The aim of this work was to characterize ordered structures within cokes produced from single bituminous coals and from their blends. Three Polish coals of varying rank and caking ability were collected from the Krupiński, Szczygłowice, and Zofiówka mines, respectively. These coals were used for preparation of 19 blends: single (trivial blends), binary, and ternary ones. Cokes were manufactured in a laboratory scale using an apparatus with a Jenkner’s retort with a charge of 1000 g and heat-treatment temperature of 1000 °C. The X-ray diffraction (XRD) and Raman spectroscopy were used for the study. To determine the kind and size of ordered structures, the following parameters were discussed: interlayer spacing, d 002, crystallite stack height, L c, obtained from the XRD studies as well as the fractional contribution of ordered elements to all kinds of structures, and ratio of the amount of graphite structures (G type) to the amount of D2-type structures (less ordered than graphite), determined with Raman spectroscopy. The cokes produced from blends were treated as a compound system dependent upon properties of its components, single coal cokes. Additivity of the structural parameters of the cokes from blends was verified by the series model. Well-ordered structures, including the graphite-like ones, were found in all cokes studied. The highest degree of ordering was found in the single coke from very good caking Zofiówka coal. A similar structure was found in the cokes from binary and ternary blends of medium content of this coal of about 30–50 wt %. The preparation of cokes with well-ordered structures from blends of considerable lower concentration of the Zofiówka coal is promising, because the cost of these coke productions is lower than that of single coke from the Zofiówka coal. Discrepancy between the experimental data and those obtained from the series model confirmed mutual interactions between coals in a blend that affects forming of well-ordered structures in the cokes. This interaction was found to be the strongest in the blends with the content of the Zofiówka coal equal to 30–50 wt %.

This work discusses the development of the microstructure and mechanical properties of medium-carbon steel that contains silicon, aluminium and microadditions of Nb and Ti. Two cooling strategies were designed based on the thermodynamic equilibrium calculations and continuous cooling transformation diagram, which was determined for plastically deformed austenite. The cooling paths enabled the production of ferrite based and bainite based steels. The specimens were obtained via the thermomechanical rolling process with isothermal holding of steel at 450°C. Microstructure investigations were performed using light, scanning and transmission microscopy methods. The distribution and amount of retained austenite were determined using the electron backscatter diffraction technique, whereas transmission electron microscopy allowed the identification of the morphology of the γ phase. The amount of austenite and its carbon content were assessed using X-ray diffraction. Relations between microstructure and mechanical properties were formulated based on the mechanical stability of the retained austenite.

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The general topic of this paper is the computer simulation with use of finite element method (FEM) for determining the internal stresses of selected gradient and single-layer PVD coatings deposited on the sintered tool materials, including cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics by cathodic arc evaporation CAE-PVD method. Developing an appropriate model allows the prediction of properties of PVD coatings, which are also the criterion of their selection for specific items, based on the parameters of technological processes. In addition, developed model can to a large extent eliminate the need for expensive and time-consuming experimental studies for the computer simulation. Developed models of internal stresses were performed with use of finite element method in ANSYS environment. The experimental values of stresses were calculated using the X-ray sin2ψ technique. The computer simulation results were compared with the experimental results. Microhardness and adhesion as well as wear range were measured to investigate the influence of stress distribution on the mechanical and functional properties of coatings. It was stated that occurrence of compressive stresses on the surface of gradient coating has advantageous influence on their mechanical properties, especially on microhardness. Absolute value reduction of internal stresses in the connection zone in case of the gradient coatings takes profitably effects on improvement the adhesion of coatings. It can be one of the most important reasons of increase the wear resistance of gradient coatings in comparison to single-layer coatings.

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