TY - GEN A1 - Evdokimov, Anton A1 - Obrosov, Aleksei A1 - Ossenbrink, Ralf A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Mechanical properties of dissimilar steel-aluminum weld T2 - Materials Science and Engineering: A N2 - Knowledge of the properties of dissimilar welds is of great significance for the development of multi-material lightweight structures. In this study, stainless steel (1.4301) and aluminum alloy (6082-T6) sheets were welded in overlap configuration in keyhole mode. The resulting weld metals were investigated with respect to their mechanical properties. Several samples were cut out of different locations along the welds and their cross-sections were subjected to indentation testing and energy dispersive X-ray (EDS) analysis. Young's modulus E, yield stress σy, and strain hardening exponent n, were determined by means of reverse analysis of the indentation load (P) – depth (h) curves, allowing construction of true stress – true strain relations. An essential increase in yield stress in comparison to the one of the base alloys was observed inside the weld metal. In contrary, Young's modulus and strain hardening exponent of the welds were almost identical to corresponding values of the base steel metal. Due to the sensitivity of yield stress to the aluminum content, slight variations of the welding parameters lead to significant changes in elastic-plastic behavior of the weld metal. KW - Mechanical properties KW - Indentation KW - Reverse analysis KW - EDS measurements KW - Dissimilar steel aluminum welding KW - FEM Y1 - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0921509318303563 U6 - https://doi.org/https://doi.org/10.1016/j.msea.2018.03.019 SN - 0921-5093 VL - Volume 722 SP - 242 EP - 254 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Kashkarov, Egor B. A1 - Weiß, Sabine T1 - Oxidation behavior of Zr–1Nb in air at 400°C after Titanium Plasma Immersion Ion Implantation N2 - Zirconium alloys have been widely used in nuclear reactors due to low thermal neutron capture cross-section, excellent corrosion resistance and acceptable mechanical properties [1, 2]. Nowadays several methods apply for improving hydrogen and corrosion resistance such as addition of stabilizing additives (yttrium) [3, 4], deposition of thin solid films [5, 6], micro-arc oxidation [7] and modification of the surface by electron beam [8, 9]. Despite the multiplicity of the methods hydrogen embrittlement is still a pressing issue. Previous results [10, 11] have shown the positive influence of plasma immersion titanium implantation on the hydrogenation behavior of Zr–1Nb and Zr–2.5 Nb. After Ti implantation hydrogen preferably accumulates in the modified surface layer comprising the implanted Ti. Furthermore, the hydrogen concentration is considerably less inside the zirconium modified sample than in the as-received samples. The integration of elements into the zirconium lattice can influence the valence of the surface and change corrosion and oxidation rates of the alloys. So it is very important not to decrease the zirconium oxidation resistance due to Ti implantation. Therefore, the purpose of this research is to study of the influence of Ti implantation on surface morphology, oxidation rate and phase structure of the Zr–1Nb alloy after oxidation on air at 400 0C for 5, 24, 72 and 240 h. The surface structure of the samples and their elemental composition were investigated with the scanning electron microscope Mira II XMH (Tescan) with energy dispersive x-ray spectroscopy system (EDS). X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) as well as X-ray diffraction (XRD) was used to characterise the influence of titanium implantation on the oxidation behaviour. The results show that the oxidation kinetics after Ti modification of the zirconium alloy changed. Although the weight gain of the implanted sample remains approximately the same, it can be considered that Ti implantation stabilizes the oxide layer and has beneficial influence on the oxidation protection of Zr-1Nb. KW - Zr–1Nb KW - titanium ion implantation KW - oxidation KW - DSC KW - plasma immersion ion implantation (PIII) Y1 - 2018 UR - https://www.pse-conferences.net/tl_files/abstract-print/PSE2018-PO4029.pdf ER - TY - GEN A1 - Abang, Roger Atini A1 - Weiß, Sabine A1 - Krautz, Hans Joachim T1 - Impact of increased power plant cycling on the oxidation and corrosion of coal-fired superheater materials T2 - Fuel N2 - As power generation from variable renewable energy sources such as wind and solar power continues to increase in the future, fewer baseload power plants will be needed. As a result, high operational flexibility is