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Number of results: 48
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Abstract

Empathy and psychopathy seem to be two distant extremes, which only differ, with nothing similar. Therefore, the question that seems to be surprising is whether such a theoretical perspective is justified. Empathy exerts significant influence on social relationships and is associated with moral development, whereas psychopathy seems to be an opposite phenomenon, as it is associated with the lack of deep interpersonal bonds and the violation of legal norms. As studies from various disciplines and scientific areas indicate, such concepts as behavioral effectiveness, morality or altruism might help explain the complex nature of the interrelationship between psychopathy and empathy. The authors tried to explore and describe the complexity of the two presented concepts in the light of the conducted research, and the resulting theoretical and empirical implications.
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Abstract

In this paper, an analysis of various factors affecting machined surface texture is presented. The investigation was focused on ball end mill inclination against the work piece (defined by surface inclination angle a. Surface roughness was investigated in a 3D array, and measurements were conducted parallel to the feed motion direction. The analysis of machined surface irregularities as a function of frequency (wavelength A), on the basis of the Power Density Spectrum - PDS was also carried out. This kind of analysis is aimed at valuation of primary factors influencing surface roughness generation as well as its randomness. Subsequently, a surface roughness model including cutter displacements was developed. It was found that plain cutting with ball end mill (surface inclination angle a= 0°) is unfavorable from the point of view of surface roughness, because in cutter’s axis the cutting speed vc ~ 0 m/min. This means that a cutting process does not occur, whereas on the machined surface some characteristics marks can be found. These marks do not appear in case of a* 0°, because the cutting speed vc * 0 on the fill I length of the active cutting edge and as a result, the machined surface texture is more homogenous. Surface roughness parameters determined on the basis of the model including cutter displacements are closer to experimental data for cases with inclination angles a* 0°, in comparison with those determined for plain cutting (a= 0°). It is probably caused by higher contribution in surface irregularities generation of plastic and elastic deformations cumulated near the cutter’s free end than kinematic and geometric parameters, as well as cutter displacements.
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Abstract

Determination of the physico-chemical interactions between liquid and solid substances is a key technological factor in many industrial processes in metallurgy, electronics or the aviation industry, where technological processes are based on soldering/brazing technologies. Understanding of the bonding process, reactions between materials and their dynamics enables to make research on new materials and joining technologies, as well as to optimise and compare the existing ones. The paper focuses on a wetting force measurement method and its practical implementation in a laboratory stand – an integrated platform for automatic wetting force measurement at high temperatures. As an example of using the laboratory stand, an analysis of Ag addition to Cu-based brazes, including measurement of the wetting force and the wetting angle, is presented.
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Abstract

Lead-free alloys containing various amounts of zinc (4.5%, 9%, 13%) and constant copper addition (1%) were discussed. The results of microstructure examinations carried out by light microscopy (qualitative and quantitative) and by SEM were presented. In the light microscopy, a combinatorial method was used for the quantitative evaluation of microstructure. In general, this method is based on the phase quanta theory according to which every microstructure can be treated as an arrangement of phases/structural components in the matrix material. Based on this method, selected geometrical parameters of the alloy microstructure were determined. SEM examinations were based on chemical analyses carried out in microregions by EDS technique. The aim of the analyses was to identify the intermetallic phases/compounds occurring in the examined alloys. In fatigue testing, a modified low cycle fatigue test method (MLCF) was used. Its undeniable advantage is the fact that each time, using one sample only, several mechanical parameters can be estimated. As a result of structure examinations, the effect of alloying elements on the formation of intermetallic phases and compounds identified in the examined lead-free alloys was determined. In turn, the results of mechanical tests showed the effect of intermetallic phases identified in the examined alloys on their fatigue life. Some concepts and advantages of the use of the combinatorial and MLCF methods in materials research were also presented.
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Abstract

