@misc{GradHahnNosteretal., author = {Grad, Marius and Hahn, Konstantin and Noster, Ulf and Spieß, Lothar}, title = {Increasing the lifetime of titanium implants through a diffusion-controlled surface treatment}, series = {Th{\"u}ringer Werkstofftag 2023, 14. M{\"a}rz 2023, ILmenau}, journal = {Th{\"u}ringer Werkstofftag 2023, 14. M{\"a}rz 2023, ILmenau}, doi = {10.13140/RG.2.2.35933.59360}, language = {en} } @article{GradZentgrafSchultheissetal., author = {Grad, Marius and Zentgraf, Jan and Schultheiss, Ulrich and Esper, Lukas and Diemar, Andreas and Noster, Ulf and Spiess, Lothar}, title = {Effect of Carbon Content on the Phase Composition, Microstructure and Mechanical Properties of the TiC Layer Formed in Hot-Pressed Titanium-Steel Composites}, series = {Metals}, volume = {14}, journal = {Metals}, number = {9}, publisher = {MDPI AG}, issn = {2075-4701}, doi = {10.3390/met14090959}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-74617}, abstract = {During the hot pressing of pure titanium and different carbon steels in a temperature range of ϑ = 950-1050 °C, a compound layer up to dL≈10 μm thick is formed at the titanium-steel interface. With a higher carbon content of the used steel, the layer thickness increases. The carbon concentration within the layer is in the range of stoichiometry for TiC. Apart from TiC, no other phases can be detected by X-ray diffraction (XRD) measurements inside the formed layer. The calculation of the activation energy for the TiC layer formation is Q = 126.5-136.7 kJ mol-1 and is independent of the carbon content of the steel. The resulting microstructure has a grain size gradient, wherein the mechanical properties, such as hardness and Young's modulus, are almost constant. Statistical analysis using Response Surface Methodology (RSM) indicates that the carbon content of the steel has the most significant influence on layer thickness, followed by annealing temperature and annealing time. By selecting the appropriate carbon steel and the subsequent removal of the steel, it is possible to produce targeted TiC layers on titanium substrates, which holds enormous potential for this material in wear-intensive applications.}, language = {en} } @article{ChavezVegaZiolkowskiSchorretal., author = {Chavez Vega, Jhohan Harvey and Ziolkowski, Marek and Schorr, Philipp and Spiess, Lothar and B{\"o}hm, Valter and Zimmermann, Klaus}, title = {A method to approach constant isotropic permeabilities and demagnetization factors of magneto-rheological elastomers}, series = {Journal of Magnetism and Magnetic Materials}, volume = {527}, journal = {Journal of Magnetism and Magnetic Materials}, publisher = {Elsevier}, doi = {10.1016/j.jmmm.2021.167742}, abstract = {The use of non-conventional materials is nowadays of much interest in scientific community. Magneto-rheological elastomers are hybrid materials, which in presence of magnetic fields state a change in their mechanical properties. They are composed by an elastomeric matrix with embedded magnetic particles. One of the most attractive features of these materials is that as soon as the magnetic field is removed from the material, the original mechanical properties are completely recovered, with negligible differences in comparison to the original state. This paper focuses on the study of magnetic characteristics of these smart materials, such as relative permeability and demagnetizing factors, for samples with different volume concentration of ferromagnetic particles.}, language = {en} } @article{GradHonigDiemaretal., author = {Grad, Marius and Honig, Lars-Hauke and Diemar, Andreas and Flock, Dominik and Spieß, Lothar}, title = {Complex material analysis of a TiC coating produced by hot pressing with optical light microscopy, EDS, XRD, GDOES and EBSD}, series = {Surface \& Coatings Technology}, volume = {476}, journal = {Surface \& Coatings Technology}, publisher = {Elsevier}, doi = {10.1016/j.surfcoat.2023.130265}, abstract = {The present study investigates the interface between carbon steel and titanium samples annealed at different temperatures (𝜗1 = 800 ◦C and 𝜗2 = 1050 ◦C). In both cases, an observable layer forms at the interface, with its thickness increasing from t𝜗1= 2.75 ± 0.15 μm at 800 ◦C to t𝜗2= 8.86 ± 0.29 μm at 1050 ◦C. The layer's composition and thickness evolve with temperature. Analysis reveals approximately 40 at.-\% carbon concentration in the exterior region, indicating likely titanium carbide creation. X-ray diffraction identifies titanium carbide peaks, while microscopy and elemental mapping confirm compositional gradients at the interface. Electron Backscatter Diffraction (EBSD) shows a gradient in grain size near the TiC surface, reflecting TiC nucleation rates. XRD data detect both titanium carbide and titanium phases, with TiC becoming more prominent at 1050 ◦C. Rietveld analysis further confirms TiC formation. Notably, distinct diffraction patterns on the contact and rear sides suggest a Ti(C, O, N) presence. Depth profiles exhibit varying surface and depth carbon concentrations, attributed to temperature effects. The study successfully demonstrates TiC coating fabrication through hot pressing, wherein Ti(C, O, N) coatings arise from titanium's affinity for reacting with oxygen and nitrogen. This research contributes to the understanding of phase transformations and interfacial properties in titanium-carbon steel systems.}, language = {en} } @article{GradSchultheissDiemaretal., author = {Grad, Marius and Schultheiß, Ulrich and Diemar, Andreas and Spieß, Lothar and Noster, Ulf}, title = {Preparation methodology for the microstructural characterization of diffusion layers in a titanium/steel composite}, series = {Practical Metallography}, volume = {61}, journal = {Practical Metallography}, number = {12}, publisher = {Walter de Gruyter GmbH}, issn = {2195-8599}, doi = {10.1515/pm-2024-0087}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-78346}, pages = {938 -- 946}, abstract = {Hot pressing of titanium and carbon steel leads to the formation of a diffusion layer at the interface. Depending on the carbon content of the steel used, it either exclusively contains TiC or additional other phases. In the case of steel with a medium carbon concentration (0.67 wt.\% C), a pure TiC layer forms. A preparation methodology was developed to make statements about functional and microstructural properties of the respective layers such as layer thickness, porosity, or grain size. However, apart from the diffusion layer's microstructure, it also reveals the microstructure of the two base substrates. A comparison based on electron backscatter diffraction (EBSD) examinations yields similar results in terms of microstructure. A micrograph analysis based on the new preparation methodology also allows confirming the element distribution measurement by glow discharge optical emission spectroscopy (GDOES). The methodology therefore provides a way of quickly and reliably controlling the layer formation during the hot pressing process of titanium and carbon steel.}, language = {en} }