TY - CONF
AU - Weiler, David
AU - Burde, Jan-Philipp
AU - Große-Heilmann, Rike Isabel
AU - Lachner, Andreas
AU - Riese, Josef
AU - Schubatzky, Thomas
ID - 45408
T2 - PhyDid B-Didaktik der Physik-Beiträge zur DPG-Frühjahrstagung 2021
TI - Entwicklung eines Seminars zur Förderung des Konzeptverständnisses mittels digitaler Medien
ER -
TY - CHAP
AU - Haghani Fazl, Mohammad
ED - Grössl, Johannes
ED - von Stosch, Klaus
ID - 45436
T2 - Impeccability and Temptation: Understanding Christ's Divine and Human Will
TI - The Scope of ‘iṣma and Qur’anic Evidence
ER -
TY - JOUR
AU - Hein, Maxwell
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 41511
IS - 7
JF - Materialwissenschaft und Werkstofftechnik
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0933-5137
TI - Additively processed TiAl6Nb7 alloy for biomedical applications
VL - 52
ER -
TY - JOUR
AB -
Purpose
The currently existing restrictions regarding the deployment of additively manufactured components because of poor surface roughness, porosity and residual stresses as well as their influence on the low-cycle fatigue (LCF) strength are addressed in this paper.
Design/methodology/approach
This study aims to evaluating the effect of different pre- and post-treatments on the LCF strength of additively manufactured 316L parts. Therefore, 316L specimens manufactured by laser powder bed fusion were examined in their as-built state as well as after grinding, or coating with regard to the surface roughness, residual stresses and LCF strength. To differentiate between topographical effects and residual stress-related phenomena, stress-relieved 316L specimens served as a reference throughout the investigations. To enable an alumina coating of the 316L components, atmospheric plasma spraying was used, and the near-surface residual stresses and the surface roughness are measured and investigated.
Findings
The results have shown that the applied pre- and post-treatments such as stress-relief heat treatment, grinding and alumina coating have each led to an increase in LCF strength of the 316L specimens. In contrast, the non-heat-treated specimens predominantly exhibited coating delamination.
Originality/value
To the best of the authors’ knowledge, this is the first study of the correlation between the LCF behavior of additively manufactured uncoated 316L specimens in comparison with additively manufactured 316L specimens with an alumina coating.
AU - Garthe, Kai-Uwe
AU - Hoyer, Kay-Peter
AU - Hagen, Leif
AU - Tillmann, Wolfgang
AU - Schaper, Mirko
ID - 41507
IS - 5
JF - Rapid Prototyping Journal
KW - Industrial and Manufacturing Engineering
KW - Mechanical Engineering
SN - 1355-2546
TI - Correlation between pre- and post-treatments of additively manufactured 316L parts and the resulting low cycle fatigue behavior
VL - 28
ER -
TY - JOUR
AB - Processing aluminum alloys employing powder bed fusion of metals (PBF-LB/M) is becoming more attractive for the industry, especially if lightweight applications are needed. Unfortunately, high-strength aluminum alloys such as AA7075 are prone to hot cracking during PBF-LB/M, as well as welding. Both a large solidification range promoted by the alloying elements zinc and copper and a high thermal gradient accompanied with the manufacturing process conditions lead to or favor hot cracking. In the present study, a simple method for modifying the powder surface with titanium carbide nanoparticles (NPs) as a nucleating agent is aimed. The effect on the microstructure with different amounts of the nucleating agent is shown. For the aluminum alloy 7075 with 2.5 ma% titanium carbide nanoparticles, manufactured via PBF-LB/M, crack-free samples with a refined microstructure having no discernible melt pool boundaries and columnar grains are observed. After using a two-step ageing heat treatment, ultimate tensile strengths up to 465 MPa and an 8.9% elongation at break are achieved. Furthermore, it is demonstrated that not all nanoparticles used remain in the melt pool during PBF-LB/M.
AU - Heiland, Steffen
AU - Milkereit, Benjamin
AU - Hoyer, Kay-Peter
AU - Zhuravlev, Evgeny
AU - Kessler, Olaf
AU - Schaper, Mirko
ID - 41506
IS - 23
JF - Materials
KW - General Materials Science
SN - 1996-1944
TI - Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts
VL - 14
ER -
TY - JOUR
AB - Implants often overtake body function just for a certain time and remain as an unnecessary foreign body or have to be removed. Thus, resorbable implants are highly beneficial to reduce patient burden. Besides established materials, Iron-(Fe)-based alloys are in focus due to superior mechanical properties and good biocompatibility. However, their degradation rate needs to be increased. Phases with high electrochemical potential could promote the dissolution of residual material based on the galvanic coupling. Silver (Ag) is promising due to its high electrochemical potential (+0.8 V vs. SHE), immiscibility with Fe, biocompatibility, and anti-bacterial properties. But to prevent adverse consequences the Ag-particles, remaining after dissolution of the matrix, need to dissolve. Thus, a bioresorbable Ag-alloy is required. Regarding the electrochemical potential and degradation behavior of binary alloys, Cerium (Ce) and Lanthanum (La) are well-suited considering their biocompatibility and antibacterial behavior. Accordingly, this research addresses AgCe and AgCeLa alloys as additives for Fe-based materials with adapted degradation behavior. Furthermore, degradable Ag-alloys combined with inert implant materials could enable the controlled release of antibacterial active Ag-ions.
AU - Krüger, Jan Tobias
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 24790
JF - Materials Letters
SN - 0167-577X
TI - Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants
VL - 306
ER -
TY - JOUR
AU - Tillmann, Wolfgang
AU - Lopes Dias, Nelson Filipe
AU - Franke, Carlo
AU - Kokalj, David
AU - Stangier, Dominic
AU - Filor, Viviane
AU - Mateus-Vargas, Rafael Hernán
AU - Oltmanns, Hilke
AU - Kietzmann, Manfred
AU - Meißner, Jessica
AU - Hein, Maxwell
AU - Pramanik, Sudipta
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
AU - Nienhaus, Alexander
AU - Thomann, Carl Arne
AU - Debus, Jörg
ID - 41516
JF - Surface and Coatings Technology
KW - Materials Chemistry
KW - Surfaces
KW - Coatings and Films
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Chemistry
SN - 0257-8972
TI - Tribo-mechanical properties and biocompatibility of Ag-containing amorphous carbon films deposited onto Ti6Al4V
VL - 421
ER -
TY - JOUR
AU - Andreiev, Anatolii
AU - Hoyer, Kay-Peter
AU - Dula, Dimitri
AU - Hengsbach, Florian
AU - Grydin, Olexandr
AU - Frolov, Yaroslav
AU - Schaper, Mirko
ID - 41512
JF - Materials Science and Engineering: A
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0921-5093
TI - Laser beam melting of functionally graded materials with application-adapted tailoring of magnetic and mechanical performance
VL - 822
ER -
TY - JOUR
AU - Pramanik, Sudipta
AU - Andreiev, Anatolii
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 41510
JF - International Journal of Fatigue
KW - Industrial and Manufacturing Engineering
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
KW - Modeling and Simulation
SN - 0142-1123
TI - Quasi in-situ analysis of fracture path during cyclic loading of double-edged U notched additively manufactured FeCo alloy
VL - 153
ER -
TY - JOUR
AU - Krüger, Jan Tobias
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 41509
JF - Materials Letters
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0167-577X
TI - Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants
VL - 306
ER -
TY - JOUR
AU - Andreiev, Anatolii
AU - Hoyer, Kay-Peter
AU - Dula, Dimitri
AU - Hengsbach, Florian
AU - Haase, Michael
AU - Gierse, Jan
AU - Zimmer, Detmar
AU - Tröster, Thomas
AU - Schaper, Mirko
ID - 23898
JF - Journal of Materials Processing Technology
SN - 0924-0136
TI - Soft-magnetic behavior of laser beam melted FeSi3 alloy with graded cross-section
ER -
TY - JOUR
AB - AbstractWithin this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$
⟨
001$$\rangle$$
⟩
||TD, $$\langle$$
⟨
011$$\rangle$$
⟩
||TD are hard orientations and $$\langle$$
⟨
111$$\rangle$$
⟩
||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$
⟨
111$$\rangle$$
⟩
is the most active slip system, and {112}$$\langle$$
⟨
111$$\rangle$$
⟩
is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior.
