous morphology and robust chemical separation strength.

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“…where the interplay between the surface free energy of the substrate (γSG), the Bi film (γLG) and the interface between substrate and film (γSL) determines the contact angle (θC) for dewetting. As the surface, free energy of Bi is described in the literature as about 0.4 J/m 2 (or 2.5 eV/nm 2 ) [75] and the surface free energy of the sapphire substrate about 1.3 J/m 2 [76], as an educated guess one would expect the film to wet the substrate, not knowing the role of the interface of Bi and substrate.…”

Section: Discussionmentioning

confidence: 99%