bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rolling Contact Fatigue of Hot Isostatic Pressed WC-NiCrBSi Thermal Spray Coatings
Authors: Stewart S. , Ahmed R. , Itsukaichi M.Tsuyoshi , Tobe S. 
Published: September 2022

Abstract
The aim of this experimental study was to comprehend the relative performance and failure modes of WC-NiCrBSi Thermal Spray coatings in As–Sprayed and HIPed (Hot Isostatically Pressed) conditions in rolling/sliding contact. Recently a number of scientific studies have addressed the fatigue performance and durability of Thermal spray coatings in rolling/sliding contact, but as of yet there have been no investigations on Thermal Spray Coatings which have undergone the post treatment HIPing. The understanding of the mechanisms of failure in rolling /sliding contact after HIPing is therefore critical in optimising the parameters associated with this post treatment to achieve superior performance. Coatings were deposited by a JP5000 system and HIPing was carried out at two different furnace temperatures of 1123K and 1473K. At both HIPing temperatures the rate of cooling was kept constant at 8°C/minute. Rolling Contact Fatigue tests were conducted using a modified four ball machine under various tribological conditions of contact stress, configuration and lubrication. Results are discussed in terms of as-sprayed and HIPed surface examination of rolling elements using Scanning Electron Microscope (SEM) and Light Microscope.
Elastic Modulus Measurements via Laser-Ultrasonic and Knoop Indentation Techniques
Authors: Lima R.S. , Kruger S.E. , Lamouche G. , Marple B.R. 
Published: September 2022

Abstract
Nondestructive techniques for evaluating and characterizing coatings have been extensively demanded by the thermal spray community; nonetheless, few results have been produced in practice due to difficulties in analyzing the complex structure of thermal spray coatings. Of particular interest is knowledge of the elastic modulus values and Poisson’s ratios, which are very important when seeking to understand and/or model the mechanical behavior or develop life prediction models of thermal spray coatings employed in various applications (e.g., wear, fatigue and high temperatures (TBCs)). In the present study, two techniques, laser-ultrasonics and Knoop indentation, were used to determine the elastic modulus of thermal spray coatings. Laser ultrasonics is a non-contact and nondestructive evaluation method that uses lasers to generate and detect ultrasound. Ultrasonic velocities in a material are directly related to its elastic modulus value. The Knoop indentation technique, which has been widely used as a method for determining elastic modulus values, was employed in order to compare and validate the measurements of the laser-ultrasonic technique. The determination of elastic modulus values via the Knoop indentation technique is based on the measurement of elastic recovery of the dimensions of the Knoop indentation impression. The approach used in the present study was to focus on evaluating the elastic modulus of very uniform, dense and near-isotropic titania and WC-Co thermal spray coatings using these two techniques. Four different coatings were evaluated: two titania coatings produced by APS and HVOF and two types of WC-Co coatings, conventional and multimodal (nanostructured and micro-sized particles), deposited by HVOF.
Young's Modulus and Fatigue Behavior of Plasma Sprayed Alumina Coatings
Authors: Kovářík O. , Siegl J. , Nohava J. , Chráska P. 
Published: September 2022

Abstract
Fatigue behavior and Young’s modulus of plasma sprayed gray alumina on low-carbon steel substrates were investigated. The investigation of the properties of composite material “coating-substrate” included the measurements of microhardness profile, residual stress on the top of the coating and residual stress profile in substrate. Fatigue samples were periodically loaded as a cantilever beam on a special testing machine. Failed samples were observed in SEM to determine failure processes in the coating. The Young’s modulus of the coating was measured by the four-point bending method. Samples were tested both in tension and compression at low (300 N) and high (800 N) loads. Our experiments revealed that the average fatigue lives of coated specimens were nearly 2 times longer than those of the uncoated specimens. The Young’s modulus of the coating varied between 27 and 53 GPa with an average value of 43 GPa. Loading in tension caused decrease in Young’s modulus of the coating while loading in compression lead to increase in Young’s modulus. Increase in the lifetime of coated samples was likely due to compressive residual stresses in the substrate, originating from the spray process. Failure of the coating consisted of several processes, among which the most important are splat cracking, splat debonding and coalescence of cracks through the voids in the coating.
Quantitative Characterization of the Microstructure of Plasma-sprayed Alumina Coatings Based on Visualization of Infiltrated Element
Authors: Li C.-J. , Wang W.-Z. , Wang H.-Y. 
Published: September 2022

Abstract
The visualization of the detailed microstructure of plasma sprayed ceramic coatings is carried out through quantitative analysis of the distribution of the infiltrated element as a tracer. A method to characterize quantitatively the microstructure of spray coating is proposed based on an idealized layer structure model and the distribution of the tracer in the coating. The microstructural parameters include mean thickness of lamellae, bonding ratio between flattened lamellae, distribution and average lamellar interface gap, and vertical crack related parameters. The experiment is performed for plasma sprayed alumina coating with the infiltration of Cr2O3 through chromium acid. The Cr distribution along the lines perpendicular to lamellae is obtained by EDAX line analysis in the form of digital signal at intervals of 2 µm. The processing method of the signal to evolve the structural parameters is introduced.
Microstructural Characterization Across Length Scales of Thermal Sprayed Ni-5wt%Al Coatings
Authors: Deshpande S. , Sampath S. , Gouma P.I. , Herman H. 
Published: September 2022

Abstract
Thermal spray processing involves a multitude of interdependent process variables resulting in a complex layered microstructure with each layer composed of several splats separated by splat-splat interfaces. Each splat contains columnar/equiaxed grains with multiple orientations. A typical microstructure also contains defects such as globular pores, and interlamellar pores. This gamut of features encompasses a range of macro, micro and nano length scales. This study involves a thorough microstructural characterization across length scales of Ni-5wt%Al coatings to understand the dependence of microstructural variability on processing conditions and its profound influence on coating properties. Studied here are coatings produced by four different spray methods, namely twin wire-arc, air plasma, high velocity oxyfuel and cold spraying with distinct variations w.r.t. nature of feedstock, method of material injection, amount of melting, and process parameters such as particle velocity and temperature in flight. Macro-scale, Micro-scale and Nanoscale microstructural characterization of these Ni5Al coatings elucidates the variations in oxide content, splat structure, grain structure and phases obtained, based on differences in processing parameters. Through characterization of these bond-coats, using Optical microscopy, Image analysis, Scanning and Transmission electron microscopy techniques, variations in coating properties such as porosity and thermal conductivity can be explained with respect to coating microstructure and process characteristics.
Titanium Suboxide Coatings Prepared by VPS Spraying
Authors: Naumann T. , Berger L.-M. , Ingwerth M. , Vuoristo P. 
Published: September 2022

Abstract
Titanium oxide is established as an oxide material for thermally sprayed coating solutions and has received increasing interest over the last few years. Scientific and technological research focuses on electrical conductivity, solid lubrication and photocatalytic properties of titanium oxide (TiOx) coatings of differing stoichiometry. The aim of this study was to investigate the effect of oxygen loss by reduction with hydrogen occurring in the conditions of vacuum plasma spraying (VPS) from commercial titanium oxide feedstock on coating microstructure, hardness, phase composition, abrasion wear resistance and electrical resistivity. The X-ray diffraction pattern showed the presence of rutile, with peaks decreasing in intensity with increasing hydrogen content in the plasma-forming gas. The intensities of the peaks showed significant deviations from those of the standard. An increase in hydrogen flow rate did not influence the coating microstructure, hardness or abrasion wear resistance, but it caused the electrical resistivity to decrease. VPS coatings prepared from commercial fused and crushed powder show a resistivity in the range of 0.01-0.1 Ohm*cm, which corresponds exactly to the range published in the literature. Comparison with results for APS- and HVOFsprayed coatings reveals that VPS coatings yield the best combination of abrasion wear resistance and electrical resistivity when commercial titanium oxide spray powder is used.
New Material Concepts for the Next Generation of Plasma-Sprayed Thermal Barrier Coatings
Authors: Stöver D. , Pracht G. , Lehmann H. , Dietrich M. , Döring J.-E. , Vaßen R. 
Published: September 2022

Abstract
For the application as a thermal barrier coating (TBC) the partially stabilized zirconia approaches some limits of performance, which hardly can be overcome in the near future. To further enhance the efficiency of gas turbines, higher temperature and a longer lifetime of the coating are needed for the next generation of TBC´s. This paper presents the development of new materials and concepts for application as TBC. Materials such as compositions with pyrochlore structure or doped zirconias are compared with new concepts like nanolayer between top- and bondcoat, metal-glass composites and double layer structures. One concept is to use new compositions in a combination with zirconia, as a double, multi or graded layer coating. In this case the benefits of zirconia will be combined with the promising properties of the new top-coating. For the concept of metal glass composites the influences of different plasma spraying processes on the microstructure are described. The quality of these coating systems are evaluated by a burner rig test.
Non-Destructive Microstructural Evaluation of Thermal Barrier Coatings by Electrochemical Impedance Spectroscopy
Authors: Vishweswaraiah S. , Jayaraj B. , Du T. , Desai V.H. , Sohn Y.H. 
Published: September 2022