AU - Pramanik, Sudipta
AU - Tasche, Lennart
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 41517
IS - 11
JF - Journal of Materials Engineering and Performance
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 1059-9495
TI - Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy
VL - 30
ER -
TY - JOUR
AB - The addition of Ag to amorphous carbon (a-C) films is highly effective in tailoring the tribo-mechanical properties and biocompatibility. For biomedical applications, Ag-containing a-C (a-C:Ag) represents a promising film material for improving the biofunctional surface properties of Ti-based alloys. In a sputtering process, a-C:Ag films, with Ag contents up to 7.5 at.%, were deposited with a chemically graded TixCy interlayer onto Ti6Al4V. The tribo-mechanical and biocompatible properties of a-C:Ag were evaluated. The influence of the Ag content on these properties was analyzed and compared to those of uncoated Ti6Al4V.
Raman spectroscopy reveals that the amount of incorporated Ag does not induce significant structural changes in the disordered network, only a reduced number of vacancies and sp3-coordinated C bonds within the sp2-dominant a-C network is assigned to the films with high Ag concentration. With increasing Ag content, stresses, hardness, and elastic modulus decrease from (2.02 ± 0.07) to (1.15 ± 0.03) GPa, from (17.4 ± 1.5) to (13.4 ± 0.9) GPa, and from (171.8 ± 8.1) to (138.5 ± 5.8) GPa, respectively. In tribometer tests, the friction behavior against Al2O3 in lubricated condition with a simulated-body-fluid-based lubricant is not affected by the Ag concentration, but the Al2O3 counterpart wear is reduced for all a-C:Ag films compared to a-C. The friction against ultra-high-molecular-weight polyethylene (UHMWPE) decreases continuously with increasing Ag concentration and the counterpart wear is lower at higher Ag contents. Compared to a-C:Ag, Ti6Al4V demonstrates lower friction against UHMWPE and higher friction against Al2O3. The a-C:Ag films are not exposed to abrasion by Al2O3 or pronounced material transfer of UHMWPE. The hardness difference and chemical affinity between the friction partners are decisive for the tribological behavior of a-C:Ag. Compared to Ti6Al4V, the a-C:Ag films show antibacterial activity against Staphylococcus aureus, while the proliferation of osteoblast-like cells is reduced by Ag.
AU - Tillmann, Wolfgang
AU - Lopes Dias, Nelson Filipe
AU - Franke, Carlo
AU - Kokalj, David
AU - Stangier, Dominic
AU - Filor, Viviane
AU - Mateus-Vargas, Rafael Hernán
AU - Oltmanns, Hilke
AU - Kietzmann, Manfred
AU - Meißner, Jessica
AU - Hein, Maxwell
AU - Pramanik, Sudipta
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
AU - Nienhaus, Alexander
AU - Thomann, Carl Arne
AU - Debus, Jörg
ID - 24243
JF - Surface and Coatings Technology
SN - 0257-8972
TI - Tribo-mechanical properties and biocompatibility of Ag-containing amorphous carbon films deposited onto Ti6Al4V
ER -
TY - JOUR
AB - Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al5Fe2, monoclinic Al13Fe4 and cubic Al19Fe4MnSi2. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium.
AU - Křivská, Barbora
AU - Šlapáková, Michaela
AU - Veselý, Jozef
AU - Kihoulou, Martin
AU - Fekete, Klaudia
AU - Minárik, Peter
AU - Králík, Rostislav
AU - Grydin, Olexandr
AU - Stolbchenko, Mykhailo
AU - Schaper, Mirko
ID - 29815
IS - 24
JF - Materials
KW - General Materials Science
SN - 1996-1944
TI - Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet
VL - 14
ER -
TY - JOUR
AB - Laser beam melting (LBM) is an advanced manufacturing technology providing
special features and the possibility to produce complex and individual parts directly
from a CAD model. TiAl6V4 is the most common used titanium alloy particularly
in biomedical applications. TiAl6Nb7 shows promising improvements especially
regarding biocompatible properties due to the substitution of the hazardous
vanadium. This work focuses on the examination of laser beam melted TiAl6Nb7.
For microstructural investigation scanning electron microscopy including energydispersive
x-ray spectroscopy as well as electron backscatter diffraction are utilized.