The multiple direct remelting of composites based on the A359 alloy reinforced with 20% of Al2O3 particles was performed. The results of both gravity casting and squeeze casting were examined in terms of the obtained microstructure and mechanical characteristics. In microstructure examinations, the combinatorial method based on phase quanta theory was used. In mechanical tests, the modified low cycle fatigue method (MLCF) was applied. The effects obtained after both gravity casting and squeeze casting were compared. It was noted that both characteristics were gradually deteriorating up to the tenth remelting. The main cause was the occurrence of shrinkage porosity after the gravity casting. Much better results were obtained applying the squeeze casting process. The results of microstructure examinations and fatigue tests enabled drawing the conclusion that the A359 alloy reinforced with Al2O3 particles can confer a much better fatigue life behavior to the resulting composite than the A359 alloy without the reinforcement. At the same time, comparing these results with the results of the previous own research carried out on the composites based also on the A359 alloy but reinforced in the whole volume with SiC particles, it has been concluded that both types of the composites can be subjected to multiple remelting without any significant deterioration of the structural and mechanical characteristics. The concepts and advantages of using the combinatorial and MLCF methods in materials research were also presented
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Abstract

The study includes the results of research conducted on selected lead-free binary solder alloys designed for operation at high temperatures. The results of qualitative and quantitative metallographic examinations of SnZn alloys with various Zn content are presented. The quantitative microstructure analysis was carried out using a combinatorial method based on phase quanta theory, per which any microstructure can be treated as an array of elements disposed in the matrix material. Fatigue tests were also performed using the capabilities of a modified version of the LCF method hereinafter referred to in short as MLCF, which is particularly useful in the estimation of mechanical parameters when there are difficulties in obtaining many samples normally required for the LCF test. The fatigue life of alloys was analyzed in the context of their microstructure. It has been shown that the mechanical properties are improved with the Zn content increasing in the alloy. However, the best properties were obtained in the alloy with a chemical composition close to the eutectic system, when the Zn-rich precipitates showed the most preferred morphological characteristics. At higher content of Zn, a strong structural notch was formed in the alloy because of the formation in the microstructure of a large amount of the needle-like Zn-rich precipitates deteriorating the mechanical characteristics. Thus, the results obtained during previous own studies, which in the field of mechanical testing were based on static tensile test only, have been confirmed. It is interesting to note that during fatigue testing, both significant strengthening and weakening of the examined material can be expected. The results of fatigue tests performed on SnZn alloys have proved that in this case the material was softened.
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Abstract

The article presents the study results of Sn-Zn lead-free solders with the various Zn content. The results concern the hypoeutectic, eutectic and hypereutectic alloys containing respectively 4.5% Zn, 9% Zn and 13.5% Zn. Moreover, these alloys contain the constant Ag (1%) addition. The aim of the study was to determine the microstructural conditionings of their fatigue life. In particular it was focused on answer the question what meaning can be assigned to the Ag addition in the chemical composition of binary Sn-Zn alloys. The research includes a qualitative and quantitative assessments of the alloy microstructures, that have been carried out in the field of light microscopy (LM). In order to determine some geometrical parameters of the microstructure of alloys the combinatorial method based on the phase quanta theory was applied. Moreover, for the identification necessities the chemical analyses in the micro-areas by SEM/EDS technics were also performed. Based on the SEM/EDS results the phases and intermetallic compounds existing in the examined lead-free solders were identified. The mechanical characteristics were determined by means of the modified low cycle test (MLCF). Based on this method and on the results obtained every time from only one sample the dozen of essential mechanical parameters were evaluated. The research results were the basis of analyzes concerning the effects of microstructural geometrical parameters of lead-free alloys studied on their fatigue life at ambient temperature.
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Abstract

The paper presents the results of investigations concerning the application of zinc oxide - a wideband gap semiconductor in optical planar waveguide structures. ZnO is a promising semiconducting material thanks to its attractive optical properties. The investigations were focused on the determination of the technology of depositions and the annealing of ZnO layers concerning their optical properties. Special attention was paid to the determination of characteristics of the refractive index of ZnO layers and their coefficients of spectral transmission within the UV-VIS-NIR range. Besides that, also the mode characteristics and the attenuation coefficients of light in the obtained waveguide structures have been investigated. In the case of planar waveguides, in which the ZnO layers have not been annealed after their deposition, the values of the attenuation coefficient of light modes amount to a~ 30 dB/cm. The ZnO layers deposited on the heated substrate and annealed by rapid thermal annealing in an N2 and O2 atmosphere, are characterized by much lower values of the attenuation coefficients: a~ 3 dB/cm (TE0 and TM0 modes). The ZnO optical waveguides obtained according to our technology are characterized by the lowest values of the attenuation coefficients a encountered in world literature concerning the problem of optical waveguides based on ZnO. Studies have shown that ZnO layers elaborated by us can be used in integrated optic systems, waveguides, optical modulators and light sources.
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