Abstract
Thermal barrier coatings (TBCs) deposited either by air plasma spray (APS) or electron beam physical vapor deposition (EB-PVD) provides thermal insulation to the superalloy blades and vanes. The durability and reliability of TBCs play an important role in the service reliability and durability of hot-section components in advanced turbine engines. Development of non-destructive evaluation (NDE) techniques for quality control, lifetime monitoring and lifetime prediction of TBCs have been the focus of research for designers, manufacturers and users of the advanced turbine engines. In this work, electrochemical impedance spectroscopy (EIS) has been used as a NDE technique to evaluate the varying microstructure and chemistry of as-coated TBCs. EIS were acquired at the corrosion potential for TBCs with varying thickness, microstructure and chemistry using 0.01 M [Fe(CN)6]–3/ [Fe(CN)6]-4·3H2O electrolyte solution. Equivalent circuits corresponding to the multiplayer constituents of TBCs were then correlated to the experimental EIS data. Resistance and capacitance of various components in TBCs can provide useful information regarding the microstructure and chemistry as-coated TBCs.
Fracture Mechanics Analysis of Microcracks in Thermally Cycled Thermal Barrier Coatings
Authors: Liu Y. , Persson C. , Melin S. 
Published: September 2022

Abstract
The effects from thermal shock loading on pre-existing microcracks within thermal barrier coatings (TBCs) have been investigated through a finite element based fracture mechanical analysis. The TBC system consists of a metallic bond coat and a ceramic top coat. The rough interface between the top and bond coats holds an alumina oxide layer. Stress concentrations at the interface due to the interface roughness as well as the effect of residual stresses were accounted for. At eventual closure between the crack surfaces, Coulomb friction was assumed. To judge the risk of fracture from edge cracks and centrally placed cracks, the stress intensity factors were continuously monitored during simulation of thermal shock loading of the TBC. It was found that fracture from edge cracks is more likely than from centrally placed cracks. It was also concluded that propagation of an edge crack is initiated already during the first load cycle whereas the crack tip position of a central crack determines whether or not propagation will occur.
Analysis of Deposition Process for Composite Polymer Thermally Sprayed Coatings
Authors: Borisov Yu. , Sviridova I. , Korzhik V. , Fialko N. 
Published: September 2022

Abstract
An important factor in the process of formation of a metal-polymer coating is the effect of a high-temperature gas jet on the "coating-substrate" system, as the jet favours penetration and spread of a polymeric material over the surface of the substrate. It is this factor that makes this form of thermal spraying radically different from spraying metallic coatings. On the other hand, excessive heating of the surface can lead to oxidation and degradation of the polymeric component. Therefore, thermal phenomena taking place during the formation of thermal sprayed metal-polymeric coatings, i.e. the level and distribution of temperatures through the thickness of a coating were analysed. Based on the results of mathematical modeling, recommendations for the thermal spraying of metal-polymeric coatings (heat source speed, spraying distance, flow rate of working gases, etc.) were developed.
Microstructure and Properties of Thermally Sprayed Functionally Graded Coatings for Polymeric Substrates
Authors: Ivosevic M. , Knight R. , Kalidindi S.R. , Palmese G.R. , Sutter J.K. 
Published: September 2022

Abstract
The use of polymer matrix composites (PMC's) in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance but their useful lifetime is limited by their poor erosion resistance. High velocity oxy-fuel (HVOF) sprayed polymer/cermet functionally graded (FGM) coatings are being investigated as a method to address this technology gap by providing erosion and oxidation protection to polymer matrix composites. The FGM coating structures are based on a polyimide matrix filled with varying volume fractions of WC-Co. The graded coating architecture was produced using a combination of internal and external feedstock injection, via two computer-controlled powder feeders and controlled substrate preheating. Porosity, coating thickness and volume fraction of the WC-Co filler retained in the coatings were determined using standard metallographic techniques and computer image analysis. The pull-off strength (often refered to as the adhesive strength) of the coatings was evaluated according to the ASTM D 4541 standard test method, which measured the greatest normal tensile force that the coating could withstand. Adhesive/cohesive strengths were determined for three different types of coating structures and compared based on the maximum indicated load and the surface area loaded. The nature and locus of the fractures were characterized according to the percent of adhesive and/or cohesive failure, and the tested interfaces and layers involved were analyzed by Scanning Electron Microscopy.
Renewable energy of the EU countries in the context of risks of import dependence
Authors: KUDYRKO Liudmyla , KOROHOD Alona , BUONOCORE Maria Nicola 
Published: September 2022