The laser beam melted related acicular microstructure as well as the corresponding
mechanical properties, which are determined by hardness measurements
and tensile tests, are investigated. The laser beam melted alloy meets,
except of breaking elongation A, the mechanical demands like ultimate tensile
strength Rm, yield strength Rp0.2, Vickers hardness HV of international standard
ISO 5832-11. Next steps contain comparison between TiAl6Nb7 and TiAl6V4 in
different conditions. Further investigations aim at improving mechanical properties
of TiAl6Nb7 by heat treatments and assessment of their influence on the microstructure
as well as examination regarding the corrosive behavior in human bodylike
conditions.
AU - Hein, Maxwell
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 24086
JF - Materialwissenschaft und Werkstofftechnik
KW - Laser beam melting
KW - titanium alloy
KW - TiAl6Nb7
KW - biomedical engineering
KW - implants
SN - 0933-5137
TI - Additively processed TiAl6Nb7 alloy for biomedical applications
VL - 52
ER -
TY - JOUR
AU - Cieslar, Miroslav
AU - Králík, Rostislav
AU - Bajtošová, Lucia
AU - Křivská, Barbora
AU - Hájek, Michal
AU - Belejová, Sára
AU - Grydin, Olexandr
AU - Stolbchenko, Mykhailo
AU - Schaper, Mirko
ID - 29813
IS - S2
JF - Microscopy and Microanalysis
KW - Instrumentation
SN - 1431-9276
TI - High Temperature Annealing of Twin-Roll Cast Al-Li-Based Alloy Studied by In-situ SEM and STEM
VL - 27
ER -
TY - JOUR
AU - Krüger, Jan Tobias
AU - Hoyer, Kay-Peter
AU - Filor, Viviane
AU - Pramanik, Sudipta
AU - Kietzmann, Manfred
AU - Meißner, Jessica
AU - Schaper, Mirko
ID - 41514
JF - Journal of Alloys and Compounds
KW - Materials Chemistry
KW - Metals and Alloys
KW - Mechanical Engineering
KW - Mechanics of Materials
SN - 0925-8388
TI - Novel AgCa and AgCaLa alloys for Fe-based bioresorbable implants with adapted degradation
VL - 871
ER -
TY - JOUR
AU - Křivská, Barbora
AU - Šlapáková, Michaela
AU - Minárik, Peter
AU - Fekete, Klaudia
AU - Králík, Rostislav
AU - Stolbchenko, Mykhailo
AU - Schaper, Mirko
AU - Grydin, Olexandr
ID - 29814
IS - S2
JF - Microscopy and Microanalysis
KW - Instrumentation
SN - 1431-9276
TI - Intermetallic Phase Growth in Al-steel Clad Strip during In-situ Heating in TEM
VL - 27
ER -
TY - JOUR
AU - Pramanik, Sudipta
AU - Tasche, Lennart
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 41515
JF - Additive Manufacturing
KW - Industrial and Manufacturing Engineering
KW - Engineering (miscellaneous)
KW - General Materials Science
KW - Biomedical Engineering
SN - 2214-8604
TI - Investigating the microstructure of an additively manufactured FeCo alloy: an electron microscopy study
VL - 46
ER -
TY - JOUR
AU - Camberg, Alan Adam
AU - Andreiev, Anatolii
AU - Pramanik, Sudipta
AU - Hoyer, Kay-Peter
AU - Tröster, Thomas
AU - Schaper, Mirko
ID - 27700
JF - Materials Science and Engineering: A
SN - 0921-5093
TI - Strength enhancement of AlMg sheet metal parts by rapid heating and subsequent cold die stamping of severely cold-rolled blanks
ER -
TY - JOUR
AB - AbstractWithin this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$
⟨
001$$\rangle$$
⟩
||TD, $$\langle$$
⟨
011$$\rangle$$
⟩
||TD are hard orientations and $$\langle$$
⟨
111$$\rangle$$
⟩
||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$
⟨
111$$\rangle$$
⟩
is the most active slip system, and {112}$$\langle$$
⟨
111$$\rangle$$
⟩
is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior.
AU - Pramanik, Sudipta
AU - Tasche, Lennart
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 24090
JF - Journal of Materials Engineering and Performance
SN - 1059-9495
TI - Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy
ER -
TY - JOUR
AB -
Purpose
The currently existing restrictions regarding the deployment of additively manufactured components because of poor surface roughness, porosity and residual stresses as well as their influence on the low-cycle fatigue (LCF) strength are addressed in this paper.
