TY - CHAP A1 - Obrosov, Aleksei A1 - Kashkarov, Egor B. A1 - Weiß, Sabine A1 - Volinsky, Alex A. ED - Tiwari, Ashutosh T1 - Mechanical and tribological behaviour of hydrogenated CrxN coatings deposited at different pressure and voltages on IN718 T2 - American Advanced Materials Congress 2016 N2 - Hydrogen degradation is a serious problem in industrial applications like power plants (boilers, turbines), marine structures, car and aircraft components, as it leads to failures as well as to deterioration of properties. Inconel 718 is one of the most commonly used materials for these applications. Different metal nitrides like TiN coatings have been deposited in past to prevent hydrogen degradation, which are also known for their high hardness and good wear resistance [1, 2]. However, reports on hydrogen degradation of CrN coatings, which shows better oxidation and corrosion resistance, higher temperature stability and lower friction coefficient than TiN [3, 4] has not been reported till now. Despite a lot of publications about CrN films, up to now the effect of hydrogenation on mechanical and tribological properties of CrN coatings is still not completely understood. In the current work CrxN coatings were deposited by Direct Current Magnetron Sputtering (dcMS) on Inconel 718 substrate at different chamber pressures and substrate voltages. Substrate voltage is one of the most important process parameters which determines the structure of the coating and the adhesion between substrate and coating. Simultaneously a study of the chamber pressure is also needed to understand the deposited structure and growth rate because at higher pressures the high number of argon atoms reduce the number of ionized ions available for the deposition leading to low deposition rates [5]. Gas-phase hydrogenation of the samples was performed at a temperature of 600° C and hydrogen pressure of 2 atm. It was found that CrxN coatings are resistant against hydrogen exposure as compared to uncoated surfaces. The results of changes in the mechanical, tribological properties and phase composition of the coatings after hydrogenation are discussed. Coating microstructure was studied by scanning electron microscopy (SEM). The mechanical properties of the coatings were characterized by means of nanoindentation and scratch test. KW - CrxN coating KW - mechanical properties KW - microstructure KW - hydrogenation KW - XRD Y1 - 2016 SN - 978-91-88252-03-6 PB - VBRI Press CY - Linköping ER - TY - GEN A1 - Obrosov, Aleksei A1 - Naveed, Muhammad A1 - Krupp, Ulrich A1 - Solovev, Mikhail A1 - Weiß, Sabine T1 - Investigation of TiAlN HiPIMS coating deposited on the newly developed Ni-based superalloy AD730 N2 - The development of new alloys for gas turbine engines has been focused on withstanding against increasing service temperatures. AD730™ is a recently developed nickel-based superalloy for turbine disk applications with superior properties at 700°C, which is higher than the common service temperature for IN718. Use of coatings to enhance the properties of materials, such as wear resistance is widely known in various applications. This research presents an experimental study of TiAlN coatings, deposited onto AD730 superalloy using High Power Impulse Magnetron Sputtering (HiPIMS). Phase structure and chemical composition of the TiAlN films were characterized by X-ray diffractometry. Transmission electron microscopy as well as scanning electron microscopy were used to analyze the microstructure of the coating. Mechanical properties, including hardness, Young's modulus, and adhesion strength were measured using nanoindentation und scratch test. KW - TiAlN coating KW - HiPIMS KW - Ni-based superalloy KW - AD730 TEM XRD Y1 - 2016 UR - http://www.pse-conferences.net/poster-wednesday.html UR - http://www.pse-conferences.net/tl_files/abstract-print/PSE2016-PO3023.pdf N1 - 16th International Conference on Plasma Surface Engineering ER - TY - GEN A1 - Obrosov, Aleksei A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Effect of pulse time on structure and mechanical properties of HPPMS deposited AlTiN coatings N2 - The use of PVD AlTiN as a protective coating on cutting tools is well known. With the