Tailoring absorptivity of highly reflective Ag powders by pulsed-direct current magnetron sputtering for additive manufacturing processes
Wadge, Matthew D. and Lowther, Morgan and Cooper, Timothy P. and Reynolds, William J. and Speidel, Alistair and Carter, Luke N. and Rabbitt, Daisy and Kudrynskyi, Zakhar R. and Felfel, Reda M. and Ahmed, Ifty and Clare, Adam T. and Grant, David M. and Grover, Liam M. and Cox, Sophie C. (2023) Tailoring absorptivity of highly reflective Ag powders by pulsed-direct current magnetron sputtering for additive manufacturing processes. Journal of Materials Processing Technology, 317. 117985. ISSN 0924-0136 (https://doi.org/10.1016/j.jmatprotec.2023.117985)
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Abstract
Processing of highly reflective and high thermally conductive materials (Cu, Ag, etc.) by laser powder bed fusion (LPBF) is of increasing interest to broaden the range of materials that can be additively manufactured. However, these alloys are challenged by high reflectivity resulting in unmelted particles and porosity. This is exacerbated for in-situ alloying techniques, where divergent optical properties of blended powders further narrow the stable processing window. One possible route to improved uniformity of initial melting is through coating powders with an optically absorptive layer. In-situ alloying of Ti-Ag was chosen as a model to assess this, given the potential of Ti-Ag as a novel antimicrobial biomedical alloy, facilitating an ideal model to assess this approach. High purity Ag powder was coated with Ti via physical vapour deposition. Barriers to reliable coating were investigated, with agglomeration of particles observed at a sputtering power of 100 W. In-situ laser micro calorimetry demonstrated a significant improvement in melting performance for coated Ag powder, with continuous tracks attained at 280 W vs. 320 W for uncoated powder, and absorptivity increasing from 27 % to 45 % at 320 W incident laser power. Subsequent in-situ alloying of the Ag powder when blended with commercially pure Ti powder demonstrated that improved absorptivity allowed for more uniform densification of the blended powder bed at lower energy density (0.7 ± 1.0 vs 7.1 ± 2.0 % porosity at 133 J.m-1). Ultimately, this offers a promising route to improved alloy development via LPBF, through application of a homogeneous, relevant coating.
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Item type: Article ID code: 85779 Dates: DateEvent31 August 2023Published11 April 2023Published Online9 April 2023Accepted27 January 2023SubmittedSubjects: Technology > Mechanical engineering and machinery Department: Faculty of Engineering > Mechanical and Aerospace Engineering Depositing user: Pure Administrator Date deposited: 13 Jun 2023 10:55 Last modified: 25 Sep 2024 00:49 URI: https://strathprints.strath.ac.uk/id/eprint/85779