bluuebunny/crossref_metadata_2025 huggingface dataset:
Vliv vybraných proměnných na environmentální gramotnost žáků 2. stupně základní školy
Authors: Svobodová Silvie
Published: July 2017

The contribution is devoted to investigating the impact of sociodemographic variables of the area on the cognitive and affective aspect of environmental literacy among 12-15 years old students in Žatec, Square 28 October 1019, district of Louny. The author tested two research instruments: MSELS and two-dimensional scales of 2-MEV on the research sample consisting from 87 respondents from 6 to 9th grades of these school. The study presents the results regarding the influence of gender, domicile, age of the respondents and their leisure time activities on the measured figures of environmental knowledge and proenvironmental attitudes. The relation between the knowledge and the attitudes was identified not too tight in contrast to medium-strong positive correlation between the two factors of 2- MEV scales. In the case of sex and place of residence (village/city) no significant effect was proved, either in one of the aspects. The identical conclusions were confirmed concerning the age of respondents, and leisure time activities in relation to their knowledge. However, talking about attitudes there was a significant effect of both determinants. Leisure time outdoor and sports activities in the nature manifested the most positive influence on the affective component. Even if these results are not representative, the new research questions for wider survey are offered in the conclusions.
The moderating role of self-regulated learning in job characteristics and attitudes towards web-based continuing learning in the airlines workplace
Authors: Lin Xiao-Fan , Liang Jyh-Chong , Tsai Chin-Chung , Hu Qintai
Published: July 2017

With the increasing importance of adult and continuing education, the present study aimed to examine the factors that influence continuing web-based learning at work. Three questionnaires were utilised to investigate the association of the job characteristics from Karasek et al.’s (1998) job demand-control-support model and the self-regulated learning with web-based continuing learning; exploratory factor analyses indicate their adequate reliability and validity. A sample of 203 employees of an airline company completed three questionnaires. The path analysis reveals that job demands did not have any significant correlation with any other variables. However, job control, social support and self-regulated learning constituted signiﬁcant predictors of attitudes towards web-based continuing learning. Furthermore, self-regulated learning mediated job characteristics and attitudes. In conclusion, this is one of the few studies to consider perceptions of both personal online learning (i.e., self-regulated learning and attitudes towards web-based continuing learning) and work-related variables (i.e., job characteristics). The study advances interdisciplinary perspectives on education, information and communications technology and psychology, which has implications for continuing adult education and successful implementation of online workplace learning.
A comprehensive investigation of TPACK within pre-service teachers’ ICT profiles: Mind the gap!
Authors: Tondeur Jo , Scherer Ronny , Siddiq Fazilat , Baran Evrim
Published: July 2017

This study aims to identify profiles of pre-service teachers in order to explore their readiness to integrate technology in education. The assumption is that pre-service teacher characteristics such as technological pedagogical content knowledge (TPACK), go together with the influence of their teacher training. Specifically, this study examines whether pre-service teachers can be clustered on the basis of their TPACK, a typical set of ICT-related characteristics (e.g., general ICT attitudes, attitudes towards ICT in education, ease of use, ICT self-efficacy), and the perceived support at their training institution to adequately integrate ICT in education. Data were collected from a sample of 688 last-year pre-service teachers in 18 teacher training institutions in Flanders (the Dutch-speaking part of Belgium). Using correlational and latent profile analysis, the results suggest that: (1) two profiles can be distinguished, (2) TPACK and other individual ICT-related characteristics are positively correlated, and (3) pre-service teachers in a profile with strong TPACK, attitudes, and self-efficacy scores also report high scores on the support they perceive at their teacher training institution. Implications for the role of teacher training institutions are discussed with a specific focus on how to close the gap between the two identified profiles.
Eliciting teachers’ technological pedagogical knowledge
Authors: Heitink Maaike , Voogt Joke , Fisser Petra , Verplanken Liesbet , Van Braak Johan
Published: July 2017

This paper starts from the understanding that teachers’ knowledge is situated, grounded in knowledge derived from formal training and from experiences in practice. Based on this understanding we examine teachers’ reasoning in relation to the pedagogical choices teachers make while using ICT in practice. We argue that teachers’ reasoning about pedagogy elicits their technological pedagogical knowledge (TPK). Data from 29 video cases show how elementary teachers used ICT to facilitate specific pedagogical strategies (e.g., activating learning, classroom management, dealing with diversity, fostering learning strategies). Findings indicate that teachers used ICT mostly to promote activation of learning. Many teachers reasoned about using ICT for adapting their teaching to student needs, but this was seldom observed in practice. The few teachers who showed behaviour supporting adaptive teaching and fostering learning strategies almost always used ICT to facilitate these pedagogical strategies. We argue that for effective teaching with ICT it is important that teachers learn to reason explicitly about how ICT can support specific pedagogical strategies. The results from this study provide suggestions for what is needed in teacher education programs and professional development initiatives to support teachers in acquiring TPK.
Resetting educational technology coursework for pre-service teachers: A computational thinking approach to the development of technological pedagogical content knowledge (TPACK)
Authors: Mouza Chrystalla , Yang Hui , Pan Yi-Cheng , Yilmaz Ozden Sule , Pollock Lori
Published: July 2017

