TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A.I. A1 - Orts Gil, Guillermo A1 - Schneider, Thomas A1 - Ren, H. A1 - Sun, X. T1 - Verification of nanometre-scale modelling of tribofilm sliding behaviour N2 - A model based on movable cellular automata has been applied to study the sliding behaviour of tribofilms formed during automotive braking. Since it is not possible yet to determine the composition of real tribofilms quantitatively, final verification of modelling results is needed. This was done by preparing artificial third bodies with compositions and nanostructures matching the ones assumed for modelling. Pin-on-disc tests were performed while applying the artificial third bodies to the contact. The results revealed that not only the structure of the third body but also the amount of the applied normal pressure determines the COF obtained by modelling and that much better correlation between experimental and modelling results was obtained while assuming high normal pressures at asperity contacts. KW - Automotive braking KW - Third body KW - Modelling KW - Sliding simulation PY - 2013 U6 - https://doi.org/10.1016/j.triboint.2013.02.018 SN - 0301-679X VL - 62 SP - 155 EP - 162 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-27946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Orts Gil, Guillermo A1 - Gross, Thomas A1 - Deutsch, Cornelius A1 - Hinrichs, R. A1 - Vasconcellos, M.A.Z. A1 - Zoz, H. A1 - Yigit, D. A1 - Sun, X. T1 - Impact of high energy ball milling on the nanostructure of magnetite-graphite and magnetite-graphite-molybdenum disulphide blends N2 - Different, partly complementary and partly redundant characterization methods were applied to study the transition of magnetite, graphite and MoS2 powders to mechanically alloyed nanostructures. The applied methods were: Transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), Raman spectroscopy (RS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The main objective was to prepare a model material providing the essential features of a typical tribofilm forming during automotive braking, and to assess the impact of different constituents on sliding behaviour and friction level. Irrespective of the initial grain size, the raw materials were transferred to a nanocrystalline structure and mixed on a nanoscopic scale during high energy ball milling. Whereas magnetite remained almost unchanged, graphite and molybdenum disulphide were transformed to a nanocrystalline and highly disordered structure. The observed increase of the coefficient of friction was attributed to a loss of lubricity of the latter ingredient due to this transformation and subsequent oxidation. KW - Ball milling KW - Mössbauer spectroscopy KW - Raman spectroscopy KW - Transmission electron microscopy KW - X-ray diffraction KW - X-ray photoelectron spectroscopy PY - 2013 U6 - https://doi.org/10.1016/j.matchar.2013.09.007 SN - 1044-5803 SN - 1873-4189 VL - 86 SP - 28 EP - 38 PB - Elsevier Inc. CY - New York, NY AN - OPUS4-29697 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, C. A1 - Tian, X. A1 - Wang, L. A1 - Liu, Y. A1 - Wirth, Cynthia A1 - Günster, Jens A1 - Li, D. A1 - Jin, Z. T1 - Effect of particle size gradation on the performance of glass-ceramic 3D printing process N2 - Particle size gradation is regarded as an effective method for overcoming the contradicting requirements in three-dimensional printing (3DP). In present work, particle size gradation was optimized to obtain both acceptable flowability of the powder material and high-strength 3D-printed glass-ceramic products. The effect of gradation on the printing process, sintering process and performance of the 3D-printed glass-ceramic products was investigated comprehensively. The glass-ceramic powders with three size ranges were mixed in certain proportions and applied to print parts. The result showed parts printed with powder mixed by 60 wt% 45–100 µm and 40 wt% 0–25 µm particles had satisfactory density of 1.60 g/cm³ and bending strength of 13.8 MPa. The flowability decreased with an increasing proportion of fine particles. Part density was determined by the powder bulk density in the powder bed as well as the shrinkage during sintering while strength of part was found to be dependent on the sintering degree. KW - Flowability KW - Glass-ceramic KW - Particle size gradation KW - Three-dimensional printing KW - Mechanical properties PY - 2017 U6 - https://doi.org/10.1016/j.ceramint.2016.09.197 SN - 0272-8842 VL - 43 IS - 1 SP - 578 EP - 584 PB - Elsevier AN - OPUS4-39783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, X. A1 - Zhang, S. A1 - Lu, J. A1 - Tang, F. A1 - Dong, K. A1 - Yu, Z. A1 - Hilger, A. A1 - Osenberg, M. A1 - Markötter, Henning A1 - Wilde, F. A1 - Zhang, S. A1 - Zhao, J. A1 - Xu, G. A1 - Manke, I. A1 - Sun, F. A1 - Cui, G. T1 - Unveiling the Electro-Chemo-Mechanical Failure Mechanism of Sodium Metal Anodes in Sodium–Oxygen Batteries by Synchrotron X-Ray Computed Tomography N2 - Rechargeable sodium–oxygen batteries (NaOBs) are receiving extensive research interests because of their advantages such as ultrahigh energy density and cost efficiency. However, the severe failure of Na metal anodes has impeded the commercial development of NaOBs. Herein, combining in situ synchrotron X-ray computed tomography (SXCT) and other complementary characterizations, a novel electro-chemo-mechanical failure mechanism of sodium metal anode in NaOBs is elucidated. It is visually showcased that the Na metal anodes involve a three-stage decay evolution of a porous Na reactive interphase layer (NRIL): from the initially dot-shaped voids evolved into the spindle-shaped voids and the eventually-developed ruptured cracks. The initiation of this three-stage evolution begins with chemical-resting and is exacerbated by further electrochemical cycling. From corrosion science and fracture mechanics, theoretical simulations suggest that the evolution of porous NRIL is driven by the concentrated stress at crack tips. The findings illustrate the importance of preventing electro-chemo-mechanical degradation of Na anodes in practically rechargeable NaOBs. KW - Synchrotron radiation KW - X-ray imaging KW - NaO-battery PY - 2024 U6 - https://doi.org/10.1002/adfm.202402253 SN - 1616-301X SP - 1 EP - 12 PB - Wiley VHC-Verlag AN - OPUS4-59820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, J. A1 - Zhang, S. A1 - Yao, J. A1 - Guo, Z. A1 - Osenberg, M. A1 - Hilger, A. A1 - Markötter, Henning A1 - Wilde, F. A1 - Manke, I. A1 - Zhang, X. A1 - Sun, F. A1 - Cui, G. T1 - Synergistic Effect of CO2 in Accelerating the Galvanic Corrosion of Lithium/Sodium Anodes in Alkali Metal−Carbon Dioxide Batteries N2 - Rechargeable alkali metal−CO2 batteries, which combine high theoretical energy density and environmentally friendly CO2 fixation ability, have attracted worldwide attention. Unfortunately, their electrochemical performances are usually inferior for practical applications. Aiming to reveal the underlying causes, a combinatorial usage of advanced nondestructive and postmortem characterization tools is used to intensively study the failure mechanisms of Li/Na−CO2 batteries. It is found that a porous interphase layer is formed between the separator and the Li/Na anode during the overvoltage rising and battery performance decaying process. A series of control experiments are designed to identify the underlying mechanisms dictating the observed morphological evolution of Li/Na anodes, and it is found that the CO2 synergist facilitates Li/Na chemical corrosion, the process of which is further promoted by the unwanted galvanic corrosion and the electrochemical cycling conditions. A detailed compositional analysis reveals that the as-formed interphase layers under different conditions are similar in species, with the main differences being their inconsistent quantity. Theoretical calculation results not only suggest an inherent intermolecular affinity between the CO2 and the electrolyte solvent but also provide the most thermodynamically favored CO2 reaction pathways. Based on these results, important implications for the further development of rechargeable alkali metal−CO2 batteries are discussed. The current discoveries not only fundamentally enrich our knowledge of the failure mechanisms of rechargeable alkali metal−CO2 batteries but also provide mechanistic directions for protecting metal anodes to build high-reversible alkali metal−CO2 batteries. KW - Alkali metal batteries KW - Synchrotron X-ray computed tomography KW - Lithium/sodium−carbon dioxide batteries KW - Battery failure mechanisms KW - Alkali metal anodes PY - 2024 U6 - https://doi.org/10.1021/acsnano.4c02329 SP - 1 EP - 16 AN - OPUS4-59922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -