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14 pages, 3108 KB

Open AccessArticle

Combined Treatment of Parts Produced by Additive Manufacturing Methods for Improving the Surface Quality

by Sergey Grigoriev, Alexander Metel, Marina Volosova, Yury Melnik and Enver Mustafaev

Technologies 2022, 10(6), 130; https://doi.org/10.3390/technologies10060130 - 11 Dec 2022

Cited by 6 | Viewed by 3377

To improve the quality of a part manufactured by the additive method, it is necessary to eliminate the porosity and high roughness of its surface, as well as to deposit a coating on it. For this purpose, in the present work, we studied the combined processing in a gas discharge plasma of complex shape parts obtained by the additive manufacturing method, which includes explosive ablation of surface protrusions when voltage pulses are applied to the part immersed in the plasma; polishing with a concentrated beam of fast neutral argon atoms at a large angle of incidence on the surface of the part, and magnetron deposition of a coating on it with assistance by fast argon atoms. Combined processing made it possible to completely get rid of porosity and reduce the surface roughness from Ra ~ 5 µm to Ra ~ 0.05 µm. Full article

(This article belongs to the Special Issue 3D Printing Technologies II)

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13 pages, 2901 KB

Open AccessArticle

Improvement of Thin Film Adhesion Due to Bombardment by Fast Argon Atoms

by Sergey Grigoriev, Alexander Metel, Marina Volosova and Yury Melnik

Coatings 2018, 8(9), 303; https://doi.org/10.3390/coatings8090303 - 28 Aug 2018

Cited by 7 | Viewed by 5570

Abstract

A new hollow cathode sputtering system is used for beam-assisted deposition of thin films on dielectric substrates. A copper target placed at the hollow cathode bottom is uniformly sputtered by argon ions from the glow discharge plasma filling the cathode. Through an emissive grid, sputtered copper atoms leave the cathode together with accelerated argon ions. On their way to the substrate, the ions—due to charge exchange collisions—turn into fast argon atoms bombarding the growing film. With increasing argon ion energy, continuous bombardment results in the film adhesion improvement and reduction of the deposition rate down to zero, at an energy of about 2 keV. The pulsed bombardment does not influence the film deposition rate, and results in a monotonic growth of the film adhesion up to 20 MPa when increasing the fast atom energy up to 10 keV. Full article

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11 pages, 3829 KB

Open AccessArticle

Automated Control of Plasma Ion-Assisted Electron Beam-Deposited TiO₂ Optical Thin Films

by Bing Hui, Xiuhua Fu, Des Gibson, David Child, Shigeng Song, Lewis Fleming, Guntis Rutins, Hin On Chu, Caspar Clark and Stuart Reid

Coatings 2018, 8(8), 272; https://doi.org/10.3390/coatings8080272 - 5 Aug 2018

Cited by 6 | Viewed by 7543

Abstract

A hollow cathode plasma source has been operated automatically, demonstrating independent control of plasma ion energy and ion current density for plasma ion-assisted electron beam-deposited titania (TiO₂). The lanthanum hexaboride hollow cathode design described in this work utilizes both the interior and exterior cathode surfaces, with the additional electrons generated removing the need for a separate neutralizing source. Automatic feedback control of plasma source cathode-to-anode accelerator voltage (AV—via argon gas flow to the anode and/or cathode plasma source areas) and accelerator current (AC—via an external high-current power supply) provides independent control of the ion energy distribution function and ion current density, respectively. Automated run-to-run reproducibility (over six separate deposition runs) in TiO₂ refractive index (550 nm) was demonstrated as 2.416 ± 0.008 (spread quoted as one standard deviation), which is well within the required refractive index control for optical coating applications. Variation in refractive index is achievable through control of AV (ion energy) and/or AC (ion current density), directly influencing deposited TiO₂ structural phase. Measured dependencies of TiO₂ refractive index and extinction coefficient on AV and AC are described. Optimum plasma source parameters for assisted electron beam deposition of TiO₂ optical thin-film applications are highlighted. Full article

(This article belongs to the Special Issue Applications of Optical Thin Film Coatings)

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