introduction of pulsed deposition techniques like High Power Pulsed Sputtering (HPPMS), a possibility is provided to the coating developers to design their coatings by the variation in pulse parameters. To analyze the effect of pulse time HPPMS AlTiN coatings were deposited on Si (100) as well as 100Cr6 steel plates at a temperature of 500°C in a reactive gas environment. Oscilloscope measurements depicted a change in current-voltage characteristics with variation in pulse time. This influence the coating structure, deposition rates and phase formations as well. Nanoindentation results show a variation in the mechanical properties of the coatings with the change in pulse time. This study focuses on the potential of HPPMS technology for enhancement of mechanical and structural properties of AlTiN coating. KW - HPPMS KW - AlTiN KW - wear KW - cutting tools KW - pulse time Y1 - 2016 UR - http://www.pse-conferences.net/poster-wednesday.html UR - http://www.pse-conferences.net/tl_files/abstract-print/PSE2016-PO3055.pdf N1 - 16th International Conference on Plasma Surface Engineering ER - TY - CHAP A1 - Bambach, Markus A1 - Sizova, Irina A1 - Bolz, Sebastian A1 - Weiß, Sabine T1 - Development of a dynamic recrystallization model for a β-solidifying titanium aluminide alloy using Kocks-Mecking plots T2 - ESAFORM 2016, proceedings of the 19th International ESAFORM Conference on Material Forming, Nantes, France, 27-29 April 2016 Y1 - 2016 SN - 978-0-7354-1427-3 U6 - https://doi.org/10.1063/1.4963545 SP - 160002-1 EP - 160002-7 PB - AIP Publishing CY - Melville, New York ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Nikitenkov, Nikolay A1 - Sutygina, Alina A1 - Laptev, Roman A1 - Bordulev, Yuriy A1 - Obrosov, Aleksei A1 - Liedke, Maciej O. A1 - Zak, Andrzej A1 - Weiß, Sabine T1 - Microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb treated by plasma immersion Ti ion implantation and deposition T2 - Journal of Alloys and Compounds N2 - The effect of low energy plasma immersion ion implantation and deposition of titanium on microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb was studied. Defect structure and distribution were analyzed by Doppler broadening using slow positron beam. The surface microstructure after modification is represented by nanostructured Ti grains with random orientation. The gradient distribution of titanium as well as vacancy type defects were analyzed. The concentration of vacancy type defects is rising with increasing bias voltage. Gas-phase hydrogenation of the Ti-modified Zr-1Nb alloy was performed at 400 °C for 60 min. The strong interaction of hydrogen with vacancy type defects was demonstrated. Two different changes in the defect structure after hydrogenation were observed: when a titanium film is formed on the surface (after deposition at 500 V) hydrogen trapping occurs with the formation of titanium hydride phases, while in the implanted layer (deposition at 1000 and 1500 V) hydrogen is trapped due to interaction with vacancy type defects. The physical basis of Ti diffusion and its influence on the evolution of defect structure after surface modification and hydrogenation were discussed. KW - Zirconium KW - Ion implantation KW - Titanium KW - Diffusion KW - Surface modification KW - Hydrogen trapping KW - Microstructure KW - Slow positrons KW - Doppler broadening KW - Defects Y1 - 2018 UR - http://www.sciencedirect.com/science/article/pii/S0925838817335879 U6 - https://doi.org/10.1016/j.jallcom.2017.10.151 SN - 0925-8388 VL - 732 SP - 80 EP - 87 ER - TY - GEN A1 - Shulepov, Ivan A. A1 - Kashkarov, Egor B. A1 - Stepanov, Igor B. A1 - Syrtanov, Maxim S. A1 - Sutygina, Alina A1 - Shanenkov, Ivan A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - The Formation of Composite Ti-Al-N Coatings Using Filtered Vacuum Arc Deposition with Separate Cathodes T2 - Metals N2 - Ti-Al-N coatings were deposited on high-speed steel substrates by filtered vacuum arc deposition (FVAD) during evaporation of aluminum and titanium cathodes. Distribution of elements, phase composition, and mechanical properties of Ti-Al-N coatings were investigated using Auger electron spectroscopy (AES), X-ray diffraction (XRD), transmission electron