becoming a vital requirement for conventional power plants to allow for the smooth integration of the variable renewable energy sources (v-RES) into the grid. To understand the impact of high operational flexibility (increased cycling) for coal-fired power plant materials, five commercial coal boiler superheater and reheater materials were investigated under isothermal and cyclic conditions for 1000 h each. The candidate alloys investigated were: T91, VM12-SHC, TP347-HFG, DMV304 HCu and DMV310 N. The results (weight change kinetics and metallographic analysis) after exposure at a metal surface temperature of 650 °C clearly showed the impact of increased flexibility on the corrosion and oxidation of the materials. Oxide growth (weight gain), metal loss, oxide spallation, and grain boundary attack were found to be more severe under cyclic conditions than under isothermal conditions. KW - Power plant flexibility, Isothermal oxidation, Cyclic oxidation, High temperature corrosion, Superheaters Y1 - 2018 U6 - https://doi.org/10.1016/j.fuel.2018.02.047 SN - 0016-2361 VL - 2018 IS - 220 SP - 521 EP - 534 ER - TY - GEN A1 - Santhanakrishnan Balakrishnan, Venkateswaran A1 - Seidlitz, Holger A1 - Weiß, Sabine T1 - Layup Configuration Effect on Notch Residual Strength in Composite Laminates T2 - Materials N2 - The current trend shows an increasing demand for composites due to their high stiffness to weight ratio and the recent progress in manufacturing and cost reduction of composites. To combine high strength and stiffness in a cost-effective way, composites are often joined with steel or aluminum. However, joining of thermoset composite materials is challenging because circular holes are often used to join them with their metal counterparts. These design based circular holes induce high stress concentration around the hole. The purpose of this paper is to focus on layup configuration and its impact on notch stress distribution. To ensure high quality and uniformity, the holes were machined by a 5 kW continuous wave (cw) CO2 laser. The stress distribution was evaluated and compared by using finite element analysis and Lekhnitskii’s equations. For further understanding, the notch strength of the laminates was compared and strain distributions were analyzed using the digital image correlation technique. KW - composite KW - notch stress KW - digital image correlation KW - ekhnitskii’s equation Y1 - 2018 U6 - https://doi.org/10.3390/ma11020308 SN - 1996-1944 VL - 11 IS - 2 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Ryabchikov, Alexander I. A1 - Kurochkin, Alexander A1 - Syrtanov, Maxim S. A1 - Shevelev, Alexey A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Hydrogen Interaction with Deep Surface Modified Zr-1Nb Alloy by High Intensity Ti Ion Implantation T2 - Metals N2 - A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb. Gas-phase hydrogenation was performed to evaluate protective properties of the modified layer against hydrogen permeation into Zr-1Nb alloy. The effects of ion implantation and hydrogen on microstructure, phase composition and elemental distribution of TiZr layer were analyzed by scanning electron microscopy, X-ray diffraction, and glow-discharge optical emission spectroscopy, respectively. It was revealed that TiZr layer (~10 μm thickness) is represented by α′ + α(TiZr) lamellar microstructure with gradient distribution of Ti through the layer depth. It was shown that the formation of TiZr layer provides significant reduction of hydrogen uptake by zirconium alloy at 400 and 500 °C. Hydrogenation of the modified layer leads to refinement of lamellar plates and formation of more homogenous microstructure. Hydrogen desorption from Ti-implanted Zr-1Nb alloy was analyzed by thermal desorption spectroscopy. Hydrogen interaction with the surface modified TiZr layer, as well as its resistance properties, are discussed. KW - zirconium alloy KW - titanium KW - low energy ion implantation KW - hydrogen KW - sorption KW - microstructure KW - morphology KW - martensitic phase Y1 - 2018 UR - https://www.mdpi.com/2075-4701/8/12/1081/htm U6 - https://doi.org/10.3390/met8121081 SN - 2075-4701 VL - 8 IS - 12 ER - TY - GEN A1 - Gunther, Victor A1 - Yasenchuk, Yuri A1 - Chekalkin, Timofey A1 - Marchenko, Ekaterina A1 - Gunther, Sergey A1 - Baigonakova, Gulsharat A1 - Hodorenko, Valentina A1 - Kang, Ji-hoon A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - Formation of pores and amorphous-nanocrystalline phases in porous TiNi alloys made by self-propagating high-temperature synthesis (SHS) T2 - Advanced Powder Technology N2 - The objective of this study was to examine the mechanism how the