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The article offers a systematic approach to the method of developing mathematical models of a chemical-technological system (CTS) in conditions of deficit and fuzziness of initial information using available data of various types. Based on the results of research and processing of the collected quantitative and qualitative information, mathematical models of the reactor are constructed. Formalized and obtained mathematical statements of the control problem for choosing effective modes of operation of technological systems are based on mathematical modeling. Based on the obtained expert information, linguistic variables were described and a database of rules describing the operation of the input parameters of the reactor unit of the catalytic cracking unit was obtained.

This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry analysis, metallographic analysis, macroscopy, scanning electron microscopy, as well as hardness measurements were performed. It was observed that the working surface was non-uniformly worn. The smallest wear affects the molding cavities situated on the outermost edges of the ring. The wear increases as the center of the ring is approximated, and it reaches its maximum at the middle of the ring. The molding cavities also wear asymmetrically. For the shape considered in this study, the lower part of a cavity is subject to a higher wear rate. We found that the material of the working ring was carburized, but its hardness was significantly lower than required. The roller ring microstructure changes depended on the distance from the cavity’s face. An investigation of the wear mechanisms showed different types of abrasive wear, corrosive processes, and plastic deformation. The exact type and course of wear were described, depending on the location on the working surface.

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This work presents results of investigations using the Mössbauer spectroscopy technique and their interpretation concerning transformation of to cementite carbides during tempering in relation to the previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The influence of the tempering time on nucleation and solubility of carbides, and on cementite nucleation and growth, was determined. The analysis of phase transformations during various periods of tempering using the Mössbauer spectroscopy technique made possible to reveal fine details connected with the processes.

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SummaryNickel is known to increase the resistance to cleavage fracture of iron and decrease a ductile-to-brittle transition temperature. The medium-carbon, low-alloy martensitic steels attain the best combination of properties in low-tempered condition, with tempered martensite, retained austenite and transition carbides in the microstructure. This paper is focused on the influence of Ni addition (from 0.35 to 4.00%) on the microstructure and fracture toughness of structural steels after tempering. In this research, four model alloys of different concentration of Ni and constant concentration of carbon and other elements were used. All samples were in as-quenched and tempered conditions. Quenching was performed in oil at room temperature. After quenching, samples were tempered at 200• C for 2 h. The microstructure of the investigated steels was analyzed using JEM200CX transmission electron microscope. An increase of nickel content in the investigated structural steels causes a decrease of ε carbide concentration in their microstructure after tempering. In these steels, cementite precipitates independently in the boundaries of martensite needles and in the twin boundaries in the areas where the Fe 2.4 C carbide has been dissolved. These results will be used to design new technologies of tempering of structural steels with nickel addition.

This paper presents the results of the investigations of the properties of saddle-shaped copper alloy chips briquettes produced in a roller press. The physical and mechanical properties of the investigated briquettes were examined on their external surfaces as well as on their cross-sections. The density, chemical composition, microstructure analysis obtained with a 3D and scanning microscope, surface roughness and hardness of the obtained briquettes were investigated. The research proved the differentiation of the physical and mechanical properties of briquettes depending on the investigated area of their surface. The analysis of changes in the porosity of briquettes on their cross-section showed zones of various densification levels. This research expands the knowledge of the processes taking place during the compaction and consolidation of granular materials in roller presses as well as the knowledge concerning designing the geometry of forming tools.