microscopy (TEM) and nanoindentation, respectively. Additionally, tribological tests and scratch tests of the coatings were performed. The stoichiometry of the coating changes from Ti0.6Al0.4N to Ti0.48Al0.52N with increasing aluminum arc current from 70 A to 90 A, respectively. XRD and TEM showed only face-centered cubic Ti-Al-N phase with preferred orientation of the crystallites in (220) direction with respect to the sample normal and without precipitates of AlN or intermetallics inside the coatings. Incorporation of Al into the TiN lattice caused shifting of the (220) reflex to a higher 2θ angle with increasing Al content. Low content and size of microdroplets were obtained using coaxial plasma filters, which provides good mechanical and tribological properties of the coatings. The highest value of microhardness (36 GPa) and the best wear-resistance were achieved for the coating with higher Al content, thus for Ti0.48Al0.52N. These coatings exhibit good adhesive properties up to 30 N load in the scratch tests. KW - filtered vacuum arc KW - deposition KW - TiAlN KW - separate cathodes KW - phase composition KW - hardness KW - wear-resistance Y1 - 2017 UR - http://www.mdpi.com/2075-4701/7/11/497/htm U6 - https://doi.org/10.3390/met7110497 SN - 2075-4701 VL - 7 IS - 11 ER - TY - GEN A1 - Severin, Stefanie A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Effect of HPPMS pulse-frequency on plasma discharge and deposited AlTiN coating properties T2 - Advances in Materials Science and Engineering N2 - Coatings like TiAlN (titanium content more than 50 %) or AlTiN (aluminium content more than 50 %) are well established as hard and wear resistant tool coatings, often prepared by physical vapour deposition (PVD) like arc evaporation or direct current magnetron sputtering (dcMS). With increasing challenges of operating conditions, a constant need in improvement of mechanical properties is required to withstand extreme loading conditions. This can be obtained by a higher amount of ionized sputtered metal atoms during the deposition process. To increase the metal-ion flux a high-power pulse magnetron sputtering (HPPMS) was developed. In order to understand the relation between HPPMS process parameters and mechanical properties of the AlTiN coatings, the present study discusses how different pulse frequencies (for a constant pulse length) influence AlTiN coating structure growth and their mechanical properties. In addition, film deposition rate and phase formation are influenced by altering process parameters like pulse length and frequency. Hence, different pulse-frequencies produce specific coatings with corresponding properties for functional requirements. Based on the established findings, answers to new scientific queries along with the demand to further optimize these coatings for tool applications are required. KW - High power pulsed magnetron sputtering KW - Pulse frequency KW - Nanostructured AlTiN coatings KW - Mechanical properties Y1 - 2017 SN - 1687-8442 VL - 2017 ER - TY - GEN A1 - Doncheva Bambach, Margarita A1 - Bambach, Markus A1 - Sviridov, Alexander A1 - Weiß, Sabine T1 - New process chains involving additive manufacturing and metal forming - a chance for saving energy? T2 - Procedia Engineering KW - additive manufacturing KW - laser deposition welding KW - aluminium KW - energy consumption Y1 - 2017 U6 - https://doi.org/10.1016/j.proeng.2017.10.1049 SN - 1877-7058 N1 - International Conference on the Technology of Plasticity, ICTP 2017, 17-22 September 2017, Cambridge, United Kingdom VL - 207 SP - 1176 EP - 1181 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Manakhov, Anton A1 - Bolz, Sebastian A1 - Weiß, Sabine A1 - Kashkarov, Egor B. T1 - Oxidation Behavior of Zr–1Nb Corroded in Air at 400 °C after Plasma Immersion Titanium Implantation T2 - Metals N2 - In this paper, the influence of plasma immersion titanium implantation into the zirconium alloy Zr-1Nb on the oxidation behavior at 400 °C for 5, 24, 72, and 240 h in air under normal atmospheric pressure (101.3 kPa) was shown. The influence of implantation on the protective properties of the modified layer was shown. The valence of the oxides before and after implantation was