Design/methodology/approach
This study aims to evaluating the effect of different pre- and post-treatments on the LCF strength of additively manufactured 316L parts. Therefore, 316L specimens manufactured by laser powder bed fusion were examined in their as-built state as well as after grinding, or coating with regard to the surface roughness, residual stresses and LCF strength. To differentiate between topographical effects and residual stress-related phenomena, stress-relieved 316L specimens served as a reference throughout the investigations. To enable an alumina coating of the 316L components, atmospheric plasma spraying was used, and the near-surface residual stresses and the surface roughness are measured and investigated.
Findings
The results have shown that the applied pre- and post-treatments such as stress-relief heat treatment, grinding and alumina coating have each led to an increase in LCF strength of the 316L specimens. In contrast, the non-heat-treated specimens predominantly exhibited coating delamination.
Originality/value
To the best of the authors’ knowledge, this is the first study of the correlation between the LCF behavior of additively manufactured uncoated 316L specimens in comparison with additively manufactured 316L specimens with an alumina coating.
AU - Garthe, Kai-Uwe
AU - Hoyer, Kay-Peter
AU - Hagen, Leif
AU - Tillmann, Wolfgang
AU - Schaper, Mirko
ID - 27509
JF - Rapid Prototyping Journal
SN - 1355-2546
TI - Correlation between pre- and post-treatments of additively manufactured 316L parts and the resulting low cycle fatigue behavior
ER -
TY - JOUR
AB - Resorbable implants are highly beneficial to reduce patient burden since they need not be removed after a defined period. Currently, magnesium (Mg) and polymers are being applied as bioresorbable materials. However, for some applications the insufficient mechanical properties and high degradation rate of Mg cause the need for new materials. Iron (Fe)-based alloys are promising due to their biocompatibility and good mechanical properties, but their degradation rate is too low and needs to be adapted eg. via alloying with manganese (Mn). Besides, phases with high electrochemical potential lead to increased degradation of residual material with lower potential based on the galvanic coupling. Here, silver (Ag) is promising for the formation of such phases due to its high electrochemical potential (+0.8 V vs. SHE), immiscibility with Fe, biocompatibility, and anti-bacterial properties. Since remaining silver particles can lead to adverse consequences as thrombosis, these particles need to dissolve after the matrix material. Thus a silver alloy with high electrochemical potential, biocompatibility, and adjusted degradation behavior is required as an additive for iron-based bioresorbable materials. Several silver alloying systems are possible, but regarding the electrochemical potential and degradation behavior of binary alloys, calcium (Ca) and lanthanum (La) are best-suited considering their biocompatibility. Accordingly, this research addresses AgCa and AgCaLa alloys as additives for iron-based degradable materials with adapted degradation behavior.
AU - Krüger, Jan Tobias
AU - Hoyer, Kay-Peter
AU - Filor, Viviane
AU - Pramanik, Sudipta
AU - Kietzmann, Manfred
AU - Meißner, Jessica
AU - Schaper, Mirko
ID - 24087
JF - Journal of Alloys and Compounds
SN - 0925-8388
TI - Novel AgCa and AgCaLa alloys for Fe-based bioresorbable implants with adapted degradation
ER -
TY - JOUR
AB - Implementing the concept of mixed construction in modern automotive engineering requires the joining of sheet metal or extruded profiles with cast components made from different materials. As weight reduction is desired, these cast components are usually made from high-strength aluminium alloys of the Al-Si (Mn, Mg) system, which have limited weldability. The mechanical joinability of the cast components depends on their ductility, which is influenced by the microstructure. High-strength cast aluminium alloys have relatively low ductility, which leads to cracking of the joints. This limits the range of applications for cast aluminium alloys. In this study, an aluminium alloy of the Al-Si system AlSi9 is used to investigate relationships between solidification conditions during the sand casting process, microstructure, mechanical properties, and joinability. The demonstrator is a stepped plate with a minimum thickness of 2.0 mm and a maximum thickness of 4.0 mm, whereas the thickness difference between neighbour steps amounts to 0.5 mm. During casting trials, the solidification rates for different plate steps were measured. The microscopic investigations reveal a correlation between solidification rates and microstructure parameters such as secondary dendrite arm spacing. Furthermore, mechanical properties and the mechanical joinability are investigated.