Introduction. The large-scale invasion of the Russian Federation into Ukraine hastened the decision of the civilized world, in particular the EU countries, regarding the need to minimize, and in the future, completely eliminate, energy dependence on the aggressor country.
Problem. The development of mechanisms for strengthening the energy security of the importing countries includes, among a number of prerequisites, the abandonment of fossil fuels of the aggressor country. Russia's dominance in global energy markets leads to dangerous manipulations on its part in the field of European energy security.
The aim of the article is to reveal the state of dependence of the economies of the EU countries on the import of energy resources from the Russian Federation and to identify variable scenarios of refusal to finance an important strategic sector of the aggressor country due to the development of renewable energy.
Methods. Methods of analysis and synthesis, comparison, grouping and systematization, elements of institutional analysis and process approach were used.
Results. A high level of dependence of the economies of the EU countries on the import of energy carriers was identified against the background of the dominance of the Russian Federation as a priority supplier of the main types of fossil fuels. The decarbonization of the world economy and the transition to renewable energy sources is a long-term trend and a priority of the national energy strategies of the EU countries. The war of the Russian Federation against Ukraine acted as a powerful catalyst for the decarbonization of European economies. Trade relations between European states and the Russian Federation in the field of energy supply is directly related to the problem of their national security and sovereignty. The priority areas of development of the renewable energy sector of the EU are characterized.
Conclusions. The EU’s efforts to reduce the level of energy dependence on Russian fossil fuels are reflected in a set of strategic measures in the field of foreign policy and coordination of efforts at the level of global partnership. They are compatible with the medium-term objectives of achieving climate neutrality of the EU by 2050.
Prospects for further research can be seen in the assessment of the consequences of reducing the level of dependence of the economies of the EU countries on the import of energy carriers from the Russian Federation.
Система державного фінансового регулювання розвитку людського капіталу
Authors: МАКОГОН Валентина 
Published: September 2022

Вступ. На сьогодні вагомим для суспільного розвитку є завдання належного фінансового забезпечення розвитку людського капіталу. Успіх виконання цього завдання безпосередньо зале­жить від якості системи державного фінан­сового регулювання розвитку людського капіталу з урахуванням економічних трансформацій.
Проблема. Наразі активізувались питання пошуку альтернативних джерел зміцнення людського капіталу, оптимізації структури фінансового забезпечення його розвитку.
Метою статті є розкриття основних засад державного фінансового регулювання розвитку людського капіталу та обґрунтування його стра­тегічних завдань в умовах економічних трансформацій.
Методи. У дослідженні застосовано системний метод, порівняльний аналіз, наукове абстрагування, аналіз і синтез.
Результати. Визначено роль державного фінансового регулювання розвитку людського капіталу в умовах економічних трансформацій. Розкрито особливості інструментарію державного фінансового регулювання розвитку людського капіталу. Здійснено аналіз та оцінку видатків зведеного бюджету на освіту та охорону здоров’я. Розвинуто підходи щодо застосування фінансово-бюджетного інструментарію у сфері освіти та охорони здоров’я. Обґрунтовано напрями удосконалення державного фінансового регулювання розвитку людського капіталу в умовах економічних трансформацій.
Висновки. Прийняття раціональних управ­лінських рішень щодо зміни структури державних фінансових ресурсів, спрямованих на розвиток людського капіталу має базуватись не лише на оцінці тенденцій та динаміці їхнього вико­рис­тання, а й за ступенем їх обґрунтованості, враховуючи важливість забезпечення адаптивності фінансово-бюджетної політики до суспільних процесів.
Цифровізація освіти: європейський формат
Authors: ZOLOTAROVA Oksana , MEREZHKO Nina 
Published: September 2022

Bступ. Протягом останнього десятиліття перехід на цифрову освіту став одним з головних питань політики Європейського Союзу. Важливість реагування на виклики, з якими стикаються викладачі закладів вищої освіти у цифровому світі, – очевидна.
Проблема. Безпрецедентний перехід до онлайн-навчання, спричинений пандемією COVID‑19, показав реальну неготовність освітньої системи ЄС до повного переходу на веб-освіту та продемонстрував основні недоліки політики, які необхідно усунути.
Методи. Застосовано загальнонаукові методи: аналіз і синтез, порівняння, узагальнення, аналітичні та статистичні.
Результати. У Плані дій Європейської комісії з цифрової освіти на 2021–2027 рр. зазначено, що цифрові компетенції мають бути одними з основних навичок для всіх викладачів та навчального персоналу. Рада ЄС у своєму Висновку підтвердила важливість цифрових компетенцій викладачів. Європейський парламент у своїй резолюції підкреслив важливість надання фінансової підтримки для навчальних курсів і забезпечення їх доступності, щоб гарантувати, що викладачі володіють необхідними цифровими навичками. Європейська асоціація університетів наголосила на важливості дій урядів країн – членів ЄС як головних розробників політики на національному рівні щодо забез­печення фінансової та професійної підтримки персоналу університетів.
Висновки. Лише терміновий перехід до онлайн-навчання, викликаний повним закриттям освітніх закладів усіх рівнів під час COVID-19, показав реальний стан системи цифрової освіти в ЄС та з’ясував основні проблеми, які мають вирішувати політики ЄС. Визначено два стратегічні пріоритети, які варто просувати на рівні ЄС: сприяння розвитку високоефективної екосистеми цифрової освіти та підвищення цифрових навичок і компетенцій для цифрової трансформації.