This study presents the design of an educational technology course for pre-service teachers specific to incorporating computational thinking in K-8 classroom settings. Subsequently, it examines how participation in the course influences pre-service teachers' dispositions and knowledge of computational thinking concepts and the ways in which such knowledge can be combined with content and pedagogy to promote meaningful student outcomes. Data were collected from a self-reported survey and case reports focusing on the design, implementation, and outcomes of computational thinking related lessons in K-8 classrooms. Results indicated that the course positively influenced pre-service teachers’ knowledge of computational thinking concepts, tools, and practices. Yet, some participants demonstrated only surface understanding of computational thinking and were unable to design lessons that meaningfully integrated computational thinking concepts and tools with disciplinary content and pedagogy. Findings have implications for the design of teacher education experiences that help prepare pre-service teachers develop technological pedagogical content knowledge in relation to computational thinking concepts and practices.
Editorial 33(3): TPCK/TPACK research and development: Past, present, and future directions
Authors: Harris Judith B , Phillips Michael , Koehler Matthew J , Rosenberg Joshua M
Published: July 2017

Scholarship addressing technological pedagogical content knowledge (TPCK or TPACK) has examined how to develop, apply, and assess it in diverse educational settings and content areas. During the last 12 years, multiple ways to understand this knowledge and support its development have emerged, generating approximately 1,200 publications that utilise the construct, impacting the practice of postsecondary faculty, administrators, and others invested in meaningful educational uses of technology. Perhaps inevitably, TPACK’s enthusiastic reception and rapid dissemination have generated multiple points of divergence, which in turn need further study; especially the construct's accurate measurement and validation; how to assist preservice and in-service teachers' TPACK development; contextual influences upon teachers' TPACK; and the relationship of TPACK-based knowledge to teachers' decision-making and action. Given the widespread diffusion of TPACK, research focusing on these and related issues will help to determine the direction of future post-secondary learning and teaching with technologies. Therefore, this special issue of AJET addresses future directions in TPCK/TPACK research and development.
Towards freedom and social awareness: Hopeful narratives and performatives in American theatre and literature
Authors: Lacko Ivan
Published: July 2017

The paper addresses the complexity of social issues in contemporary American society through the prism of its reflection in theatre and literature. The characteristic features of American narratives and performatives are freedom and an almost utopian belief in diversity and social understanding. At the same time, the discussed works present a comprehensive look at social issues using a great variety of forms and genres, and appealing to the aesthetic sensitivity of different groups of recipients. In the face of future problems in the political arena, American art offers an interesting transatlantic perspective on the complexity of 21st-century issues which are relevant all over the world.
Protected values and the meaning of life in Marilynne Robinson’s novel Gilead
Authors: Hricková Mária
Published: July 2017

The paper examines the protected values in Marilynne Robinson’s Pulitzer Prize winning novel Gilead (2004). The aim of the study is to show the significance of three major values, namely faith, family and education. It also attempts to suggest how complexly these values interrelate and eventually represent the central tenets of the life worth living.
Upper Homerian (Silurian) high-resolution correlation using cyclostratigraphy: an example from western Lithuania
Authors: Radzevičius Sigitas , Tumakovaitė Brigita , Spiridonov Andrej
Published: July 2017

The Gėluva regional stage stratigraphically corresponds to the late Wenlock. This time interval witnessed significant graptolite extinctions and turnovers of conodont faunas, as well as a large positive Mulde carbon isotopic excursion. Thus, the development of a detailed stratigraphy is a necessary step in understanding the complex patterns of regional and global variations in the sediments accumulating during the time interval studied. Therefore, in this contribution we present a cyclostratigraphic analysis of gamma ray (GR) logs from four wells, which are located in the deep water facies belt of the Lithuanian part of the Silurian Baltic Basin of the Gėluva regional stage. The analysis was performed using REDFIT spectral estimation, continuous wavelet transform and signal filtering techniques. As a result two 4thorder and five 5thorder cycles were distinguished and named in all sections. The correlation of cycles between sections was calibrated with the graptolite biozones. The comparative analysis revealed that intra-basinal cyclostratigraphic correlation could achieve resolution of the order of several tens of thousands of years.
A unique fossil record from neptunian sills: the world’s most extreme example of stratigraphic condensation (Jurassic, western Sicily)
Authors: Wendt Jobst
Published: July 2017

Neptunian sills at Rocca Busambra, a fragment of the Trapanese/Saccense Domain in western Sicily, host the most abundant ammonite and gastropod fauna which has ever been recorded from the Jurassic of the western Tethys. The fauna is dominated by parautochthonous organisms which were swept into the sills by gentle transport. Ammonites are characterized by perfect preservation and small size, a feature which is due to the predominance of microconchs but also of stunting. The most complete sill is 0.7 m thick and could be separated into 17 levels which range in age from the early Toarcian into the late Kimmeridgian, thus representing the most extreme case of palaeontologically and depositionally documented stratigraphic condensation in Earth history. The unique feature of the Rocca Busambra sills is due to the interaction of three processes: extreme stratigraphic condensation on the sea floor, weak tectonic fracturing of the host rock and repeated reopening on top of already existing sills. Contrasting percentages of gastropods in individual levels reflect sea-level oscillations which correspond to long known low- and highstands during the Jurassic of the western Tethys. Comparisons with other ammonite-bearing sill faunas reveal several similarities, but represent only short-timed phases of tectonic pulses and deposition.
Analysis of Thermal Stresses and Strains Developing during the Heat Treatment of Windmill Shaft
Authors: Cebo-Rudnicka A. , Malinowski Z. , Telejko T.
Published: July 2017

