Introduction of polymers into the cement composites improves same of the properties of concretes and mortars. Therefore, the polymer-cement composites are successfully used in construction. The model of microstructure formation in cement composites modified with thermoplastic polymer (pre-mix modifiers) has already been developed and successfully implemented. However, the formation of microstructure in the case of epoxy-cement composites (containing post-mix modifier) demonstrates same peculiarities which should be taken into account when modelling the process. The microstructure of epoxy-cement composites and its formation is discussed in the paper. The model is offered, formulated on the basis of the microscopic observations and results of testing.
A method of using the electric charge in a capacitor was applied for the manufacture of thermocouple micro-joints. The motivation for the study was the need to produce a stable welded connection without affecting the geometry of the substrate, which was a thin sheet of Inconel 625 alloy (UNS designation N06625). Within the framework of the research work, a suitable workstation for micro-joints elaboration was built and welding experiments were performed using different electric charges. Studies carried out within the framework of the present work have shown that joints based on Inconel 625 alloy and platinum have the best application properties in the range of small-scale temperature measurements. They can be used, e.g., for monitoring the temperature distribution on the inner surfaces of electric motor casings. An undeniable advantage is in this case the high thermal resistance of both materials used to produce the joint, i.e. the Inconel 625 alloy and platinum. This allows them to be used at high temperatures under atmospheric conditions.
The results presented in this article are part of the research on fatigue life of various foundry alloys carried out in recent years in the Lukasiewicz Research Network – Institute of Precision Mechanics and AGH University of Science and Technology, Faculty of Foundry Engineering. The article discusses the test results obtained for the EN-GJS-600-3 cast iron in an original modified low-cycle fatigue test (MLCF), which seems to be a beneficial research tool allowing its users to evaluate the mechanical properties of materials with microstructural heterogeneities under both static and dynamic loads. For a comprehensive analysis of the mechanical behaviour with a focus on fatigue life of alloys, an original modified low cycle fatigue method (MLCF) adapted to the actually available test machine was used. The results of metallographic examinations carried out by light microscopy were also presented. From the analysis of the results of the conducted mechanical tests and structural examinations it follows that the MLCF method is fully applicable in a quick and economically justified assessment of the quality of ductile iron after normalizing treatment.
This paper presents the results of studies of high-alloyed white cast iron modified with lanthanum, titanium, and aluminium-strontium. The
samples were taken from four melts of high-vanadium cast iron with constant carbon and vanadium content and near-eutectic
microstructure into which the tested inoculants were introduced in an amount of 1 wt% respective of the charge weight. The study
included a metallographic examinations, mechanical testing, as well as hardness and impact resistance measurements taken on the obtained
alloys. Studies have shown that different additives affect both the microstructure and mechanical properties of high-vanadium cast iron.
The paper presents research results on the selection of parameters for the asymmetric rolling process of bimetallic plates 10CrMo9-10 + X2CrNiMo17-12-2. They consisted in determining the optimum parameters of the process, which would be ensured to obtain straight bands. Such deformation method introduces in the band the deformations resulting from shear stress, which affect changes in the microstructure. But their effect on the structure is more complicated than in the case of homogeneous materials. It has been shown that the introduction of asymmetric conditions into the rolling process results in greater grain refinement in the so-called hard layer. There was no negative effect on the structural changes in the soft layer observed.
Ultrasonic pulse echo technique was used to study cupric oxide (CuO) thin films. CuO thin films were prepared using sol gel technique. They were doped with Lithium (Li) (1%, 2% and 4%).
Thin films’ thickness (d) and band gap energy (Eg) were measured. In addition, elastic moduli (longitudinal (L), shear (G), bulk (K) and Young’s (E)) and Poisson’s ratio (v) were determined to estimate the microstructure properties of the prepared films.
The study ameliorated the used transducers to overcome their dead zone and beam scattering; wedges were developed. The results showed the effectiveness of these wedges. They enhanced transducers’ sensitivity by changing the dead zone, beam diameter, beam directivity and waves’ transmission.
Also, the study noted that Li doping caused the improvement of CuO thin films to be more useful in solar cell fabrication. Li-CuO thin films had narrower band gap. Thus, they acquired a high quantum yield for the excited carriers; also they gained more efficiency to absorb solar light.