AU - Neuser, Moritz
AU - Grydin, Olexandr
AU - Andreiev, Anatolii
AU - Schaper, Mirko
ID - 23913
JF - Metals
SN - 2075-4701
TI - Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy
ER -
TY - JOUR
AB - AbstractLaser surface treatment of metals is one option to improve their properties for adhesive bonding. In this paper, a pulsed YVO4 Laser source with a wavelength of 1064 nm and a maximum power of 25 W was utilized to increase the surface area of the steel HCT490X in order to improve its bonding properties with a carbon fibre reinforced polymer (CFRP). Investigated was the influence of the scanning speed of the laser source on the bonding properties. For this purpose, the steel surfaces were ablated at a scanning speed between 1500 and 4500 mm/s. Afterwards the components were bonded with the adhesive HexBond™ 677. After lap shear tests were carried out on the specimen, the surfaces were inspected using scanning electron microscopy (SEM). The experiments revealed that the bonding quality can be improved with a high scanning speed, even when the surface is not completely ablated.
AU - Voswinkel, Dietrich
AU - Kloidt, D.
AU - Grydin, Olexandr
AU - Schaper, Mirko
ID - 24565
IS - 2
JF - Production Engineering
SN - 0944-6524
TI - Time efficient laser modification of steel surfaces for advanced bonding in hybrid materials
VL - 15
ER -
TY - JOUR
AU - Engelkemeier, Katja
AU - Sun, Aijia
AU - Voswinkel, Dietrich
AU - Grydin, Olexandr
AU - Schaper, Mirko
AU - Bremser, Wolfgang
ID - 24566
JF - ChemElectroChem
SN - 2196-0216
TI - Zinc Anodizing: Structural Diversity of Anodic Zinc Oxide Controlled by the Type of Electrolyte
ER -
TY - JOUR
AU - Andreiev, Anatolii
AU - Hoyer, Kay-Peter
AU - Dula, Dimitri
AU - Hengsbach, Florian
AU - Grydin, Olexandr
AU - Frolov, Yaroslav
AU - Schaper, Mirko
ID - 23897
JF - Materials Science and Engineering: A
SN - 0921-5093
TI - Laser beam melting of functionally graded materials with application-adapted tailoring of magnetic and mechanical performance
ER -
TY - JOUR
AU - Pramanik, Sudipta
AU - Andreiev, Anatolii
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 23911
JF - International Journal of Fatigue
SN - 0142-1123
TI - Quasi in-situ analysis of fracture path during cyclic loading of double-edged U notched additively manufactured FeCo alloy
ER -
TY - JOUR
AU - Pramanik, Sudipta
AU - Tasche, Lennart
AU - Hoyer, Kay-Peter
AU - Schaper, Mirko
ID - 24088
JF - Additive Manufacturing
SN - 2214-8604
TI - Investigating the microstructure of an additively manufactured FeCo alloy: an electron microscopy study
ER -
TY - JOUR
AU - Reitz, Alexander
AU - Grydin, Olexandr
AU - Schaper, Mirko
ID - 23803
JF - Materials Data for Smart Forming Technologies
TI - Characterization of phase transformations during graded thermo- mechanical treatment of steel 22MnB5 by means of optical methods
ER -
TY - JOUR
AU - Wallmeier, Nadine
ID - 37239
JF - Kreis Höxter Jahrbuch
TI - Plattdeutsch im Kreis Höxter. "Der Dialektatlas Mittleres Westdeutschland (DMW)" und die Frage "Wie klingt Plattdeutsch im Kreis Höxter?"