In the paper the results of evaluation of the temperature and stress fields during four cycles of the heat treatment process of the windmill shaft has been presented. The temperature field has been calculated from the solution to the heat conduction equation over the whole heat treatment cycles of the windmill shaft. To calculate the stress field an incremental method has been used. The relations between stresses and strains have been described by Prandtl-Reuss equation for the elastic-plastic body. In order to determine the changes in the temperature and stress fields during heat treatment of the windmill shaft self-developed software utilizing the Finite Element Method has been used. This software can also be used to calculate temperature changes and stress field in ingots and other axially symmetric products. In the mathematical model of heating and cooling of the shaft maximum values of the strains have been determined, which allowed to avoid the crack formation. The critical values of strains have been determined by using modified Rice and Tracy criterion.
The Influence of the Angle of the Working Part of the Die on the High Speed Drawing Process of Low Carbon Steel Wires
Authors: Suliga M. , Wartacz R. , Michalczyk J.
Published: July 2017

The paper contains the theoretical and experimental analysis of the impact of the drawing angle on the drawing process and the properties of low carbon steel wires. A multi-stage drawing wire rod with a diameter of 5.5 mm on a wire with a diameter of 1.0 mm has been carried out in two stages. The first one consisted of preliminary drawing wire rod for the wire with a diameter of 2.2 mm which was next subjected to the drawing process at a speed of 25 m/sec at the final wire with a diameter of 1.0 mm. The wires were drawn in conventional dies with drawing angle α = 3, 4, 5, 6, 7 degrees.

For the wires drawn in respective variants, the investigation of the mechanical properties was performed and the amount of lubricant on the surface of steel wires was determined. Numerical analysis of the process of drawing in the Drawing 2D complemented the experimental studies.

It has been shown that when drawing at high speeds, properly chosen the value of the angle of the working part of the die can improve the lubrication conditions and mechanical properties of steel wires.
Physical Modeling of Plastic Working Conditions for Rods of 7xxx Series Aluminum Alloys
Authors: Dyja H. , Tussupkaliyeva E. , Bajor T. , Laber K.
Published: July 2017

The continuing high level of demand for lightweight structural materials is the reason for the ever-growing interest in aluminum alloys. The main areas of application for aluminum alloys products are the aerospace and automotive industries. Production of profiles and structural elements from lightweight alloys gives possibility to reduce the curb weight of construction, which directly translates into among other reduction of fuel consumption and lower amount of generated exhaust gas.

Determination of heat treatment and plastic working parameters to obtain the required mechanical properties of the manufactured products is a complex process that requires among others knowledge of the material behavior during the deformation process. To carry out the study the torsion plastometer STD 812 was used. On the basis of obtained results of the research the value of the yield stress, formability limit and the thermal effect of the deformed 7xxx series aluminum alloy were specified for different schemes and conditions of deformation.
Electrical and Thermal Properties of Na1–xLixNbO3 (x = 0.08, 0.1 and 0.2) Ceramics Near the Morphotropic Phase Boundary Region
Authors: Konieczny K. , Czaja P.
Published: July 2017

Na1-xLixNbO3ceramics (for x = 0.08, 0.1, 0.2) were fabricated by the conventional solid state reaction method. The influence of LiNbO3on the microstructure, electric, thermal properties of Na1-xLixNbO3ceramics was studied and a significant influence of doped Li ions on the electrical properties was observed. The electrical properties were improved and are described as the best for x = 0.1 (near a morphotropic phase boundary) Na1–xLixNbO3solid solutions. After crossing the morphotropic phase boundary for x = 0.2, the electric properties are getting worse. These types of solid compounds show some interesting properties suitable for practical applications.
Investigation of Stress Corrosion Cracking in Magnesium Alloys by Quantitative Fractography Methods
Authors: Sozańska M. , Mościcki A. , Chmiela B.
Published: July 2017

The article shows that the use of quantitative fracture description may lead to significant progress in research on the phenomenon of stress corrosion cracking of the WE43 magnesium alloy. Tests were carried out on samples in air, and after hydrogenation in 0.1 M Na2SO4 with cathodic polarization. Fracture surfaces were analyzed after different variants of the Slow Strain Rate Test. It was demonstrated that the parameters for quantitative evaluation of fracture surface microcracks can be closely linked with the susceptibility of the WE43 magnesium alloy operating under complex state of the mechanical load in corrosive environments. The final result of the study was the determination of the quantitative relationship between Slow Strain Rate Test parameters, the mechanical properties, and the parameters of the quantitative evaluation of fracture surface (microcracks).
Digital Material Representation Model of Porous Microstructure Based on 3D Reconstruction Algorithm
Authors: Madej Ł. , Mojżeszko M. , Chrapoński J. , Roskosz S. , Cwajna J.
Published: July 2017