analyzed by means of X-ray photoelectron spectroscopy (XPS). Grazing incidence X-ray diffraction (GIXRD) was carried out to examine the phase composition after titanium ion implantation and oxidation. Differential scanning calorimetry (DSC) revealed that titanium implantation exhibited effects of stabilizing the β phase. The formation of the t-ZrO2 and m-ZrO2 was observed during the oxidation of the as-received and modified Zr-1Nb. The measurement of weight gain showed an improvement in oxidation resistance of Ti implanted Zr-1Nb at the oxidation up to 24 h when compared with that of the as-received Zr-1Nb. However, at longer oxidation cycle the oxidation rate of Ti-implanted zirconium alloy is the same with the as-received alloy, which attributed to the layer thickness. Nevertheless, the corrosion of the Ti-implanted alloy is more uniform, while a local corrosion and cracks was detected on the surface of the as-received alloy. KW - zirconium alloy KW - titanium KW - ion implantation KW - PIII KW - oxidation KW - DSC KW - XPS KW - surface morphology KW - X-ray diffraction Y1 - 2018 UR - http://www.mdpi.com/2075-4701/8/1/27/htm U6 - https://doi.org/10.3390/met8010027 SN - 2075-4701 VL - 8 IS - 1 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Nikitenkov, Nikolay A1 - Sutygina, Alina A1 - Obrosov, Aleksei A1 - Manakhov, Anton A1 - Polčak, Josef A1 - Weiß, Sabine T1 - Hydrogen absorption by Ti-implanted Zr-1Nb alloy T2 - International journal of hydrogen energy N2 - This paper describes the hydrogenation behavior of Zr-1Nb alloy Ti-implanted by plasma immersion ion implantation (PIII). Hydrogen sorption kinetics of the Ti-modified alloy was investigated under gas-phase hydrogenation at 400 °C for 1 h. The influence of implantation time on the protective properties of the modified layer was shown. The lowest hydrogen absorption as well as the highest hydrogen trapping efficiency was achieved after PIII for 30 min. The main contribution to the reduction of hydrogen permeation is the formation of an oxide layer consisting of mixed TiO2 and ZrO2 on the modified surface of the alloy. X-ray photoelectron spectroscopy (XPS) revealed that PIII titanium oxide exists on the surface in the form of TiO2, which transforms to mixed Ti2O3 and TiO2 after hydrogenation. The thickness of the modified layer increases with implantation time that improves the efficiency of hydrogen trapping. All the absorbed hydrogen is gradually distributed in the modified layer and no hydrides are formed after hydrogenation in Ti-modified Zr-1Nb for 15 and 30 min. KW - Zirconium KW - Titanium implantation KW - Hydrogenation KW - X-ray photoelectron spectroscopy KW - Glow discharge optical emission spectroscopy KW - X-ray diffraction Y1 - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0360319917346359 U6 - https://doi.org/10.1016/j.ijhydene.2017.12.003 SN - 0360-3199 VL - 43 IS - 4 SP - 2484 EP - 2491 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Uludintceva, Elena A1 - Mitrofanov, Andrei A1 - Weiß, Sabine T1 - Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering T2 - Coatings N2 - In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrNₓ) thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD) results reveal a change from mixed fcc-CrN + hcp-Cr₂N to the approximately stoichiometric hcp-Cr₂N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS). The texture coefficients of (113), (110), and (111) planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113) textured hcp-Cr₂N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrNx coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr₂O₃ oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40%. The lowest value of 0.25 ± 0.02 was reached for the CrNₓ coating deposited at 60 V after hydrogenation. KW - CrNx coatings KW - Physical Vapour Deposition (PVD) KW - hydrogenation KW - tribology KW - mechanical properties KW - X-ray diffraction Y1 - 2018 UR - http://www.mdpi.com/2079-6412/8/2/66/htm U6 - https://doi.org/10.3390/coatings8020066 SN - 2079-6412 N1 - Special Issue "Surface Preparation and Treatments for Enhancing the Coating Performance" VL - 8 IS - 2 ER - 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 -