ER -
TY - BOOK
AU - Tophinke, Doris
AU - Wallmeier, Nadine
AU - Merten, Marie-Luis
ID - 22515
TI - Das paderbörnische Platt. Niederdeutsch im Gebiet der Kreise Paderborn und Höxter
ER -
TY - CONF
AU - Mutschler, Tanja
AU - Buschhüter, David
AU - Schröder, Jan
AU - Riese, Josef
AU - Borowski, Andreas
ED - Habig, Sebastian
ID - 45449
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020
TI - Theoriekonformität von Unterrichtsplanungen im Fach Physik vor und nach dem Praxissemester
VL - 41
ER -
TY - CONF
AU - Große-Heilmann, Rike Isabel
AU - Riese, Josef
ED - Habig, Sebastian
ID - 45461
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020. Essen: Universität Duisburg-Essen
TI - Erwerb physikdidaktischen Wissens zum Einsatz digitaler Medien im Physikunterricht
VL - 41
ER -
TY - CONF
AU - Joswig-Käfer, Ann-Kathrin
AU - Riese, Josef
ED - Habig, Sebastian
ID - 45460
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020. Essen: Universität Duisburg-Essen
TI - Längsschnitt Physikdidaktischen Wissens: Ursachen für Veränderungen
VL - 41
ER -
TY - CONF
AU - Ermel, Dorothee
AU - Riese, Josef
ED - Habig, Sebastian
ID - 45463
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020. Essen: Universität Duisburg-Essen
TI - Praktische technische Kompetenzen im Techniklehramt
VL - 41
ER -
TY - CONF
AU - Albert, Gerrit
AU - Riese, Josef
ED - Habig, Sebastian
ID - 45462
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020. Essen: Universität Duisburg-Essen
TI - Digitale Kompetenzen im Techniklehramt
VL - 41
ER -
TY - CONF
AU - Schröder, Jan
AU - Vogelsang, Christoph
AU - Riese, Josef
ID - 45450
T2 - Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch? Gesellschaft für Didaktik der Chemie und Physik. Online Jahrestagung 2020
TI - Entwicklung der Fähigkeit zur Unterrichtsplanung im Fach Physik
VL - 41
ER -
TY - JOUR
AU - Masendorf, Lukas
AU - Wächter, Michael
AU - Esderts, Alfons
AU - Otroshi, Mortaza
AU - Meschut, Gerson
ID - 21545
JF - Fatigue & Fracture of Engineering Materials & Structures
SN - 8756-758X
TI - Service life estimation of self‐piercing riveted joints by linear damage accumulation
ER -
TY - JOUR
AB - We consider a measure given as the continuum limit of a one-dimensional Ising model with long-range translationally invariant interactions. Mathematically, the measure can be described by a self-interacting Poisson driven jump process. We prove a correlation inequality, estimating the magnetic susceptibility of this model, which holds for small norm of the interaction function. The bound on the magnetic susceptibility has applications in quantum field theory and can be used to prove existence of ground states for the spin boson model.
AU - Hasler, David
AU - Hinrichs, Benjamin
AU - Siebert, Oliver
ID - 43493
JF - Stochastic Processes and their Applications
SN - 0304-4149
TI - Correlation bound for a one-dimensional continuous long-range Ising model
VL - 146
ER -
TY - CONF
AU - Schubert, Philipp
AU - Hermann, Ben
AU - Bodden, Eric
AU - Leer, Richard
ID - 26406
T2 - SCAM '21: IEEE International Working Conference on Source Code Analysis and Manipulation (Engineering Track)
TI - Into the Woods: Experiences from Building a Dataflow Analysis Framework for C/C++
ER -
TY - CONF
AU - Schubert, Philipp
AU - Sattler, Florian
AU - Schiebel, Fabian
AU - Hermann, Ben
AU - Bodden, Eric
ID - 26405
T2 - 2021 IEEE 21st International Working Conference on Source Code Analysis and Manipulation (SCAM)
TI - Modeling the Effects of Global Variables in Data-Flow Analysis for C/C++
ER -
TY - CONF
AB - We present a monolithically integrated electronic-photonic Mach-Zehnder modulator with a linear, segmented driver on the same silicon substrate. As metric for the modulation efficiency, the external V$\pi$ is hereby reduced to only 420 mV.