Development of the Digital Material Representation (DMR) model, based on 3D reconstruction algorithm and serial sectioning, is the main goal of the present paper. Details on the serial sectioning and image processing algorithms are presented first. Serial sectioning is realized on the basis of light microscopy (LM). Then concept of 3D reconstruction and developed algorithms are presented. Two approaches, based on shape coefficients and the flood fill algorithms, are developed to identify corresponding features on subsequent 2D images. Then, the interpolation algorithm to reconstruct 3D volume between 2D images is presented. Finally, obtained 3D model is an input for finite element mesh generation software for subsequent finite element calculations.
Metallographic Study and Repeatability Analysis of γ' Phase Precipitates in Cored, Thin-Walled Castings Made from IN713C Superalloy
Authors: Szczotok A. , Pietraszek J. , Radek N.
Published: July 2017

The study describes the influence of a surface modification in cored, thin-walled castings of blades from IN-713C nickel superalloy onγ'phase precipitates. The blades were produced by using the investment casting process in the laboratory conditions as parts for a low-pressure turbine rotor. The microstructural observations of theγ'phase precipitates on the cross sections of the blades were performed. The observations were followed by quantitative metallography evaluation, and finally, a comparison of the precipitates between one blade with the conventionally applied ceramic core and one with the core covered layer contained a surface modifier (5% of CoAl2O4) was made.
The Multicomponent PZT-type Ceramics for Micromechatronic Applications
Authors: Bochenek D. , Niemiec P. , Adamczyk M. , Skulski R. , Zachariasz R. , Wodecka-Duś B. , Machnik Z.
Published: July 2017

In the paper two compositions of the multi-component PZT-type ceramics admixtures by Mn4+, Sb3+, W6+, Ni2+were presented. The ceramic powders were synthesized by the calcination of powders while their densification was carried out by free sintering method. The dielectric, ferroelectric, piezoelectric studies and DC electrical conductivity of the multicomponent PZT-type samples were presented. The results of the multi-component ceramics predispose these type materials in micromechatronic and microelectronic applications for example as element of the actuators.
Statistical Assessment of the Microstructure of Barite Aggregate from Different Deposits Using X-Ray Microtomography and Optical Microscopy
Authors: Żołek N. , Ranachowski Z. , Ranachowski P. , Jóźwiak-Niedźwiedzka D. , Kudela S. , Dvorak T.
Published: July 2017

Two different barite ore (barium sulfate BaSO4) specimens from different localizations were tested and described in this paper. Analysis of the microstructure was performed on polished sections, and on thin sections using X-ray microtomography (micro-CT), and optical microscopy (MO). Microtomography allowed obtaining three-dimensional images of the barite aggregate specimens. In the tomograms, the spatial distribution of the other polluting phases, empty space as well as cracks, pores, and voids – that exceeded ten micrometers of diameter-were possible to visualize. Also, the micro-CT allowed distinguishing between minerals of different density, like SiO2and BaSO4. Images obtained and analyzed on thin sections with various methods using the optical microscopy in transmitted light delivered additional information on the aggregate microstructure, i.e. allow for estimation of the different kinds of inclusions (like the different density of the minerals) in the investigated specimens. Above methods, which were used in the tests, completed each another in order to supply a set of information on inclusions’ distribution and to present the important differences of the barite aggregate specimens microstructure.
Corrosion Resistance of Some Stainless Steels in Chloride Solutions
Authors: Kasprzyk D. , Stypuła B.
Published: July 2017

The present work compares corrosion behaviour of four types of S30403, S31603, S32615 austenitic and S32404 austenitic-ferritic stainless steels in chloride solutions (1%, 3% NaCl) and in Ringer solution, at 37°C temperature. Corrosion resistance was determined by potentiodynamic polarization measurements and a thirty day immersion test conducted in Ringer solution. The immersion test was performed in term of biomedical application. These alloy were spontaneously passivated in all electrolytes, wherein S30403, S31603 and S32404 undergo pitting corrosion. Only S32615 containing 5.5% Si shows resistance to pitting corrosion.
Formalization of Technological Knowledge in the Field of Metallurgy using Document Classification Tools Supported with Semantic Techniques
Authors: Regulski K.
Published: July 2017

The process of knowledge formalization is an essential part of decision support systems development. Creating a technological knowledge base in the field of metallurgy encountered problems in acquisition and codifying reusable computer artifacts based on text documents. The aim of the work was to adapt the algorithms for classification of documents and to develop a method of semantic integration of a created repository. Author used artificial intelligence tools: latent semantic indexing, rough sets, association rules learning and ontologies as a tool for integration. The developed methodology allowed for the creation of semantic knowledge base on the basis of documents in natural language in the field of metallurgy.
Modelling of the Working Process of Vibratory Conveyors Applied in the Metallurgical Industry
Authors: Bednarski Ł. , Michalczyk J.
Published: July 2017

