The influence of structure, sensitization and corrosion on the fatigue properties of austenitic steelHudecová, S; Uhríčik, M; Palček, P; Mikolajčík, M; Chvalníková, V; Slezák, M
doi: 10.1088/1742-6596/2712/1/012008pmid: N/A
The article will be focused on examining and comparing the influence of structure, sensitization and corrosion on the fatigue properties of austenitic stainless steel. The methodology of the experiment includes fatigue tests of samples attacked by intercrystalline corrosion. Therefore, the test samples were subjected to heat treatment for sensitization. Then these samples were subjected to long-term exposure in an aggressive corrosion solution. Experiments deal with microstructural material analysis, fractographic analysis, mechanical and fatigue tests.
Modification of Ce3+ luminescence in Li+ and Mg2+ codoped GAGG:Ce scintillators: A comparative study using synchrotron radiationBartosiewicz, K; Kurosawa, S; Yamaji, A; Zorenko, Y; Yoshikawa, A
doi: 10.1088/1742-6596/2712/1/012011pmid: N/A
The luminescence characteristics of Gd3Al2Ga3O12:Ce3+ garnet scintillator crystals codoped with Li+ and Mg2+ ions were investigated. The excitation and emission spectra were obtained within the energy range of 3.6-21.6 eV, at both liquid helium and room temperature conditions to examine the effects of Li+ and Mg2+ codoping on cerium valence states, gadolinium-cerium energy transfer, and defect formation. Codoping with Mg2+ was found to efficiently convert Ce3+ to Ce4+, evidenced by significant changes in the shapes of the excitation spectra profile for Ce3+ luminescence in the exciton range, while Li+ had little impact. The presence of the high concentration of Ce4+ ions hampered the Gd3+→Ce4+ energy transfer. Redshifts in Ce3+ emission peaks indicated codopant-induced perturbations to the crystal field environment. The significant changes in the location of the Ce3+ excitation bands of Ce3+ luminescence in the exciton range further suggested alterations in the elemental distributions by the creation of complex defect clusters, particularly with Mg2+ codoping. The results demonstrate that Li+ and Mg2+ uniquely impact cerium valence, energy transfer processes, and structural properties in GAGG:Ce crystals.
Effect of bias voltage on the structural properties of WN/NbN nanolayer coatings deposited by cathodic-arc evaporationSmyrnova, K; Sahul, M; Haršáni, M; Čaplovič, Ľ; Beresnev, V; Čaplovičová, M; Kusy, M; Pogrebnjak, A
doi: 10.1088/1742-6596/2712/1/012014pmid: N/A
In this work, WN/NbN nanolaminate coatings were synthesized by cathodic-arc physical vapor deposition (CA-PVD) technique on a stainless-steel substrate. The paper reports the microstructure, cross-sectional morphology, surface roughness, and adhesion strength changes caused by variations in the absolute values of the negative substrate bias voltage, Us, in the 50-200 V range. Synthesized coatings were analyzed by Grazing incidence X-ray diffraction (GI-XRD), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and Daimler-Benz test. The phase analysis revealed that multilayer coatings had complex polycrystalline microstructure. They consisted of face-cantered cubic (fcc) β-W2N, fcc δ-NbN, and hexagonal ε-NbN phases. The total thickness and surface roughness had a descending trend with an increase in the absolute value of the negative bias voltage. Moreover, the WN/NbN coating deposited at Us = -50 V demonstrated the best adhesion strength to the substrate, suitable for protective coatings.
Assessment of cutting tool wear using a numerical FEM simulation modelNecpal, M; Vozár, M
doi: 10.1088/1742-6596/2712/1/012021pmid: N/A
The advancement of computational modeling techniques, such as FEM, has allowed to simulate complex machining processes with improved accuracy. Wear prediction is a crucial aspect in understanding and optimizing machining processes, as it directly impacts tool life, surface quality and overall machining efficiency. This work focuses on the FEM simulation, specially utilizing the DEFORM software, in conjunction with the Usui wear model, for wear prediction in machining operations. The Usui wear model, a well-established and widely used wear prediction approach, accounts for multiple wear mechanisms that include adhesion, abrasion, and diffusion. By incorporating the Usui wear model into the FEM simulation framework within the DEFORM software, it is possible to understand wear phenomena in machining processes. The integration of Usui wear model algorithms into DEFORM enables the simulation to accurately predict wear rates, distribution patterns, and progression of tool deterioration. This predictive capability facilitates the identification of critical wear zones and guides proactive measures to improve tool life, reduce production costs, and optimize machining productivity. This work presents research focused on wear prediction in cutting processes, utilizing FEM simulation with DEFORM software and incorporating the Usui wear model. Through a comprehensive analysis of wear phenomena, this research aims to optimize cutting parameters, improve tool life, and contribute to the advancement of machining and manufacturing technologies.
The effect of long-term exposure in mixed sulfuric acid and copper sulfate solution on corrosion behavior of austenitic stainless steelsZatkalíková, V; Markovičová, L
doi: 10.1088/1742-6596/2712/1/012003pmid: N/A
Corrosion resistance of austenitic stainless steels in sulfuric acid solutions depends mainly on concentration and temperature of the sulfuric acid, the presence of contaminants and velocity flow. Current studies aim mostly at evaluation of electrochemical parameters in sulfuric acid solutions. Research focused on long-term exposure is lacking. This article deals with the corrosion behavior of AISI 304 and AISI 316L stainless steels in mixed 10 wt. % sulfuric acid and 10 wt. % copper sulfate solution. Sensitized (650 °C/40 hours) and solution annealed (1050 °C/15 min) specimens together with the untreated (as received) ones are evaluated by long-term (22-month) exposure immersion test at the temperature of 22 ± 3 °C on the bases of optical microscopy, SEM and mass losses. Both tested stainless steels in as received and solution annealed state proved high corrosion resistance in the given corrosive environment. The cross-sections edges of sensitized specimens revealed a close relationship between local corrosion sites and weakened grain boundaries, which indicates incipient intergranular corrosion.
Prefacedoi: 10.1088/1742-6596/2712/1/011001pmid: N/A
32nd Joint Seminar DMSRE32 2023Development of Materials Science in Research and Education4 – 8 September 2023, hotel IRIS, Pavlov, CzechiaThe first Joint Seminar “Development of Materials Science in Research and Education” (DMSRE) was held at Gabcíkovo in Czechoslovakia in 1991. On 4 – 8 September 2023, the 32ndedition of the DMSRE seminar took place at the Iris Hotel in Pavlov, Czechia. The seminar is organized by the Czechoslovak Association for Crystal Growth and the Slovak Expert Group of Solid State Chemistry and Physics under the auspices of the Institute of Physics of the Czech Academy of Sciences, Faculty of Chemical and Food Technology SUT Bratislava, and Slovak Society for Industrial Chemistry every year with one break in 2021 (COVID-19 pandemic).The Seminar brings together a unique combination of scientists across a multidisciplinary spectrum and provides an ideal forum for the presentations and discussions of recent developments and achievements in all theoretical and experimental aspects of preparation processes, characterization and applications of materials in bulk, thin film, nano-crystalline and glassy states.The scientific sessions covered the following topics on materials science:– trends in development of the materials research– results of materials science research– education of materials science at the universities– information on equipment for preparation and characterisation of materials.The ambition of the conference organizers was to prepare a pleasant, open, friendly atmosphere for establishing new contacts, supporting mutual cooperation, spreading new scientific ideas and acquired knowledge, and also supporting education in the field of materials science.At the seminar, 66 participants presented 54 onsite and 4 online talks, of which 27 papers are included in this Proceeding. Abstracts of all contributions and seminar program are available on the conference website https://dms.fzu.cz/32/.Mária Behúlová and Zdenek Kožíšek (Editors)List of Organized by, Under the auspicies of, Scientific Committee, Organizing Committee, Sponsors, Editors are available in this pdf.
