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Dissimilar micro beam welding of titanium to Nitinol and stainless steel using biocompatible filler materials for medical applications
(2022-11-16)
In the present investigation, thin sheet geometries of commercially pure titanium (cp, grade 4) are butt-welded to AISI 316L stainless steel as well as Nitinol by means of micro electron beam welding using filler materials. In order to avoid mixing of the base materials, the refractory metals tantalum, niobium and hafnium are applied as intermediate layers. Owing to the biocompatibility of these filler materials, the final products are suitable for medical technology applications. In combination with low energy inputs ...
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Verbesserung der CO₂-Bilanz von Kalksandsteinen durch den Einsatz von Sägeschlamm als Optimierungszuschlag
(2023-12-06)
Rund 20% der aus den Rohstoffen Kalk, Sand und Wasser hergestellten Kalksandsteine (KS) in KS-XL-Formaten werden zur Vorkonfektionierung gesägt. Dabei fallen in den KS-Werken insgesamt rd. 20.000 t Sägeschlämme pro Jahr an, die derzeit keiner gezielten Verwendung zugeführt werden. Allerdings handelt es sich dabei bereits unter Einsatz von CO₂-intensivem Branntkalk gehärtetes Material, welches als Optimierungszusatz genutzt werden kann.
Insgesamt 13 verschiedene Sägeschlämme (SäS) wurden hinsichtlich ihrer Eignung ...
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Spatially resolved in situ analyses of the adsorption behavior of different admixtures on binders
(2023-12-06)
Admixtures play a key role in improving the performance of the cement paste matrix. A more efficient matrix can allow a reduction the binder content while maintaining the same properties. There is currently a lack of knowledge about the spatial distribution of admixtures in situ on binder surfaces which would facilitate the use of admixtures in general in inorganic binder systems. Imaging techniques such as confocal laser scanning microscopy (CLSM) and fluorescence microscopy can be used to study the spatiotemporal ...
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Mechanically induced dye-release from polyurea microcapsules in a rubbery adhesive
(2023-07-13)
Especially in the building industry the demand for in situ monitoring concepts of adhesive joints persists. In a new approach, microcapsules filled with special dyes, are added into a rubbery adhesive. Certain stress levels within the adhesive lead to a breakage of the capsules, which release their liquid cores. This results in a detectable colour change and thus, enables non-destructive condition monitoring of the bond. Dye-filled polyurea microcapsules were produced by interfacial polymerization by varying synthesis ...
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High-Strength Dissimilar Welds Between a NiTi Shape Memory Alloy and Titanium Obtained by Intermixing Niobium Using Pulsed Laser Beam Welding
(2023-11-17)
Joining of NiTi shape memory alloys with commercially pure titanium (Ti) is of great interest for manifold industrial applications. However, dissimilar fusion welding of these materials is associated with the formation of extremely brittle intermetallic compounds, e.g., Ti2Ni and TiNi3, which drastically limit the mechanical properties of NiTi/Ti joints. The present investigation seeks to improve both chemical compatibility and mechanical performance through intermixing of a niobium foil as filler material into a ...
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On the Monotonic and Cyclic Behavior of an Al-Mg-Zn-Cu-Si Compositionally Complex Alloy
(2023-08-03)
In present work, the monotonic and cyclic properties of a novel Al-Mg-Zn-Cu-Si compositionally complex alloy (CCA) are investigated. Microstructural studies reveal that a eutectic phase and fishbone-type structures are embedded in the Al-matrix. The mechanical properties of this CCA obtained under compressive loading are found to be promising. However, low ultimate strength and brittle behavior are seen under tension. The fatigue performance of the alloy in the low-cycle fatigue (LCF) regime is poor. Microstructural ...
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UVC Irradiation as a Surface Treatment of Polycarbonate to Generate Adhesion to Liquid Silicone Rubber in an Overmolding Process
(2024-04-18)
This study investigates the adhesion properties of polycarbonate (PC) and liquid silicone rubbers (LSR) through surface activation using ultraviolet C (UVC) radiation. While self-adhesive LSRs adhere easily to certain thermoplastic composites such as polybutylene terephthalate (PBT) and polyamides (PAs), bonding to PC typically requires surface treatment due to the lack of compatible functional groups. Previous methods like plasma or flame treatment have been effective, but the use of UVC radiation for surface ...