surface of porous TiNi compounds produced by SHS method evolves. The prepared samples were investigated using light-microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDS). The results indicated that the surface of all pores is represented by a granular stratum due to dendrite liquation by peritectic crystallization mechanism. The voids of 2–15 μm in size are formed owing to a capillary spreading of the liquid. Reaction gases with dissociated carbon, nitrogen, and oxygen are responsible for heat-and-mass transfer through the forming pores. High pressure-temperature effect of reaction gases on the melt causes the forming voids to coalesce, as well as transfers the peritectic liquid (PL) throughout the open pores catalyzing a distinctive spitted topography. It is through the chemisorption of gasiform nonmetallics by the pore surface melt, where these impurities are chemically bound, that it was formed a massive corrosion-resistant amorphous-nanocrystalline stratified shell deduced as an intermetallic oxycarbonitride layer. KW - Porous TiNi alloys KW - SHS KW - Pore formation KW - Surface structures KW - Heat-and-mass transfer Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S092188311830387X?via%3Dihub U6 - https://doi.org/10.1016/j.apt.2018.12.011 SN - 0921-8831 VL - 30 IS - 4 SP - 673 EP - 680 ER - TY - GEN A1 - Yasenchuk, Yuri A1 - Gunther, Victor A1 - Marchenko, Ekaterina A1 - Chekalkin, Timofey A1 - Baigonakova, Gulsharat A1 - Hodorenko, Valentina A1 - Gunther, Sergey A1 - Kang, Ji-hoon A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - Formation of mineral phases in self-propagating high-temperature synthesis (SHS) of porous TiNi alloy T2 - Materials Research Express N2 - The complex structural-phase composition, morphology and elemental composition of surface and nonmetallics in porous TiNi compounds produced by self-propagating high-temperature synthesis (SHS) in a flow reactor in the layer-by-layer combustion mode were analyzed. The samples were investigated using light microscopy (LM), X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDS). The findings indicate that in addition to the TiNi and Ti2Ni intermetallic constituents, the pore's surface contains numerous Ti4Ni2(O,N,C) nanocrystalline oxycarbonitrides, spinels, polysilicates, and residual amorphous phases. The elemental composition of the surface and crystalline inclusions is investigated by the EDS method. LM, SEM, TEM, and EDS instrumental examination revealed the entire surface comprising a continuous shell of intermetallic superficial bulb-shaped structures, as well as crystalline inclusions of polysilicates and spinels in the intergranular peritectic phase. Prominent morphology was confirmed to appear throughout the pore's surface owing to the interaction of the peritectic liquid (PL) with reaction gases. The epitaxial, nanocrystalline strata of intermetallic oxycarbonitrides were shown to have the intricate nature. Reaction gases chemisorbed by the PL are responsible for the continuous and dense substrate, which ultrafine structure modulates a high corrosion resistance. On the contrary, the sparse and foamy overlay resulted from a convective transfer of the PL by reaction gases facilitates in vivo bio-integration of the alloy. Overall, this sheds light on and may be more indicative of the complex role of superficial strata and nonmetallic crystals in enhanced biocompatibility of the unwrought porous TiNi alloy. KW - Porous TiNi alloys KW - SHS KW - Pore formation KW - Surface structures KW - Reaction gases KW - Amorphous layer Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/2053-1591/ab01a1 U6 - https://doi.org/10.1088/2053-1591/ab01a1 SN - 2053-1591 VL - 6 IS - 5 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Djellabi, Ridha A1 - Samad, Mohammed Abdul A1 - Touhami, Mohamed Zine A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Rapid and enhanced recovery of poly-dispersed nonionic surfactant (TX-100) from organic mediums using dehydrated and rehydrated kaolin T2 - Applied Clay Science N2 - The recovery of surfactants from organic mediums is of great economic and environmental interests in the field of petrochemicals sector. The aim of this study was to recover poly-dispersed nonionic surfactant (TX-100) from organic medium by the use of dehydrated and rehydrated kaolin. It was found that the presence of water after kaolin rehydration decreases considerably the amount of TX-100 adsorption from 28.7 μmol.g−1 onto dehydrated kaolin to 23.4 μmol.g−1 onto rehydrated kaolin. The estimation of the number of statistical layers of water deposited on kaolin was observed to be about 7 to 9. The effect of