X-ray assisted point defects creation in micron-size Zn, Mo oxide particles at liquid nitrogen temperatureBuryi, M; Babin, V; Remeš, Z; Mičová, J
doi: 10.1088/1742-6596/2712/1/012005pmid: N/A
Charge trapping processes induced by the X-ray irradiation in the heavy Mo doped ZnO and MoO3 micropowders synthesized by the hydrothermal growth method were investigated in detail. Electron paramagnetic resonance (EPR) and thermally stimulated luminescence (TSL) were applied in a correlated manner to discover the role of the Mo doping in the charge trapping processes in ZnO. Thermally unstable oxygen- and molybdenum-related charge trapping centers were studied. Molybdenum and oxygen created electron-hole trapping pairs in some cases were observed. Some part of the hole trapping centers seemed to be directly connected with the creation of Mo5+. The correlation between EPR and TSL data was found.
Heat source models for numerical simulation of laser welding processes – a short reviewBehúlová, M; Babalová, E
doi: 10.1088/1742-6596/2712/1/012018pmid: N/A
In recent decades, numerical modeling and computer simulation have become an integral part of the design, analysis and optimization of fusion welding processes, including laser welding. In general, laser welding processes involve the interaction of multiple physical phenomena, such as thermal, fluid, metallurgical, chemical, mechanical, and diffusion effects, which makes the development of a simulation model difficult and complex. In addition to the geometric characteristics of the parts to be welded, their material properties must be specified in a wide temperature range, as well as the conditions for heat removal to the environment or shielding gas. One of the most complex tasks in the preparation of a simulation model of the laser welding processes consists in the selection of an appropriate heat source model to accurately determine the heat input to the weld. Very important is also the process of experimental verification and validation of the developed simulation models. In this paper, a short examination of significant mathematical heat source models for numerical simulation of laser welding is provided. Numerical analysis of laser welding of sheets made of S650MC steel is accomplished using conical 3D heat source model with the support of the ANSYS code. The effect of geometrical characteristics of the conical volumetric heat source model on the computed width, length, and depth of the weld pool is discussed, along with evaluation of maximum weld pool temperature.
Characterization of different types of silica-based materialsBabčenko, O; Remeš, Z; Beranová, K; Kolářová, K; Čermák, J; Kromka, A; Prošek, Z; Tesárek, P
doi: 10.1088/1742-6596/2712/1/012010pmid: N/A
Waste glasses based on silicon dioxide (silica) belong to one of the most demanded secondary raw materials. Besides the glass industry, with strict requirements for source materials, silica-based granular materials from waste glasses are considered suitable for use as fillers in alkali-activated cement-based composites. However, due to variations of ground waste glass powder composition and properties a comprehensive characterization is often needed. This study investigated commercially available silica-based powders by scanning electron microscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy and Fourier transform infrared Raman spectroscopy, zeta-potential and pH measurements, etc. The differences found in the non-silica impurities composition and structure of SiO2 particles (amorphous vs crystalline) were considered as determinative factors that will affect particles’ interaction with water and cement binder. The observed results provide a fundamental background and will contribute to a better understanding and explanation of the silica-based secondary raw materials interaction reactions in concrete or mortar.
The spectrally resolved photoluminescence decay in YAG:Er, ZnO and SiO2 crystalsRemeš, Z; Buryi, M; Pejchal, J; Babčenko, O; Remeš, Š; Novák, R; Mičová, J
doi: 10.1088/1742-6596/2712/1/012004pmid: N/A
We present an optical setup for measuring spectrally resolved photoluminescence (PL) mean decay time using conventional UV LED with sinusoidal excitation and a phase shift method. The phase sensitive detection was applied on the Er-doped yttrium aluminium garnet single crystal (YAG:Er, grown by the micro-pulling-down method) and hydrothermally grown zinc oxide micro-crystallites (ZnO). Commercial ZnO and silicon oxide (SiO2) microcrystalline powders were measured for comparison. SiO2 powder was annealed in O2 plasma at 500 °C for cleaning. While YAG:Er shows well resolved greenish PL peaks with mean decay time about 15 μs related to the Stark splitting of Er3+ (4f11) states and ZnO micro-powder broad reddish PL with similar PL decay time, the plasma treated SiO2 powder shows weak bluish defect-related PL with significantly faster mean decay times below 100 ns.