Ellendt, Nils
Lade...
Preferred name
Ellendt, Nils
Official Name
Ellendt, Nils
ORCID
GND
3 Ergebnisse
Gerade angezeigt 1 - 3 von 3
- Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Impact of process flow conditions on particle morphology in metal powder production via gas atomizationAdditive manufacturing processes as for instance selective laser melting or electron beam melting are becoming more common and just turning into standard manufacturing processes for metal components. Nevertheless, these processes are still new compared to classic powder metallurgy manufacturing routes such as pressing and sintering. Hence not all necessary requirements for the powders in use are fully known yet. This makes an increase in control of the powder properties a crucial task to achieve. To reach this goal one must understand the different influences on the powder production process from the beginning of the whole production route. In this work, the influence of the spray chamber flow on the particle morphology is examined. The nozzle system used to produce the metal powders is a close-coupled atomization system with a convergent-divergent gas nozzle configuration. The particle morphology as well as the particle size distribution have been analyzed to examine the influence of the atomization gas flow compared to an additional use of a coaxial gas flow. To review the changes of the flow patterns, computational fluid dynamic simulations have been performed. The particle trajectories were calculated to assess the change in particle behavior as well. Atomization experiments have been conducted with an AISI 52100 (1.3505) steel in a small batch atomization plant to evaluate the influence of the change in flow on the particle size distribution and circularity. The experimental results show that a use of additional coaxial gas leads to an increase in particle circularity up to 10% for relevant particle sizes. An approach for the quantification of satellite occurrence is given by examination of the shift of the particle size distribution to smaller diameters.Wissenschaftlicher ArtikelBand:31Heft:182 118 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Schule in Farbigen Zuständen - Lernmodule für den 5. Jahrgang(2022-06-22); ; ; ; Mit dem Ziel, frühzeitig Interesse an Technik und Naturwissenschaften zu fördern, kooperierte der Sonderforschungsbereich SFB 1232 „Farbige Zustände“, Universität Bremen, mit einer Oberschule. Für eine Profilklasse gestalteten Lehrkräfte und Wissenschaftler*innen gemeinsam forschendes Lernen. Die im 5. Jahrgang durchgeführten Unterrichtseinheiten sind hier mit Arbeitsmaterial und Ablaufplänen für Lehrkräfte als Blaupause zusammengefasst.Buch720 257 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, A comparative study of in-situ alloying in laser powder bed fusion for the stainless steel X2CrNiMoN20-10-3(Elsevier Science, 2023-05-22); ; ; ; This paper compares, for the first time, laser powder bed fusion (PBF-LB/M) processing of a powder mixture (PM), also known as in-situ alloying, with that of a pre-alloyed (PA) powder from gas atomization with the same chemical composition, using the example of X2CrNiMoN20–10–3 ferritic-austenitic stainless steel. The focus is on the differences in the microstructure formation mechanisms during PBF-LB/M between PM and PA using different energy inputs, in order to gain new insights into the process transferability of in-situ alloying to the processing of pre-alloyed powders. The microstructure investigations are carried out using electron backscattered diffraction (EBSD), energy dispersive (EDS) as well as wavelength dispersive X-ray spectrometry (WDS), X-ray diffraction (XRD) and magneto-inductive method (Feritscope®). The microstructures of samples produced from PM and PA differ significantly in terms of the resulting ferritic and austenitic phase fractions, so that a ferritic-austenitic microstructure forms for PM, while the PA is predominantly austenitic. The differences are mainly based on the increased chemical inhomogeneities for the PM in comparison to the PA state, which are discussed based on EDS map analysis through spatial statistics. With increasing energy input, the chemical homogeneity of the PM approaches that of the PA, but it cannot reach it even with maximum energy input. The formation of a ferritic-austenitic microstructure in the case of the PM leads to the formation of a finer microstructure compared to single-phase PA steel resulting in higher hardness of PBF-LB/M-built PM.Wissenschaftlicher ArtikelBand:31865 42