In this article the structural and mechanical properties of grain refinement of Cu-Sn alloys with tin content of 10%, 15% and 20% using the KOBO method have been presented. The direct extrusion by KOBO (name from the combination of the first two letters of the names of its inventors – A. Korbel and W. Bochniak) method employs, during the course of the whole process, a phenomenon of permanent change of strain travel, realized by a periodical, two-sided, plastic metal torsion. Moreover the aim of this work was to study corrosion resistance. The microstructure investigations were performed using an optical microscope Olimpus GX71, a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM). The mechanical properties were determined with INSTRON 4505/5500 machine. Corrosion tests were performed using «Autolab» set – potentiostat/galvanostat from EcoChemie B.V. with GPES software ver. 4.9. The obtained results showed possibility of KOBO deformation of Cu-Sn casting alloys. KOBO processing contributed to the refinement of grains and improved mechanical properties of the alloys. The addition of tin significantly improved the hardness. Meanwhile, with the increase of tin content the tensile strength and yield strength of alloys decrease gradually. Ductility is controlled by eutectoid composition and especially δ phase, because they initiate nucleation of void at the particle/matrix interface. No significant differences in the corrosion resistance between cast and KOBO processed materials were found.
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.
High-tin bronzes are used for church bells and concert bells (carillons). Therefore, beside their decorative value, they should also offer
other functional properties, including their permanence and good quality of sound. The latter is highly influenced by the structure of bell
material, i.e. mostly by the presence of internal porosity which interferes with vibration of the bell waist and rim, and therefore should be
eliminated. The presented investigations concerning the influence of tin content ranging from 20 to 24 wt% on mechanical properties of
high-tin bronzes allowed to prove the increase in hardness of these alloys with simultaneous decrease in the tensile and the impact
strengths (Rm and KV, respectively) for the increased tin content. Fractures of examined specimens, their porosity and microstructures
were also assessed to explain the observed regularities. A reason of the change in the values of mechanical properties was revealed to be
the change in the shape of α-phase crystals from dendritic to acicular one, and generation of grain structure related to the increased Sn
content in the alloy.
In Poland, researchers have a very strong interest in archaeometallurgy, which, as presented in classical works, focuses on dating artefacts
from the prehistoric and early medieval periods in the form of cast iron and copper castings. This study, extending the current knowledge,
presents the results of a microstructure investigation into the findings from the Modern era dating back to the late Middle Ages. The
investigated material was an object in the form of a heavy solid copper block weighing several kilograms that was excavated by a team of
Polish archaeologists working under the direction of Ms Iwona Młodkowska-Przepiórowska during works on the marketplace in the city of
Czestochowa during the summer of 2009. Pre-dating of the material indicates the period of the seventeenth century AD.
The solid copper block was delivered in the form of a part shaped like a bell, named later in this work as a “kettlebell”. To determine the
microstructure, the structural components, chemical composition, and homogeneity, as well as additives and impurities, investigations
were carried out using light microscopy, scanning electron microscopy including analysis of the chemical composition performed in
micro-areas, and qualitative X-ray phase analysis in order to investigate the phase composition.
Interpretation of the analytical results of the material’s microstructure will also help modify and/or develop new methodological
assumptions to investigate further archaeometallurgical exhibits, throwing new light on and expanding the area of knowledge of the use
and processing of seventeenth-century metallic materials.
Trials of cast steel filtration using two types of newly-developed foam filters in which carbon was the phase binding ceramic particles have
been conducted. In one of the filters the source of carbon was flake graphite and coal-tar pitch, while in the other one graphite was
replaced by a cheaper carbon precursor. The newly-developed filters are fired at 1000o
C, i.e. at a much lower temperature than the
currently applied ZrO2-based filters. During filtration trials the filters were subjected to the attack of a flowing metal stream having
a temperature of 1650°C for 30 seconds.
Characteristic of the filters’ properties before and after the filtration trial were done. It was found, that the surface reaction of the filter
walls with molten metal, which resulted in local changes of the microstructure and phase composition, did not affect on expected filter
lifetime and filtration did not cause secondary contamination of cast steel.
The results of studies presented in this article are an example of the research activity of the authors related to lead-free alloys. The studies covered binary SnZn90 and SnZn95 lead-free alloys, including their microstructure and complex mechanical characteristics. The microstructure was examined by both light microscopy (LM) and scanning electron microscopy (SEM). The identification of alloy chemical composition in micro-areas was performed by SEM/EDS method. As regards light microscopy, the assessment was of both qualitative and quantitative character. The determination of the geometrical parameters of microstructure was based on an original combinatorial method using phase quantum theory. Comprehensive characterization of mechanical behavior with a focus on fatigue life of alloys was performed by means of the original modified low cycle fatigue method (MLCF) adapted to the actually available test machine. The article discusses the fatigue life of binary SnZn90 and SnZn95 alloys in terms of their microstructure. Additionally, the benefits resulting from the use of the combinatorial method in microstructure examinations and MLCF test in the quick estimation of several mechanical parameters have been underlined.
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.
The present paper is a presentation of results of a study on morphology, chemical composition, material properties (HVIT, HIT, EIT), and nanoindentation elastic and plastic work for carbide precipitates in chromium cast iron containing 24% Cr. It has been found that the carbides differ in chemical composition, as well as in morphology and values characterizing their material properties. The carbides containing the most chromium which had the shape of thick and long needles were characterized with highest values of the analyzed material properties.
This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.