The work presents results of the research on changes in microstructural, and mechanical properties of the structural XAR 400 wear-resistant steel caused by the welding procedure. Metallographic and microhardness studies revealed complex microstructure of the welds that turned out to vary with the distance from the weld axis: predominance of the acicular ferrite (ACF) structures in the weld itself, quasi-polygonal ferrite (QPF) crystals with precipitates of troostite (T) in the heat-affected zone, and the bainitic ferrite (BF) structures in the heat-partially-affected zone.
This study addressed the advanced micro-morphological characterization of 3D surfaces of thin films based on composites of an organic matrix of poly-methyl-methacrylate and inorganic titanium-dioxide nanocrystals. The films were prepared by spin-coating of a series of solutions with increasing loading concentration of the nanocrystals, from 5 up to 40% by weight. The film surfaces were investigated by atomic force microscopy, and the resulting images were analyzed in detail to obtain a full quantitative description of their surface micro-morphology. The fractal analysis of the surface roughness was used to extract the characteristics of amplitude, spatial distribution, and pattern. A fractal geometry was indeed observed, and the corresponding fractal dimension D was determined for all the samples. In view of the possible use of these thin films as functional coatings, the calculated quantities are discussed with respect to the foreseen durability of these surfaces during operation under wear.
The paper presents results of numerical analysis of AFM images of a surface of sandblasted Ti6Al7Nb alloys before and after wet etching procedure usually used for preparing commercially viable dental implants. Obtained results demonstrate that etching procedure efficiently cleans the implants as it leaves almost pure Ti-Al-Nb surface with trace amounts of alkali metals and increased hydrophobicity. Apart of that, it turned out that simple statistical measures of the height variations (root mean square roughness) only slightly change upon the treatment procedure, especially for scan lengths below 20 μm. On the other hand, correlation analysis exhibits bifractal surface patterns composed of regular residues left on otherwise helical ridges of the base material. Etching leaves its fingerprint in fractal dimension, but not in the corner frequency.
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