Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4719

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  • Article
    Citation - WoS: 8
    Citation - Scopus: 11
    Spreadability of Metal Powders for Laser-Powder Bed Fusion Via Simple Image Processing Steps
    (MDPI, 2022) Ahmetoğlu, Çekdar Vakıf; Hasdemir, Beyza; Biasetto, Lisa
    This paper investigates the spreadability of the spherical CoCrWMo powder for laser- powder bed fusion (PBF-LB) by using image processing algorithms coded in MATLAB. Besides, it also aims to examine the spreadability dependence with the other characteristics such as powder size distribution, apparent density, angle of repose. Powder blends in four different particle size distributions are prepared, characterized, and spreadability tests are performed with the PBF-LB. The results demonstrate that an increase in fine particle ratio by volume (below 10 µm) enhances the agglomeration and decreases the flowability, causing poor spreadability. These irregularities on the spread layers are quantified with simple illumination invariant analysis. A clear relation between powder spreadability and 3D printed structures properties in terms of residual porosity could not be defined since structural defects in 3D printed parts also depends on other processing parameters such as spatter formation or powder size over layer height ratio.
  • Article
    Citation - WoS: 9
    Citation - Scopus: 11
    Synthesis, Bottom Up Assembly and Thermoelectric Properties of Sb-Doped Pbs Nanocrystal Building Blocks
    (MDPI, 2021) Cadavid, Doris; Wei, Kaya; Liu, Yu; Zhang, Yu; Li, Mengyao; Genc, Aziz; Berestok, Taisiia
    The precise engineering of thermoelectric materials using nanocrystals as their building blocks has proven to be an excellent strategy to increase energy conversion efficiency. Here we present a synthetic route to produce Sb-doped PbS colloidal nanoparticles. These nanoparticles are then consolidated into nanocrystalline PbS:Sb using spark plasma sintering. We demonstrate that the introduction of Sb significantly influences the size, geometry, crystal lattice and especially the carrier concentration of PbS. The increase of charge carrier concentration achieved with the introduction of Sb translates into an increase of the electrical and thermal conductivities and a decrease of the Seebeck coefficient. Overall, PbS:Sb nanomaterial were characterized by two-fold higher thermoelectric figures of merit than undoped PbS.