AU - Kress, Christian
AU - Singh, Karanveer
AU - Schwabe, Tobias
AU - Preußler, Stefan
AU - Schneider, Thomas
AU - Scheytt, J. Christoph
ID - 29203
KW - Analog to digital converters
KW - Extinction ratios
KW - Grating couplers
KW - Modulation
KW - Modulators
KW - Phase shift
T2 - OSA Advanced Photonics Congress 2021
TI - High Modulation Efficiency Segmented Mach-Zehnder Modulator Monolithically Integrated with Linear Driver in 0.25 \textmum BiCMOS Technology
ER -
TY - JOUR
AB - An analysis of an optical Nyquist pulse synthesizer using Mach-Zehnder modulators is presented. The analysis allows to predict the upper limit of the effective number of bits of this type of photonic digital-to-analog converter. The analytical solution has been verified by means of electro-optic simulations. With this analysis the limiting factor for certain scenarios: relative intensity noise, distortions by driving the Mach-Zehnder modulator, or the signal generator phase noise can quickly be identified.
AU - Kress, Christian
AU - Bahmanian, Meysam
AU - Schwabe, Tobias
AU - Scheytt, J. Christoph
ID - 29204
IS - 15
JF - Opt. Express
KW - Analog to digital converters
KW - Diode lasers
KW - Laser sources
KW - Phase noise
KW - Signal processing
KW - Wavelength division multiplexers
TI - Analysis of the effects of jitter, relative intensity noise, and nonlinearity on a photonic digital-to-analog converter based on optical Nyquist pulse synthesis
VL - 29
ER -
TY - THES
AU - Fanasch, Patrizia
ID - 45670
TI - Governance and Reputation in the Market for Experience Goods
ER -
TY - JOUR
AB - The role of domain-specific content knowledge is discussed controversially for the early childhood context. Therefore, this review aims at untangling the research on domain-specific content knowledge for early childhood educators by systematically reviewing the conceptual and operational definition of and results on early childhood educators' content knowledge in different domains. Using the scientific databases ERIC, PsycInfo and Web of Sciences, we identified 36 studies on early childhood educators' domain-specific content knowledge. By comparing these studies, we found that conceptualizations of early childhood educators' content knowledge move on a continuum between a scientific related perspective and a practice related perspective. The scientific related perspective defines content knowledge as the knowledge of key concepts, facts and rules of the domain integrating knowledge taught in primary, secondary or upper secondary school. The practice related perspective includes knowledge of key concepts, facts and rules of the domain limited to the knowledge explicitly relevant for teaching in early childhood education as well as selected domain-specific knowledge of children and teaching. Our review shows that the results and implications drawn by the study authors depend on how these authors conceptualize early childhood educators' content knowledge on this continuum. Further research, therefore, needs to consider carefully how early childhood educators' content knowledge is conceptualized. The paper further discusses gaps in this research field, such as validating methods for measuring early childhood educators' content knowledge or implementing more rigorous experimental designs to examine effects of early childhood educators' content knowledge.
AU - Bruns, Julia
AU - Gasteiger, Hedwig
AU - Strahl, Carolin
ID - 34822
IS - 2
JF - Review of Education
KW - content knowledge
KW - domain-specific learning
KW - early childhood education
KW - teacher knowledge
SN - 2049-6613
TI - Conceptualising and measuring domain-specific content knowledge of early childhood educators: A systematic review
VL - 9
ER -
TY - JOUR
AU - Bruns, Julia
AU - Schopferer, T.
ID - 45687
JF - . TPS – Theorie und Praxis der Sozialpädagogik
TI - Eine mustergültige Wissenschaft
VL - 11
ER -
TY - CONF
AU - Jensen, Solveig
AU - Gasteiger, Hedwig
AU - Bruns, Julia
ED - Inprasitha, Maitree
ED - Changsri, Narumon
ED - Boonsena, Nisakorn
ID - 36527
T2 - Proceedings of the 44th Conference of the International Group for the Psychology of Mathematics Education
TI - Place value and regrouping as seperate constructs of place value understanding
VL - 3
ER -
TY - JOUR
AU - Bruns, Julia
AU - Gasteiger, Hedwig
AU - Strahl, Carolin
ID - 34823
IS - 2
JF - Review of Education
SN - 2049-6613
TI - Context and Implications Document for: Conceptualising and measuring domain-specific content knowledge of early childhood educators: A systematic review
VL - 9
ER -
TY - CONF
AU - Jensen, Solveig
AU - Gasteiger, Hedwig
AU - Bruns, Julia
ID - 36536
T2 - Beiträge zum Mathematikunterricht 2021
TI - Stellenwertverständnis: Verständnis von Stellenwertprinzip und Bündelungsprinzip als separate Konstrukte
ER -