ÚK-odbor reverzního inženýrství a aditivních technologií


Recent Submissions

Now showing 1 - 5 of 9
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    Influence of Process Energy on the Formation of Imperfections in Body-Centered Cubic Cells with Struts in the Vertical Orientation Produced by Laser Powder Bed Fusion from the Magnesium Alloy WE43
    (MDPI, 2024-02-15) Jaroš, Jan; Vaverka, Ondřej; Senck, Sascha; Koutný, Daniel
    The low specific density and good strength-to-weight ratio make magnesium alloys a promising material for lightweight applications. The combination of the properties of magnesium alloys and Additive Manufacturing by the Laser Powder Bed Fusion (LPBF) process enables the production of complex geometries such as lattice or bionic structures. Magnesium structures are intended to drastically reduce the weight of components and enable a reduction in fuel consumption, particularly in the aerospace and automotive industries. However, the LPBF processing of magnesium structures is a challenge. In order to produce high-quality structures, the process parameters must be developed in such a way that imperfections such as porosity, high surface roughness and dimensional inaccuracy are suppressed. In this study, the contour scanning strategy is used to produce vertical and inclined struts with diameters ranging from 0.5 to 3 mm. The combination of process parameters such as laser power, laser speed and overlap depend on the inclination and diameter of the strut. The process parameters with an area energy of 1.15-1.46 J/mm2 for struts with a diameter of 0.5 mm and an area energy of 1.62-3.69 J/mm2 for diameters of 1, 2 and 3 mm achieve a relative material density of 99.2 to 99.6%, measured on the metallographic sections. The results are verified by CT analyses of BCCZ cells, which achieve a relative material density of over 99.3%. The influence of the process parameters on the quality of struts is described and discussed.
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    Comparison of Sublimation 3D Scanning Sprays in Terms of Their Effect on the Resulting 3D Scan, Thickness, and Sublimation Time
    (MDPI, 2023-09-11) Franke, Jakub; Koutecký, Tomáš; Koutný, Daniel
    This study compared eight sublimation scanning sprays in terms of their effect on 3D scanning results, coating thickness, and sublimation time. The work used an automated spraying system to ensure the same deposition conditions for all tested materials. All experiments were performed under the same environmental conditions to exclude the influence of the ambient environment on the coatings. All tested scanning sprays created coatings with thicknesses in the order of tens of micrometers that were detectable by the 3D scanner Atos III Triple Scan. The coatings must be applied carefully when accurate measurements are required. All used materials enabled the capture of the highly reflective surface of the Si-wafer. However, the differences between some sprays were significant. Sublimation time measurements showed that all coatings disappeared from the Si-wafer surface completely. Nevertheless, all coatings left visible traces on the mirror-like surface. They were easily wiped off with a cloth.
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    Biodegradable WE43 Magnesium Alloy Produced by Selective Laser Melting: Mechanical Properties, Corrosion Behavior, and In-Vitro Cytotoxicity
    (MDPI, 2022-03-10) Lovašiová, Patrícia; Lovaši, Tomáš; Kubásek, Jiří; Jablonská, Eva; Msallamová, Šárka; Michalcová, Alena; Vojtěch, Dalibor; Suchý, Jan; Koutný, Daniel; Alzubi, Enas
    In this work, selective laser melting (SLM) technology was used to prepare Mg-4Y-3Nd-Zr (WE43) alloy. This alloy and production method are promising for the design of biodegradable implants. The aim of this study was to investigate the chemical composition, microstructure, mechanical properties, corrosion behavior in simulated body fluid (SBF), and cytotoxicity of the alloy produced by SLM method and to compare it with conventionally gravity cast reference alloy. Analysis of the surface of the revealed an oxygen content of 7 wt.%. Undesirable unmelted and only partially adhered spherical particles of the starting powder were also found. The microstructure of the material was very fine and consisted of alpha-Mg dendritic matrix, beta-Mg-41(Nd, Y)(5) intermetallic phase, Y2O3 inclusions, and 0.6 vol.% of residual porosity. The Vickers hardness, compressive yield strength, compressive strength, and maximum compressive strain were 88 HV0.1, 201 MPa, 394 MPa, and 14%, respectively, which are close to the reference values in as-cast. The in vitro corrosion rates determined by immersion and potentiodynamic tests were 2.6 mm/year and 1.3 mm/year, respectively. Cytotoxicity tests indicated good biocompatibility of the 3D-printed alloy.
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    Different Response of Cast and 3D-Printed Co-Cr-Mo Alloy to Heat Treatment: A Thorough Microstructure Characterization
    (MDPI, 2021-04-22) Roudnická, Michaela; Bigas, Jiří; Molnárová, Orsolya; Paloušek, David; Vojtěch, Dalibor
    The Co-Cr-Mo alloy is a biomaterial with very good corrosion resistance and wear resistance; thus, it is widely applied for knee replacements. The wear resistance is influenced by the amount of hcp phase and morphology of carbidic precipitates, which can both be altered by heat treatment. This study compares a conventional knee replacement manufactured by investment casting with a material prepared by the progressive technology of 3D printing. The first set of results shows a different response of both materials in increasing hardness with annealing at increasing temperatures up to the transformation temperature. Based on these results, solution treatment and subsequent aging at conditions to reach the maximum hardness was applied. Microstructural changes were studied thoroughly by means of optical, scanning electron and transmission electron microscopy. While increased hardness in the conventional material is caused by the precipitation of fine hard carbides combined with an increase in the hcp phase by isothermal transformation, a massive fcc -> hcp transformation is the main cause for the hardness increase in the 3D-printed material.
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    Microstructure of Selective Laser Melted Titanium Lattices and In Vitro Cell Behaviour
    (Tanger, 2021-09-15) Hernandez Tapia, Laura Guadalupe; Carranza-Trejo, Azalia Mariel; Kashimbetova, Adelia; Tkachenko, Serhii; Koledová, Zuzana; Koutný, Daniel; Malý, Martin; Čelko, Ladislav; Montufar Jimenez, Edgar Benjamin
    Selective laser melting (SLM) is a metal additive manufacturing technology that allows the fabrication of complex near-net-shape titanium parts. Among possible applications, titanium is important for the biomedical sector, in particular for orthopaedics due to its low elastic modulus, biocompatibility, high mechanical strength and corrosion resistance. Several studies show the structural properties and mechanical behaviour of titanium lattices that in parallel exhibited the porosity, mechanical strength and elastic modulus of trabecular bone. However, less attention has been devoted to study the biological response to titanium parts fabricated by SLM. Therefore, this work aimed to fabricate commercially pure titanium lattices by SLM and study the behaviour of bone-forming cells cultured on the lattices. The results show that Saos-2 osteoblast-like cells proliferated and covered the entire available surface of the titanium lattices becoming confluent and quiescent. The activity of alkaline phosphatase and the production of extracellular calcium deposits confirmed the growth of viable and mature osteoblasts. The cytocompatibility of the titanium lattices is an additional advantage that adds to the possibility to mimic the porosity and mechanical properties of bone by computer-aided design and subsequently implement the lattice fabrication by SLM, fitting the requirements of individual patients and, consequently, offering a broad range of new bone repair alternatives in orthopaedics. Keywords: selective laser melting, titanium, microstructure, osteoblast, cytocompatibility.