The suitability of the currently used vibratory transport models for the case of applying the vibratory conveyors in the metallurgical industry, was analysed in the hereby paper. It was found that these models, due to not taking into account an influence of the air flow through the feed layer, do not usually correspond with conditions occurring in this industry. The analysis of the productivity of vibratory conveyors applied in the metallurgical industry should include an influence of dusty and powdery fractions present in transported materials, since the air flow resistance can cause-in such cases-a significant decrease of the transport velocity. The mathematical and simulation model of the feed, taking into account the influence of the air flowing through the feed, was formulated in the study. Its compatibility with experimental investigations was also pointed out.
Energy-Based Yield Criteria for Orthotropic Materials, Exhibiting Strength-Differential Effect. Specification for Sheets under Plane Stress State
Authors: Szeptyński P.
Published: July 2017

A general proposition of an energy-based limit condition for anisotropic materials exhibiting strength-differential effect (SDE) based on spectral decomposition of elasticity tensors and the use of scaling pressure-dependent functions is specified for the case of orthotropic materials. A detailed algorithm (based on classical solutions of cubic equations) for the determination of elastic eigenstates and eigenvalues of the orthotropic stiffness tensor is presented. A yield condition is formulated for both two-dimensional and three-dimensional cases. Explicit formulas based on simple strength tests are derived for parameters of criterion in the plane case. The application of both criteria for the description of yielding and plastic deformation of metal sheets is discussed in detail. The plane case criterion is verified with experimental results from the literature.
The Mechanism of Redox Reaction between Palladium(II) Complex Ions and Potassium Formate in Acidic Aqueous Solution
Authors: Wojnicki M. , Podborska A.
Published: July 2017

The kinetics studies of redox reaction between palladium(II) chloride complex ions and potassium formate in acidic aqueous solutions was investigated. It was shown, that the reduction reaction of Pd(II) is selective in respect to Pd(II) complex structure. The kinetic of the process was monitored spectrophotometrically. The influence of chloride ions concentration, Pd(II) initial concentration, reductant concentration, ionic strength as well as the temperature were investigated in respect to the process dynamics. Arrhenius equation parameters were determined and are equal to 65.8 kJ/mol, and A = 1.12×1011s−1.
Analysis of Selected Properties 100CrMnSi6-4 Surface Layer after Laser Micro-Smelting
Authors: Napadłek W.
Published: July 2017

The use of laser ablation phenomenon with the “thermal effect” to produce surface textures, mainly lubricant micro-containers in the form of spherical micro-bowls in the surface layer of 100CrMnSi6-4 alloy of bearing steel. This is interesting research topic. The application the local (zonal) laser hardening of the steel surface layer on the surface of the bearing raceway or casts gives technological opportunities to deploy those technologies in the production process. The article presents the selected results of the own laboratory studies of hardness, microstructure and surface stereometry bearing steel 100CrMnSi6-4 in different states after volume hardening and low tempering, as well as those obtained as a result of laser surface texturing and laser pulsed hardening. The study results can be used to modify the surface layer of 100CrMnSi6-4 bearing steel and in the nearest future use ablative laser texturing of the rolling bearings treadmill surface in the production of lubricanting micro-containers, for improving the wear resistance tribological pair of roller – raceway in the friction conditions.
Analysis of Thermal Stability of CrCN Coatings Deposited on Nitrided Substrates Using Modulated Temperature Thermodilatometry
Authors: Mydłowska K. , Myśliński P. , Szparaga Ł. , Ratajski J. , Gilewicz A. , Jędrzejewski R.
Published: July 2017

The aim of the research was to investigate the influence of nitriding of the substrate made of 42CrMo4 steel on thermal stability of the antiwear CrCN coating deposited on its surface using Cathodic Arc Evaporation method. Samples of non-nitrided and nitrided substrate/CrCN coating systems were tested with Modulated Temperature Thermodilatometry, which program included system annealing in 26 h, temperature of 290°C and argon atmosphere. Recorded during tests, changes in substrate elongation in response for changes of sample temperature, enabled qualitative determination of changes in stress states in the coatings as a result of samples annealing. Annealing of the system with nitrided substrate resulted in smaller change in residual stress in coating than for the system with non-nitrided substrate, which can indicate its better thermal stability. Values of residual stresses in coatings calculated by sin2ψ method before and after annealing on the basis of tests performed using X-Ray diffraction, agree with results of dilatometric tests.
The Influence of Thermal Expansion of Unbonded Foundry Sands on the Deformation of Resin Bonded Cores
Authors: Svidró J. , Diószegi A. , Tóth L. , Svidró J.T.
Published: July 2017

Depending on the preparation and the applied materials, moulds and cores can be of high rigidity or can be flexible. Although, chemically bonded moulding materials have relatively good flexibility, their high temperature behaviour determines the dimensional accuracy, the stresses in the castings and can induce several casting defects, such as rattail, veining, etc. The phenomenon is based on two major effects: the thermal expansion of the unbonded foundry sands and the deformation of the sand mixtures. The main objective of the present work was to study the relationship between these two effects, and to improve the knowledge related to the thermo-mechanical interactions between the casting and the mould. Dilatometric analysis of unbonded sand samples were performed and compared to the results of hot distortion tests of moulding mixture specimens. The results showed, that the thermal expansion of foundry sand largely influences the hot distortion behaviour, but depending on the type of binder used.
Effect of Hydrostatic Pressure on Thermodynamic Properties of NiTi Shape Memory Alloy
Authors: Tatar C. , Yildirim Z. , Kaygili O.
Published: July 2017

