Papers by Author: Sebastian Stach

Abstract: The study's aim was to identify the 3-D surface spatial parameters that describe the 3-D surface microtexture of the nickel–carbon (Ni–C) nanocomposite thin films composed of Ni nanoparticles with different average sizes embedded in amorphous hydrogenated carbon, prepared by the combining radio frequency magnetron sputtering technique and plasma-enhanced chemical vapor deposition (RF-PECVD). The deposition time was varied at 7, 10 and 13 min, respectively. The sample investigation was performed using an atomic force microscope, and the obtained data were analyzed and visualized using MountainsMap^® Premium software to determine their stereometric surface engineering characteristics. The results from this study provide not only fundamental insights into the texture characteristics, but also directions toward their implementation in nanotribological models.

Abstract: This paper analyses the data stereometric of three samples obtained using the atomic force microscope. The data concern the two butterfly species: Euploea mulciber (known as “Striped Blue Crow”) and Morpho didius (also named as “Giant Blue Morpho”). These species have a strong correlation color wings of the angle of incidence of light. This is structural coloration and it depends on the surface topography. Here we present a method for the topography evaluation. A script created in Matlab software version R2012 by MathWorks® was used for segmentation data stereometric and analysis of localized motifs occurring on the surface of the samples. An analysis of the data using stereometric software MountainsMap® Premium version 7.3.7746 by Digital Surf was made to compare the results obtained using the script developed in Matlab, for identification of all sorts of motifs, such as peaks, pits, or irregular shapes in correlation with the surface statistical parameters. The analysis of motifs is essential when choosing the appropriate technique for imaging the 3-D (three-dimensional) microtextured features of butterfly wings surfaces. This stereometric analysis proves to be an effective method that can be successfully used for estimation of micro- and nano- topography by processing of AFM data

Abstract: The aim of this study was to gather methodological clues in the scope of a fractal description of non-planar surfaces, which clues can be used for testing biomaterials. The fundamentals of a few most popular fractal methods of surface analysis are discussed here and two new methods are proposed by presenting their basic assumptions. On this basis, appropriate programs for numerical calculations have been developed, while simultaneously using measuring files from instruments which enable stereometric measurement of surfaces (profilographometers, confocal microscopes, etc.).

Abstract: The aim of the paper is to present comparative studies of the parameters of the fracture surface topography of titanium alloy, obtained by means of two techniques. The research equipment consisted of a Taylor Hobson profilographometer, Talysurf, and a confocal microscope, LEXT OLS 3000 by Olympus. By means of a contact and non-contact method, files of coordinates of the investigated surfaces were obtained, based on which some chosen stereometric parameters were calculated. The tests carried out as part of the study confirmed the usefulness and the possibility of using a confocal microscope as a modern instrument for evaluating the topography of non-planar surfaces. In the case of statistical parameters representing the whole surface under examination, very high convergence of the stereometric structure parameters was obtained, described by means of profilographometry and confocal microscopy methods.

Abstract: Analysis of issues related to the cracking process of materials requires a quantitative description of the problem which frequently, due to its complexity, is difficult or impossible to solve. In a number of cases, the deficiencies of a quantitative description made using classical methods are compensated for by such unconventional tools as percolation, which requires creating an appropriate model. The aim of the study was to use a three-dimensional minimal spanning tree (3DMST) to create a model of the crack path, based on an example of a metallic biomaterial. For this purpose, a stereometric file, obtained as a result of measuring its fracture surface, was applied.

Abstract: A quantitative description of overlaps on fractures in sialon ceramics, is presented in the paper. A conventional analysis, aiming at the determination of the percentage share of overlaps on the basis of quantitative fractography, was preceded by stereometric/fractal analyses. They enabled the selection of representative sections of samples and then, the production of transverse microsections in those places for an analysis of the fractures’ profiles using the light microscopy method and fractographic image analysis. Based on the compared results from both methods, a successful verification was made of the research methodology developed earlier for sintered carbides and proven for a chromium-molybdenum steel.

Abstract: Resistance to brittle cracking is one of the most important functional properties of sialon ceramics. Evaluation of the resistance requires an analysis of decohesion processes occuring in the material. Aiming at a comprehensive description of the morphology of typically brittle fractures, a quantitative characterization was made using different methods and techniques, regarding the surface of fractures formed in a three-point bending test. By using the parameter Sdr, determined via the surface stereometry method, the fracture surface development coefficient, RS, typical for fractography, was calculated. Analysis of the research results indicates a proportional relation between parameter RS and the sialon ceramics’ bending strength.