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EN
The article describes the impact of germanium on the course of surface phenomena in casting alloys of silver used in gold smithing. The aim of this works is to describe the assessment of resulting alloys, comparing the area of raw castings and the impact of the addition content of the alloy on the hardness of the samples. The evaluation also was subject to corrosion resistance of giving a comparison of their use in relations to traditional silver alloys.
EN
Image analysis allows to acquire a number of valuable quantitative informations on the observed structure and make appropriate conclusions. So far, a large part of analyzed images came only from light microscopes, where it was a possibility of accurately distinguish the different phases on the plane. However, the problem happened in the case of the observation of images obtained by scanning electron microscopy. In this case, the presence of various shades of gray, and the spaciousness of the image attained. To perform the analysis the matrix images of the ausferritic ductile iron were used. Full analysis was carried out using the computer program MicroMeter 1.03. Results obtained in the analysis were related directly to the results from X-ray diffraction. Obtained as a result of the analysis were related directly to the results from X-ray diffractometer. The following technique has weaknesses, including the misinterpretation by the operator microscope or program. After all, it was possible to obtain similar results to the result that has been obtained from X-ray diffractometer.
EN
The paper discusses possible applications of the percolation theory in analysis of the microstructure images of polycrystalline materials. Until now, practical use of this theory in metallographic studies has been an almost unprecedented practice. Observation of structures so intricate with the help of this tool is far from the current field of its application. Due to the complexity of the problem itself, modern computer programmes related with the image processing and analysis have been used. To enable practical implementation of the task previously established, an original software has been created. Based on cluster analysis, it is used for the determination of percolation phenomena in the examined materials. For comparative testing, two two-phase materials composed of phases of the same type (ADI matrix and duplex stainless steel) were chosen. Both materials have an austenitic - ferritic structure. The result of metallographic image analysis using a proprietary PERKOLACJA.EXE computer programme was the determination of the content of individual phases within the examined area and of the number of clusters formed by these phases. The outcome of the study is statistical information, which explains and helps in better understanding of the planar images and real spatial arrangement of the examined material structure. The results obtained are expected to assist future determination of the effect that the internal structure of two-phase materials may have on a relationship between the spatial structure and mechanical properties.
EN
The article presents an analysis of changes in the outer surface of the casting made in a modified ceramic form. The introduction of the modification in the inner surface of the form, as a metallic coating was intended to produce a high quality of the casting surface. To describe the results, the three parameters have been chosen to characterize the surface roughness, i.e. Ra, Rz and Rq. In implementing the popular method of casting was used, so – called the lost polymer models. The models made from different plastic materials are chemically and electrochemically coated with a layer of nickel. The next step was to remove the model from the form and pouring the liquid metal over it. The observation of the casting surface was performed by using the scanning electron microscope and a profilometer. As a result of these attempts a number of castings have been obtained with an outside layer generated of lower roughness than the casting made in the normal gypsum form. The proposed method can be called an innovative one because it reduces the technological cycle by one processing operation of investment casting. During the process of casting both the cast and the outer layer improving the properties of the manufactured product is being produced.
5
Content available Structure Modelling Based on Percolation Theory
EN
The paper discusses the possibility of application of percolation theory to model the structure of materials in a virtual space. The designed models were transferred to real space using modern incremental manufacturing techniques like 3D printing. Studies of model materials of this type based on percolation theory are expected to provide more accurate knowledge of the problem, which is extremely important from the point of view of the properties of most construction materials. Reference of percolation phenomena to materials science is more and more frequently done in the design of various types of composite materials, such as e.g. conductive composites. In this study, the percolation theory has been used to design in microscale an optimum material through model analysis done in macroscale. Since studies of percolation in polycrystalline materials are difficult, and there are also some technical limitations imposed on the evaluation done in a volume of material, this phenomenon is usually examined in a simplified manner, which means that it is reduced only to statistical analysis of potential percolation with determination of its threshold value. To generate a potential structure based on percolation theory, popular computer programmes for solid modelling were used. Real shapes were conferred to the designed models using a widely known technique of 3D printing. It allows the production of parts in ABS material. The subject of the present study combines modern design techniques with modern manufacturing techniques, relating both to the fundamentals of materials science. Today's software tools enable creating more complex solids, while their transfer to reality allows better understanding of dependencies that exist in the structure of materials. The originality of this study consists in the art of creating new construction materials with planned properties. The article offers a new approach to the capabilities of scheduling modern engineering materials with the help of percolation theory.
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