The effect of hydrostatic pressure and different heating/cooling rates on physical properties and microstructure of NiTi shape memory alloy has been investigated. The transformation temperatures and physical properties of the alloy have changed with applied pressure. It has been clearly seen from Differential Scanning Calorimetry (DSC) that with the increase of applied pressure, whileAsandAf, andMftransformation temperatures decrease,Msvalue increase. Moreover, based on the increase of the pressure amount applied on the sample, there was an average increase of 48% for Gibbs free energy and 18% for elastic strain energy. Entropy of the alloys decreases depending on the increase in the amount of applied pressure for all heating rates. Depending on the amount of applied pressure on the sample, an interior strain of 0.177% at most was observed. With the increase of applied pressure on the sample, it was determined that activation energy increased. Additionally, the Scanning Electron Microscopy (SEM) images of the samples show that the grain sizes of the unpressured sample and the samples on which pressure is applied are between 40 and 120 μm, which was determined by Image Analysis Method.
Structural, Mechanical and Thermodynamic Properties under Pressure Effect of Rubidium Telluride: First Principle Calculations
Authors: Bidai K. , Ameri M. , Ameri I. , Bensaid D. , Slamani A. , Zaoui A. , Al-Douri Y.
Published: July 2017

First-principles density functional theory calculations have been performed to investigate the structural, elastic and thermodynamic properties of rubidium telluride in cubic anti-fluorite (anti-CaF2-type) structure. The calculated ground-state properties of Rb2Te compound such as equilibrium lattice parameter and bulk moduli are investigated by generalized gradient approximation (GGA-PBE) that are based on the optimization of total energy. The elastic constants, Young’s and shear modulus, Poisson ratio, have also been calculated. Our results are in reasonable agreement with the available theoretical and experimental data. The pressure dependence of elastic constant and thermodynamic quantities under high pressure are also calculated and discussed.
Using an Interdigital Micromixer for Separation of In3+ from Zinc Hydrometallurgical Process with D2EHPA as an Extractant
Authors: Li C. , Jiang F. , Ju S. , Peng J. , Wei Y. , Zhang L.
Published: July 2017

Experiments were performed in an interdigital micromixer with 30 microchannels (40 μm width of each channel) to separate In3+, Fe3+and Zn2+from sulfate solutions using Di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. The effects of pH, extractant concentration and flow rate on the extraction efficiency and flow rate on mass transfer coefficient of In3+, Fe3+and Zn2+were investigated. At a phase flow rate of 7.0 mL/min and initial solution pH of 0.423, the extraction efficiency of In3+, Fe3+and Zn2+was 99.29%, 3.43% and 2.54%, respectively and mass transfer coefficient of In3+, Fe3+and Zn2+was 144.307 s−1, 1.018 s−1and 0.750 s−1. Then, the loaded organic phase was stripped in an interdigital micromixer. At a phase flow rate of 9.0 mL/min and HCl concentration of 160 g/L, stripping efficiency of In3+was 98.92% and mass transfer coefficient of In3+was 169.808 s−1, while concentration of Fe3+and Zn2+was lower than 0.005 g/L with good separation of In3+from Fe3+and Zn2+.
Selected Problems of the Microstructure Evolution During Microalloyed Steel Wire Rod Production Process
Authors: Kwiecień M. , Graca P. , Muszka K. , Majta J.
Published: July 2017

In the present study, we have discussed the selected problems of microstructure development during the whole manufacturing process, i.e. continuous casting, thermomechanical processing, and cold metal forming of the microalloyed steels wires. In the investigated steels, the microstructure development was controlled by the history of deformation and by the effects of microalloying elements, mostly Nb, Ti, and B. It has been concluded that obtained in the ultrafine grained microalloyed steel wires mechanical properties were first of all resulting from specific structural composition and grain refinement. Additionally, it has been proven that austenite grain refinement, that increases nucleation rate during the austenite-to-ferrite phase transformation, as a result of the thermomechanical processing, are very beneficial from point of view of the final mechanical properties. This problem starts to be very important when the microalloyed steel products are subjected to severe plastic deformation, as it has been shown discussed in the present work for combined processes of wire drawing and wire flattening.
Double Fillet Welding of Carbon Steel T-Joint by Double Channel Shielding Gas Metal Arc Welding Method Using Metal Cored Wire
Authors: Mert T. , Gultekin N. , Karaaslan A.
Published: July 2017

