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29 results on '"Sehrt, Jan T."'

10. Influence of silver nanoparticle additivation on Nd-Fe-B permanent magnets produced by Laser Powder Bed Fusion

Author

Gabriel, Philipp, primary, Liu, Jianing, additional, Staab, Franziska, additional, Oyedeji, Timileyin David, additional, Yang, Yangyiwei, additional, Hantke, Nick, additional, Scheibel, Franziska, additional, Adabifiroozjaei, Esmaeil, additional, Recalde-Benitez, Oscar, additional, Molina-Luna, Leopoldo, additional, Rao, Ziyuan, additional, Gault, Baptiste, additional, Sehrt, Jan T., additional, Skokov, Konstantin, additional, Xu, Bai-Xiang, additional, Durst, Karsten, additional, Gutfleisch, Oliver, additional, Barcikowski, Stephan, additional, and Ziefuß, Anna Rosa, additional

Published
2023
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17. Improved Process Efficiency in Laser-Based Powder Bed Fusion of Nanoparticle Coated Maraging Tool Steel Powder

Author

Pannitz, Oliver (M.Sc.), Großwendt, Felix, Lüddecke, Arne (M.Sc.), Kwade, Arno (Prof. Dr.-Ing.), Röttger, Arne (Prof. Dr.-Ing.), and Sehrt, Jan T.

Subjects
Technology, Microscopy, QC120-168.85, nanocomposite, microstructure, QH201-278.5, mechanical properties, Engineering (General). Civil engineering (General), PBF-LB/M, tool steel (1.2709), Article, TK1-9971, Descriptive and experimental mechanics, Electrical engineering. Electronics. Nuclear engineering, TA1-2040, additive manufacturing
Abstract

Research and development in the field of metal-based additive manufacturing are advancing steadily every year. In order to increase the efficiency of powder bed fusion of metals using a laser beam system (PBF LB/M), machine manufacturers have implemented extensive optimizations with regard to the laser systems and build volumes. However, the optimization of metallic powder materials using nanoparticle additives enables an additional improvement of the laser–material interaction. In this work, tool steel 1.2709 powder was coated with silicon carbide (SiC), few-layer graphene (FLG), and iron oxide black (IOB) on a nanometer scale. Subsequently, the feedstock material and the modified powder materials were analyzed concerning the reflectance of the laser radiation and processed by PBF-LB/M in a systematic and consistent procedure to evaluate the impact of the nano-additivation on the process efficiency and mechanical properties. As a result, an increased build rate is achieved, exhibiting a relative density of 99.9% for FLG/1.2709 due to a decreased reflectance of this modified powder material. Furthermore, FLG/1.2709 provides hardness values after precipitation hardening with only aging comparable to the original 1.2709 material and is higher than the SiC- and IOB-coated material. Additionally, the IOB coating tends to promote oxide-formation and lack-of-fusion defects.

Published
2021

18. The Development of a Novel Peristaltic Test Stand “Swallow-Sim” for the Mechanical Evaluation of Esophageal Stents

Author

Berger, Daniel Michael, Sehrt, Jan T., Brinkmann, Thomas, Henrichs, Niclas Norman, Bilec, Oguzhan, Fuchs, Karl-Hermann, and Meining, Alexander

Abstract

The development of medical products begins with the “in silico” phase, where the development and simulation of new stent types are carried out. This is followed by the “in vitro” phase. Here, tests are done in a test stand to obtain initial conclusions about the interaction of the environment. The approval process is completed in the “in vivo” phase, where testing in living beings happen. Here, preclinical studies are carried out in animals first, followed by clinical studies on patients. A big part of the development fails in this final phase, as this is where the interactions of all influences from the stent environment are investigated. Since this not only causes high costs for the developers but also unnecessarily destroys living resources in animal studies, this publication describes the development of a test stand called “Swallow-Sim” that superimposes the mechanical influences of the esophagus, the chemical stress caused by hydrochloric acid and increased body temperature. Furthermore, tests of the acting pressures are carried out using esophageal manometry, a temperature test of the test stand and a test run of the gastric juice. At the end of this publication, the results are evaluated with a six-week test of a Nickel Titanium Naval Ordnance Laboratory stent, which loses much of its mechanical properties and is partially destroyed by the load. The results show a clear correlation with the findings from reality. The test stand should be further optimized and examined in more detail in further tests and subjected to a reality check.

Published
2024
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24. Static Strength Analysis of Beam Melted Parts Dependent on Various Elements

Author

Witt, Gerd and Sehrt, Jan T.

Subjects
static strength, material properties, beam melted parts, surface finish
Abstract

For the optimum design and correct use of beam melted parts extensive material comprehension is necessary. For this reason this paper presents static strength analysis of beam melted parts dependent on various influences such as manufacturing position and orientation, exposure strategy and surface quality. It turned out that the anisotropic material properties can be described by the transversal isotropy (2D) since the azimuth angle displays small dependence especially in combination with the rotate scan strategy. In contrast to this the polar angle has the biggest influence at all exposure strategies. Another great influence arises from the surface finish - the better the surface finish the higher the static strength. The exposure strategies in turn have the smallest effect on the static strength.

Published
2010
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29. Boosting Coercivity of 3D Printed Hard Magnets through Nano-Modification of the Powder Feedstock.

Author

Gabriel P, Nallathambi V, Liu J, Staab F, Oyedeji TD, Yang Y, Hantke N, Adabifiroozjaei E, Recalde-Benitez O, Molina-Luna L, Rao Z, Gault B, Sehrt JT, Scheibel F, Skokov K, Xu BX, Durst K, Gutfleisch O, Barcikowski S, and Ziefuss AR

Abstract

The demand for strong, compact permanent magnets essential for the energy transition drives innovation in magnet manufacturing. Additive manufacturing, particularly Powder Bed Fusion of metals using a laser beam (PBF-LB/M), offers potential for near-net-shaped Nd-Fe-B permanent magnets but often falls short compared to conventional methods. A less explored strategy to enhance these magnets is feedstock modification with nanoparticles. It is demonstrated that modifying a Nd-Fe-B-based feedstock with 1 wt.% Ag nanoparticles boost the coercivity of the magnets to a record value of 935 ± 6 kA m -1 without further post-processing or heat treatments. Suitable volumetric energy densities for the PBF-LB/M process are determined using finite element simulations predicting melt pool behavior and part density. Microstructural analyses reveal finer grain sizes and more equiaxed nanocrystalline structures due to the modification. Atom probe tomography identifies three phases in the Ag-modified samples, with Ag forming nanophase regions with rare-earth elements near the amorphous Zr-Ti-B-rich intergranular phase, potentially decoupling the Nd 2 Fe 14 B primary phase. The study shows that superior magnetic properties primarily result from microstructure modification rather than part density. These findings highlight inventive material design approaches via feedstock surface modification to achieve superior magnetic performance in additively manufactured Nd-Fe-B magnets., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Published
2024
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