type of solvents (heptane, cyclohexane and benzene) on the adsorption onto rehydrated kaolin revealed a reduction in the adsorbed quantity; the adsorbed amounts were found to be 28.7 μmol.g−1, 26.7 μmol.g−1 and 24.2 μmol.g−1 in heptane, cycloheptane and benzene phases, respectively. On the other hand, it was observed that a temperature increased from 20 °C to 35 °C and 45 °C negatively affects the adsorption of TX-100 onto dehydrated and/or hydrated kaolin in heptane medium. KW - Adsorption KW - Organic medium KW - Surfactant recovery KW - Dehydrated/rehydrated kaolin KW - Petrochemical pollution Y1 - 2019 U6 - https://doi.org/10.1016/j.clay.2019.05.004 SN - 0169-1317 VL - 177 SP - 43 EP - 50 ER - TY - GEN A1 - Santhanakrishnan Balakrishnan, Venkateswaran A1 - Obrosov, Aleksei A1 - Kuke, Felix A1 - Seidlitz, Holger A1 - Weiß, Sabine T1 - Influence of metal surface preparation on the flexural strength and impact damage behaviour of thermoplastic FRP reinforced metal laminate made by press forming T2 - Composites Part B: Engineering N2 - In this paper the relationship between surface energy and flexural strength of metal laminate made by reinforcing glass fibre reinforced polymer on steel surfaces was investigated. Sand blasting was performed on 22MnB5 steel surface. This steel was stacked together with layers of unidirectional glass/polyamide-6 prepreg, followed by pressing in a hot press. Influenced parameters are pressure, temperature and time. 3D profilometer analysis was used to investigate the roughness profile on the surface of the steel generated by the sand blasting. The surface energy of the steel surface was calculated from a set of contact angles measured by three different liquids. To identify the optimal surface treatment, the variation of surface energy, flexural strength and roughness of the steel surface was determined as function of the surface treatment. Surface roughness (Ra of 1.08 μm), results indicate that increasing surface roughness leads to improvement in flexural modulus. The increase further leads to decrease in flexural modulus. In addition, the influence of surface energy and flexural strength on the impact damage behaviour was investigated too. The results showed that the sample with highest flexural modulus had the lowest impact-induced damage area. KW - Fiber reinforced plastic (FRP) KW - FRP reinforced metal composite KW - Sand blasting surface treatment KW - Surface energy KW - Contact angle Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S135983681930318X U6 - https://doi.org/10.1016/j.compositesb.2019.05.094 SN - 1359-8368 VL - 173 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Kosman, Stephania A1 - Megias, Alberto A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Biotribocorrosion behaviour of newly developed nanostructured near β-types Titanium based Alloys for Biomedical Applications T2 - nanoMAT2019 – 2nd International Conference on Nanomaterials and Their Applications N2 - The biotribocorrosion behavior of newly developed nanocristalline near β-types Ti-15Nb and Ti-15Mo alloys surfaces, sintered by powder metallurgy and sequentially milled, has been investigated in SBF simulated body fluid (PBS solution) at OCP, an applied potential in the passive region and EIS. Reciprocating sliding tests using a ball-on-plate tribometer under differentes applied loads 3, 7 and 10 N load and anodic potentials were applied to evaluate the effect of applied lad and the effect of Nb and Mo elements on tribocorrosion behaviors of samples. Results showed that, Ti-Nb exhibited better anticorrosive properties than Ti-Mo. Under tribological action the nanostructured both of alloys showed similar friction coefficient, while Ti-Nb present lower tendency to corrosion compared to Ti-Mo. Furthermore, Nb diffusion increased the repassivation rate with respect to Ti-Mo surfaces due to its stable passive film. Due to the high chemical reaction rate in β-type Ti-15Mo alloy as compared to Ti-15Nb. The β- Ti-15Nb showed lower volume loss, lower friction coefficient values and exhibited better corrosion resistance during tribocorrosion tests than Ti-15Mo. Prevailing electrochemical conditions between -1 and 2 V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear. Also, wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys. However, considering biomedical applications, the β- Ti15 Mo and Ti15Nb alloys may be good candidates with low elastic modulus and without toxic alloying elements. KW - Biotribocorrosion KW - titanium based alloys KW - Biomedical Applications Y1 - 2019 UR - http://nanomat2019.org/wp-content/uploads/2019/04/Book-of-Abstracts-nanomath2019.pdf SP - 170 ER -