Low carbon steel material and T-joints are frequently used in ship building and steel constructions. Advantages such as high deposition rates, high quality and smooth weld metals and easy automation make cored wires preferable in these industries. In this study, low carbon steel materials with web and flange thicknesses of 6 mm, 8 mm and 10 mm were welded with conventional GMAW and double channel shielding gas metal arc welding (DMAG) method to form double fillet T-joints using metal cored wire. The difference between these two methods were characterized by measurements of mean welding parameters, Vickers hardness profiles, weld bead and HAZ geometry of the joints and thermal camera temperature measurements. When weld bead and HAZ geometries are focused, it was seen filler metal molten area increased and base metal molten area decreased in DMAG of low carbon steel. When compared with traditional GMAW, finer and acicular structures in weld metal and more homogenous and smaller grains in HAZ are obtained with double channel shielding gas metal arc welding.
Recent Developments on Discontinuous Precipitation
Authors: Zięba P.
Published: July 2017

The discontinuous precipitation (DP) belongs to a group of diffusive solid state phase transformations during which the formation of a new phase is heterogeneous and limited to a migrating reaction front (RF). The use of analytical electron microscopy provided reliable information that there is no differences in the diffusion rate at the stationary grain boundary and moving RF of DP reaction. On the other hand, the use of “in situ” transmission electron microscopy observations indicated the importance of stop-go motion or oscillatory movement of the RF.

During 2004-2016 period more or less 280 papers were published in which the terms “discontinuous precipitation, “cellular precipitation”, discontinuous coarsening” appeared either in the abstract or in key-words.

In the present contribution, the research on the DP reaction will be reviewed taking into account new aspects of theories and modelling, new evidences and findings, effect of various factors including third element, external stresses, plastic deformation and GB orientation, occurrence in less known systems and alloys like: superalloys, nitrided Fe-based alloys and Cu-based alloys. Finally, some suggestions for the future research will be formulated.
Solvent Extraction of Co, Ni and Mn from NCM Sulfate Leaching Solution of Li(NCM)O2 Secondary Battery Scraps
Authors: Hong Hyun Seon , Kim Dae Weon , Choi Hee Lack , Ryu Sung-Soo
Published: July 2017

As a part of the study on recycling Li(NCM)O2lithium-ion battery scraps, solvent extraction experiments were performed using different extraction agents such as PC88A, Cyanex272 and D2EHPA to separate Co, Ni and Mn from the leaching solution. When the ratio of Mn to Ni was about 0.4 in the leaching solution, the separation factor for Co and Mn was found to be less than 10 so that the separation of Co and Ni was insufficient. When solvent extraction was done using the solution with the lower Mn/Ni ratio of 0.05 where Mn was removed by potassium permanganate and chlorine dioxide, more than 99% of Mn could be extracted through five courses of extraction using 30vol% D2EHPA while the extraction rates of Co and Ni were around 17% and 11%, respectively. In the case that Mn was removed from the solution, the extraction rate of Co was higher than 99% whereas less than 7% Ni was extracted using Cyanex272 suggesting that Co and Ni elements were effectively separated.
Development of Crack Detection Method with 2 Dimensionally Generated 3 Dimensionally Reconstructed Images in THT Solder Joints
Authors: Gergely G. , Koncz-Horváth D. , Weltsch Z. , Gácsi Z.
Published: July 2017

This work represents an interesting development in the detection and interpretation of crack evolution in through hole technology (THT) solder joints, which based on the development of general and common method. Serial sectioning is a useful method because it overcomes the problems associated with traditional two-dimensional metallographic techniques by providing information about (micro)structures in three-dimensions.

In our work, serials sectioning with reconstruction method was utilized to visualize the 3D nature of cracks in through hole solder joint. Accurate quantitive analysis of the cracks, such as crack length, position and extension are presented with a help of the developed method: newly defined parameter and serial-cross sectioning method.
Fabrication of AZ31/CNT Surface Nano-Composite by Double-Pass Friction Stir Processing
Authors: Kim Jae-Yeon , Hwang Jung-Woo , Kim Hye-Young , Lee Seung-Mi , Jung Woo-Sang , Byeon Jai-Won
Published: July 2017

Double-pass Friction Stir Processing (FSP) was applied to fabricate an AZ31/CNT nano-composite for surface hardening of lightweight structural components. The effects of double-pass FSP as well as groove depth (i.e., volume fraction of CNT) on the CNT distribution, dynamically recrystallized grain size, and resulting microhardness were studied. Double-pass FSP was performed for the CNT-filled plate-type specimen with different groove depths of 2, 3, and 4 mm. By applying double-pass FSP, the average size of CNT clusters decreased, implying a more homogeneous distribution. Compared with the FSPed specimen without CNT, grain size was refined from 19 μm to 3 μm and microhardness increased from 52 Hv to 83 Hv (i.e., 71% increase).
Investigation of Multicomponent Lead-Free Solders
Authors: Gyenes A. , Benke M. , Teglas N. , Nagy E. , Gacsi Z.
Published: July 2017

According to the directives (RoHS and WEEE) adopted by the European Union, lead has been banned from the manufacturing processes because of its health and environmental hazards. Therefore, the development of lead-free solders is one of the most important research areas of the electronic industry. This paper investigates multicomponent Sn-Ag-Cu based lead-free solders with different compositions. The properties of the six-component Innolot (SAC+BiSbNi) and two low-Ag containing alloys were compared with the widespread used SAC307 solder. Microstructure investigations and X-ray diffraction measurements were performed to analyze and identify the formed phases, furthermore, tensile tests and microhardness measurements were executed to determine the mechanical properties of the examined solders.
High-Temperature Oxidation Behavior and Kinetics of Forged 12Cr-MoVW Steel
Authors: Kim Yong Hwan , Oak Jeong-Jung , Bae Ki-Chang , Lee Wook Jin , Park Yong Ho
Published: July 2017

The oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2) atmosphere at 873-1073 K (Δ50 K) using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K) for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr)2O3.
Carbon Co-Deposition During Gas Reduction of Water-Atomized Fe-Cr-Mo Powder
Authors: Ali B. , Choi S.H. , Seo S.J. , Maeng D.Y. , Lee C.G. , Kim T.S. , Park K.T.
Published: July 2017

The water atomization of iron powder with a composition of Fe-3Cr-0.5Mo (wt.%) at 1600°C and 150 bar creates an oxide layer, which in this study was reduced using a mixture of methane (CH4) and argon (Ar) gas. The lowest oxygen content was achieved with a 100 cc/min flow rate of CH4, but this also resulted in a co-deposition of carbon due to the cracking of CH4. This carbon can be used directly to create high-quality, sinter hardenable steel, thereby eliminating the need for an additional mixing step prior to sintering. An exponential relationship was found to exist between the CH4gas flow rate and carbon content of the powder, meaning that its composition can be easily controlled to suit a variety of different applications.
Preparation of Submicroscale Ag-Coated Cu Particles by Multi-Step Addition of Ag Plating Solution and Antioxidation Properties for Different Ag Shell Thicknesses
Authors: Choi Eun Byeol , Lee Jong-Hyun
Published: July 2017

For application as a low-cost conductive filler material, submicroscale Cu@Ag particles were fabricated at room temperature without any reductants by a multi-step addition method using an ethylene glycol-based Ag plating solution. Scanning electron microscopy images of the Ag-coated Cu particles demonstrated the formation of discrete Ag particles less than 100 nm in size as well as a thin Ag coating on Cu particles, during the early addition steps. However, as the thickness of the Ag coating increased, the small Ag particles agglomerated into Ag coatings with an increase in the number of Ag plating steps. Owing to the absence of additives such as surfactants, a comparison between the microstructural images and calculations indicated increased agglomeration between fabricated Ag-coated Cu particles with an increase in the number of Ag plating steps. However, thermogravimetric-differential scanning calorimetry of the agglomerated Ag-coated Cu particles after the fifth addition of the Ag plating solution demonstrated their antioxidation behavior even after 70 min in air at 150°C.
Recycling of Gallium from End-of-Life Light Emitting Diodes
Authors: Nagy S. , Bokányi L. , Gombkötő I. , Magyar T.
Published: July 2017

Nowadays Light Emitting Diodes (LEDs) are widely utilized. They are applied as backlighting in Liquid Crystal Displays (LCD) and TV sets or as lighting equipments in homes, cars, instruments and street-lightning. End of life equipments are containing more and more LEDs. The recovery of valuable materials – such as Ga, Au, Cu etc. – from the LEDs is essential for the creating the circular economy. First task is the development of a proper recycling technology. Most of the researchers propose fully chemical or thermal-chemical pathway for the recycling of LEDs.

In the meantime our approach based on the thorough investigation of the structure and composition of LEDs, and shown in this paper, is the combination of mechanical and chemical techniques in order to recover more valuable products, as well as to facilitate the mass transfer. Our laboratory scale experiments are introduced, the final aim of which is Ga recovery in accordance with our above approach. It was experimentally proved that the LED chips contain Ga and can be recovered by mechanical processes along with copper-product. Ga is presented on the surface of the chips in GaN form. Mechano-chemical activation in high energy density stirred medium mill and the following acidic leaching resulted in the enrichment of 99.52% of gallium in the pregnant solution.
Magnetic Properties of (Nia-Znb)X Cu1-X Ferrite Nanoparticle Fabricated by Sol-Gel Process
Authors: Yang S. , Kim J.-Gon.
Published: July 2017

In future, more mobile devices with different frequencies will be used at the same time. Therefore, it is expected that the trouble caused by wave interference between devices will be further intensified. In order to prevent this trouble, investigation of selective frequency transmission or absorption material is required. In this paper, magnetic properties of nickel-zinc-copper ferrite nano powder was researched as wave absorber. (Nia-Znb)xCu1-xFe2O4(NZCF) nanoparticles were fabricated by the sol-gel method. The influence of copper substitution on lattice parameter change was analyzed by X-ray diffraction (XRD), particle size was analyzed by scanning electron microscopy (SEM), and Magnetic properties analyzed by vibrating sample magnetometer (VSM). The NZCF and Nickel-zinc ferrite (NZF) lattice parameter difference was 0.028 Å and particle size was calculated as 30 nm with the XRD peak. The VSM results of (Ni0.3-Zn0.3)0.6Cu1-0.6Fe2O4 annealed sample at 700°C for 3hous were 58.5 emu/g (Ms), 22.8 Oe (Hc). It was the most suitable magnetic properties for wave absorber in this investigation.